Chapter 1 Introduction to Anatomy Physiology Expected Learning

Chapter 1 Introduction to Anatomy & Physiology

• Expected Learning Outcomes – Define anatomy and physiology and relate them to each other. – Describe several ways of studying human anatomy. – Define a few subdisciplines of human physiology.

Anatomy • Describes the structures of the body: – what they are made of – where they are located – associated structures

Physiology • Is the study of: – functions of anatomical structures – individual and cooperative functions

Specialties of Anatomy (1 of 3) • Gross anatomy, or macroscopic anatomy examines large, visible structures: – surface anatomy: • exterior features – regional anatomy: • body areas

Specialties of Anatomy (2 of 3) – systemic anatomy: • groups of organs working together – developmental anatomy: • from egg (embryology) to maturity – clinical anatomy: • medical specialties

Specialties of Anatomy (3 of 3) • Microscopic anatomy examines cells and molecules: – cytology: • cells and their structures • cyt = cell – histology: • tissues and their structures

Specialties of Physiology • Cell physiology: – processes within and between cells • Special physiology: – functions of specific organs • Systemic physiology: – functions of an organ system • Pathological physiology: – effects of diseases

Scientific Method • Expected Learning Outcomes – Describe the inductive and hypothetico– deductive methods of obtaining scientific knowledge. – Describe some aspects of experimental design that help to ensure objective and reliable results. – Explain what is meant by hypothesis, fact, law, and theory in science. 1 -9

The Scientific Method: A powerful way of “knowing”. 1. Starts with a question or problem, based on observations of the natural world. 2. Propose a hypothesis, a possible answer that presents a reasonable explanation or solution. 3. Make a prediction that tests the hypothesis. 4. Design an experiment to see if the prediction is correct. Example: 1. Problem: The computer cannot connect to the internet. 2. Hypothesis: The cable is faulty. 3. Prediction: If I use the cable from my roommate’s laptop, which is working, I should be able to connect. 4. Experiment: Connect the known good cable and try to connect. 5. (Using a cable that is known to be good and changing just that one thing while keeping the rest the same provides a “control”)

The Inductive Method • Described by Francis Bacon – Making numerous observations until one becomes confident in drawing generalizations and predictions from them – Knowledge of anatomy obtained by this method • Proof in science – Reliable observations – Tested and confirmed repeatedly – Not falsified by any credible observation • In science, all truth is tentative – “Proof beyond a reasonable doubt” 1 -11

The Hypothetico–Deductive Method • More physiological knowledge gained by this method • Investigator asks a question • Formulates a hypothesis—an educated speculation or possible answer to the question – Characteristics of a good hypothesis • Consistent with what is already known • Testable and possibly falsifiable with evidence 1 -12

The Hypothetico–Deductive Method • Falsifiability—if we claim something is scientifically true, we must be able to specify what evidence it would take to prove it wrong • Hypothesis—to suggest a method for answering questions: written as “if–then” statements 1 -13

Facts, Laws, and Theories • Scientific fact – Information that can be independently verified by a trained person • Law of nature – Generalization about the predictable way matter and energy behave • Results from inductive reasoning and repeated observations • Written as verbal statements or mathematical formulae • Theory – An explanatory statement or set of statements derived from facts, laws, and confirmed hypotheses • Summarizes what we know • Suggests direction for further study 1 -14

Human Origins and Adaptations • Expected Learning Outcomes – Explain why evolution is relevant to understanding human form and function. – Define evolution and natural selection. – Describe some human characteristics that can be attributed to the tree-dwelling habits of earlier primates. – Describe some human characteristics that evolved later in connection with upright walking. 1 -15

Human Origins and Adaptations • Charles Darwin – On the Origin of Species by Means of Natural Selection (1859)—‟the book that shook the world” – The Descent of Man (1871)—human evolution, anatomy and behavior, relationship to other animals • Theory of natural selection – How species originate and change through time – Changed prevailing view of our origin, nature and our place in the universe – Increases understanding of human form and function 1 -16

Evolution, Selection, and Adaptation • Evolution – Change in genetic composition of population of organisms • Development of bacterial resistance to antibiotics • Appearance of new strains of AIDS virus • Natural selection – Some individuals within a species have hereditary advantage over their competitors • Better camouflage • Disease resistance • Ability to attract mates – Selection pressures—natural forces that promote the reproductive success of some individuals more than others 1 -17

Evolution, Selection, and Adaptation • Adaptations—features of an organism’s anatomy, physiology, or behavior that have evolved in response to these selection pressures and enable the organism to cope with the challenges of its environment – Model—animal species selected for research on a particular problem 1 -18

Evolution, Selection, and Adaptation • Closest relative: chimpanzee – Difference of only 1. 6% in DNA structure – Chimpanzees and gorillas differ by 2. 3% • Study of evolutionary relationships – Help us chose animals for biomedical research (the animal model) – Rats and mice used extensively due to issues involved with using chimpanzees 1 -19

Vestiges of Human Evolution • Vestigial organs—remnants of organs that apparently were better developed and more functional in the ancestors of a species, and now serve little or no purpose – Piloerector muscle – Auricularis muscles 1 -20

Our Basic Primate Adaptations • Primates—order of mammals to which humans, monkeys, and apes belong • Earliest primates – Squirrel-sized, arboreal, insect-eating African mammals – Moved to trees due to safety, food supply, and lack of competition 1 -21

Our Basic Primate Adaptations • Adaptations for arboreal (treetop) lifestyle – Mobile shoulders – Opposable thumbs made hands prehensile to grasp branches and encircle them with the thumb and finger – Forward-facing eyes (stereoscopic vision) • Depth perception for leaping and catching prey – Color vision • Distinguish ripe fruit and young, less toxic foliage – Larger brains and good memory • Remember food sources and improved social organization 1 -22

Our Basic Primate Adaptations Copyright © The Mc. Graw-Hill Companies, Inc. Permission required for reproduction or display. Monkey Human Figure 1. 5 Figure 1. 6 1 -23

Walking Upright • African forest became grassland 4 to 5 million years ago – Producing more predators and less protection • Bipedalism—standing and walking on two legs – Helps spot predators, carry food or infants • Adaptations for bipedalism – Skeletal and muscular modifications – Increased brain volume – Family life and social changes 1 -24

Walking Upright • Australopithecus—oldest bipedal primate • Homo genus (appeared 2. 5 million years ago) – Taller, larger brain volume, probable speech, toolmaking • Homo erectus (appeared 1. 8 million years ago) – Migrated from Africa to parts Asia 1 -25

Walking Upright • Other Homo species discovered recently still matter of considerable debate • Homo sapiens originated in Africa 200, 000 years ago – Sole surviving hominid species 1 -26

Human Structure • Expected Learning Outcomes – List the levels of human structure from the most complex to the simplest. – Discuss the value of both reductionistic and holistic viewpoints to understanding human form and function. – Discuss the clinical significance of anatomical variation among humans. 1 -27

The Hierarchy of Structural Organization

The Hierarchy of Complexity Copyright © The Mc. Graw-Hill Companies, Inc. Permission required for reproduction or display. • Organism is composed of organ systems Organism • Organ systems composed of organs • Organs composed of tissues • Tissues composed of cells Organ system Tissue Organ • Cells composed of organelles Cell • Organelles composed of molecules • Molecules composed of atoms Macromolecule Organelle Atom Molecule Figure 1. 7 1 -29

Organizing a Muscle • • • Protein molecules (chemical level) Protein filaments (organelle level) Muscle cells (cellular level) Cardiac muscle tissue (tissue level) Heart (organ level)

Anatomical Variation • No two humans are exactly alike – 70% most common structure – 30% anatomically variant – Variable number of organs • Missing muscles, extra vertebrae, renal arteries – Variation in organ locations (situs solitus, situs inversus, dextrocardia, situs perversus) 1 -31

Anatomical Variation Copyright © The Mc. Graw-Hill Companies, Inc. Permission required for reproduction or display. Normal Pelvic kidney Horseshoe kidney Figure 1. 8 Normal 1 -32 Variations in branches of the aorta

Human Function • Expected Learning Outcomes – State the characteristics that distinguish living organisms from nonliving objects. – Explain the importance of defining a reference man and woman. – Define homeostasis and explain why this concept is central to physiology. – Define negative feedback, give an example of it, and explain its importance to homeostasis. – Define positive feedback and give examples of its beneficial and harmful effects. 1 -33

Homeostasis and Negative Feedback • Homeostasis—the body’s ability to detect change, activate mechanisms that oppose it, and thereby maintain relatively stable internal conditions • Claude Bernard (1813– 78) – Constant internal conditions regardless of external conditions • Internal body temperature ranges from 97°– 99°F despite variations in external temperature 1 -34

Mechanisms of Regulation • Autoregulation (intrinsic): – automatic response in a cell, tissue, or organ • Extrinsic regulation: – responses controlled by nervous and endocrine systems

Negative Feedback Loop • Body senses a change and activates mechanisms to reverse it— dynamic equilibrium • Because feedback mechanisms alter the original changes that triggered them (temperature, for example), they are called feedback loops Copyright © The Mc. Graw-Hill Companies, Inc. Permission required for reproduction or display. Room temperature fallsto 66°F(19°C) 1 C 10° 15° 20° 25° 6 Room cools down F 50° 60° 70° 80° 2 C 10° 15° 20° 25° Thermost atactivates furnace F 50° 60° 70° 80° Figure 1. 9 a 5 Thermostat shuts off furnace 4 Room temperature rises to 70°F (21°C) 3 Heat output (a) 1 -36

Negative Feedback Copyright © The Mc. Graw-Hill Companies, Inc. Permission required for reproduction or display. Room temperature (o. F) 75 (b) Furnace turned off at 70 o. F 70 Set point 68 o. F 65 Furnace turned on at 66 o. F 60 Figure 1. 9 b Time • Example: Room temperature does not stay at set point of 68°F —it only averages 68°F 1 -37

Negative Feedback Copyright © The Mc. Graw-Hill Companies, Inc. Permission required for reproduction or display. Core body temperature Sweating 37. 5 o. C (99. 5 o. F) Vasodilation 37. 0 o. C (98. 6 o. F) 36. 5 o. C (97. 7 o. F) Set point Vasoconstriction Figure 1. 10 Time Shivering • Example: Brain senses change in blood temperature – If too warm, vessels dilate (vasodilation) in the skin and sweating begins (heat-losing mechanism) – If too cold, vessels in the skin constrict (vasoconstriction) and shivering begins (heat-gaining mechanism) 1 -38

Homeostasis and Negative Feedback • Sitting up in bed causes a drop in blood pressure in the head and upper torso region (local imbalance in homeostasis); detected by baroreceptors • Baroreceptors (sensory nerve endings) in the arteries near the heart alert the cardiac center in the brainstem. They transmit to the cardiac center 1 -39

Homeostatis and Negative Feedback • Sitting up in bed causes a drop in blood pressure in the head and upper torso region (local imbalance in homeostasis); detected by baroreceptors • Baroreceptors (sensory nerve endings) in the arteries near the heart alert the cardiac center in the brainstem. They transmit to the cardiac center 1 -40

Homeostatis and Negative Feedback • Cardiac center sends nerve signals that increase the heart rate and return the blood pressure to normal; regulates heart rate • Failure of this to feedback loop may produce dizziness in the elderly 1 -41

Postural Change in Blood Pressure Copyright © The Mc. Graw-Hill Companies, Inc. Permission required for reproduction or display. Person rises from bed Blood pressure rises to normal; homeostasis is restored Cardiac center accelerates heartbeat Blood drains from upper body, creating homeostatic imbalance Baroreceptors above heart respond to drop in blood pressure Figure 1. 11 Baroreceptors send signals to cardiac center of brainstem

Homeostasis and Negative Feedback • Receptor—senses change in the body (e. g. , stretch receptors that monitor blood pressure) • Integrating (control) center—control center that processes the sensory information, “makes a decision, ” and directs the response (e. g. , cardiac center of the brain) • Effector—carries out the final corrective action to restore homeostasis (e. g. , cell or organ) 1 -43

Positive Feedback and Rapid Change • Self-amplifying cycle – Leads to greater change in the same direction – Feedback loop is repeated—change produces more change • Normal way of producing rapid changes – Occurs with childbirth, blood clotting, protein digestion, fever, and generation of nerve signals 1 -44

A positive feed back mechanism: blood clotting and wound healing

Positive Feedback and Rapid Change • During birth, the head of the fetus pushes against the cervix and stimulates its nerve endings – Hormone oxytocin is secreted from the pituitary gland – Oxytocin travels through the bloodstream to the uterus stimulating it to contract – This action pushes the fetus downward toward cervix, thus stimulating the cervix more, causing the positive feedback loop to be repeated 1 -46

Positive Feedback Loops Copyright © The Mc. Graw-Hill Companies, Inc. Permission required for reproduction or display. 3 Brain stimulates pituitary gland to secrete oxytocin 4 Oxytocin stimulates uterine contractions and pushes fetus toward cervix 2 Nerve impulses from cervix transmitted to brain 1 Head of fetus pushes against cervix 1 -47

Positive Feedback and Rapid Change • Fever > 104°F – – Metabolic rate increases Body produces heat even faster Body temperature continues to rise Further increasing metabolic rate • Cycle continues to reinforce itself • Becomes fatal at 113°F 1 -48

Integration means working together • Systems integration: – systems work together to maintain homeostasis

The History of Anatomical Terminology • Standard international anatomical terminology – Terminologia Anatomica (TA) was codified in 1998 by professional associations of anatomists • About 90% of medical terms from 1, 200 Greek and Latin roots 1 -50

Analyzing Medical Terms • Terminology based on word elements – Lexicon of 400 word elements on the inside back cover of textbook • Scientific terms – – One root (stem) with core meaning Combining vowels join roots into a word Prefix modifies core meaning of root word Suffix modifies core meaning of root word 1 -51

Analyzing Medical Terms • Acronyms formed from first letter, or first few letters, of series of words – Calmodulin comes from the phrase “calciummodulating protein” 1 -52

The Importance of Precision • Be precise in your terms • Spell correctly • Health-care professions demand the same type of precision • People’s lives will be in your hands 1 -53

Review of Major Themes • Cell theory – All structure and function result from the activity of cells • Homeostasis – The purpose of most normal physiology is to maintain stable conditions within the body • Evolution – The human body is a product of evolution • Hierarchy of structure – Human structure can be viewed as a series of levels of complexity • Unity of form and function – Form and function complement each other; physiology cannot be divorced from anatomy 1 -54

Anatomical Landmarks Figure 1– 6

Positional terms • Anatomical position: – hands at sides, palms forward • Supine: – lying down, face up • Prone: – lying down, face down

Quadrants and Regions • 4 abdominopelvic quadrants around umbilicus

• 9 abdominopelvic regions Figure 1– 7 b

• Internal organs associated with abdominopelvic regions Figure 1– 7 c

Which Direction? • Lateral: – side view • Frontal: – front view • Anatomical direction: – refers to the patient’s left or right

Which Direction?

3 Dimensions • Plane: – a 3 -dimensional axis • Section: – a slice parallel to a plane

3 Dimensions

• Coelom: – divided by the diaphragm into the thoracic cavity and the abdominopelvic cavity The Ventral Body Cavity

Serous membranes The pericardium

The 11 organ systems Some structural associations 1. Integumentary - skin 2. Skeletal - bones, cartilage, joints 3. Muscular - skeletal cardiac and smooth 4. Nervous - central & peripheral, voluntary & involuntary 5. Endocrine - glands & hormones 6. Cardiovascular - blood, blood vessels & the heart 7. Lymphatic & Immune - lymph vessels, organs, tissues & cells 8. Respiratory - nasal structures, larynx, airways & lungs 9. Digestive - alimentary canal & accessory organs 10. Urinary - kidneys, ureters & urethra 11. Reproductive - gonads, accessory organs (primary and secondary structures)

The 11 organ systems Some general functions 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. Integumentary - protection, water regulation, endocrine Skeletal - protection, support, movement Muscular - movement, transportation, heat Nervous - communication & control, rapid to intermediate Endocrine - communication & control, short to long term Cardiovascular - transportation, thermal regulation, defenses, water Lymphatic & Immune - water balance, absorption, immunity Respiratory - gas exchange Digestive - absorption, energy storage & production, filtration Urinary - water & p. H balance, blood pressure, toxin removal Reproductive -makin’ babies!

Some main points: • Scientific method • • Complementarity of structure and function Hierarchy of structural organization • Homeostasis - the balancing act of living systems – Hypothesis – Theory – law – – – Atoms Molecules Compounds Biochemical Organelles Cells Tissues Organ systems (we organize them into distinct 11 systems) Organisms Populations – Negative feedback – Positive feedback

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