Anatomy and Physiology: The Study of Form

• Anatomy and Physiology (A & P) studies the structure and function (the biology) of the human body
• A & P form a foundation for advanced study in health care, exercise physiology, and pathophysiology, among other related fields
• Chapter 1 introduces A & P history, human evolution, central concepts in physiology, and medical terminology

Anatomy: The Study of Form

• Inspection is visual examination of the body
• Palpation involves feeling structures with the hands
• Auscultation is listening to bodily sounds
• Percussion involves tapping the body to assess underlying structures
• Cadaver dissection involves cutting and separating tissues to study tissue relationships
• Comparative anatomy studies multiple species to learn about form, function, and evolution
• Exploratory surgery involves opening the body to examine structures
• Medical imaging allows viewing the inside of the body without surgery
• Radiology is the branch of medicine concerned with imaging
• Gross anatomy studies structures visible to the naked eye
• Histology (microscopic anatomy) involves microscopic examination of tissues
• Histopathology involves microscopic examination of tissues for signs of disease
• Cytology studies the structure and function of cells
• Ultrastructure views fine detail using an electron microscope

Physiology: The Study of Function

• Neurophysiology studies the physiology of the nervous system
• Endocrinology studies the physiology of hormones
• Pathophysiology studies the mechanisms of disease
• Comparative physiology studies different species to learn about body functions
• Comparative physiology forms the basis for much understanding of human physiology along with the development of new drugs and medical procedures

Origins of Biomedical Science

• Hippocrates was a Greek physician known as the "Father of Medicine"
• Hippocrates established a code of ethics known as the Hippocratic Oath
• Hippocrates urged physicians to seek natural causes of disease
• Aristotle believed diseases had either supernatural (theologi) or physical (physiologi) causes
• Aristotle's beliefs gave rise to the terms physician and physiology
• Galen was a physician to Roman gladiators who performed animal dissections as human cadaver use was banned
• Maimonides (Moses ben Maimon) was a Jewish physician who authored 10 influential medical texts and served as physician to the Egyptian sultan, Saladin
• Avicenna (Ibn Sina) from the Muslim world, known as "The Galen of Islam", combined both Galen and Aristotle's findings and wrote The Canon of Medicine used for 500 years
• Andreas Vesalius oversaw his own dissections due to relaxed restrictions, and published the first atlas of anatomy, De Humani Corporis Fabrica in 1543
• William Harvey, an early physiologist, published De Motu Cordis (On the Motion of the Heart) in 1628, realizing blood flows out from and back to the heart again
• Robert Hooke greatly improved the compound microscope, invented several components, and published Micrographia in 1665
• Antony van Leeuwenhoek invented an effective simple microscope (200X magnification)
• Matthias Schleiden and Theodor Schwann proposed that all organisms were composed of cells, considered the first tenet of cell theory

Scientific Method

• Francis Bacon and René Descartes were philosophers who invented new habits of scientific thought
• Scientific thought encourages a creative, objective process that seeks similarities, differences, and trends to draw useful generalizations from observable facts
• Inductive Method described my Francis Bacon
• Inductive Method makes numerous observations until one becomes confident in drawing generalizations and predictions
• Reliable observations are repeatedly confirmed
• Reliable observations are not falsified by any credible observation
• Knowledge of anatomy has been obtained by the inductive method
• The Hypothetico-Deductive Method is the most physiological knowledge
• An Investigator formulates a hypothesis - an educated speculation of a possible answer to a question
• Good hypotheses are consistent with what is already known and are testable
• Falsifiability is if we claim something as scientifically true, we must be able to specify what evidence it would take to prove it wrong

Experimental Design

• Sample size is the number of subjects in a study
• Controls: The control group resembles treatment group but does not receive treatment
• Psychosomatic effects are the effects of a subject's state of mind on their physiology; such are tested by giving a placebo to control group
• Experimenter bias is avoided with double-blind study
• Statistical testing provides a statement of probability that treatment was effective
• Peer review involves critical evaluation by experts, done prior to funding or publication, and ensures honesty, objectivity, and quality in science
• Scientific Fact: Information that can be independently verified
• Law of Nature: Generalization about the way matter and energy behave with results from inductive reasoning and repeated observations, and is written as verbal statement or mathematical formula
• Theory: An explanatory statement derived from facts, laws, and confirmed hypotheses which summarizes current knowledge and suggests directions for further study

Human Origins and Adaptations

• Charles Darwin published On the Origin of Species by Means of Natural Selection (1859) and The Descent of Man (1871)
• Evolution is a change in the genetic composition of a population of organisms.
• Natural selection determines ow evolution works
• Natural selection: Selection pressures are forces that promotes reproductive success of some individuals more than others
• Adaptations include inherited features of anatomy and physiology that evolved in response to pressures, and that enable an organism to succeed
• Humans' closest relative is the chimpanzee with only a 1.6% difference in DNA structure
• Evolutionary relationships help us chose animals for biomedical research (the animal model) while rats and mice are used extensively due to cost and ethical considerations
• Primates are the order of mammals including humans, monkeys, and apes.
• Early arboreal (tree-dwelling) primates evolved mobile shoulders for better movement among branches
• Early arboreal (tree-dwelling) primates evolved opposable thumbs and prehensile hands to grasp branches and manipulate objects
• Early arboreal (tree-dwelling) primates evolved Forward-facing eyes with stereoscopic vision for depth perception
• Early arboreal (tree-dwelling) primates evolved Color vision to find ripe fruit
• Early arboreal (tree-dwelling) primates evolved Large brain for remembering and efficient food finding
• Bipedalism is standing and walking on two legs that Helps spot predators and carry food, tools, and infants
• Skeletal and muscular modifications along with changes to family structure are adaptation of bipedalism
• Australopithecus was a bipedal primate genus that lived more than 3 million years ago
• Homo genus appeared 2.5 million years ago and had Taller, larger brain volume, and were good tool-makers
• Homo erectus appeared 1.8 million years ago and Migrated from Africa to parts Asia
• Homo sapiens originated in Africa 200,000 years ago
• Evolutionary medicine traces some of our diseases to differences between modern and prehistoric environments.

Human Structure

• The hierarchy of complexity is: organism; organ systems; organs; tissues; cells; organelles; molecules; atoms
• Reductionism studies large, complex systems by studying their simpler components and is essential to scientific thinking
• Holism, Humans are more than the sum of their parts and the "emergent properties" of the whole organism cannot be predicted from the properties of the separate parts
• No two humans are exactly alike because anatomy books show the most common organization of structures
• Anatomical variation can include the lack of certain muscles
• Anatomical variation can include an atypical number of vertebrae or organs
• Some individuals show situs inversus: left-right reversal of organ placement

Human Function

• Characteristics of Life: Organization, cellular composition, metabolism, responsiveness, movement, homeostasis, development, reproduction, evolution
• Sex, age, diet, weight, physical activity, genetics, and environment influence physiological variation
• Reference man is 22 years old, 154 lb, and consumes 2,800 kcal/day with light physical activity
• Reference woman is same as reference man except 128 lb and 2,000 kcal/day
• Failure to consider variation can lead to overmedication of elderly or medicating women on the basis of research done on men
• Homeostasis is the ability to detect change with mechanisms that oppose it, thereby maintaining relatively stable internal conditions
• Claude Bernard (1813–78) noted fairly constant internal conditions despite changing external conditions
• Walter Cannon (1871–1945) coined the term homeostasis
• Negative feedback allows for dynamic equilibrium within a limited range around a set point
• The body senses a change and negates or reverses the change
• Feedback mechanisms that alter the original changes that triggered them are called feedback loops.
• Body temperature: If too warm, vessels dilate in the skin and sweating begins (heat-losing mechanism)
• Body temperature: If too cold, vessels in the skin constrict and shivering begins (heat-gaining mechanism)
• Loss of homeostatic control causes illness or death
• The receptor senses change in the body, such as stretch receptors above the heart that monitor blood pressure
• The integrating (control) center is the control center that processes the sensory information, "makes a decision," and directs the response, such as the cardiac center of the brain
• The effector is the cell or organ that carries out the final corrective action to restore homeostasis, such as the heart
• Positive feedback is a self-amplifying cycle which leads to greater change in the same direction, and the feedback loop is repeated until change produces more change
• Rapid changes include childbirth, blood clotting, protein digestion, and generation of nerve signals
• A negative examples of positive feed back is a vicious circle of runaway fever
• A gradient is a difference in chemical concentration, charge, temperature, or pressure between two points
• Matter and energy tend to flow down gradients.
• Example: blood flows from a place of higher pressure to a place of lower pressure
• Movement in the opposite direction is "up the gradient" and requires spending metabolic energy
• Chemicals flow down concentration gradients, with charged particles flowing down electrical gradients, and heat flowing down thermal gradients

Medical Terminology

• About 90% of current medical terms come from 1,200 Greek and Latin roots
• The Renaissance brought progress and confusion with the same structures named differently by different countries, and some structures named after people (eponyms)
• In 1895, anatomists established worldwide naming conventions and rejected eponyms, while using unique Latin names
• In 1998, Terminologia Anatomica (TA) provided Latin names and English equivalents
• Terminologia Anatomica (TA) was adopted by anatomists in over 50 countries
• Medical terminology is based on word elements
• 400 word elements are written in the back of some textbooks
• Scientific terms have one root (stem) with core meaning
• Combining vowels join roots into a word, and a prefix and/or suffix may modify meaning of root word
• Acronyms are pronounceable words formed from first letter, or first few letters, of series of words Plural forms vary such as from cortex to cortices, and corpus to corpora
• Adjective often follows noun it modifies, such as Biceps brachii and the adjectival form of a term can appear different than the noun form
• An example of adjectival form is brachium (n.): arm vs. brachii (adj.): of the arm
• Pronunciation and spelling are very important
• Many terms are spelled similarly but have very different meanings
• Health-care professions demand precision in order to maintain patient safety

Review of Major Themes

• Anatomy and physiology complement each other and cannot be divorced from one another
• All structure and function result from the activity of cells
• The human body is a product of evolution
• Human structure can be viewed as a series of levels of complexity
• The purpose of most normal physiology is to maintain stable conditions within the body
• Matter and energy tend to flow down gradients

Medical Imaging

• Radiography (X-rays): William Roentgen's discovery in 1885
• More than half of all medical imaging is Radiography uses X-rays that penetrates tissues to darken photographic film beneath the body; dense tissue appears white
• Radiopaque substances can be injected or swallowed to fill hollow structures, such as blood vessels or the intestinal tract
• Digital subtraction angiography is useful for showing blockages and blood flow Computed tomography (CT scan) was formerly called a CAT scan
• Computed tomography (CT scan) uses Low-intensity X-rays and computer analysis to produce a Slice-type image with increased sharpness of image
• Magnetic resonance imaging (MRI) is better than CT scans in quality, has superior quality to CT scan and no X-ray exposure, and It is best for soft tissue imaging
• Functional MRI (fMRI) shows real time changes in the brain
• Positron emission tomography (PET) scan assesses metabolic state of tissue
• Positron emission tomography (PET) scan injects radioactively labeled glucose and its image color indicates shows tissues using the most glucose at that moment, which can show Damaged tissues as being dark
• Sonography is the second oldest and second most widely used imaging technique
• Sonography uses High-frequency sound waves echoing back from internal organs which avoids harmful X-rays and is thus good for Obstetrics, but its Image is not very sharp