Survey
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Human Anatomy & Physiology I BIO 201 Major Themes of Anatomy & Physiology Chapter 1 By Abdul Fellah, Ph.D. Major Themes of Anatomy & Physiology • Form and Function • Origins of Biomedical Science • Scientific Method • Human Origins and Adaptations • Human Structure • Human Function • Language of Medicine Anatomy - The Study of Form • Observation of surface structure • Cadaver dissection is cutting & separation of organs to study their relationships • Comparative anatomy is the study of more than one species to analyze evolutionary trends • Physical examination – palpation, auscultation, percussion • Gross anatomy is what is visible with naked eye • Histology is examination of cells with microscope Physiology - The Study of Function • Study of bodily functions by use of methods of experimental science • Comparative physiology involves the study of different species • Basis for the development of new drugs and medical procedures Beginnings of Medicine • Physicians in Mesopotamia & Egypt 3000 years ago used herbal drugs, salts & physical therapy • Greek physician Hippocrates established a code of ethics & urged physicians to seek causes of disease • Aristotle called causes for disease physiologi & said that complex structures are built from simpler parts Beginnings of Medicine • Galen, physician to the Roman gladiators, saw science as a method of discovery – did animal dissections since use of cadavers banned – wrote book advising followers to trust their own observation Birth of Modern Medicine • Little advancement during the Middle ages since medicine was taught as dogma with no new ideas • Avicenna from Muslim world supported free inquiry over authority – wrote The Canon of Medicine, used in medical schools until 16th century • Vesalius published accurate gross anatomy atlas (1543) • Harvey realized blood flow out from heart & back in 1628 • Leeuwenhoek invented microscope to look at fabrics (1632-1723) Birth of Modern Medicine • Hooke (1665) and Zeiss (1860) developed & improved compound microscope (described plant cell walls in 1665) • Schleiden & Schwann thought that all organisms were composed of cells -- cell theory of 1839 • Clinical practice was in dismal state – bleeding patients to remove toxins, operate with dirty hands, no anesthesia for amputations Early Microscopes Living in a Revolution • Pioneers in 19th & 20th centuries – established scientific way of thinking – replaced superstition with natural laws – momentous discoveries • germ theory of disease • heredity & structure of DNA • Now at threshold of modern biomedical science – technology enhanced diagnostic ability & life-support strategies – genetic revolution --library of the molecular structure of every human gene is finished • Gene therapy being used to treat disease Scientific Method • Bacon (1561-1626) and Descartes (1596-1650) – were not scientists but did invent new habits of scientific thought • scientific method as habits of disciplined creativity, careful observations, logical thinking & analysis of observations • way of seeking trends & drawing generalizations • Convinced governments of England & France to form academies of science that still exist today • Scientific way of thinking based on assumptions & methods that are reliable, objective & testable Inductive Method • First described by philosopher Francis Bacon • Making observations until capable of drawing generalizations and making predictions – anatomy is a product of inductive method • Proof in science can not go past “proved beyond reasonable doubt” – reliable methods of observation – tested and confirmed repeatedly – not falsified by any credible observation • In science, all truth is tentative Hypothetico-Deductive Method • Physiological knowledge gained by this method • Ask a question and formulate a hypothesis -an educated possible answer • Good hypothesis – consistent with what is already known – capable of being tested and falsified with certain evidence • If nothing could prove it wrong, it is not a scientific belief • Hypotheses are written as If-Then predictions – modified and rewritten after testing Experimental Design • Sufficient sample size to prevent chance event • Control group and treatment group receive the same treatment except for the variable being tested • Prevention of psychosomatic effects – use of placebo in control group • Experimenter bias – prevented with double-blind study • Statistical testing to be sure the difference between groups was not random, but was due to variable being tested Peer Review • Critical evaluation by other experts in the field – prior to funding – verification and repeatability of results • Ensures honesty, objectivity & quality in science Facts, Laws and Theories • Scientific fact is information that can be independently verified by any trained person – iron deficiency leads to anemia • Law of nature is a description of the way matter and energy behave – resulting from inductive reasoning & repeated observations – written as verbal statements or mathematical formulae • Theory is a summary of conclusions drawn from observable facts – it provides explanations and predictions – sliding filament theory of muscle contraction Human Origins and Adaptations • Charles Darwin’s theory of natural selection explains how species originate and change through time – On the Origin of Species by Means of Natural Selection (1859) – The Descent of Man (1871) discussed human evolution & our relationships to other animals • Changed our view of our origin, our nature & our place in the universe • Good understanding of our evolutionary history deepens our understanding of form & function Evolution, Selection, and Adaptation • Evolution is change in genetic composition of a population of organisms – development of bacterial resistance to antibiotics, new strains of AIDS virus and emergence of new species • Theory of natural selection – some individuals have hereditary advantages (adaptations) enabling them to produce more offspring – if they pass these characteristics on it brings about a genetic change in the population (evolution) – forces that favor some individuals over others are called selection pressures -- climate, disease, etc. Adaptations • Adaptations are useful features that evolved in response to selection pressures • DNA hybridization suggests a difference of only 1.6% in DNA structure between humans & chimpanzees • Evolutionary developments help explain some aspects of our anatomy (vestigial organs) – piloerector muscle in the skin have no use – auricularis muscles do not move in most people • Evolutionary relationships help us chose animals for biomedical research – rats & mice used extensively Primate Adaptations • Some human features can be traced to the earliest primates • Squirrel-sized, insect-eating mammals became arboreal probably due to safety, food supply & lack of competition – shoulder became more mobile (reach any direction) – thumbs became opposable to encircle branches with thumb & fingers (prehensile) – forward-facing eyes provide depth perception • judge distances accurately for leaping & catching prey – color vision to distinguish ripe fruit – larger brains & good memory to remember food sources Walking Upright • African forest became grassland 5 million years ago • Bipedalism (standing & walking on 2 legs) evolved – spot predators, carry food or infants • Adaptations for bipedalism – pelvis, femur, knee, great toe, arch, skull, vertebrae, etc. • Australopithecus (2.5mya) gave rise Homo habilis – taller, larger brain volume, speech, tool-making • Homo erectus (1.1mya) and Homo sapiens (.3mya) • Homo sapiens include Neanderthal & Cro-Magnon • Evolutionary medicine traces our diseases to evolutionary past Primate Phylogeny Human Structure • Hierarchy of complexity – organism is composed of organ systems – organ systems composed of organs – organs composed of tissues – tissues composed of cells – organelles composed of molecules – molecules composed of atoms – Atoms compose molecules • Reductionism versus holism Anatomical Variation • No 2 humans are exactly alike • Missing organs – palmaris longus or plantaris muscles • More or less organs than normal – 2 spleens, single kidney, 6 or 4 lumbar vertebrae • Variation in organ locations (situs inversus, dextrocardia, situs perversus) Human Function • Characteristics of life – organization – cellular composition – excretion – metabolism – responsiveness and movement – homeostasis – development (growth or differentiation) – reproduction – evolution • Clinical death is no brain waves for 24 hours Physiological Variation • Differs with sex, age, diet, weight, degree of physical activity • Typical human values – reference man • 22 years old, 154 lbs, light physical activity • 2800 kcal/day – reference woman • same as man except 128 lbs and 2000 kcal/day Homeostasis • Hippocrates noted that body normally returns to a state of equilibrium by itself – needs to detect the change & oppose it • Walter Cannon (1871-1945) coined the term homeostasis indicating stable internal environment • Internal environment described as dynamic equilibrium – fluctuates within a range around a certain set point • Loss of homeostatic control causes illness or death Negative Feedback Loops • Mechanism to keep a variable close to its set point • Body senses a change & activates mechanisms to reverse it Negative Feedback, Set Point • Room temperature does not stay at set point of 68 degrees -- it only averages 68 degrees Human Thermoregulation • Blood temperature sensing nerve cells in base of brain control shivering, sweating & vasomotor activity – vasodilation with heat & vasoconstriction with cold • Evaporation of water & heat radiation occur Control of Blood Pressure • Rise in blood pressure detected – stretch receptors in wall of heart and major arteries • Nerve signals travel to cardiac center in brainstem • Nerve signals slow heart and lower blood pressure Structures Needed for Feedback Loop • Receptor = structure that senses change – stretch receptors in heart & large blood vessels send information of an elevated BP to integrator • Integrator = control center – cardiac center in brainstem that signals heart to slow • Effector = structures that carry out commands of the control center – heart slows and BP decreases – sweating begins and evaporation cools the body Positive Feedback Loops • Physiological change that leads to an even greater change in the same direction (self-amplifying) • Normal way of producing rapid changes – birth, blood clotting, protein digestion, generation of nerve signals Life-Threatening Fever • If temperature rises above 108 degrees due to bacterial infection – metabolic rate increases causing body to produce heat faster still • Temperature increases & cycle repeats • Fatal at 113 degrees History of Anatomical Terminology • Most medical terms are formed from Greek and Latin roots • Fast-paced anatomical discoveries during the Renaissance resulted in naming confusion – different countries naming same structures with different names – structures being named after people (eponyms) • Anatomy meetings in 1895 began search for uniform international terminology – Nomina Anatomica (NA) rejected all eponyms • gave each structure a unique Latin name to be used worldwide – Terminologia Anatomica was codified in 1998 Analyzing Medical Terms • Medical terminology based on word elements – lexicon of 400 common word elements in back of book • Scientific terms are composed of the following elements – at least one root (stem) that bears the core meaning – combining vowels that join roots together – prefix that modifies the core meaning of the word – suffix that modifies the core meaning of the word • acronyms – words composed of the first few letters of a series of words Useful Tables in Textbook Review of Major Themes • Unifying principles behind all aspects of human anatomy and physiology – cell theory: all structure & function result from the activity of cells – homeostasis: maintaining stable conditions within the body – evolution: the body is a product of evolution, molded by years of natural selection – hierarchy of structure: levels of complexity – unity of form and function: physiology can not be separated from anatomy Medical Imaging • Radiography – x-rays discovered (William Roentgen) in 1885 – penetrate soft tissues & darken photographic film on other side of the body – dense tissue (bone, teeth and tumors) are not penetrated so photographic film remains white – radiopaque substances can be either injected (angiography) or swallowed for examination of the gastrointestinal tract • Sonography – high-frequency ultrasound waves echoes back from internal organs – obstetrics uses to locate placenta, evaluate fetal age, position and development Medical Imaging • Computed Tomography (CT scan) – low-intensity X rays applied to the body – computer analysis produces an image of a slice of the body about as thin as a coin – tumors, aneurysms, hemorrhages, kidney stones, etc • Magnetic Resonance Imaging (MRI) – magnetic field aligns hydrogen atoms; radio waves realign the atoms; when radio is turned off the atoms give off energy depending on tissue type – computer analysis produces a “slice” type image – better for soft tissue analysis than CT Medical Imaging • Positron Emission Tomography (PET scan) – assesses the metabolic state of a tissue – injection of radioactively labeled glucose emits positrons – colliding positrons & electrons give off gamma rays that are analyzed by computer – color image of glucose usage at that moment • extent of damaged heart tissue • activity of brain of neurology patients Basic Anatomical Terminology • Anatomical position • Regions of the body • Anatomical planes, sections and directional terms Anatomical Position • Standardized position from which to describe directional terms – – – – – – standing upright facing the observer, head level eyes facing forward feet flat on the floor arms at the sides palms turned forward • Prone position = lying face down • Supine position = lying face up anatomical position? Common Regional Names • Clinical terminology based on a Greek or Latin root word. Planes and Sections • A plane is an imaginary flat surface that passes through the body. • A section is one of the 2 surfaces (pieces) that results when the body is cut by a plane passing through it. Sagittal Plane • Sagittal plane – divides the body or an organ into left and right sides • Midsagittal plane – produces equal halves • Parasagittal plane – produces unequal halves Other Planes and Sections • Frontal or coronal plane – divides the body or an organ into front (anterior) and back (posterior) portions • Transverse(cross-sectional) or horizontal plane – divides the body or an organ into upper (superior) or lower (inferior) portions • Oblique plane – some combination of 2 other planes Planes and Sections of the Brain (3-D anatomical relationships revealed) • Horizontal Plane • Frontal Plane • Midsagittal Plane Major Directional Terms • See Definitions page 14 Superior or Inferior • Superior – towards the head – The eyes are superior to the mouth. • Inferior – away from the head – The stomach is inferior to the heart. Dorsal or Ventral • Dorsal or Posterior – at the back of the body – The brain is posterior to the forehead. • Ventral or Anterior – at the front of the body – The sternum is anterior to the heart. Medial or Lateral • Medial – nearer to the midline of the body – The heart lies medial to the lungs. • Lateral – farther from the midline of the body – The thumb is on the lateral side of the hand. Proximal or Distal • Proximal – nearer to the attachment of the limb to the trunk – The knee is proximal to the ankle. • Distal – farther from the attachment of the limb to the trunk – The wrist is distal to the elbow. Dorsal Body Cavity • Near dorsal surface of body • 2 subdivisions – cranial cavity • holds the brain • formed by skull – vertebral or spinal canal • contains the spinal cord • formed by vertebral column • Meninges line dorsal body cavity Ventral Body Cavity • Near ventral surface of body • 2 subdivisions – thoracic cavity above diaphragm – abdominopelvic cavity below diaphragm • Diaphragm = large, dome-shaped muscle • Organs called viscera • Organs covered with serous membrane Abdominopelvic Cavity • Inferior portion of ventral body cavity below diaphragm • Encircled by abdominal wall, bones & muscles of pelvis Thoracic Cavity • Encircled by ribs, sternum, vertebral column and muscle • Divided into 2 pleural cavities by mediastinum • Mediastinum contains all thoracic organs except lungs Mediastinum • Midline wall of tissue that contains heart and great vessels, esophagus, trachea and thymus. Serous Membranes • Thin slippery membrane lines body cavities not open to the outside – parietal layer lines walls of cavities – visceral layer covers viscera within the cavities • Serous fluid reduces friction Pleural & Pericardial Cavities • Visceral pleura clings to surface of lungs --- Parietal pleura lines chest wall • Visceral pericardium covers heart --- Parietal pericardium lines pericardial sac Peritoneum • Visceral peritoneum --- serous membrane that covers the abdominal viscera • Parietal peritoneum --- serous membrane that lines the abdominal wall Abdominopelvic Regions & Quadrants • Describe locations of organs or source of pain • Tic-tac-toe grid or intersecting lines through navel