Misplaced Pages

#990009

69-442: A fontanelle (or fontanel ) (colloquially, soft spot ) is an anatomical feature of the infant human skull comprising soft membranous gaps ( sutures ) between the cranial bones that make up the calvaria of a fetus or an infant . Fontanelles allow for stretching and deformation of the neurocranium both during birth and later as the brain expands faster than the surrounding bone can grow. Premature complete ossification of

138-444: A head , hair , neck , torso (which includes the thorax and abdomen ), genitals , arms , hands , legs , and feet . The internal human body includes organs, teeth , bones , muscle , tendons , ligaments , blood vessels and blood , lymphatic vessels and lymph . The study of the human body includes anatomy , physiology , histology and embryology . The body varies anatomically in known ways. Physiology focuses on

207-519: A cell . Here, parts of DNA are copied and sent to the body of the cell via RNA . The RNA is then used to create proteins , which form the basis for cells, their activity, and their products. Proteins dictate cell function and gene expression, a cell is able to self-regulate by the amount of proteins produced. However, not all cells have DNA; some cells such as mature red blood cells lose their nucleus as they mature. The body consists of many different types of tissue , defined as cells that act with

276-420: A number of body cavities , separated areas which house different organ systems. The brain and central nervous system reside in an area protected from the rest of the body by the blood brain barrier . The lungs sit in the pleural cavity . The intestines , liver , and spleen sit in the abdominal cavity . Height, weight, shape and other body proportions vary individually and with age and sex. Body shape

345-399: A number of sexually transmitted infections including syphilis , HIV , chlamydia , HPV and genital warts . Cancer can affect most parts of the reproductive system including the penis , testicles , prostate , ovaries , cervix , vagina , fallopian , uterus and vulva . The respiratory system consists of the nose, nasopharynx , trachea , and lungs . It brings oxygen from

414-505: A specialised function. The study of tissues is called histology and is often done with a microscope . The body consists of four main types of tissues. These are lining cells ( epithelia ), connective tissue , nerve tissue and muscle tissue . Cells that line surfaces exposed to the outside world or gastrointestinal tract ( epithelia ) or internal cavities ( endothelium ) come in numerous shapes and forms – from single layers of flat cells , to cells with small beating hair-like cilia in

483-491: A three- to six-month period. Occasionally these bones fail to close, but the dog is still healthy. In these cases, however, the dog's owners need to be very careful, since any injury or bumps to the animal's head could cause significant brain damage, as well as conditions like epilepsy. An open fontanelle, known as a molera , is a recognized feature of the Chihuahua breed. The American Kennel Club breed standard states that

552-442: Is swallowed , and moves through the esophagus to the stomach . In the stomach, food is mixed with gastric acids to allow the extraction of nutrients . What is left is called chyme ; this then moves into the small intestine , which absorbs the nutrients and water from the chyme. What remains passes on to the large intestine , where it is dried to form feces ; these are then stored in the rectum until they are expelled through

621-433: Is a common disease in which one or more stones form in the gallbladder or biliary tract . Most people are asymptomatic but if a stone blocks the biliary tract, it causes a gallbladder attack , symptoms may include sudden pain in the upper right abdomen or center of the abdomen. Nausea and vomiting may also occur. Typical treatment is removal of the gallbladder through a procedure called a cholecystectomy . Having gallstones

690-444: Is a risk factor for gallbladder cancer , which although quite uncommon, is rapidly fatal if not diagnosed early. The circulatory system consists of the heart and blood vessels ( arteries , veins and capillaries ). The heart propels the circulation of the blood, which serves as a "transportation system" to transfer oxygen , fuel, nutrients, waste products, immune cells and signaling molecules (i.e. hormones ) from one part of

759-469: Is a third bigger fontanelle other than posterior and anterior ones in a newborn. In one study, the frequency of third fontanelles in an unselected population of newborn infants was 6.3%. It is very common in Down syndrome and some congenital infections. If present, the physician should rule out serious conditions associated with the third fontanelle. In apes the fontanelles fuse soon after birth. In chimpanzees

SECTION 10

#1732772255991

828-456: Is assumed that the term spring is used because of the analogy of the dent in a rock or earth where a spring arises. Parents may worry that their infant may be more prone to injury at the fontanelles. In fact, although they may colloquially be called "soft-spots", the membrane covering the fontanelles is extremely tough and difficult to penetrate. Fontanelles allow the infant brain to be imaged using ultrasonography . Once they are closed, most of

897-415: Is brought by the ureters from the kidneys down to the bladder . The smooth muscle lining the ureter walls continuously tighten and relax through a process called peristalsis to force urine away from the kidneys and down into the bladder. Small amounts of urine are released into the bladder every 10–15 seconds. The bladder is a hollow balloon shaped organ located in the pelvis . It stores urine until

966-419: Is influenced by the distribution of bones, muscle and fat tissue . Human physiology is the study of how the human body functions. This includes the mechanical, physical, bioelectrical , and biochemical functions of humans in good health, from organs to the cells of which they are composed. The human body consists of many interacting systems of organs. These interact to maintain homeostasis , keeping

1035-509: Is mostly responsible for gathering information with sensory neurons and directing body movements with motor neurons . From a functional perspective, the nervous system is again typically divided into two component parts: the somatic nervous system (SNS) and the autonomic nervous system (ANS). The SNS is involved in voluntary functions like speaking and sensory processes . The ANS is involved in involuntary processes, such as digestion and regulating blood pressure . The nervous system

1104-405: Is similar to the circulatory system in terms of both its structure and its most basic function, to carry a body fluid. The musculoskeletal system consists of the human skeleton (which includes bones , ligaments , tendons , joints and cartilage ) and attached muscles . It gives the body basic structure and the ability for movement. In addition to their structural role, the larger bones in

1173-430: Is subject to many different diseases. In epilepsy , abnormal electrical activity in the brain can cause seizures . In multiple sclerosis , the immune system attacks the nerve linings , damaging the nerves' ability to transmit signals. Amyotrophic lateral sclerosis (ALS), also known as Lou Gehrig 's disease, is a motor neuron disease which gradually reduces movement in patients. There are also many other diseases of

1242-425: Is the organ of thought , emotion, memory , and sensory processing ; it serves many aspects of communication and controls various systems and functions. The special senses consist of vision , hearing , taste , and smell . The eyes , ears , tongue , and nose gather information about the body's environment. From a structural perspective, the nervous system is typically subdivided into two component parts:

1311-442: Is the study of the shape and form of the human body. The human body has four limbs (two arms and two legs), a head and a neck , which connect to the torso . The body's shape is determined by a strong skeleton made of bone and cartilage , surrounded by fat ( adipose tissue ), muscle, connective tissue , organs, and other structures. The spine at the back of the skeleton contains the flexible vertebral column , which surrounds

1380-433: Is variable in shape and size. It stores bile before it is released into the small intestine via the common bile duct to help with digestion of fats . It receives bile from the liver via the cystic duct , which connects to the common hepatic duct to form the common bile duct . The gallbladder gets its blood supply from the cystic artery , which in most people, emerges from the right hepatic artery . Gallstones

1449-441: The anus . The endocrine system consists of the principal endocrine glands : the pituitary , thyroid , adrenals , pancreas , parathyroids , and gonads , but nearly all organs and tissues produce specific endocrine hormones as well. The endocrine hormones serve as signals from one body system to another regarding an enormous array of conditions, resulting in variety of changes of function. The immune system consists of

SECTION 20

#1732772255991

1518-520: The central nervous system (CNS), composed of the brain and the spinal cord ; and the peripheral nervous system (PNS), composed of the nerves and ganglia outside the brain and spinal cord. The CNS is mostly responsible for organizing motion , processing sensory information , thought, memory, cognition and other such functions. It remains a matter of some debate whether the CNS directly gives rise to consciousness . The peripheral nervous system (PNS)

1587-468: The heart , lungs and liver . Many organs reside within cavities within the body. These cavities include the abdomen (which contains the stomach, for example) and pleura , which contains the lungs. The heart is an organ located in the thoracic cavity between the lungs and slightly to the left. It is surrounded by the pericardium , which holds it in place in the mediastinum and serves to protect it from blunt trauma, infection and help lubricate

1656-441: The kidneys filter the blood through their respective nephrons , removing waste products like urea , creatinine and maintaining the proper balance of electrolytes and turning the waste products into urine by combining them with water from the blood. The kidneys filter about 150 quarts (170 liters) of blood daily, but most of it is returned to the blood stream with only 1-2 quarts (1-2 liters) ending up as urine. The urine

1725-456: The ovary of a female is penetrated by sperm . The egg then lodges in the uterus , where an embryo and later fetus develop until birth . Growth and development occur after birth, and include both physical and psychological development, influenced by genetic, hormonal, environmental and other factors. Development and growth continue throughout life, through childhood , adolescence , and through adulthood to old age , and are referred to as

1794-407: The sinoatrial node traveling through the atria causing them to pump blood into the ventricles . It then travels to the atrioventricular node , which makes the signal slow down slightly allowing the ventricles to fill with blood before pumping it out and starting the cycle over again. Coronary artery disease is the leading cause of death worldwide , making up 16% of all deaths. It is caused by

1863-400: The spinal cord , which is a collection of nerve fibres connecting the brain to the rest of the body. Nerves connect the spinal cord and brain to the rest of the body. All major bones, muscles, and nerves in the body are named, with the exception of anatomical variations such as sesamoid bones and accessory muscles . Blood vessels carry blood throughout the body, which moves because of

1932-421: The spleen and bone marrow . The digestive system consists of the mouth including the tongue and teeth , esophagus , stomach , ( gastrointestinal tract , small and large intestines , and rectum ), as well as the liver , pancreas , gallbladder , and salivary glands . It converts food into small, nutritional, non-toxic molecules for distribution and absorption into the body. These molecules take

2001-432: The testicles . The testicle is the gonad , the sex gland that produces the sperm cells . Unlike the egg cells in the female, sperm cells are produced throughout life. Other internal sex organs are the epididymides , vasa deferentia , and some accessory glands . Diseases that affect the reproductive system include polycystic ovary syndrome , a number of disorders of the testicles including testicular torsion , and

2070-427: The uterus , and the cervix . At birth there are about 70,000 immature egg cells that degenerate until at puberty there are around 40,000. No more egg cells are produced. Hormones stimulate the beginning of menstruation, and the ongoing menstrual cycles . The female external sex organs are the vulva ( labia , clitoris , and vestibule ). The male external genitalia include the penis and scrotum that contains

2139-441: The white blood cells , the thymus , lymph nodes and lymph channels, which are also part of the lymphatic system . The immune system provides a mechanism for the body to distinguish its own cells and tissues from outside cells and substances and to neutralize or destroy the latter by using specialized proteins such as antibodies , cytokines , and toll-like receptors , among many others. The integumentary system consists of

Fontanelle - Misplaced Pages Continue

2208-766: The University of Minnesota that found no correlation between the presence or size of a molera and hydrocephalus". This is also incorrect. This study was entitled "Hydrocephalus in the Dog: Utility of Ultrasonography as an Alternate Diagnostic Imaging Technique" published in Journal of the American Animal Hospital Association in 1992. The question that this study actually addressed was whether ventricles and associated cerebrospinal fluid pathways could be investigated by ultrasound through

2277-436: The ages of 9 and 13 and is characterized by ovulation and menstruation ; the growth of secondary sex characteristics, such as growth of pubic and underarm hair , breast , uterine and vaginal growth, widening hips and increased height and weight, also occur during puberty. Male puberty sees the further development of the penis and testicles . The female inner sex organs are the two ovaries, their fallopian tubes ,

2346-435: The air and excretes carbon dioxide and water back into the air. First, air is pulled through the trachea into the lungs by the diaphragm pushing down, which creates a vacuum . Air is briefly stored inside small sacs known as alveoli (sing.: alveolus) before being expelled from the lungs when the diaphragm contracts again. Each alveolus is surrounded by capillaries carrying deoxygenated blood, which absorbs oxygen out of

2415-420: The air and into the bloodstream . For the respiratory system to function properly, there need to be as few impediments as possible to the movement of air within the lungs. Inflammation of the lungs and excess mucus are common sources of breathing difficulties. In asthma , the respiratory system is persistently inflamed, causing wheezing or shortness of breath . Pneumonia occurs through infection of

2484-400: The alveoli, and may be caused by tuberculosis . Emphysema , commonly a result of smoking , is caused by damage to connections between the alveoli. The urinary system consists of the two kidneys , two ureters , bladder , and urethra . It removes waste materials from the blood through urine, which carries a variety of waste molecules and excess ions and water out of the body. First,

2553-432: The anterior fontanelle is fully closed by 3 months of age. One of the more serious problems that can affect canines is known as an "open fontanelle", which occurs when the skull bones at the top of the head fail to close. The problem is often found in conjunction with hydrocephalus, which is a condition in which too much fluid is found within and around the brain, placing pressure on the brain and surrounding tissues. Often

2622-406: The beating of the heart . Venules and veins collect blood low in oxygen from tissues throughout the body. These collect in progressively larger veins until they reach the body's two largest veins, the superior and inferior vena cava , which drain blood into the right side of the heart. From here, the blood is pumped into the lungs where it receives oxygen and drains back into the left side of

2691-477: The belief that a molera is clinically irrelevant finding not associated with other structural abnormalities. Explanation of often misquoted veterinary sources (Greene and Braund / Rivers and Walker) Many internet sources state incorrectly that there was a study on molera performed by which (paraphrasing) "did not find an connection between moleras and hydrocephalus in toy breeds such as the Chihuahua". There

2760-427: The body contain bone marrow , the site of production of blood cells. Also, all bones are major storage sites for calcium and phosphate . This system can be split up into the muscular system and the skeletal system . The nervous system consists of the body's neurons and glial cells, which together form the nerves , ganglia and gray matter , which in turn form the brain and related structures. The brain

2829-423: The body in a stable state with safe levels of substances such as sugar and oxygen in the blood. Each system contributes to homeostasis, of itself, other systems, and the entire body. Some combined systems are referred to by joint names. For example, the nervous system and the endocrine system operate together as the neuroendocrine system . The nervous system receives information from the body, and transmits this to

Fontanelle - Misplaced Pages Continue

2898-441: The body to another. Paths of blood circulation within the human body can be divided into two circuits: the pulmonary circuit , which pumps blood to the lungs to receive oxygen and leave carbon dioxide , and the systemic circuit, which carries blood from the heart off to the rest of the body. The blood consists of fluid that carries cells in the circulation, including some that move from tissue to blood vessels and back, as well as

2967-558: The body. The adult male body is about 60% total body water content of some 42 litres (9.2 imp gal; 11 US gal). This is made up of about 19 litres (4.2 imp gal; 5.0 US gal) of extracellular fluid including about 3.2 litres (0.70 imp gal; 0.85 US gal) of blood plasma and about 8.4 litres (1.8 imp gal; 2.2 US gal) of interstitial fluid , and about 23 litres (5.1 imp gal; 6.1 US gal) of fluid inside cells. The content, acidity and composition of

3036-572: The brain is inaccessible to ultrasound imaging, because the bony skull presents an acoustic barrier. A very tense or bulging anterior fontanelle indicates raised intracranial pressure . Increased cranial pressure in infants may cause the fontanelles to bulge or the head to begin to enlarge abnormally. It can occur due to: A sunken (also called "depressed") fontanelle indicates dehydration or malnutrition . The fontanelles may be enlarged, may be slow to close, or may never close, most commonly due to causes like: Rarer causes include: Sometimes there

3105-412: The brain signals it to relax the urinary sphincter and release the urine into the urethra starting urination . A normal bladder can hold up to 16 ounces (half a liter) for 3–5 hours comfortably. Numerous diseases affect the urinary system including kidney stones , which are formed when materials in the urine concentrate enough to form a solid mass, urinary tract infections , which are infections of

3174-463: The brain via nerve impulses and neurotransmitters . At the same time, the endocrine system releases hormones, such as to help regulate blood pressure and volume. Together, these systems regulate the internal environment of the body, maintaining blood flow, posture, energy supply, temperature, and acid balance ( pH ). Development of the human body is the process of growth to maturity. The process begins with fertilisation, where an egg released from

3243-481: The buildup of plaque in the coronary arteries supplying the heart, eventually the arteries may become so narrow that not enough blood is able to reach the myocardium , a condition known as myocardial infarction or heart attack , this can cause heart failure or cardiac arrest and eventually death. Risk factors for coronary artery disease include obesity , smoking , high cholesterol , high blood pressure , lack of exercise and diabetes . Cancer can affect

3312-412: The cell numbers of all the organs of the body and cell types . The skin of the body is also host to billions of commensal organisms as well as immune cells. Not all parts of the body are made from cells. Cells sit in an extracellular matrix that consists of proteins such as collagen , surrounded by extracellular fluids. Cells in the body function because of DNA . DNA sits within the nucleus of

3381-447: The child's head to pass through the birth canal. The ossification of the bones of the skull causes the anterior fontanelle to close over by 9 to 18 months. The sphenoidal and posterior fontanelles close during the first few months of life. The closures eventually form the sutures of the neurocranium. Other than the anterior and posterior fontanelles, the mastoid fontanelle and the sphenoidal fontanelle are also significant. In humans,

3450-432: The covering of the body (the skin ), including hair and nails as well as other functionally important structures such as the sweat glands and sebaceous glands . The skin provides containment, structure, and protection for other organs, and serves as a major sensory interface with the outside world. The lymphatic system extracts, transports and metabolizes lymph, the fluid found in between cells. The lymphatic system

3519-698: The dogs in the study were 6 weeks old or less i.e. the study was predominantly in puppies not adult dogs. The older dog was a 5 year old Shih Tzu. In other words all the Chihuahua in this study were affected with hydrocephalus and molera; this study did not investigate presence or size of a molera and hydrocephalus. Kiviranta, A‐M, Rusbridge, C, Lappalainen, AK, Junnila, JJT, Jokinen, TS. Persistent fontanelles in Chihuahuas. Part II: Association with craniocervical junction abnormalities, syringomyelia, and ventricular volume. J Vet Intern Med. 2021; 1– 9. https://doi.org/10.1111/jvim.16123 Greene CE. Braund KG. Diseases of

SECTION 50

#1732772255991

3588-458: The form of proteins (which are broken down into amino acids ), fats , vitamins and minerals (the last of which are mainly ionic rather than molecular). After being swallowed , food moves through the gastrointestinal tract by means of peristalsis : the systematic expansion and contraction of muscles to push food from one area to the next. Digestion begins in the mouth , which chews food into smaller pieces for easier digestion. Then it

3657-433: The head will appear dome-shaped, and the open fontanelle is noticeable as a "soft spot" on the top of the dog's head. The fluid-filled spaces within the brain, known as ventricles, also become swollen. The increased pressure damages or prevents the development of brain tissue. Not all open fontanelles are connected with hydrocephalus. In many young dogs the skull bones are not fused at birth, but instead will close slowly over

3726-403: The heart , though it is exceedingly rare and has usually metastasized from another part of the body such as the lungs or breasts . This is because the heart cells quickly stop dividing and all growth occurs through size increase rather than cell division . The gallbladder is a hollow pear-shaped organ located posterior to the inferior middle part of the right lobe of the liver . It

3795-434: The heart. From here, it is pumped into the body's largest artery , the aorta , and then progressively smaller arteries and arterioles until it reaches tissue. Here, blood passes from small arteries into capillaries , then small veins and the process begins again. Blood carries oxygen , waste products, and hormones from one place in the body to another. Blood is filtered at the kidneys and liver . The body consists of

3864-490: The lateral, 3rd and cranial cerebral aqueduct. Ultrasound through the molera was also useful in revealing ventriculomegaly in 5 of 20 (supposedly) clinically normal dogs and these included Chihuahua (9 months old, mentation depressed), Lhasa Apso (5 weeks old), 2x Shih Tzu (3 and 5 weeks old) and Affenpinscher (9 weeks old – and returned to breeder because dull).The remaining 15 dogs (14 shih tzu and 1 Lhasa Apso) had normal ventricle size according to this ultrasound study. 14/15 of

3933-421: The lungs, to column-like cells that line the stomach . Endothelial cells are cells that line internal cavities including blood vessels and glands. Lining cells regulate what can and cannot pass through them, protect internal structures, and function as sensory surfaces. Organs , structured collections of cells with a specific function, mostly sit within the body, with the exception of skin . Examples include

4002-415: The movement of the heart via pericardial fluid . The heart works by pumping blood around the body allowing oxygen , nutrients , waste , hormones and white blood cells to be transported. The heart is composed of two atria and two ventricles . The primary purpose of the atria is to allow uninterrupted venous blood flow to the heart during ventricular systole . This allows enough blood to get into

4071-407: The nervous system. The purpose of the reproductive system is to reproduce and nurture the growth of offspring. The functions include the production of germ cells and hormones. The sex organs of the male reproductive system and the female reproductive system develops and mature at puberty . These systems include the internal and external genitalia . Female puberty generally occurs between

4140-432: The persistent bregmatic fontanelle (molera). There were 26 dogs in the study of which 6 had clinical hydrocephalous (i.e. were neurologically abnormal). Of the 6 dogs with clinical hydrocephalus (2 x chihuahua, 1 x poodle x, 1 x Pomeranian, 1 x Boston terrier and 1 x Yorkshire terrier), ultrasound through the molera was helpful in confirming the diagnosis of hydrocephalus noninvasively and provided information about dilation of

4209-415: The process of aging . Molera A Finnish study from (University of Helsinki with University of Surrey) found that increased number and size of persistent fontanelles in Chihuahuas were associated with small body size , syringomyelia (fluid filled cavities in the spinal cord), ventriculomegaly (i.e. enlargement of the lateral ventricles), and craniocervical junction abnormalities . The challenges

SECTION 60

#1732772255991

4278-434: The sequence of fontanelle closure is as follows: The fontanelle may pulsate, and although the precise cause of this is not known, it is normal and seems to echo the heartbeat, perhaps via the arterial pulse within the brain vasculature, or in the meninges . This pulsating action is how the soft spot got its name – fontanelle is borrowed from the old French word fontenele, which is a diminutive of fontaine, meaning "spring". It

4347-569: The skull of the Chihuahua should be domed, with or without the molera being present. However, the Fédération Cynologique Internationale (FCI) standard for the Chihuahua lists an open fontanelle as a disqualification. Human body The human body is the entire structure of a human being . It is composed of many different types of cells that together create tissues and subsequently organs and then organ systems . The external human body consists of

4416-422: The sutures is called craniosynostosis . After infancy, the anterior fontanelle is known as the bregma . An infant's skull consists of five main bones: two frontal bones , two parietal bones , and one occipital bone . These are joined by fibrous sutures , which allow movement that facilitates childbirth and brain growth . During birth, fontanelles enable the bony plates of the skull to flex, allowing

4485-525: The systems and organs of the human body and their functions. Many systems and mechanisms interact in order to maintain homeostasis , with safe levels of substances such as sugar , iron , and oxygen in the blood. The body is studied by health professionals , physiologists, anatomists, and artists to assist them in their work. The human body is composed of elements including hydrogen , oxygen , carbon , calcium and phosphorus . These elements reside in trillions of cells and non-cellular components of

4554-405: The urinary tract and can cause pain when urinating, frequent urination and even death if left untreated. Renal failure occurs when the kidneys fail to adequately filter waste from the blood and can lead to death if not treated with dialysis or kidney transplantation . Cancer can affect the bladder , kidneys , urethra and ureters , with the latter two being far more rare. Human anatomy

4623-417: The ventricles during atrial systole . Consequently, the atria allows a cardiac output roughly 75% greater than would be possible without them. The purpose of the ventricles is to pump blood to the lungs through the right ventricle and to the rest of the body through the left ventricle. The heart has an electrical conduction system to control the contraction and relaxation of the muscles. It starts in

4692-401: The water inside and outside cells is carefully maintained. The main electrolytes in body water outside cells are sodium and chloride , whereas within cells it is potassium and other phosphates . The body contains trillions of cells , the fundamental unit of life. At maturity, there are roughly 30 trillion cells, and 38 trillion bacteria in the body, an estimate arrived at by totaling

4761-424: Was no such study. This was an unreferenced statement, although it reflected clinical experience, and was made over 30 years ago in the 3rd edition of Ettinger's Veterinary Internal Medicine. This statement was not kept in subsequent editions and this tome is now being revised for the 9th edition. It is also incorrectly stated on multiple websites that there was "a separate study conducted by Dr. Walker and Dr. Rivers at

#990009