92-524: A brother ( pl. : brothers or brethren ) is a man or boy who shares one or more parents with another; a male sibling. The female counterpart is a sister . Although the term typically refers to a familial relationship, it is sometimes used endearingly to refer to non-familial relationships. A full brother is a first degree relative . The term brother comes from the Proto-Indo-European *bʰréh₂tēr, which becomes Latin frater , of
184-752: A gender binary in which man is one of the two genders, the other being woman . Most men are cisgender , and their gender identity aligns with their male sex assignment at birth. Trans men have a male gender identity that does not align with their female sex assignment at birth, and may undergo masculinizing hormone replacement therapy and/or sex reassignment surgery . Intersex men may have sex characteristics that do not fit typical notions of male biology. A 2016 systemic review estimated that 0.256% of people self-identify as female-to-male transgender. A 2017 survey of 80,929 Minnesota students found that roughly twice as many female-assigned adolescents self-identified as transgender, compared to adolescents with
276-569: A gender identity that does not align with their female sex assignment at birth, while intersex men may have sex characteristics that do not fit typical notions of male biology. The English term "man" is derived from the Proto-Indo-European root *man- (see Sanskrit / Avestan manu- , Slavic mǫž "man, male"). More directly, the word derives from Old English mann . The Old English form primarily meant "person" or "human being" and referred to men, women, and children alike. The Old English word for "man" as distinct from " woman " or "child"
368-417: A complex interface region known as the musculotendinous junction also known as the myotendinous junction , an area specialised for the primary transmission of force. At the muscle-tendon interface, force is transmitted from the sarcomeres in the muscle cells to the tendon. Muscles and tendons develop in close association, and after their joining at the myotendinous junction they constitute a dynamic unit for
460-558: A higher capability for electrochemical transmission of action potentials and a rapid level of calcium release and uptake by the sarcoplasmic reticulum. The fast twitch fibers rely on a well-developed, anaerobic , short term, glycolytic system for energy transfer and can contract and develop tension at 2–3 times the rate of slow twitch fibers. Fast twitch muscles are much better at generating short bursts of strength or speed than slow muscles, and so fatigue more quickly. The slow twitch fibers generate energy for ATP re-synthesis by means of
552-757: A higher density of capillaries . However, muscle cells cannot divide to produce new cells, and as a result there are fewer muscle cells in an adult than in a newborn. There are a number of terms used in the naming of muscles including those relating to size, shape, action, location, their orientation, and their number of heads. Broadly there are two types of muscle fiber: Type I , which is slow, and Type II which are fast. Type II has two divisions of type IIA (oxidative), and type IIX (glycolytic), giving three main fiber types. These fibers have relatively distinct metabolic, contractile, and motor unit properties. The table below differentiates these types of properties. These types of properties—while they are partly dependent on
644-462: A long term system of aerobic energy transfer. These mainly include the ATPase type I and MHC type I fibers. They tend to have a low activity level of ATPase, a slower speed of contraction with a less well developed glycolytic capacity. Fibers that become slow-twitch develop greater numbers of mitochondria and capillaries making them better for prolonged work. Individual muscles tend to be
736-491: A majority of on the job deaths. Further, medical doctors provide men with less service, less advice, and spend less time with men than they do with women per medical encounter. Male sexuality and attraction varies between individuals, and a man's sexual behavior can be affected by many factors, including evolved predispositions , personality , upbringing , and culture . While most men are heterosexual , significant minorities are homosexual or bisexual . Most cultures use
828-414: A male karyotype (XY). The SRY gene is typically found on the Y chromosome and causes the development of the testes, which in turn govern other aspects of male sex differentiation . Sex differentiation in males proceeds in a testes-dependent way while female differentiation is not gonad dependent. Primary sex characteristics (or sex organs) are characteristics that are present at birth and are integral to
920-400: A male sex assignment. Masculinity (also sometimes called manhood or manliness ) is the set of personality traits and attributes associated with boys and men. Although masculinity is socially constructed , some research indicates that some behaviors considered masculine are biologically influenced. To what extent masculinity is biologically or socially influenced is subject to debate. It
1012-432: A man's attractiveness to a heterosexual woman may increase with the more he resembles her brother, while his unattractiveness may increase the more his likeness diverges from her brother. Females with a twin or very close-in-age brother, sometimes view him as their male alter ego, or what they would have been like, if they had a Y chromosomes. The book Nicomachean Ethics, Book VIII written by Aristotle in 350 B.C.E., offers
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#17327663053181104-441: A man's wardrobe include shirts, trousers, suits, and jackets, which are designed to provide both comfort and style while prioritizing functionality. Men's fashion also encompasses more casual garments such as t-shirts , sweatshirts , jeans , shorts , and swimwear , which are typically intended for informal settings. Cultural and regional traditions often influence men's fashion, resulting in diverse styles and garments that reflect
1196-417: A mixture of various fiber types, but their proportions vary depending on the actions of that muscle. For instance, in humans, the quadriceps muscles contain ~52% type I fibers, while the soleus is ~80% type I. The orbicularis oculi muscle of the eye is only ~15% type I. Motor units within the muscle, however, have minimal variation between the fibers of that unit. It is this fact that makes
1288-468: A muscle, and are often termed as muscle fibers . A single muscle such as the biceps in a young adult male contains around 253,000 muscle fibers. Skeletal muscle fibers are multinucleated with the nuclei often referred to as myonuclei . This occurs during myogenesis with the fusion of myoblasts each contributing a nucleus. Fusion depends on muscle-specific proteins known as fusogens called myomaker and myomerger . Many nuclei are needed by
1380-479: A narrower pelvis and hips , and smaller breasts and nipples . Throughout human history , traditional gender roles have often defined men's activities and opportunities. Men often face conscription into military service or are directed into professions with high mortality rates . Many religious doctrines stipulate certain rules for men, such as religious circumcision . Men are over-represented as both perpetrators and victims of violence . Trans men have
1472-456: A number of different environmental factors. This plasticity can, arguably, be the strongest evolutionary advantage among organisms with muscle. In fish, different fiber types are expressed at different water temperatures. Cold temperatures require more efficient metabolism within muscle and fatigue resistance is important. While in more tropical environments, fast powerful movements (from higher fast-twitch proportions) may prove more beneficial in
1564-725: A proactive role, initiate the relationship, plan dates, and propose marriage. Anthropology has shown that masculinity itself has social status , just like wealth, race and social class. In Western culture , for example, greater masculinity usually brings greater social status. Many English words such as virtue and virile (from the Indo-European root vir meaning man ) reflect this. In most cultures, male privilege allows men more rights and privileges than women. In societies where men are not given special legal privileges, they typically hold more positions of power, and men are seen as being taken more seriously in society. This
1656-463: A reliance on glycolytic enzymes. Fibers can also be classified on their twitch capabilities, into fast and slow twitch. These traits largely, but not completely, overlap the classifications based on color, ATPase, or MHC ( myosin heavy chain ). Some authors define a fast twitch fiber as one in which the myosin can split ATP very quickly. These mainly include the ATPase type II and MHC type II fibers. However, fast twitch fibers also demonstrate
1748-483: A tendon. Multipennate muscles have fibers that are oriented at multiple angles along the force-generating axis, and this is the most general and most common architecture. Muscle fibers grow when exercised and shrink when not in use. This is due to the fact that exercise stimulates the increase in myofibrils which increase the overall size of muscle cells. Well exercised muscles can not only add more size but can also develop more mitochondria , myoglobin , glycogen and
1840-418: A way in which people should view the relationships between biological brothers. The relationship of brothers is laid out with the following quote: "The friendship of brothers has the characteristics found in that of comrades and in general between people who are like each other, is as much as they belong more to each other and start with a love for each other from their very birth, and in as much as those born to
1932-480: A woman. Since sperm that enters a woman's uterus and then fallopian tubes goes on to fertilize an egg which develops into a fetus or child, the male reproductive system plays no necessary role during the gestation . The study of male reproduction and associated organs is called andrology . Testosterone stimulates the development of the Wolffian ducts , the penis, and closure of the labioscrotal folds into
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#17327663053182024-516: Is armed conflicts , where men are often the immediate victims. A study of conflicts in 13 countries from 1955 to 2002 found that 81% of all violent war deaths were male. Apart from armed conflicts, areas with high incidence of violence, such as regions controlled by drug cartels , also see men experiencing higher mortality rates. This stems from social beliefs that associate ideals of masculinity with aggressive, confrontational behavior. Lastly, sudden and drastic changes in economic environments and
2116-541: Is distinct from the definition of the biological male sex , as both males and females can exhibit masculine traits. Men generally face social stigma for embodying feminine traits, more so than women do for embodying masculine traits. This can also manifest as homophobia . Standards of manliness or masculinity vary across different cultures and historical periods. While the outward signs of masculinity look different in different cultures, there are some common aspects to its definition across cultures. In all cultures in
2208-488: Is "fanciful" and all the historical evidence favours "the conclusion of the French classical scholar Claude de Saumaise " that it is derived from θρ , the contraction of a Greek epithet for Mars, θοῦρος ( Thouros ). Muscle mass Skeletal muscle (commonly referred to as muscle ) is one of the three types of vertebrate muscle tissue , the other being cardiac muscle and smooth muscle . They are part of
2300-400: Is a predominance of type II fibers utilizing glycolytic metabolism. Because of the discrepancy in fast twitch fibers compared to humans, chimpanzees outperform humans in power related tests. Humans, however, will do better at exercise in aerobic range requiring large metabolic costs such as walking (bipedalism). Across species, certain gene sequences have been preserved, but do not always have
2392-405: Is a slow twitch-fiber that can sustain longer contractions ( tonic ). In lobsters, muscles in different body parts vary in the muscle fiber type proportions based on the purpose of the muscle group. In the early development of vertebrate embryos, growth and formation of muscle happens in successive waves or phases of myogenesis . The myosin heavy chain isotype is a major determinant of
2484-485: Is an adult male human . Before adulthood, a male human is referred to as a boy (a male child or adolescent ). Like most other male mammals , a man's genome usually inherits an X chromosome from the mother and a Y chromosome from the father. Sex differentiation of the male fetus is governed by the SRY gene on the Y chromosome. During puberty, hormones which stimulate androgen production result in
2576-642: Is associated with a "gender-role strain" in which men face increased societal pressure to conform to gender roles. The earliest known recorded name of a man in writing is potentially Kushim , who would have lived sometime between 3400 and 3000 BC in the Sumerian city of Uruk ; though his name may have been a title rather than his actual name. The earliest confirmed names are that of Gal-Sal and his two slaves named En-pap X and Sukkalgir, from c. 3100 BC . Men may have children, whether biological or adopted ; such men are called fathers. The role of men in
2668-499: Is attached to other organelles such as the mitochondria by intermediate filaments in the cytoskeleton. The costamere attaches the sarcomere to the sarcolemma. Every single organelle and macromolecule of a muscle fiber is arranged to ensure that it meets desired functions. The cell membrane is called the sarcolemma with the cytoplasm known as the sarcoplasm . In the sarcoplasm are the myofibrils. The myofibrils are long protein bundles about one micrometer in diameter. Pressed against
2760-505: Is expressed in other mammals, so is still accurately seen (along with IIB) in the literature. Non human fiber types include true IIb fibers, IIc, IId, etc. Further fiber typing methods are less formally delineated, and exist on more of a spectrum. They tend to be focused more on metabolic and functional capacities (i.e., oxidative vs. glycolytic , fast vs. slow contraction time). As noted above, fiber typing by ATPase or MHC does not directly measure or dictate these parameters. However, many of
2852-399: Is not the same as ATPase fiber typing. Almost all multicellular animals depend on muscles to move. Generally, muscular systems of most multicellular animals comprise both slow-twitch and fast-twitch muscle fibers, though the proportions of each fiber type can vary across organisms and environments. The ability to shift their phenotypic fiber type proportions through training and responding to
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2944-778: Is overwhelmingly discriminatory , currently only ten countries include women in their conscription programs. Men continue to hold more dangerous jobs than women, even in developed countries. In the United States in 2020, ten times as many men died on the job as women, and a man was ten times more likely to die on the job than a woman. Media portrayals of men often replicate traditional understanding of masculinity. Men are portrayed more frequently in television than women and most commonly appear as leads in action and drama programming. Men are typically more active in television programming than women and typically hold more power and status. Due to their prominence, men are more likely to be both
3036-404: Is preceded by the formation of connective tissue frameworks, usually formed from the somatic lateral plate mesoderm . Myoblasts follow chemical signals to the appropriate locations, where they fuse into elongated multinucleated skeletal muscle cells. Between the tenth and the eighteenth weeks of gestation, all muscle cells have fast myosin heavy chains; two myotube types become distinguished in
3128-523: Is stigmatized. Domestic violence against men is similarly stigmatized, although men make up half of the victims in heterosexual couples. Opponents of circumcision describe it as a human rights violation. The fathers' rights movement seeks to support separated fathers that do not receive equal rights to care for their children. The men's movement is the response to issues faced by men in Western countries. It includes pro-feminist groups such as
3220-572: Is surrounded by a type of connective tissue layer of fascia . Muscle fibers are formed from the fusion of developmental myoblasts in a process known as myogenesis resulting in long multinucleated cells. In these cells the nuclei , termed myonuclei , are located along the inside of the cell membrane . Muscle fibers also have multiple mitochondria to meet energy needs. Muscle fibers are in turn composed of myofibrils . The myofibrils are composed of actin and myosin filaments called myofilaments , repeated in units called sarcomeres, which are
3312-417: Is the role of the older brother to be a positive influence on the development of the younger brother's upbringing when it comes to the education of ethics and good actions. When positive characteristics are properly displayed to the younger brother by the older brother, these habits and characteristics are imitated and foster an influential understanding of good ethics and positive actions. Man A man
3404-427: Is unclear. This finding does, however, suggest that although sibling conflict is a risk factor for risk taking behaviour, sibling warmth does not serve as a protective factor. Some studies suggest that girls having an older brother delays the onset of menarche by roughly one year. Research also suggests that the likelihood of being gay increases with the more older brothers a man has. Some analyzers have suggested that
3496-457: Is used in fiber typing vs. MHC typing, and some ATPase types actually contain multiple MHC types. Also, a subtype B or b is not expressed in humans by either method . Early researchers believed humans to express a MHC IIb, which led to the ATPase classification of IIB. However, later research showed that the human MHC IIb was in fact IIx, indicating that the IIB is better named IIX. IIb
3588-449: The erector spinae and small vertebral muscles, and are innervated by the dorsal rami of the spinal nerves . All other muscles, including those of the limbs are hypaxial, and innervated by the ventral rami of the spinal nerves. During development, myoblasts (muscle progenitor cells) either remain in the somite to form muscles associated with the vertebral column or migrate out into the body to form all other muscles. Myoblast migration
3680-487: The men's liberation movement , and anti-feminist groups such as the manosphere . The Mars symbol (♂) is a common symbol that represents the male sex. The symbol is identical to the planetary symbol of Mars . It was first used to denote sex by Carl Linnaeus in 1751. The symbol is sometimes seen as a stylized representation of the shield and spear of the Roman god Mars . According to Stearn, however, this derivation
3772-458: The pectoral , and abdominal muscles ; intrinsic and extrinsic muscles are subdivisions of muscle groups in the hand , foot , tongue , and extraocular muscles of the eye . Muscles are also grouped into compartments including four groups in the arm , and the four groups in the leg . Apart from the contractile part of a muscle consisting of its fibers, a muscle contains a non-contractile part of dense fibrous connective tissue that makes up
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3864-580: The sarcolemma . The myonuclei are quite uniformly arranged along the fiber with each nucleus having its own myonuclear domain where it is responsible for supporting the volume of cytoplasm in that particular section of the myofiber. A group of muscle stem cells known as myosatellite cells , also satellite cells are found between the basement membrane and the sarcolemma of muscle fibers. These cells are normally quiescent but can be activated by exercise or pathology to provide additional myonuclei for muscle growth or repair. Muscles attach to tendons in
3956-438: The sexually dimorphic phenotypic traits that distinguish between the sexes, but—unlike the primary sex characteristics—are not directly part of the reproductive system . Secondary sexual characteristics that are specific to men include: Men weigh more than women. On average, men are taller than women by about 10%. On average, men have a larger waist in comparison to their hips (see waist–hip ratio ) than women. In women,
4048-436: The tendon at each end. The tendons attach the muscles to bones to give skeletal movement. The length of a muscle includes the tendons. Connective tissue is present in all muscles as deep fascia . Deep fascia specialises within muscles to enclose each muscle fiber as endomysium ; each muscle fascicle as perimysium , and each individual muscle as epimysium . Together these layers are called mysia . Deep fascia also separates
4140-410: The vasa deferentia and ejaculatory ducts , tubular structures that transfer the mature sperm to the urethra. The external male genitalia consist of the penis , an organ that expels semen , and the scrotum , a pouch of skin housing the testicles. The male reproductive system's function is to produce semen , which carries sperm and thus genetic information that can unite with an egg within
4232-465: The voluntary muscular system and typically are attached by tendons to bones of a skeleton . The skeletal muscle cells are much longer than in the other types of muscle tissue, and are also known as muscle fibers . The tissue of a skeletal muscle is striated – having a striped appearance due to the arrangement of the sarcomeres . A skeletal muscle contains multiple fascicles – bundles of muscle fibers. Each individual fiber, and each muscle
4324-552: The "head of household" and held additional social privileges. Men have traditionally held jobs that were not available to women. Such jobs tended to be either more strenuous, more prestigious, or more dangerous. Modern men increasingly take untraditional career paths, such as staying home and raising children while their partner works. Modern men tend to work longer than women, which impacts their ability to spend time with their families. Even in modern times, some jobs remain available only to men, such as military service. Conscription
4416-438: The associated related changes, not a change in fiber type. There are numerous methods employed for fiber-typing, and confusion between the methods is common among non-experts. Two commonly confused methods are histochemical staining for myosin ATPase activity and immunohistochemical staining for myosin heavy chain (MHC) type. Myosin ATPase activity is commonly—and correctly—referred to as simply "fiber type", and results from
4508-443: The basic functional, contractile units of the muscle fiber necessary for muscle contraction . Muscles are predominantly powered by the oxidation of fats and carbohydrates , but anaerobic chemical reactions are also used, particularly by fast twitch fibers . These chemical reactions produce adenosine triphosphate (ATP) molecules that are used to power the movement of the myosin heads . Skeletal muscle comprises about 35% of
4600-668: The body of humans by weight. The functions of skeletal muscle include producing movement, maintaining body posture, controlling body temperature, and stabilizing joints. Skeletal muscle is also an endocrine organ . Under different physiological conditions, subsets of 654 different proteins as well as lipids, amino acids, metabolites and small RNAs are found in the secretome of skeletal muscles. Skeletal muscles are substantially composed of multinucleated contractile muscle fibers (myocytes). However, considerable numbers of resident and infiltrating mononuclear cells are also present in skeletal muscles. In terms of volume, myocytes make up
4692-432: The common cold found that doctors underrate the symptoms of men, and are more willing to attribute symptoms and illness to women than men. Women live longer than men in all countries, and across all age groups, for which reliable records exist. In the United States, men are less healthy than women across all social classes. Non-white men are especially unhealthy. Men are over-represented in dangerous occupations and represent
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#17327663053184784-444: The development of secondary sexual characteristics that result in even more differences between the sexes. These include greater muscle mass , greater height, the growth of facial hair and a lower body fat composition. Male anatomy is distinguished from female anatomy by the male reproductive system , which includes the testicles , sperm ducts , prostate gland and epididymides , and penis . Secondary sex characteristics include
4876-545: The direct assaying of ATPase activity under various conditions (e.g. pH ). Myosin heavy chain staining is most accurately referred to as "MHC fiber type", e.g. "MHC IIa fibers", and results from determination of different MHC isoforms . These methods are closely related physiologically, as the MHC type is the primary determinant of ATPase activity. However, neither of these typing methods is directly metabolic in nature; they do not directly address oxidative or glycolytic capacity of
4968-531: The environment has served organisms well when placed in changing environments either requiring short explosive movements (higher fast twitch proportion) or long duration of movement (higher slow twitch proportion) to survive. Bodybuilding has shown that changes in muscle mass and force production can change in a matter of months. Some examples of this variation are described below. American lobster , Homarus americanus , has three fiber types including fast twitch fibers, slow-twitch and slow-tonic fibers. Slow-tonic
5060-555: The family has shifted considerably in the 20th and 21st centuries, taking on a more active role in raising children in most societies. Men would traditionally marry a woman when raising children, but in modern times many countries now allow for same-sex marriage , and for those couples to raise children either via adoption or surrogacy . Men may be single parents , and are increasingly so in modern times, though women are three times more likely to be single parents than men. In paternal societies, men have typically have been regarded as
5152-399: The fascicles can vary in their relationship to one another, and to their tendons. These variations are seen in fusiform , strap , and convergent muscles . A convergent muscle has a triangular or fan-shape as the fibers converge at its insertion and are fanned out broadly at the origin. A less common example of a parallel muscle is a circular muscle such as the orbicularis oculi , in which
5244-438: The fiber. When "type I" or "type II" fibers are referred to generically, this most accurately refers to the sum of numerical fiber types (I vs. II) as assessed by myosin ATPase activity staining (e.g. "type II" fibers refers to type IIA + type IIAX + type IIXA ... etc.). Below is a table showing the relationship between these two methods, limited to fiber types found in humans. Subtype capitalization
5336-461: The fibers are longitudinally arranged, but create a circle from origin to insertion. These different architectures, can cause variations in the tension that a muscle can create between its tendons. The fibers in pennate muscles run at an angle to the axis of force generation. This pennation angle reduces the effective force of any individual fiber, as it is effectively pulling off-axis. However, because of this angle, more fibers can be packed into
5428-593: The fibers of a skeletal muscle. It is thought that by performing endurance type events for a sustained period of time, some of the type IIX fibers transform into type IIA fibers. However, there is no consensus on the subject. It may well be that the type IIX fibers show enhancements of the oxidative capacity after high intensity endurance training which brings them to a level at which they are able to perform oxidative metabolism as effectively as slow twitch fibers of untrained subjects. This would be brought about by an increase in mitochondrial size and number and
5520-510: The great majority of skeletal muscle. Skeletal muscle myocytes are usually very large, being about 2–3 cm long and 100 μm in diameter. By comparison, the mononuclear cells in muscles are much smaller. Some of the mononuclear cells in muscles are endothelial cells (which are about 50–70 μm long, 10–30 μm wide and 0.1–10 μm thick), macrophages (21 μm in diameter) and neutrophils (12-15 μm in diameter). However, in terms of nuclei present in skeletal muscle, myocyte nuclei may be only half of
5612-403: The groups of muscles into muscle compartments. Two types of sensory receptors found in muscles are muscle spindles , and Golgi tendon organs . Muscle spindles are stretch receptors located in the muscle belly. Golgi tendon organs are proprioceptors located at the myotendinous junction that inform of a muscle's tension . Skeletal muscle cells are the individual contractile cells within
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#17327663053185704-467: The higher end of any sport tend to demonstrate patterns of fiber distribution e.g. endurance athletes show a higher level of type I fibers. Sprint athletes, on the other hand, require large numbers of type IIX fibers. Middle-distance event athletes show approximately equal distribution of the two types. This is also often the case for power athletes such as throwers and jumpers. It has been suggested that various types of exercise can induce changes in
5796-405: The human body, making up around 40% of body weight in healthy young adults. In Western populations, men have on average around 61% more skeletal muscle than women. Most muscles occur in bilaterally-placed pairs to serve both sides of the body. Muscles are often classed as groups of muscles that work together to carry out an action. In the torso there are several major muscle groups including
5888-451: The index and ring fingers tend to be either more similar in size or their index finger is slightly longer than their ring finger, whereas men's ring finger tends to be longer. The internal male genitalia consist of the testicles , gonads that produce male gametes called sperm , the prostate , seminal vesicles , and bulbourethral glands , accessory glands that partake in sperm health, the epididymides , organs that store sperm cells, and
5980-432: The inside of the sarcolemma are the unusual flattened myonuclei. Between the myofibrils are the mitochondria . While the muscle fiber does not have smooth endoplasmic cisternae, it contains sarcoplasmic reticulum . The sarcoplasmic reticulum surrounds the myofibrils and holds a reserve of the calcium ions needed to cause a muscle contraction. Periodically, it has dilated end sacs known as terminal cisternae . These cross
6072-549: The long run. In rodents such as rats, the transitory nature of their muscle is highly prevalent. They have high percentage of hybrid muscle fibers and have up to 60% in fast-to-slow transforming muscle. Environmental influences such as diet, exercise and lifestyle types have a pivotal role in proportions of fiber type in humans. Aerobic exercise will shift the proportions towards slow twitch fibers, while explosive powerlifting and sprinting will transition fibers towards fast twitch. In animals, "exercise training" will look more like
6164-436: The loss of social safety nets , in particular social subsidies and food stamps, have also been linked to higher levels of alcohol consumption and psychological stress among men, leading to a spike in male mortality rates. This is because such situations often makes it harder for men to provide for their family, a task that has been long regarded as the "essence of masculinity." A retrospective analyses of people infected with
6256-438: The muscle fiber from one side to the other. In between two terminal cisternae is a tubular infolding called a transverse tubule (T tubule). T tubules are the pathways for action potentials to signal the sarcoplasmic reticulum to release calcium, causing a muscle contraction. Together, two terminal cisternae and a transverse tubule form a triad . All muscles are derived from paraxial mesoderm . During embryonic development in
6348-468: The neck that show a potential inverse trend of fiber type percentages (one muscle has high percentage of fast twitch, while the complementary muscle will have a higher percentage of slow twitch fibers). The complementary muscles of turtles had similar percentages of fiber types. Chimpanzee muscles are composed of 67% fast-twitch fibers and have a maximum dynamic force and power output 1.35 times higher than human muscles of similar size. Among mammals, there
6440-536: The need for long durations of movement or short explosive movements to escape predators or catch prey. Skeletal muscle exhibits a distinctive banding pattern when viewed under the microscope due to the arrangement of two contractile proteins myosin , and actin – that are two of the myofilaments in the myofibrils . The myosin forms the thick filaments, and actin forms the thin filaments, and are arranged in repeating units called sarcomeres . The interaction of both proteins results in muscle contraction. The sarcomere
6532-491: The nuclei present, while nuclei from resident and infiltrating mononuclear cells make up the other half. Considerable research on skeletal muscle is focused on the muscle fiber cells, the myocytes, as discussed in detail in the first sections, below. However, recently, interest has also focused on the different types of mononuclear cells of skeletal muscle, as well as on the endocrine functions of muscle, described subsequently, below. There are more than 600 skeletal muscles in
6624-407: The objects and instigators of humorous or disparaging content. Fathers are often portrayed in television as either idealized and caring or clumsy and inept. In advertising, men are disproportionately featured in advertisements for alcohol, vehicles, and business products. Men's clothing typically encompasses a range of garments designed for various occasions, seasons, and styles. Fundamental items of
6716-612: The others. Most skeletal muscles in a human contain(s) all three types, although in varying proportions. Traditionally, fibers were categorized depending on their varying color, which is a reflection of myoglobin content. Type I fibers appear red due to the high levels of myoglobin. Red muscle fibers tend to have more mitochondria and greater local capillary density. These fibers are more suited for endurance and are slow to fatigue because they use oxidative metabolism to generate ATP ( adenosine triphosphate ). Less oxidative Type II fibers are white due to relatively low myoglobin and
6808-750: The past, and still among traditional and non-Western cultures, getting married is the most common and definitive distinction between boyhood and manhood. In the late 20th century, some qualities traditionally associated with marriage (such as the "triple Ps" of protecting, providing, and procreating ) were still considered signs of having achieved manhood. Platonic relationships are not significantly different between men and women, though some differences do exist. Friendships involving men tend to be based more on shared activities than self-disclosure and personal connection. Perceptions of friendship involving men varies among cultures and time periods. In heterosexual romantic relationships, men are typically expected to take
6900-511: The process of somitogenesis the paraxial mesoderm is divided along the embryo 's length to form somites , corresponding to the segmentation of the body most obviously seen in the vertebral column . Each somite has three divisions, sclerotome (which forms vertebrae ), dermatome (which forms skin), and myotome (which forms muscle). The myotome is divided into two sections, the epimere and hypomere, which form epaxial and hypaxial muscles , respectively. The only epaxial muscles in humans are
6992-587: The properties of individual fibers—tend to be relevant and measured at the level of the motor unit, rather than individual fiber. Slow oxidative (type I) fibers contract relatively slowly and use aerobic respiration to produce ATP. Fast oxidative (type IIA) fibers have fast contractions and primarily use aerobic respiration, but because they may switch to anaerobic respiration (glycolysis), can fatigue more quickly than slow oxidative fibers. Fast glycolytic (type IIX) fibers have fast contractions and primarily use anaerobic glycolysis. The FG fibers fatigue more quickly than
7084-592: The reproductive process. For men, primary sex characteristics include the penis and testicles . Adult humans exhibit sexual dimorphism in many other characteristics, many of which have no direct link to reproductive ability. Humans are sexually dimorphic in body size, body structure, and body composition. Men tend to be taller and heavier than women, and adjusted for height, men tend to have greater lean and bone mass than women, and lower fat mass. Secondary sex characteristics are features that appear during puberty in humans . Such features are especially evident in
7176-463: The same functional purpose. Within the zebrafish embryo, the Prdm1 gene down-regulates the formation of new slow twitch fibers through direct and indirect mechanisms such as Sox6 (indirect). In mice, the Prdm1 gene is present but does not control slow muscle genes in mice through Sox6 . In addition to having a genetic basis, the composition of muscle fiber types is flexible and can vary with
7268-428: The same meaning. Sibling warmth or affection between male siblings has been correlated to some more negative effects. In pairs of brothers, higher sibling warmth is related to more risk taking behaviour, although risk taking behaviour is not related to sibling warmth in any other type of sibling pair. The cause of this phenomenon in which sibling warmth is only correlated with risk taking behaviours in brother pairs still
7360-399: The same muscle volume, increasing the physiological cross-sectional area (PCSA). This effect is known as fiber packing, and in terms of force generation, it more than overcomes the efficiency-loss of the off-axis orientation. The trade-off comes in overall speed of muscle shortening and in the total excursion. Overall muscle shortening speed is reduced compared to fiber shortening speed, as is
7452-431: The same parents and brought up together and similarly educated are more akin in character; and the test of time has been applied most fully and convincingly in their case". For these reasons, it is the job of the older brother to influence the ethics of the younger brother by being a person of good action. Aristotle says "by imitating and reenacting the acts of good people, a child becomes habituated to good action". Over time
7544-504: The scrotum. Another significant hormone in sexual differentiation is the anti-Müllerian hormone , which inhibits the development of the Müllerian ducts . For males during puberty, testosterone, along with gonadotropins released by the pituitary gland , stimulates spermatogenesis . While a majority of the global health gender disparities is weighted against women, there are situations in which men tend to fare poorer. One such instance
7636-524: The size principal of motor unit recruitment viable. The total number of skeletal muscle fibers has traditionally been thought not to change. It is believed there are no sex or age differences in fiber distribution; however, proportions of fiber types vary considerably from muscle to muscle and person to person. Among different species there is much variation in the proportions of muscle fiber types. Sedentary men and women (as well as young children) have 45% type II and 55% type I fibers. People at
7728-432: The skeletal muscle cell for the large amounts of proteins and enzymes needed to be produced for the cell's normal functioning. A single muscle fiber can contain from hundreds to thousands of nuclei. A muscle fiber for example in the human biceps with a length of 10 cm can have as many as 3,000 nuclei. Unlike in a non-muscle cell where the nucleus is centrally positioned, the myonucleus is elongated and located close to
7820-526: The specific fiber type. In zebrafish embryos, the first muscle fibers to form are the slow twitch fibers. These cells will undergo migration from their original location to form a monolayer of slow twitch muscle fibers. These muscle fibers undergo further differentiation as the embryo matures. In larger animals, different muscle groups will increasingly require different fiber type proportions within muscle for different purposes. Turtles , such as Trachemys scripta elegans , have complementary muscles within
7912-423: The total distance of shortening. All of these effects scale with pennation angle; greater angles lead to greater force due to increased fiber packing and PCSA, but with greater losses in shortening speed and excursion. Types of pennate muscle are unipennate , bipennate , and multipennate . A unipennate muscle has similarly angled fibers that are on one side of a tendon. A bipennate muscle has fibers on two sides of
8004-406: The transmission of force from muscle contraction to the skeletal system. Muscle architecture refers to the arrangement of muscle fibers relative to the axis of force generation , which runs from a muscle's origin to its insertion . The usual arrangements are types of parallel , and types of pennate muscle . In parallel muscles, the fascicles run parallel to the axis of force generation, but
8096-531: The unique characteristics of different parts of the world. Men traditionally received more education than women as a result of single-sex education . Universal education, meaning state-provided primary and secondary education independent of gender, is not yet a global norm, even if it is assumed in most developed countries. In the 21st century, the balance has shifted in many developed nations, and men now lag behind women in education. Men are more likely than women to be faculty at universities. In 2020, 90% of
8188-449: The various methods are mechanistically linked, while others are correlated in vivo . For instance, ATPase fiber type is related to contraction speed, because high ATPase activity allows faster crossbridge cycling . While ATPase activity is only one component of contraction speed, Type I fibers are "slow", in part, because they have low speeds of ATPase activity in comparison to Type II fibers. However, measuring contraction speed
8280-472: The world's men were literate , compared to 87% of women. But sub-Saharan Africa, and southwest Asia lagged behind the rest of the world; only 72% of men in sub-Saharan Africa were literate. In most societies, men have more legal and cultural rights than women. and misogyny is far more prevalent than misandry in society. While one in six male experiences sexual assault , men typically receive less support after being victims of it, and rape of males
8372-439: The younger brother will develop the good actions of the older brother as well and be like him. Aristotle also adds this on the matter of retaining the action of doing good once imitated: "Once the habits of ethics or immorality become entrenched, they are difficult to break." The good habits that are created by the influence of the older brother become habit in the life of the younger brother and turn out to be seemingly permanent. It
8464-464: Was wer . Mann only came to mean "man" in Middle English, replacing wer , which survives today only in the compounds " werewolf " (from Old English werwulf , literally "man-wolf"), and " wergild ", literally "man-payment". In humans, sperm cells carry either an X or a Y sex chromosome. If a sperm cell carrying a Y chromosome fertilizes the female ovum , the offspring will have
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