118-413: In the anatomy of the brain of vertebrates , the forebrain or prosencephalon is the rostral (forward-most) portion of the brain . The forebrain controls body temperature, reproductive functions, eating, sleeping, and the display of emotions. Vesicles of the forebrain (prosencephalon), the midbrain (mesencephalon), and hindbrain (rhombencephalon) are the three primary brain vesicles during
236-412: A basal lamina , the upper layer of the basement membrane , the lower layer is the reticular lamina lying next to the connective tissue in the extracellular matrix secreted by the epithelial cells. There are many different types of epithelium, modified to suit a particular function. In the respiratory tract there is a type of ciliated epithelial lining; in the small intestine there are microvilli on
354-450: A copulatory organ present in most species. The eggs are surrounded by amniotic membranes which prevents them from drying out and are laid on land, or develop internally in some species. The bladder is small as nitrogenous waste is excreted as uric acid . Turtles are notable for their protective shells. They have an inflexible trunk encased in a horny carapace above and a plastron below. These are formed from bony plates embedded in
472-500: A discharge tube of Ivan Pulyui 's design. In January 1896, on reading of Röntgen's discovery, Frank Austin of Dartmouth College tested all of the discharge tubes in the physics laboratory and found that only the Pulyui tube produced X-rays. This was a result of Pulyui's inclusion of an oblique "target" of mica , used for holding samples of fluorescent material, within the tube. On 3 February 1896 Gilman Frost, professor of medicine at
590-481: A microscope . Human anatomy, physiology and biochemistry are complementary basic medical sciences, which are generally taught to medical students in their first year at medical school. Human anatomy can be taught regionally or systemically; that is, respectively, studying anatomy by bodily regions such as the head and chest, or studying by specific systems, such as the nervous or respiratory systems. The major anatomy textbook, Gray's Anatomy , has been reorganized from
708-470: A sessile lifestyle). Most animals have bodies differentiated into separate tissues and these animals are also known as eumetazoans . They have an internal digestive chamber, with one or two openings; the gametes are produced in multicellular sex organs, and the zygotes include a blastula stage in their embryonic development . Metazoans do not include the sponges , which have undifferentiated cells. Unlike plant cells , animal cells have neither
826-402: A "treatise on the heart", with vessels carrying all the body's fluids to or from every member of the body. Ancient Greek anatomy and physiology underwent great changes and advances throughout the early medieval world. Over time, this medical practice expanded due to a continually developing understanding of the functions of organs and structures in the body. Phenomenal anatomical observations of
944-490: A beam of X-rays is produced by an X-ray generator and it is projected towards the object. A certain amount of the X-rays or other radiation are absorbed by the object, dependent on the object's density and structural composition. The X-rays that pass through the object are captured behind the object by a detector (either photographic film or a digital detector). The generation of flat two-dimensional images by this technique
1062-528: A cell wall nor chloroplasts . Vacuoles, when present, are more in number and much smaller than those in the plant cell. The body tissues are composed of numerous types of cells, including those found in muscles, nerves and skin. Each typically has a cell membrane formed of phospholipids , cytoplasm and a nucleus . All of the different cells of an animal are derived from the embryonic germ layers . Those simpler invertebrates which are formed from two germ layers of ectoderm and endoderm are called diploblastic and
1180-433: A class of arachnids have four pairs of legs; a body of two segments—a cephalothorax and an abdomen . Spiders have no wings and no antennae. They have mouthparts called chelicerae which are often connected to venom glands as most spiders are venomous. They have a second pair of appendages called pedipalps attached to the cephalothorax. These have similar segmentation to the legs and function as taste and smell organs. At
1298-552: A coat of glycoproteins . In more advanced animals, many glands are formed of epithelial cells. Muscle cells (myocytes) form the active contractile tissue of the body. Muscle tissue functions to produce force and cause motion, either locomotion or movement within internal organs. Muscle is formed of contractile filaments and is separated into three main types; smooth muscle , skeletal muscle and cardiac muscle . Smooth muscle has no striations when examined microscopically. It contracts slowly but maintains contractibility over
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#17327718877741416-646: A contribution to the modulation transfer function of the imaging system. The dosage of radiation applied in radiography varies by procedure. For example, the effective dosage of a chest x-ray is 0.1 mSv, while an abdominal CT is 10 mSv. The American Association of Physicists in Medicine (AAPM) have stated that the "risks of medical imaging at patient doses below 50 mSv for single procedures or 100 mSv for multiple procedures over short time periods are too low to be detectable and may be nonexistent." Other scientific bodies sharing this conclusion include
1534-410: A faint green glow from the screen, about 1 metre away. Röntgen realized some invisible rays coming from the tube were passing through the cardboard to make the screen glow: they were passing through an opaque object to affect the film behind it. Röntgen discovered X-rays' medical use when he made a picture of his wife's hand on a photographic plate formed due to X-rays. The photograph of his wife's hand
1652-463: A few species have no limbs and resemble snakes. Lizards have moveable eyelids, eardrums are present and some species have a central parietal eye. Snakes are closely related to lizards, having branched off from a common ancestral lineage during the Cretaceous period, and they share many of the same features. The skeleton consists of a skull, a hyoid bone, spine and ribs though a few species retain
1770-513: A high metabolic rate , a light skeletal system and powerful muscles . The long bones are thin, hollow and very light. Air sac extensions from the lungs occupy the centre of some bones. The sternum is wide and usually has a keel and the caudal vertebrae are fused. There are no teeth and the narrow jaws are adapted into a horn-covered beak. The eyes are relatively large, particularly in nocturnal species such as owls. They face forwards in predators and sideways in ducks. The feathers are outgrowths of
1888-474: A latent image is known as "projection radiography". The "shadow" may be converted to light using a fluorescent screen, which is then captured on photographic film , it may be captured by a phosphor screen to be "read" later by a laser (CR), or it may directly activate a matrix of solid-state detectors (DR—similar to a very large version of a CCD in a digital camera). Bone and some organs (such as lungs ) especially lend themselves to projection radiography. It
2006-746: A mammal. Humans have a head, neck, trunk (which includes the thorax and abdomen ), two arms and hands, and two legs and feet. Generally, students of certain biological sciences , paramedics , prosthetists and orthotists, physiotherapists , occupational therapists , nurses , podiatrists , and medical students learn gross anatomy and microscopic anatomy from anatomical models, skeletons, textbooks, diagrams, photographs, lectures and tutorials and in addition, medical students generally also learn gross anatomy through practical experience of dissection and inspection of cadavers . The study of microscopic anatomy (or histology ) can be aided by practical experience examining histological preparations (or slides) under
2124-432: A medical intervention, such as angioplasty, pacemaker insertion, or joint repair/replacement. The last can often be carried out in the operating theatre, using a portable fluoroscopy machine called a C-arm. It can move around the surgery table and make digital images for the surgeon. Biplanar Fluoroscopy works the same as single plane fluoroscopy except displaying two planes at the same time. The ability to work in two planes
2242-452: A physical marker is not included, the radiographer may add the correct side marker later as part of digital post-processing. As an alternative to X-ray detectors, image intensifiers are analog devices that readily convert the acquired X-ray image into one visible on a video screen. This device is made of a vacuum tube with a wide input surface coated on the inside with caesium iodide (CsI). When hit by X-rays material phosphors which causes
2360-420: A pump action in which air is first drawn into the buccopharyngeal region through the nostrils. These are then closed and the air is forced into the lungs by contraction of the throat. They supplement this with gas exchange through the skin which needs to be kept moist. In frogs the pelvic girdle is robust and the hind legs are much longer and stronger than the forelimbs. The feet have four or five digits and
2478-539: A radiographic laboratory in the United Kingdom in 1896, before the dangers of ionizing radiation were discovered. Indeed, Marie Curie pushed for radiography to be used to treat wounded soldiers in World War I. Initially, many kinds of staff conducted radiography in hospitals, including physicists, photographers, physicians, nurses, and engineers. The medical speciality of radiology grew up over many years around
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#17327718877742596-416: A scintillator material such as CsI, or directly by capturing the electrons produced when the X-rays hit the detector. Direct detectors do not tend to experience the blurring or spreading effect caused by phosphorescent scintillators or by film screens since the detectors are activated directly by X-ray photons. Dual-energy radiography is where images are acquired using two separate tube voltages . This
2714-543: A skeleton to support or protect the body. An exoskeleton is a thickened, rigid cuticle which is stiffened by mineralization , as in crustaceans or by the cross-linking of its proteins as in insects . An endoskeleton is internal and present in all developed animals, as well as in many of those less developed. Epithelial tissue is composed of closely packed cells, bound to each other by cell adhesion molecules , with little intercellular space. Epithelial cells can be squamous (flat), cuboidal or columnar and rest on
2832-497: A systems format to a regional format, in line with modern teaching methods. A thorough working knowledge of anatomy is required by physicians, especially surgeons and doctors working in some diagnostic specialties, such as histopathology and radiology . Academic anatomists are usually employed by universities, medical schools or teaching hospitals. They are often involved in teaching anatomy, and research into certain systems, organs, tissues or cells. Invertebrates constitute
2950-453: A three-dimensional image. Radiography's origins and fluoroscopy's origins can both be traced to 8 November 1895, when German physics professor Wilhelm Conrad Röntgen discovered the X-ray and noted that, while it could pass through human tissue, it could not pass through bone or metal. Röntgen referred to the radiation as "X", to indicate that it was an unknown type of radiation. He received
3068-431: A vast array of living organisms ranging from the simplest unicellular eukaryotes such as Paramecium to such complex multicellular animals as the octopus , lobster and dragonfly . They constitute about 95% of the animal species. By definition, none of these creatures has a backbone. The cells of single-cell protozoans have the same basic structure as those of multicellular animals but some parts are specialized into
3186-479: A vertebrate is the vertebral column , formed in the development of the segmented series of vertebrae . In most vertebrates the notochord becomes the nucleus pulposus of the intervertebral discs . However, a few vertebrates, such as the sturgeon and the coelacanth , retain the notochord into adulthood. Jawed vertebrates are typified by paired appendages, fins or legs, which may be secondarily lost. The limbs of vertebrates are considered to be homologous because
3304-693: A vestige of the pelvis and rear limbs in the form of pelvic spurs . The bar under the second fenestra has also been lost and the jaws have extreme flexibility allowing the snake to swallow its prey whole. Snakes lack moveable eyelids, the eyes being covered by transparent "spectacle" scales. They do not have eardrums but can detect ground vibrations through the bones of their skull. Their forked tongues are used as organs of taste and smell and some species have sensory pits on their heads enabling them to locate warm-blooded prey. Crocodilians are large, low-slung aquatic reptiles with long snouts and large numbers of teeth. The head and trunk are dorso-ventrally flattened and
3422-594: A wide range of stretch lengths. It is found in such organs as sea anemone tentacles and the body wall of sea cucumbers . Skeletal muscle contracts rapidly but has a limited range of extension. It is found in the movement of appendages and jaws. Obliquely striated muscle is intermediate between the other two. The filaments are staggered and this is the type of muscle found in earthworms that can extend slowly or make rapid contractions. In higher animals striated muscles occur in bundles attached to bone to provide movement and are often arranged in antagonistic sets. Smooth muscle
3540-419: Is a complex and dynamic field that is constantly evolving as discoveries are made. In recent years, there has been a significant increase in the use of advanced imaging techniques, such as MRI and CT scans , which allow for more detailed and accurate visualizations of the body's structures. The discipline of anatomy is divided into macroscopic and microscopic parts. Macroscopic anatomy , or gross anatomy,
3658-462: Is a relatively low-cost investigation with a high diagnostic yield. The difference between soft and hard body parts stems mostly from the fact that carbon has a very low X-ray cross section compared to calcium. Computed tomography or CT scan (previously known as CAT scan, the "A" standing for "axial") uses ionizing radiation (x-ray radiation) in conjunction with a computer to create images of both soft and hard tissues. These images look as though
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3776-461: Is as low as possible. Lead is the most common shield against X-rays because of its high density (11,340 kg/m ), stopping power, ease of installation and low cost. The maximum range of a high-energy photon such as an X-ray in matter is infinite; at every point in the matter traversed by the photon, there is a probability of interaction. Thus there is a very small probability of no interaction over very large distances. The shielding of photon beam
3894-538: Is called projectional radiography . In computed tomography (CT scanning), an X-ray source and its associated detectors rotate around the subject, which itself moves through the conical X-ray beam produced. Any given point within the subject is crossed from many directions by many different beams at different times. Information regarding the attenuation of these beams is collated and subjected to computation to generate two-dimensional images on three planes (axial, coronal, and sagittal) which can be further processed to produce
4012-541: Is commonly taken to refer to human anatomy . However, substantially similar structures and tissues are found throughout the rest of the animal kingdom, and the term also includes the anatomy of other animals. The term zootomy is also sometimes used to specifically refer to non-human animals. The structure and tissues of plants are of a dissimilar nature and they are studied in plant anatomy . The kingdom Animalia contains multicellular organisms that are heterotrophic and motile (although some have secondarily adopted
4130-412: Is concerned with the shape, size, position, structure, blood supply and innervation of an organ such as the liver; while a physiologist is interested in the production of bile , the role of the liver in nutrition and the regulation of bodily functions. The discipline of anatomy can be subdivided into a number of branches, including gross or macroscopic anatomy and microscopic anatomy. Gross anatomy
4248-411: Is designed to maintain high quality imaging studies while using the lowest doses and best radiation safety practices available on pediatric patients. This initiative has been endorsed and applied by a growing list of various professional medical organizations around the world and has received support and assistance from companies that manufacture equipment used in radiology. Following upon the success of
4366-473: Is found in the walls of the uterus , bladder , intestines , stomach , oesophagus , respiratory airways , and blood vessels . Cardiac muscle is found only in the heart , allowing it to contract and pump blood round the body. Nervous tissue is composed of many nerve cells known as neurons which transmit information. In some slow-moving radially symmetrical marine animals such as ctenophores and cnidarians (including sea anemones and jellyfish ),
4484-415: Is generally done by radiologists . Some radiographers also specialise in image interpretation. Medical radiography includes a range of modalities producing many different types of image, each of which has a different clinical application. The creation of images by exposing an object to X-rays or other high-energy forms of electromagnetic radiation and capturing the resulting remnant beam (or "shadow") as
4602-409: Is important for orthopedic and spinal surgery and can reduce operating times by eliminating re-positioning. Angiography is the use of fluoroscopy to view the cardiovascular system. An iodine-based contrast is injected into the bloodstream and watched as it travels around. Since liquid blood and the vessels are not very dense, a contrast with high density (like the large iodine atoms) is used to view
4720-400: Is related to the wavelength . X and gamma rays have the shortest wavelength and this property leads to the ability to penetrate, travel through, and exit various materials such as carbon steel and other metals. Specific methods include industrial computed tomography . Image quality will depend on resolution and density. Resolution is the ability an image to show closely spaced structure in
4838-494: Is startlingly rapid". Between 1275 and 1326, the anatomists Mondino de Luzzi , Alessandro Achillini and Antonio Benivieni at Bologna carried out the first systematic human dissections since ancient times. Mondino's Anatomy of 1316 was the first textbook in the medieval rediscovery of human anatomy. It describes the body in the order followed in Mondino's dissections, starting with the abdomen, thorax, head, and limbs. It
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4956-430: Is the branch of morphology concerned with the study of the internal structure of organisms and their parts. Anatomy is a branch of natural science that deals with the structural organization of living things. It is an old science, having its beginnings in prehistoric times. Anatomy is inherently tied to developmental biology , embryology , comparative anatomy , evolutionary biology , and phylogeny , as these are
5074-426: Is the examination of an animal's body parts using unaided eyesight. Gross anatomy also includes the branch of superficial anatomy . Microscopic anatomy involves the use of optical instruments in the study of the tissues of various structures, known as histology , and also in the study of cells . The history of anatomy is characterized by a progressive understanding of the functions of the organs and structures of
5192-437: Is the scientific study of the structure of organisms including their systems, organs and tissues . It includes the appearance and position of the various parts, the materials from which they are composed, and their relationships with other parts. Anatomy is quite distinct from physiology and biochemistry , which deal respectively with the functions of those parts and the chemical processes involved. For example, an anatomist
5310-405: Is the study of structures large enough to be seen with the naked eye, and also includes superficial anatomy or surface anatomy, the study by sight of the external body features. Microscopic anatomy is the study of structures on a microscopic scale, along with histology (the study of tissues), and embryology (the study of an organism in its immature condition). Regional anatomy is the study of
5428-411: Is the vertebral column, composed of articulating vertebrae which are lightweight yet strong. The ribs attach to the spine and there are no limbs or limb girdles. The main external features of the fish, the fins , are composed of either bony or soft spines called rays, which with the exception of the caudal fins , have no direct connection with the spine. They are supported by the muscles which compose
5546-583: Is therefore exponential (with an attenuation length being close to the radiation length of the material); doubling the thickness of shielding will square the shielding effect. Table in this section shows the recommended thickness of lead shielding in function of X-ray energy, from the Recommendations by the Second International Congress of Radiology. In response to increased concern by the public over radiation doses and
5664-403: Is very low, much lower than projection radiography examinations. Fluoroscopy is a term invented by Thomas Edison during his early X-ray studies. The name refers to the fluorescence he saw while looking at a glowing plate bombarded with X-rays. The technique provides moving projection radiographs. Fluoroscopy is mainly performed to view movement (of tissue or a contrast agent), or to guide
5782-609: The Hippocratic Corpus , an Ancient Greek medical work written by unknown authors. Aristotle described vertebrate anatomy based on animal dissection . Praxagoras identified the difference between arteries and veins . Also in the 4th century BCE, Herophilos and Erasistratus produced more accurate anatomical descriptions based on vivisection of criminals in Alexandria during the Ptolemaic period . In
5900-854: The International Organization of Medical Physicists , the UN Scientific Committee on the Effects of Atomic Radiation , and the International Commission on Radiological Protection . Nonetheless, radiological organizations, including the Radiological Society of North America (RSNA) and the American College of Radiology (ACR), as well as multiple government agencies, indicate safety standards to ensure that radiation dosage
6018-511: The Triassic period. There is one living species, Sphenodon punctatus . The skull has two openings (fenestrae) on either side and the jaw is rigidly attached to the skull. There is one row of teeth in the lower jaw and this fits between the two rows in the upper jaw when the animal chews. The teeth are merely projections of bony material from the jaw and eventually wear down. The brain and heart are more primitive than those of other reptiles, and
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#17327718877746136-400: The epidermis and are found in localized bands from where they fan out over the skin. Large flight feathers are found on the wings and tail, contour feathers cover the bird's surface and fine down occurs on young birds and under the contour feathers of water birds. The only cutaneous gland is the single uropygial gland near the base of the tail. This produces an oily secretion that waterproofs
6254-533: The extracellular matrix . Often called fascia (from the Latin "fascia," meaning "band" or "bandage"), connective tissues give shape to organs and holds them in place. The main types are loose connective tissue, adipose tissue , fibrous connective tissue, cartilage and bone. The extracellular matrix contains proteins , the chief and most abundant of which is collagen . Collagen plays a major part in organizing and maintaining tissues. The matrix can be modified to form
6372-461: The mouthparts . The thorax has three pairs of segmented legs , one pair each for the three segments that compose the thorax and one or two pairs of wings . The abdomen is composed of eleven segments, some of which may be fused and houses the digestive , respiratory , excretory and reproductive systems. There is considerable variation between species and many adaptations to the body parts, especially wings, legs, antennae and mouthparts. Spiders
6490-533: The photocathode adjacent to it to emit electrons. These electrons are then focused using electron lenses inside the intensifier to an output screen coated with phosphorescent materials. The image from the output can then be recorded via a camera and displayed. Digital devices known as array detectors are becoming more common in fluoroscopy. These devices are made of discrete pixelated detectors known as thin-film transistors (TFT) which can either work indirectly by using photo detectors that detect light emitted from
6608-512: The radiology department of hospitals handle all forms of imaging . Treatment using radiation is known as radiotherapy . Industrial radiography is a method of non-destructive testing where many types of manufactured components can be examined to verify the internal structure and integrity of the specimen. Industrial Radiography can be performed utilizing either X-rays or gamma rays . Both are forms of electromagnetic radiation . The difference between various forms of electromagnetic energy
6726-400: The stomach . All vertebrates have a similar basic body plan and at some point in their lives, mostly in the embryonic stage, share the major chordate characteristics: a stiffening rod, the notochord ; a dorsal hollow tube of nervous material, the neural tube ; pharyngeal arches ; and a tail posterior to the anus. The spinal cord is protected by the vertebral column and is above
6844-420: The 2nd century, Galen of Pergamum , an anatomist, clinician , writer, and philosopher, wrote the final and highly influential anatomy treatise of ancient times. He compiled existing knowledge and studied anatomy through the dissection of animals. He was one of the first experimental physiologists through his vivisection experiments on animals. Galen's drawings, based mostly on dog anatomy, became effectively
6962-1022: The Image Gently campaign, the American College of Radiology, the Radiological Society of North America, the American Association of Physicists in Medicine, and the American Society of Radiologic Technologists have launched a similar campaign to address this issue in the adult population called Image Wisely. The World Health Organization and International Atomic Energy Agency (IAEA) of the United Nations have also been working in this area and have ongoing projects designed to broaden best practices and lower patient radiation dose. Contrary to advice that emphasises only conducting radiographs when in
7080-541: The arts and sciences from the Ptolemaic dynasty of Egypt helped raise Alexandria up, further rivalling other Greek states' cultural and scientific achievements. Some of the most striking advances in early anatomy and physiology took place in Hellenistic Alexandria. Two of the most famous anatomists and physiologists of the third century were Herophilus and Erasistratus . These two physicians helped pioneer human dissection for medical research, using
7198-496: The atria were parts of the heart. Herophilus's knowledge of the human body has provided vital input towards understanding the brain, eye, liver, reproductive organs, and nervous system and characterizing the course of the disease. Erasistratus accurately described the structure of the brain, including the cavities and membranes, and made a distinction between its cerebrum and cerebellum During his study in Alexandria, Erasistratus
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#17327718877747316-518: The basis of sense organs and there is a central nervous system (brain and spinal cord) and a peripheral nervous system . The latter consists of sensory nerves that transmit information from sense organs and motor nerves that influence target organs. The peripheral nervous system is divided into the somatic nervous system which conveys sensation and controls voluntary muscle , and the autonomic nervous system which involuntarily controls smooth muscle , certain glands and internal organs, including
7434-462: The body and they swim by undulating their body from side to side. Reptiles are a class of animals comprising turtles , tuataras , lizards , snakes and crocodiles . They are tetrapods , but the snakes and a few species of lizard either have no limbs or their limbs are much reduced in size. Their bones are better ossified and their skeletons stronger than those of amphibians. The teeth are conical and mostly uniform in size. The surface cells of
7552-399: The brain, appreciated the division between cerebellum and cerebrum and recognized that the brain was the "seat of intellect" and not a "cooling chamber" as propounded by Aristotle Herophilus is also credited with describing the optic, oculomotor, motor division of the trigeminal, facial, vestibulocochlear and hypoglossal nerves. Incredible feats were made during the third century BCE in both
7670-516: The cadavers of condemned criminals, which was considered taboo until the Renaissance—Herophilus was recognized as the first person to perform systematic dissections. Herophilus became known for his anatomical works, making impressive contributions to many branches of anatomy and many other aspects of medicine. Some of the works included classifying the system of the pulse, the discovery that human arteries had thicker walls than veins, and that
7788-555: The college, and his brother Edwin Frost, professor of physics, exposed the wrist of Eddie McCarthy, whom Gilman had treated some weeks earlier for a fracture, to the X-rays and collected the resulting image of the broken bone on gelatin photographic plates obtained from Howard Langill, a local photographer also interested in Röntgen's work. X-rays were put to diagnostic use very early; for example, Alan Archibald Campbell-Swinton opened
7906-418: The dermis which are overlain by horny ones and are partially fused with the ribs and spine. The neck is long and flexible and the head and the legs can be drawn back inside the shell. Turtles are vegetarians and the typical reptile teeth have been replaced by sharp, horny plates. In aquatic species, the front legs are modified into flippers. Tuataras superficially resemble lizards but the lineages diverged in
8024-402: The digestive and reproductive systems. Herophilus discovered and described not only the salivary glands but also the small intestine and liver. He showed that the uterus is a hollow organ and described the ovaries and uterine tubes. He recognized that spermatozoa were produced by the testes and was the first to identify the prostate gland. The anatomy of the muscles and skeleton is described in
8142-418: The early development of the nervous system . At the five-vesicle stage, the forebrain separates into the diencephalon ( thalamus , hypothalamus , subthalamus , and epithalamus ) and the telencephalon which develops into the cerebrum . The cerebrum consists of the cerebral cortex , underlying white matter , and the basal ganglia . In humans, by 5 weeks in utero it is visible as a single portion toward
8260-402: The egg-laying monotremes , the platypus and the echidnas of Australia. Most other mammals have a placenta through which the developing foetus obtains nourishment, but in marsupials , the foetal stage is very short and the immature young is born and finds its way to its mother's pouch where it latches on to a teat and completes its development. Humans have the overall body plan of
8378-532: The end of each male pedipalp is a spoon-shaped cymbium that acts to support the copulatory organ . In 1600 BCE, the Edwin Smith Papyrus , an Ancient Egyptian medical text , described the heart and its vessels, as well as the brain and its meninges and cerebrospinal fluid , and the liver , spleen , kidneys , uterus and bladder . It showed the blood vessels diverging from the heart. The Ebers Papyrus ( c. 1550 BCE ) features
8496-467: The epidermis are modified into horny scales which create a waterproof layer. Reptiles are unable to use their skin for respiration as do amphibians and have a more efficient respiratory system drawing air into their lungs by expanding their chest walls. The heart resembles that of the amphibian but there is a septum which more completely separates the oxygenated and deoxygenated bloodstreams. The reproductive system has evolved for internal fertilization, with
8614-413: The epidermis is normally formed of epithelial cells and secretes an extracellular matrix which provides support to the organism. An endoskeleton derived from the mesoderm is present in echinoderms , sponges and some cephalopods . Exoskeletons are derived from the epidermis and is composed of chitin in arthropods (insects, spiders, ticks, shrimps, crabs, lobsters). Calcium carbonate constitutes
8732-429: The epithelial lining and in the large intestine there are intestinal villi . Skin consists of an outer layer of keratinized stratified squamous epithelium that covers the exterior of the vertebrate body. Keratinocytes make up to 95% of the cells in the skin . The epithelial cells on the external surface of the body typically secrete an extracellular matrix in the form of a cuticle . In simple animals this may just be
8850-610: The equivalent of tissues and organs. Locomotion is often provided by cilia or flagella or may proceed via the advance of pseudopodia , food may be gathered by phagocytosis , energy needs may be supplied by photosynthesis and the cell may be supported by an endoskeleton or an exoskeleton . Some protozoans can form multicellular colonies. Metazoans are a multicellular organism, with different groups of cells serving different functions. The most basic types of metazoan tissues are epithelium and connective tissue, both of which are present in nearly all invertebrates. The outer surface of
8968-405: The father of microscopical anatomy, discovered that plants had tubules similar to those he saw in insects like the silk worm. He observed that when a ring-like portion of bark was removed on a trunk a swelling occurred in the tissues above the ring, and he unmistakably interpreted this as growth stimulated by food coming down from the leaves, and being captured above the ring. Arthropods comprise
9086-435: The feathers when the bird preens . There are scales on the legs, feet and claws on the tips of the toes. Mammals are a diverse class of animals, mostly terrestrial but some are aquatic and others have evolved flapping or gliding flight. They mostly have four limbs, but some aquatic mammals have no limbs or limbs modified into fins, and the forelimbs of bats are modified into wings. The legs of most mammals are situated below
9204-443: The features of ancient fish. They have a bony skeleton, are generally laterally flattened, have five pairs of gills protected by an operculum , and a mouth at or near the tip of the snout. The dermis is covered with overlapping scales . Bony fish have a swim bladder which helps them maintain a constant depth in the water column, but not a cloaca. They mostly spawn a large number of small eggs with little yolk which they broadcast into
9322-486: The first Nobel Prize in Physics for his discovery. There are conflicting accounts of his discovery because Röntgen had his lab notes burned after his death, but this is a likely reconstruction by his biographers: Röntgen was investigating cathode rays using a fluorescent screen painted with barium platinocyanide and a Crookes tube which he had wrapped in black cardboard to shield its fluorescent glow. He noticed
9440-427: The front of the fetus. At 8 weeks in utero, the forebrain splits into the left and right cerebral hemispheres. When the embryonic forebrain fails to divide the brain into two lobes, it results in a condition known as holoprosencephaly . The parts present in the forebain are cerebrum, thalamus and hypothalamus. Anatomy Anatomy (from Ancient Greek ἀνατομή ( anatomḗ ) ' dissection ')
9558-482: The head. The dermis is covered with separate dermal placoid scales . They have a cloaca into which the urinary and genital passages open, but not a swim bladder . Cartilaginous fish produce a small number of large, yolky eggs. Some species are ovoviviparous and the young develop internally but others are oviparous and the larvae develop externally in egg cases. The bony fish lineage shows more derived anatomical traits, often with major evolutionary changes from
9676-444: The hip (head of the femur ), lower back ( lumbar spine ), or heel ( calcaneum ) are imaged, and the bone density (amount of calcium) is determined and given a number (a T-score). It is not used for bone imaging, as the image quality is not good enough to make an accurate diagnostic image for fractures, inflammation, etc. It can also be used to measure total body fat, though this is not common. The radiation dose received from DEXA scans
9794-516: The human body were made, which contributed to the understanding of the brain, eye, liver, reproductive organs, and nervous system. The Hellenistic Egyptian city of Alexandria was the stepping-stone for Greek anatomy and physiology. Alexandria not only housed the biggest library for medical records and books of the liberal arts in the world during the time of the Greeks but was also home to many medical practitioners and philosophers. Great patronage of
9912-486: The human body. Methods have also improved dramatically, advancing from the examination of animals by dissection of carcasses and cadavers (corpses) to 20th-century medical imaging techniques, including X-ray , ultrasound , and magnetic resonance imaging . Derived from the Greek ἀνατομή anatomē "dissection" (from ἀνατέμνω anatémnō "I cut up, cut open" from ἀνά aná "up", and τέμνω témnō "I cut"), anatomy
10030-455: The internal structure of the body on an image receptor by highlighting these differences using attenuation , or in the case of ionising radiation, the absorption of X-ray photons by the denser substances (like calcium -rich bones). The discipline involving the study of anatomy through the use of radiographic images is known as radiographic anatomy . Medical radiography acquisition is generally carried out by radiographers , while image analysis
10148-423: The interrelationships of all of the structures in a specific body region, such as the abdomen. In contrast, systemic anatomy is the study of the structures that make up a discrete body system—that is, a group of structures that work together to perform a unique body function, such as the digestive system. Anatomy can be studied using both invasive and non-invasive methods with the goal of obtaining information about
10266-492: The largest phylum of invertebrates in the animal kingdom with over a million known species. Insects possess segmented bodies supported by a hard-jointed outer covering, the exoskeleton , made mostly of chitin . The segments of the body are organized into three distinct parts, a head, a thorax and an abdomen . The head typically bears a pair of sensory antennae , a pair of compound eyes , one to three simple eyes ( ocelli ) and three sets of modified appendages that form
10384-399: The length of the sides of fish, and these respond to nearby movements and to changes in water pressure. Sharks and rays are basal fish with numerous primitive anatomical features similar to those of ancient fish, including skeletons composed of cartilage. Their bodies tend to be dorso-ventrally flattened, they usually have five pairs of gill slits and a large mouth set on the underside of
10502-431: The local radiation exposure , dose , and/or dose rate, for example, for verifying that radiation protection equipment and procedures are effective on an ongoing basis). A radiopaque anatomical side marker is added to each image. For example, if the patient has their right hand x-rayed, the radiographer includes a radiopaque "R" marker within the field of the x-ray beam as an indicator of which hand has been imaged. If
10620-437: The lungs have a single chamber and lack bronchi . The tuatara has a well-developed parietal eye on its forehead. Lizards have skulls with only one fenestra on each side, the lower bar of bone below the second fenestra having been lost. This results in the jaws being less rigidly attached which allows the mouth to open wider. Lizards are mostly quadrupeds, with the trunk held off the ground by short, sideways-facing legs, but
10738-400: The main part of the trunk. The heart has two chambers and pumps the blood through the respiratory surfaces of the gills and on round the body in a single circulatory loop. The eyes are adapted for seeing underwater and have only local vision. There is an inner ear but no external or middle ear . Low frequency vibrations are detected by the lateral line system of sense organs that run along
10856-477: The more developed animals whose structures and organs are formed from three germ layers are called triploblastic . All of a triploblastic animal's tissues and organs are derived from the three germ layers of the embryo, the ectoderm , mesoderm and endoderm . Animal tissues can be grouped into four basic types: connective , epithelial , muscle and nervous tissue . Connective tissues are fibrous and made up of cells scattered among inorganic material called
10974-475: The nerves form a nerve net , but in most animals they are organized longitudinally into bundles. In simple animals, receptor neurons in the body wall cause a local reaction to a stimulus. In more complex animals, specialized receptor cells such as chemoreceptors and photoreceptors are found in groups and send messages along neural networks to other parts of the organism. Neurons can be connected together in ganglia . In higher animals, specialized receptors are
11092-439: The new technology. When new diagnostic tests were developed, it was natural for the radiographers to be trained in and to adopt this new technology. Radiographers now perform fluoroscopy , computed tomography , mammography , ultrasound , nuclear medicine and magnetic resonance imaging as well. Although a nonspecialist dictionary might define radiography quite narrowly as "taking X-ray images", this has long been only part of
11210-416: The notochord, and the gastrointestinal tract is below it. Nervous tissue is derived from the ectoderm , connective tissues are derived from mesoderm , and gut is derived from the endoderm . At the posterior end is a tail which continues the spinal cord and vertebrae but not the gut. The mouth is found at the anterior end of the animal, and the anus at the base of the tail. The defining characteristic of
11328-417: The object as separate entities in the image while density is the blackening power of the image. Sharpness of a radiographic image is strongly determined by the size of the X-ray source. This is determined by the area of the electron beam hitting the anode. A large photon source results in more blurring in the final image and is worsened by an increase in image formation distance. This blurring can be measured as
11446-719: The ongoing progress of best practices, The Alliance for Radiation Safety in Pediatric Imaging was formed within the Society for Pediatric Radiology . In concert with the American Society of Radiologic Technologists , the American College of Radiology , and the American Association of Physicists in Medicine , the Society for Pediatric Radiology developed and launched the Image Gently campaign which
11564-428: The only anatomical textbook for the next thousand years. His work was known to Renaissance doctors only through Islamic Golden Age medicine until it was translated from Greek sometime in the 15th century. Anatomy developed little from classical times until the sixteenth century; as the historian Marie Boas writes, "Progress in anatomy before the sixteenth century is as mysteriously slow as its development after 1500
11682-557: The patient and the detector to reduce the quantity of scattered x-rays that reach the detector. This improves the contrast resolution of the image, but also increases radiation exposure for the patient. Detectors can be divided into two major categories: imaging detectors (such as photographic plates and X-ray film ( photographic film ), now mostly replaced by various digitizing devices like image plates or flat panel detectors ) and dose measurement devices (such as ionization chambers , Geiger counters , and dosimeters used to measure
11800-403: The patient was sliced like bread (thus, "tomography" – "tomo" means "slice"). Though CT uses a higher amount of ionizing x-radiation than diagnostic x-rays (both utilising X-ray radiation), with advances in technology, levels of CT radiation dose and scan times have reduced. CT exams are generally short, most lasting only as long as a breath-hold, Contrast agents are also often used, depending on
11918-809: The patient's interest, recent evidence suggests that they are used more frequently when dentists are paid under fee-for-service. In medicine and dentistry, projectional radiography and computed tomography images generally use X-rays created by X-ray generators , which generate X-rays from X-ray tubes . The resultant images from the radiograph (X-ray generator/machine) or CT scanner are correctly referred to as "radiograms"/"roentgenograms" and "tomograms" respectively. A number of other sources of X-ray photons are possible, and may be used in industrial radiography or research; these include betatrons , linear accelerators (linacs), and synchrotrons . For gamma rays , radioactive sources such as Ir , Co , or Cs are used. An anti-scatter grid may be placed between
12036-417: The processes by which anatomy is generated, both over immediate and long-term timescales. Anatomy and physiology , which study the structure and function of organisms and their parts respectively, make a natural pair of related disciplines, and are often studied together. Human anatomy is one of the essential basic sciences that are applied in medicine, and is often studied alongside physiology . Anatomy
12154-493: The same underlying skeletal structure was inherited from their last common ancestor. This is one of the arguments put forward by Charles Darwin to support his theory of evolution . The body of a fish is divided into a head, trunk and tail, although the divisions between the three are not always externally visible. The skeleton, which forms the support structure inside the fish, is either made of cartilage, in cartilaginous fish , or bone in bony fish . The main skeletal element
12272-670: The shells of molluscs , brachiopods and some tube-building polychaete worms and silica forms the exoskeleton of the microscopic diatoms and radiolaria . Other invertebrates may have no rigid structures but the epidermis may secrete a variety of surface coatings such as the pinacoderm of sponges, the gelatinous cuticle of cnidarians ( polyps , sea anemones , jellyfish ) and the collagenous cuticle of annelids . The outer epithelial layer may include cells of several types including sensory cells, gland cells and stinging cells. There may also be protrusions such as microvilli , cilia, bristles, spines and tubercles . Marcello Malpighi ,
12390-448: The structure and organization of organs and systems. Methods used include dissection , in which a body is opened and its organs studied, and endoscopy , in which a video camera -equipped instrument is inserted through a small incision in the body wall and used to explore the internal organs and other structures. Angiography using X-rays or magnetic resonance angiography are methods to visualize blood vessels. The term "anatomy"
12508-741: The tail is laterally compressed. It undulates from side to side to force the animal through the water when swimming. The tough keratinized scales provide body armour and some are fused to the skull. The nostrils, eyes and ears are elevated above the top of the flat head enabling them to remain above the surface of the water when the animal is floating. Valves seal the nostrils and ears when it is submerged. Unlike other reptiles, crocodilians have hearts with four chambers allowing complete separation of oxygenated and deoxygenated blood. Birds are tetrapods but though their hind limbs are used for walking or hopping, their front limbs are wings covered with feathers and adapted for flight. Birds are endothermic , have
12626-412: The tissues needing to be seen. Radiographers perform these examinations, sometimes in conjunction with a radiologist (for instance, when a radiologist performs a CT-guided biopsy ). DEXA , or bone densitometry, is used primarily for osteoporosis tests. It is not projection radiography, as the X-rays are emitted in two narrow beams that are scanned across the patient, 90 degrees from each other. Usually
12744-401: The toes are often webbed for swimming or have suction pads for climbing. Frogs have large eyes and no tail. Salamanders resemble lizards in appearance; their short legs project sideways, the belly is close to or in contact with the ground and they have a long tail. Caecilians superficially resemble earthworms and are limbless. They burrow by means of zones of muscle contractions which move along
12862-538: The trunk, which is held well clear of the ground. The bones of mammals are well ossified and their teeth, which are usually differentiated, are coated in a layer of prismatic enamel . The teeth are shed once ( milk teeth ) during the animal's lifetime or not at all, as is the case in cetaceans . Mammals have three bones in the middle ear and a cochlea in the inner ear . They are clothed in hair and their skin contains glands which secrete sweat . Some of these glands are specialized as mammary glands , producing milk to feed
12980-442: The vertebrae. Their skulls are mostly broad and short, and are often incompletely ossified. Their skin contains little keratin and lacks scales, but contains many mucous glands and in some species, poison glands. The hearts of amphibians have three chambers, two atria and one ventricle . They have a urinary bladder and nitrogenous waste products are excreted primarily as urea . Amphibians breathe by means of buccal pumping ,
13098-696: The vessels under X-ray. Angiography is used to find aneurysms , leaks, blockages ( thromboses ), new vessel growth, and placement of catheters and stents. Balloon angioplasty is often done with angiography. Contrast radiography uses a radiocontrast agent, a type of contrast medium , to make the structures of interest stand out visually from their background. Contrast agents are required in conventional angiography , and can be used in both projectional radiography and computed tomography (called contrast CT ). Although not technically radiographic techniques due to not using X-rays, imaging modalities such as PET and MRI are sometimes grouped in radiography because
13216-437: The water column. Amphibians are a class of animals comprising frogs , salamanders and caecilians . They are tetrapods , but the caecilians and a few species of salamander have either no limbs or their limbs are much reduced in size. Their main bones are hollow and lightweight and are fully ossified and the vertebrae interlock with each other and have articular processes . Their ribs are usually short and may be fused to
13334-564: The work of "X-ray departments", radiographers, and radiologists. Initially, radiographs were known as roentgenograms, while skiagrapher (from the Ancient Greek words for "shadow" and "writer") was used until about 1918 to mean radiographer . The Japanese term for the radiograph, rentogen ( レントゲン ) , shares its etymology with the original English term. Since the body is made up of various substances with differing densities, ionising and non-ionising radiation can be used to reveal
13452-411: The young. Mammals breathe with lungs and have a muscular diaphragm separating the thorax from the abdomen which helps them draw air into the lungs. The mammalian heart has four chambers, and oxygenated and deoxygenated blood are kept entirely separate. Nitrogenous waste is excreted primarily as urea. Mammals are amniotes , and most are viviparous , giving birth to live young. Exceptions to this are
13570-425: Was also responsible for naming and describing the function of the epiglottis and the heart's valves, including the tricuspid. During the third century, Greek physicians were able to differentiate nerves from blood vessels and tendons and to realize that the nerves convey neural impulses. It was Herophilus who made the point that damage to motor nerves induced paralysis. Herophilus named the meninges and ventricles in
13688-421: Was particularly concerned with studies of the circulatory and nervous systems. He could distinguish the human body's sensory and motor nerves and believed air entered the lungs and heart, which was then carried throughout the body. His distinction between the arteries and veins—the arteries carrying the air through the body, while the veins carry the blood from the heart was a great anatomical discovery. Erasistratus
13806-534: Was the first ever photograph of a human body part using X-rays. When she saw the picture, she said, "I have seen my death." The first use of X-rays under clinical conditions was by John Hall-Edwards in Birmingham, England , on 11 January 1896, when he radiographed a needle stuck in the hand of an associate. On 14 February 1896, Hall-Edwards also became the first to use X-rays in a surgical operation . The United States saw its first medical X-ray obtained using
13924-538: Was the standard anatomy textbook for the next century. Radiography Radiography is an imaging technique using X-rays , gamma rays , or similar ionizing radiation and non-ionizing radiation to view the internal form of an object. Applications of radiography include medical ("diagnostic" radiography and "therapeutic radiography") and industrial radiography . Similar techniques are used in airport security , (where "body scanners" generally use backscatter X-ray ). To create an image in conventional radiography ,
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