Anatomy And Physiology Quotes

In examining disease, we gain wisdom about anatomy and physiology and biology. In examining the person with disease, we gain wisdom about life.

That's because only a real artist knows the actual anatomy of the terrible or the physiology of fear - the exact sort of lines and proportions that connect up with latent instincts or hereditary memories of fright, and the proper colour contrasts and lighting effects to stir the dormant sense of strangeness.

My fundamental premise about the brain is that its workings—what we sometimes call “mind”—are a consequence of its anatomy and physiology, and nothing more. —CARL SAGAN

Any magazine-cover hack can splash paint around wildly and call it a nightmare, or a witches sabbath or a portrait of the devil; but only a great painter can make such a thing really scare or ring true. That's because only a real artist knows the anatomy of the terrible, or the physiology of fear.

But it so happens that everything on this planet is, ultimately, irrational; there is not, and cannot be, any reason for the causal connexion of things, if only because our use of the word "reason" already implies the idea of causal connexion. But, even if we avoid this fundamental difficulty, Hume said that causal connexion was not merely unprovable, but unthinkable; and, in shallower waters still, one cannot assign a true reason why water should flow down hill, or sugar taste sweet in the mouth. Attempts to explain these simple matters always progress into a learned lucidity, and on further analysis retire to a remote stronghold where every thing is irrational and unthinkable. If you cut off a man's head, he dies. Why? Because it kills him. That is really the whole answer. Learned excursions into anatomy and physiology only beg the question; it does not explain why the heart is necessary to life to say that it is a vital organ. Yet that is exactly what is done, the trick that is played on every inquiring mind. Why cannot I see in the dark? Because light is necessary to sight. No confusion of that issue by talk of rods and cones, and optical centres, and foci, and lenses, and vibrations is very different to Edwin Arthwait's treatment of the long-suffering English language. Knowledge is really confined to experience. The laws of Nature are, as Kant said, the laws of our minds, and, as Huxley said, the generalization of observed facts. It is, therefore, no argument against ceremonial magic to say that it is "absurd" to try to raise a thunderstorm by beating a drum; it is not even fair to say that you have tried the experiment, found it would not work, and so perceived it to be "impossible." You might as well claim that, as you had taken paint and canvas, and not produced a Rembrandt, it was evident that the pictures attributed to his painting were really produced in quite a different way. You do not see why the skull of a parricide should help you to raise a dead man, as you do not see why the mercury in a thermometer should rise and fall, though you elaborately pretend that you do; and you could not raise a dead man by the aid of the skull of a parricide, just as you could not play the violin like Kreisler; though in the latter case you might modestly add that you thought you could learn. This is not the special pleading of a professed magician; it boils down to the advice not to judge subjects of which you are perfectly ignorant, and is to be found, stated in clearer and lovelier language, in the Essays of Thomas Henry Huxley.

Although man has included meat in his diet for thousands of years, his anatomy and physiology, and the chemistry of his digestive juices, are still unmistakably those of a frugivorous animal.

There is no doubt that the Old Testament is a physiological and anatomical textbook to those capable of reading it from a scientific viewpoint.

Obstetricians also doubted the female intellectual capacity to grasp the anatomy and physiology of childbirth, and suggested that they could not therefore be trained. But the root fear was – guess what? – you’ve got it, but no prizes for quickness: money.

It was in Alexandria that the circumference of the earth was first measured, the sun fixed at the center of the solar system, the workings of the brain and the pulse illuminated, the foundations of anatomy and physiology established, the definitive editions of Homer produced. It was in Alexandria that Euclid had codified geometry.

Anatomy is to physiology as geography is to history; it describes the theatre of events.

My pre-med studies in anatomy and physiology at Oxford had not prepared me in the least for real medicine.

Descartes was very interested in anatomy and physiology and regarded a tiny organ in the center of the brain, called the pineal gland, as the principal seat of the soul. That gland, he believed, was the place where all our thoughts are formed, the wellspring of our free will.

It was in Alexandria that the circumference of the earth was first measured, the sun fixed at the center of the solar system, the workings of the brain and the pulse illuminated, the foundations of anatomy and physiology established, the definitive editions of Homer produced.

Those who have dissected or inspected many [bodies] have at least learnt to doubt; while others who are ignorant of anatomy and do not take the trouble to attend it are in no doubt at all.

Fortunately, most of our vital physiological functions are involuntary, as some amongst us would forget them.

What do you study?" "As much as we know of the different sciences. We have, within our limits, a good deal of knowledge of anatomy, physiology, nutrition—all that pertains to a full and beautiful personal life. We have our botany and chemistry, and so on—very rudimentary, but interesting; our own history, with its accumulating psychology." "You put psychology with history—not with personal life?" "Of course. It is ours; it is among and between us, and it changes with the succeeding and improving generations. We are at work, slowly and carefully, developing our whole people along these lines. It is glorious work—splendid! To see the thousands of babies improving, showing stronger clearer minds, sweeter dispositions, higher capacities—don't you find it so in your country?

But the fact remains: in terms of physiology and anatomy, we fit together like two jigsaw pieces, much as our voices merged into one, complementing each other, when we sang the song that later became ‘ours’.

Obstetricians also doubted the female intellectual capacity to grasp the anatomy and physiology of childbirth, and suggested that they could not therefore be trained. But the root fear was – guess what? – you’ve got it, but no prizes for quickness: money. Most doctors charged a routine one guinea for a delivery. The word got around that trained midwives would undercut them by delivering babies for half a guinea! The knives were out.

In short, what Brown, Enquist, and West are saying is that evolution structured our circulatory systems as fractal networks to approximate a “fourth dimension” so as to make our metabolisms more efficient. As West, Brown, and Enquist put it, “Although living things occupy a three-dimensional space, their internal physiology and anatomy operate as if they were four-dimensional … Fractal geometry has literally given life an added dimension.

Violence and terrorism are not just low physiological arousal,97 yet this is certainly one of the active ingredients that, when combined with other influences, can move us toward a more complete understanding of killers like Kaczynski.

Just as the human body doesn’t have a single “most important” organ, several elements are essential for the creation of life. In the following section, you’ll find information on those elements and their chemical significance (as well as physiological important).

My teammates and I cut wide eyes with each other, not really understanding our emotions in that moment. Of course, we felt awkward, embarrassed, and uncomfortable. I remember specifically feeling betrayed. I thought of how our privacy as females had been entirely dismissed, violated, and ignored. There was no thought to how we would respond or how uncomfortable a male sharing this changing space with us would make us feel. It felt like we were pawns in a sick game catering to the male who claimed our identity but didn’t have the same physiology, anatomy, or chromosomes, to name a few… I desperately wanted to call my mom and dad and tell them of this situation in hopes they would reassure me that I wasn’t crazy in experiencing this as a total violation of our rights to privacy as women.

You have to imagine what it was like to be on the receiving end of vicious antagonism: sneering, contempt, ridicule, slights about one’s intelligence, integrity and motives. In those days, women even ran the risk of dismissal for their opinions. And this treatment came from other women, as well as men. In fact, “in-fighting” between various schools of nurses who had some sort of training in midwifery was particularly nasty. One eminent lady – the matron of St Bartholomew’s Hospital – branded the aspiring midwives as “anachronisms, who would in the future be regarded as historical curiosities”. The medical opposition seems to have arisen mainly from the fact that “women are striving to interfere too much in every department of life”.* Obstetricians also doubted the female intellectual capacity to grasp the anatomy and physiology of childbirth, and suggested that they could not therefore be trained. But the root fear was – guess what? – you’ve got it, but no prizes for quickness: money. Most doctors charged a routine one guinea for a delivery. The word got around that trained midwives would undercut them by delivering babies for half a guinea! The knives were out.

The basic sciences of anatomy, physiology, biology, and chemistry are linked to a patient at the bedside through very specific stories that doctors learn and eventually create. These stories, what researchers now call illness scripts, contain key characteristics of a disease to form an iconic version, an idealized model of that particular disease. … It is the story that every doctor puts together for herself with the knowledge she gains from books and patients. The more experience a doctor has with any of these illnesses, the richer and more detailed the illness script she has of the disease becomes.

It is the function which permits us to understand the organism. Thus, when they are inborn, anatomical structures should be considered as topographical conditions of the original functional development, modifiable by the function itself and thus comparable to the electrode which governs the phenomenon of electrolysis but is altered by it in return; when they are acquired, they should be considered the result of the most habitual functioning; thus anatomy should be considered as a stage in the development of physiology. Finally, if it were established that the nerve processes in each situation always tend to re-establish certain states of preferred equilibrium, these latter would represent the objective values of the organism and one would have the right to classify behavior as ordered or disordered, significant or insignificant, with respect to them. These denominations, far from being extrinsic and anthropomorphic, would belong in the living being as such.

When the time came to graduate, he was placed last on the honors list for physiology and comparative anatomy. His professor William Carpenter cited the reason for this slight in a letter to him: “I think it as well to let you know the reason why I found it requisite to place you there.… As answers to my questions, your papers were so defective, that if it had not been for the amount of original observation of which they bore evidence, I could not have placed you in the honours list at all.

[...] we have in our treatise a series of fifty-seven examinations, almost exclusively of injuries of the human body forming a group of observations furnishing us with the earliest known nucleus of fact regarding the anatomy, physiology and pathology of the human body. Crude and elementary as they are, the method by which they were collected was scientific, and these observations, together with the diagnoses and the explanatory commentary in the ancient glosses, form the oldest body of science now extant.

As long as museums and universities send out expeditions to bring to light new forms of living and extinct animals and new data illustrating the interrelations of organisms and their environments, as long as anatomists desire a broad comparative basis human for anatomy, as long as even a few students feel a strong curiosity to learn about the course of evolution and relationships of animals, the old problems of taxonomy, phylogeny and evolution will gradually reassert themselves even in competition with brilliant and highly fruitful laboratory studies in cytology, genetics and physiological chemistry.

Do you consider yourself athletic? How would you rate yourself, say, as a swimmer? Average, below average, maybe a little above average? So-so? Terrible? Well, I’ve got news for you: whether you know it or not, you are a world-class super-Olympic gold medal swimmer. I’m not kidding. You know how I know that? Because I took anatomy, physiology, bacteriology, and chemistry in college, as part of my science minor. And here’s what I learned: we all start out the same way, as tiny sperm cells. In order for you to be born, assuming your daddy had an average sperm count, you had to have out-swum some 200,000 other sperm. And it was uphill all the way. Now, I do not know what motivated you, but that little tail was wiggling like mad, and you were screaming, “Out of my way! Out of my way! I want to teach school! I want to dance! I want to be in real estate! I want to be a journalist!” or whatever it was you were screaming at the top of your little sperm voice.

The Yoruba terms obinrin and okunrin do express a distinction. Reproduction is, obviously, the basis of human existence, and given its import, and the primacy of anafemale [anatomical female] body-type, it is not surprising that the Yoruba language describes the two types of anatomy. The terms okunrin and obinrin, however, merely indicate the physiological differences between the two anatomies as they have to do with procreation and intercourse. They refer, then, to the physically marked and physiologically apparent differences between the two anatomies. They do not refer to gender categories that connote social privileges and disadvantages. Also, they do not express sexual dimorphism because the distinction they indicate is specific to issues of reproduction. To appreciate this point, it would be necessary to go back to the fundamental difference between the conception of the Yoruba social world and that of Western societies.” “… I argued that the biological determinism in much of Western thought stems from the application of biological explanations in accounting for social hierarchies. This in turn has led to the construction of the social world with biological building blocks. Thus the social and the biological are thoroughly intertwined. This worldview is manifested in male-dominant gender discourses, discourses in which female biological differences are used to explain female sociopolitical disadvantages. The conception of biology as being ‘everywhere’ makes it possible to use it as an explanation in any realm, whether it is directly implicated or not. Whether the question is why women should not vote or why they breast-feed babies, the explanation is one and the same: they are biologically predisposed.” “The upshot of this cultural logic is that men and women are perceived as essentially different creatures. Each category is defined by its own essence. Diane Fuss describes the notion that things have a ‘true essence … as a belief in the real, the invariable and fixed properties which define the whatness of an entity.’ Consequently, whether women are in the labor room or in the boardroom, their essence is said to determine their behavior. In both arenas, then, women’s behavior is by definition different from that of men. Essentialism makes it impossible to confine biology to one realm. The social world, therefore, cannot truly be socially constructed.

when we consider DNA, the genotype is the DNA sequence that contains instructions for the living organism. The phenotype is the observable characteristics of an organism, such as its anatomy, biochemistry, physiology, and behavior. The genotype interacts with the environment to produce the phenotype. To put this in an everyday situation, consider the blueprint as a house’s genotype and the actual house its phenotype. The phenotypic construction process is the building of the house using the blueprint as information about what and how to do it. The phenotype is related to the genotype that describes it, but there is a world of physical difference between the genotype and the phenotype and even the phenotypic construction process. For one, the genotype is non-dynamic; it is a quiescent, one-dimensional sequence of symbols (DNA’s symbols are nucleotides) that has no energy or time constraints. Like a blueprint, it can sit around for years, as you have probably learned from watching CSI. The genotype dictates what should be constructed (perhaps a really cute dog), but the DNA itself does not look or act anything like a cute dog. On the other hand, the phenotype (the cute dog) is dynamic and uses energy, especially if it is a border collie.

different directional terms you’ll need to memorize when you study human anatomy. These are the terms that tell you which things are higher

the hospital seemed perfectly designed to immobilize not only his body but his spirit. “The will to live is not a theoretical abstraction, but a physiological reality with therapeutic characteristics,” he wrote in Anatomy of an Illness. But the hospital environment tended to stifle that will to live.

We already know that if an impulse of intelligence wants to do something, then it does it to find its outlet, using intellect, mind, senses and matter. Intelligence can create a physiology in which thoughts of healing take place but it can also create the reverse. If we were like a computer "hard-wired," then every physiology would be predictable; in reality, there is no physiology there. Intelligence creates new circuits at will which makes each individual unique. Any life experience changes the anatomy of the brain.

Although irises come in different colors (iris = rainbow), they contain only brown pigment. When they have a lot of pigment, the eyes appear brown or black. If the amount of pigment is small and restricted to the posterior surface of the iris, the unpigmented parts simply scatter the shorter wavelengths of light and the eyes appear blue, green, or gray. Most newborn babies’ eyes are slate gray or blue because their iris pigment is not yet developed.

The cornea has no blood vessels and so it is beyond the reach of the immune system. As a result, the cornea is the only tissue in the body that can be transplanted from one person to another with little risk of rejection.

I was getting dressed back into my clothes from my practice suit when it was like someone unplugged the sound. Dead silence. My back was turned toward the door, but before I even turned around, I knew what this silence meant. It would answer my curious question of what the locker room would look like. Upon turning around and shifting my eyes upward to the 6′4″ Thomas, I immediately felt the inherent need to cover my chest, as someone with a male gaze and a male voice entered the room. Some of the girls grabbed towels, shirts, or whatever was close by and covered the exposed parts of their body. Other girls looked the other way. We were all in various stages of nakedness. None of us said a word. I can’t accurately put into words the feelings of violation when hearing a man’s voice in the locker room where you are fully nude. Thomas walked toward the corner of the locker room and began to change out of a women’s practice suit and get naked. Right in front of us. No introduction, no “Excuse me,” no explanation, no privacy for us. My teammates and I cut wide eyes with each other, not really understanding our emotions in that moment. Of course, we felt awkward, embarrassed, and uncomfortable. I remember specifically feeling betrayed. I thought of how our privacy as females had been entirely dismissed, violated, and ignored. There was no thought to how we would respond or how uncomfortable a male sharing this changing space with us would make us feel. It felt like we were pawns in a sick game catering to the male who claimed our identity but didn’t have the same physiology, anatomy, or chromosomes, to name a few… I desperately wanted to call my mom and dad and tell them of this situation in hopes they would reassure me that I wasn’t crazy in experiencing this as a total violation of our rights to privacy as women.

A significant percentage (50–75 percent) of blastocysts fail to implant;

The fundamental problem of psychology concerns the possibility of changing human behavior, not in the sense of normality, but in the sense of healthiness. The total understanding of the functioning of the neurological system must be composed of two parts: a formal one, to understand the psychic systems in themselves – a field explored by psychology and psychoanalysis; to other material, understanding the physiological and biochemical functioning of the brain, a field explored by medicine. Without complete understanding, psychology remains a phenomenology with little materiality and medicine an anatomy without formal organicity.

Let others bring knowledge of anatomy and physiology, of pharmacology and statistics. What Lainey brings to her husband is faith. Hope. And an abiding love.

So when you are next making love to that special person, and enjoying all the physiological pleasures afforded by our anatomy, give a little cry of joy for the ancient armored placoderm and all that it has given us. Because of some strange twist of biological fate, we have kept one of the most interesting parts of our reproductive anatomy from our archaic evolutionary history when other lines of animals managed to do perfectly well without it.

■Articular cartilages, which cover the ends of most bones at movable joints ■Costal cartilages, which connect the ribs to the sternum (breastbone) ■Respiratory cartilages, which form the skeleton of the larynx (voicebox) and reinforce other respiratory passageways ■Nasal cartilages, which support the external nose

■Hormone production. Bones produce osteocalcin, a hormone which not only helps regulate bone formation, but also protects against obesity, glucose intolerance, and diabetes mellitus. (Osteocalcin is discussed further in Chapter 16.)

Diaphysis A tubular diaphysis (di-af9ĭ-sis; dia 5 through, physis 5 growth), or shaft, forms the long axis of the bone. It is constructed of a relatively thick collar of compact bone that surrounds a central medullary cavity (med9u-lar-e; “middle”), or marrow cavity. In adults, the medullary cavity contains fat (yellow marrow) and is called the yellow marrow cavity.

Epiphyses The epiphyses (e-pif9ĭ-sēz; singular: epiphysis) are the bone ends (epi 5 upon). In many cases, they are broader than the diaphysis. An outer shell of compact bone forms the epiphysis exterior and their interior contains spongy bone. A thin layer of articular (hyaline) cartilage covers the joint surface of each epiphysis, cushioning the opposing bone ends during movement and absorbing stress.

A delicate connective tissue membrane called the endosteum (en-dos9te-um; “within the bone”) covers internal bone surfaces (Figure 6.4).

All of these except for the osteoclasts originate from mesenchymal cells. Each cell type is essentially a specialized form of the same basic cell type that transforms to a mature or functional form that serves bone growth in some specific way (Figure 6.5). Bone cells, like other connective tissue cells, are surrounded by an extracellular matrix of their making.

Only a few cells thick, trabeculae contain irregularly arranged lamellae and osteocytes interconnected by canaliculi. No osteons are present. Nutrients reach the osteocytes of spongy bone by diffusing through the canaliculi from capillaries in the endosteum surrounding the trabeculae.

Chemical Composition of Bone Bone contains both organic and inorganic substances. Organic components include bone cells and osteoid. Its inorganic components are mineral salts.

Bone’s resilience is thought to come from sacrificial bonds in or between collagen molecules. These bonds stretch and break easily on impact, dissipating energy to prevent the force from rising to a fracture value. In the absence of continued or additional trauma, most of the sacrificial bonds re-form.

Healthy bone is half as strong as steel in resisting compression and fully as strong as steel in resisting tension.

Ossification and osteogenesis (os0te-o-jen9ĕ-sis) are synonyms meaning the process of bone formation (os 5 bone, genesis 5 beginning).

In embryos this process leads to the formation of the bony skeleton.

Later another form of ossification known as bone growth goes on until early adulthood as the body increases in size. Bones are capable of growing thicker throughout life. However, ossification in adults serves mainly for bone remodeling and repair.

Before week 8, the skeleton of a human embryo is constructed entirely from fibrous membranes and hyaline cartilage.

Bone tissue begins to develop at about this time and eventually replaces most of the existing fibrous or cartilage structures.

■In endochondral ossification (endo 5 within, chondro 5 cartilage), a bone develops by replacing hyaline cartilage.

The resulting bone is called a cartilage, or endochondral, bone.

■In intramembranous ossification, a bone develops from a fibrous membrane and the bone is called a membrane bone.

The beauty of using flexible structures (membranes and cartilages) to fashion the embryonic skeleton is that they can accommodate mitosis. Were the early skeleton composed of calcified bone tissue from the outset, growth would be much more difficult.

Except for the clavicles, essentially all bones below the base of the skull form by endochondral ossification (en0do-kon9dral).

Beginning late in the second month of development, this process uses hyaline cartilage “bones” formed earlier as models, or patterns, for bone construction.

It is more complex than intramembranous ossification because the hyaline cartilage must be broken down as ossification proceeds.

Cartilage in the center of the diaphysis calcifies and then develops cavities.

This deterioration opens up cavities, but the bone collar stabilizes the hyaline cartilage model.

The periosteal bud invades the internal cavities and spongy bone forms.

In month 3, the forming cavities are invaded by a collection of elements called the periosteal bud,

which contains a nutrient artery and vein, nerve fibers, red marrow elements, osteogenic cells, and osteoclasts.

The entering osteoclasts partially erode the calcified cartilage matrix, and the osteogenic cells become osteoblasts and secrete osteoid around the remaining calcified fragments of hyaline cartilage, forming bone-covered cartilage trabeculae. In this way, the earliest version of spongy bone forms in a developing long bone.

The diaphysis elongates and a medullary cavity forms.

As the primary ossification center enlarges, osteoclasts break down the newly formed spongy bone and open up a medullary cavity in the center of the diaphysis.

The organic components of bone include its cells (osteogenic cells, osteoblasts, osteocytes, bone-lining cells, and osteoclasts) and osteoid (os9te-oid), the organic part of the matrix.

Because of the mineral salts they contain, bones last long after death and provide an enduring “monument.” In fact, skeletal remains many centuries old can still reveal the shapes and sizes of ancient peoples, the kinds of work they did, and many of the ailments they suffered, such as arthritis. Growth arrest lines, horizontal lines on long bones, provide visible proof of illness when the body uses nutrients to fight disease and the bones stop growing.

Inorganic Components The balance of bone tissue (65% by mass) consists of inorganic hydroxyapatites (hi-drok0se-ap9ah-tītz), or mineral salts, largely calcium phosphates present as tiny, tightly packed, needlelike crystals in and around collagen fibers in the extracellular matrix. The crystals account for the most notable characteristic of bone—its exceptional hardness, which allows it to resist compression.

Osteoid, which makes up approximately one-third of the matrix, includes ground substance (composed of proteoglycans and glycoproteins) and collagen fibers, both of which are made and secreted by osteoblasts. These organic substances, particularly collagen, contribute both to a bone’s structure and to the flexibility and tensile strength that allow it to resist stretch and twisting.

The proper combination of organic and inorganic matrix elements makes bone exceedingly durable and strong without being brittle.

Skeletal muscle has a rich blood supply. This is understandable because contracting muscle fibers use huge amounts of energy and require almost continuous delivery of oxygen and nutrients via the arteries.

■Skeletal and smooth muscle cells (but not cardiac muscle cells) are elongated, and for this reason, they are called muscle fibers.

muscle stretching that occurs during eccentric contractions causes microtears in the muscles.

Skeletal muscles are described as voluntary, but even relaxed muscles are almost always slightly contracted, a phenomenon called muscle tone.

Muscle fatigue is a state of physiological inability to contract even though the muscle still may be receiving stimuli.

Subspecialty : Botany Studies : plants Subspecialty : Zoology Studies : animals Subspecialty : Marine biology Studies : organisms living in and around oceans, and seas Subspecialty : Fresh water biology Studies : organisms living in and around freshwater lakes, streams, rivers, ponds, etc. Subspecialty : Microbiology Studies : microorganisms Subspecialty : Bacteriology Studies : bacteria Subspecialty : Virology Studies : viruses ( see Figure below ) Subspecialty : Entomology Studies : insects Subspecialty : Taxonomy Studies : the classification of organisms Subspecialty : Studies : Life Science : Cell biology What it Examines : cells and their structures (see Figure below ) Life Science : Anatomy What it Examines : the structures of animals Life Science : Morphology What it Examines : the form and structure of living organisms Life Science : Physiology What it Examines : the physical and chemical functions of tissues and organs Life Science : Immunology What it Examines : the mechanisms inside organisms that protect them from disease and infection Life Science : Neuroscience What it Examines : the nervous system Life Science : Developmental biology and embryology What it Examines : the growth and development of plants and animals Life Science : Genetics What it Examines : the genetic make up of all living organisms (heredity) Life Science : Biochemistry What it Examines : the chemistry of living organisms Life Science : Molecular biology What it Examines : biology at the molecular level Life Science : Epidemiology What it Examines : how diseases arise and spread Life Science : What it Examines : Life Science : Ecology What it Examines : how various organisms interact with their environments Life Science : Biogeography What it Examines : the distribution of living organisms (see Figure below ) Life Science : Population biology What it Examines : the biodiversity, evolution, and environmental biology of populations of organisms Life Science : What it Examines :

Whether or not fatigue occurs, vigorous exercise alters a muscle’s chemistry dramatically. For a muscle to return to its resting state, all the following must occur:

■Its oxygen reserves in myoglobin must be replenished.

■ The accumulated lactic acid must be reconverted to pyruvic acid.

■Glycogen stores must be replaced.

■ATP and creatine phosphate reserves must be resynthesized.

Once exercise stops, the repayment process begins.

Only about 40% of the energy released during muscle contraction is converted to useful work (still, this percentage is significantly higher than that of many mechanical devices).

Muscles are distinguished by their ability to transform chemical energy (ATP) into directed mechanical energy. In so doing, they become capable of exerting force.

But the power problem has its roots in anatomy and biochemistry and temperament. Power has to be curbed on the legal and political levels; that’s obvious. But it’s also obvious that there must be prevention on the individual level. On the level of instinct and emotion, on the level of the glands and the viscera, the muscles and the blood. If I can ever find the time, I’d like to write a little book on human physiology in relation to ethics, religion, politics and law.

Up there, you see, where the stars drew a path and the comet fire lit the way? That was where she found her purpose.

Biology, physiology, and anatomy have less to do with our chairs than pharaohs, kings, and executives,” she writes. One kind of historical chair, called the “klismos” by historians, evolved primarily as an historical expression of status and rank. Setting a body higher than and apart from other people, in an individual structure with rigid, flat planes—a throne, if you will—evolved as a way of recognizing an individual’s power or leadership, with the earliest known models dating to ancient Egypt and southeastern Europe. Their use as an expression of authority continued through the Middle Ages and the Renaissance, and the endurance of this symbolism lives on as metaphor in many contemporary leadership titles; to chair the committee or the department, or to sit in the designated “director’s chair” on a film set, is still to hold a seat of power.

larynx (pp. 352–354), and (2) smaller intrinsic muscles that control tension in the glottal vocal folds or that open and close the glottis. These smaller muscles insert on the thyroid, arytenoid, and corniculate cartilages. The opening or closing of the glottis involves rotational movements of the arytenoid cartilages. When you swallow, both sets of muscles work together to prevent food or drink from entering the glottis. Food is crushed and chewed into a pasty mass, known as a bolus, before being swallowed. Muscles of the neck and pharynx then elevate the larynx, bending the epiglottis over the glottis, so that the bolus can glide across the epiglottis rather than falling into the larynx. While this movement is under way, the glottis is closed. Foods or liquids that touch the vestibular folds or glottis trigger the coughing reflex. In a cough, the glottis is kept closed while the chest and abdominal muscles contract, compressing the lungs. When the glottis is opened suddenly, a blast of air from the trachea ejects material that blocks the entrance to the glottis. Sound Production How do you produce sounds? Air passing through your open glottis vibrates its vocal folds and produces sound waves. The pitch of the sound depends on the diameter, length, and tension in your vocal folds. The diameter and length are directly related to the size of your larynx. You control the tension by contracting voluntary muscles that reposition the arytenoid cartilages relative to the thyroid cartilage. When the distance increases, your vocal folds tense and the pitch rises. When the distance decreases, your vocal folds relax and the pitch falls. Children have slender, short vocal folds, so their voices tend to be high pitched. At puberty, the larynx of males enlarges much more than that of females. The vocal cords of an adult male are thicker and longer, so they produce lower tones than those of an adult female. Sound production at the larynx is called phonation (fo.-NA .-shun; phone, voice). Phonation is one part of speech production. Clear speech also requires articulation, the modification of those sounds by voluntary movements of other structures, such as the tongue, teeth, and lips to form words. In a stringed instrument, such as a guitar, the quality of the sound produced does not depend solely on the nature of the vibrating string. Rather, the entire instrument becomes involved as the walls vibrate and the composite sound echoes within the hollow body. Similar amplification and resonance take place within your pharynx, oral cavity, nasal cavity, and paranasal sinuses. The combination gives you the particular and distinctive sound of your voice. That sound changes when you have a sinus infection and your nasal cavity and paranasal sinuses are filled with mucus rather than air.

An infection or inflammation of the larynx is known as laryngitis (lar-in-JI .-tis). It commonly affects the vibrational qualities of the vocal folds. Hoarseness is the most familiar result. Mild cases are temporary and seldom serious. However, bacterial or viral infections of the epiglottis can be very dangerous. The resulting swelling may close the glottis and cause suffocation. This condition, acute epiglottitis (ep-ih-glot-TI .-tis), can develop rapidly after a bacterial infection of the throat. Young children are most likely to be affected. The Trachea The trachea (TRA .-ke.-uh), or windpipe, is a tough, flexible tube with a diameter of about 2.5 cm (1 in.) and a length of about 11 cm (4.33 in.) (Figure 23–6). The trachea begins anterior to vertebra C6 in a ligamentous attachment to the cricoid cartilage. It ends in the mediastinum, at the level of vertebra T5, where it branches to form the right and left main bronchi. The epithelium of the trachea is continuous with that of the larynx. The mucosa of the trachea resembles that of the nasal cavity and nasopharynx (look back at Figure 23–2a). The submucosa (sub-mu.-KO .-suh), a thick layer of connective tissue, surrounds the mucosa. The submucosa contains tracheal glands whose mucous secretions reach the tracheal lumen through a number of short ducts. The trachea contains 15–20 tracheal cartilages that stiffen the tracheal walls and protect the airway (see Figure 23–6a). They also prevent it from collapsing or overexpanding as pressure changes in the respiratory system. Each tracheal cartilage is C-shaped. The closed portion of the C protects the anterior and lateral surfaces of the trachea. The open portion of the C faces posteriorly, toward the esophagus (see Figure 23–6b). Because these cartilages are not continuous, the posterior tracheal wall can easily distort when you swallow, allowing large masses of food to pass through the esophagus. An elastic anular ligament and the trachealis, a band of smooth muscle, connect the ends of each tracheal cartilage (see Figure 23–6b). Contraction of the trachealis reduces the diameter of the trachea. This narrowing increases the tube’s resistance to airflow. The normal diameter of the trachea changes from moment to moment, primarily under the control of the sympathetic division of the ANS. Sympathetic stimulation increases the diameter of the trachea and makes it easier to move large volumes of air along the respiratory passageways.

anatomy means the cutting up of the body to examine its parts.

As with the ducks, Brennan’s theory rewrites the fortunes of the female dolphin, transforming her from victim to victor in the battle of the sexes. The more we discover about female sexual anatomy, physiology and behaviour, the more centuries of perceived male dominance begin to wane.

In a 7-year clinical trial, researchers found that yoga is safe and effective in managing both osteoarthritis and rheumatoid arthritis. After an 8-week yoga class, participants showed a reduction in pain by 25 percent, along with statistically significant improvements in physical fitness and quality of life.

The sheep don’t need to be instructed by a zoologist to seek escape if a tiger approaches; it knows by its signature and without argumentation that it is its enemy. Is it not much more important for the sheep to know the ferocious character of the tiger than to be informed that the latter belongs to the genus Felis? If, by some miracle, a sheep should become intellectual, it might learn so much about the external form, anatomy, physiology, and genealogy of the tiger that it would lose sight of its internal character and be devoured by it. Absurd as this example may appear, it is nevertheless the true representation of what is done in your schools daily. There the rising generation receives what they call a scientific education. They are taught all about the external form of humans and how that form may be comfortably fed, lodged, and housed. However, the sight of the real human who occupies that form is entirely lost. Their needs are neglected, starved, ill-treated, and tortured, and some of your ‘great lights of science’ have become so short-sighted that they even deny they exist.

Adults have about 5 litres (11 pt) of blood circulating around the body.