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Human Anatomy & Physiology I – Dr. Sullivan Unit I – Body Organization and Homeostasis: Chapter 1 **You should read these notes while clicking through the powerpoint slides on the website. Figures in parentheses refer to powerpoint slides and/or text (when you see a reference to a figure in the powerpoint, click to the next slide)** I. Anatomy and Physiology Defined Anatomy: The science of body structures and the relationship of those structures to each other. i. First studied by dissection: the act of carefully cutting apart the body structures to study their relationships ii. Also studied today with advanced imaging such as X-Ray, MRI, and CT Scan, among others. b. Physiology: the science of body functions, or how the body works c. Anatomy is broken up into subdivisions or “disciplines.” i. Embryology: study of structures that emerge from the time of the fertilized egg through the eighth week in utero. ii. Developmental Biology: Structures that emerge from the time of the fertilized egg to the adult form iii. Histology: Microscopic structure of tissues iv. Surface Anatomy: Anatomical landmarks throughout the surface of thebody through visualization or palpation. 1. Palpation: touching and feeling to gain information v. Gross Anatomy: Structures that can be examined without using a microscope. vi. Systemic Anatomy: Structures of specified systems of the body, such as the nervous system or the cardiovascular system. vii. Regional Anatomy: Specified regions of the body, such as the head or chest viii. Radiographic Anatomy: Body structures that can be visualized with XRays. ix. Pathological Anatomy: Structural Changes associated with disease. d. Physiology can also be broken up into subdivisions or “disciplines.” i. Neurophysiology: functional properties of nerve cells ii. Endocrinology: Hormones and how they control body functions iii. Cardiovascular Physiology: Functions of the heart and blood vessels iv. Immunology: How the body defends itself against disease-causing agents v. Respiratory Physiology: Functions of the air passageways and the lungs vi. Renal Physiology: Functions of the kidneys vii. Exercise Physiology: Changes in cell and organ function as a result of muscular activity viii. Pathophysiology: Functional changes associated with disease and aging. Human Origins and Adaptations: a. How did humans come to be as they are today? b. Understanding human origin and evolution is essential to understanding human structure & function c. Charles Darwin: while not the first to come up with the idea that humans and other animals have changed generation to generation over long periods of time, he was the first to theorize a method for that change. He called it “natural selection” i. Darwin was a naturalist that collected several samples of animals and plants while on a 5-year voyage around the world on the ship the H.M.S. Beagle. ii. While analyzing his samples he noticed that animals differed from location to location based on the food supply, climate, terrain, predators, etc. i.e. birds that lived on islands whose seeds were inside hard nuts (the bird’s food supply), had short, thick beaks for hammering the nuts open. However, birds that lived on islands whose seeds were deep inside narrow flowers had a. II. e. f. g. h. i. j. k. l. III. long, thin beaks for reaching into the flowers. Other than beaks, the birds were remarkably similar. d. Darwin theorized that these animals adapted to the environmental pressures (food, climate, predators, etc.) Birds with long beaks survived on the island with deep-flower seeds while the ones who couldn’t get the food, died off. The birds that survived would be able to reproduce and pass their long-beak traits on to their offspring (he didn’t even know about genes & heredity yet!). Nature ‘selected’ the traits that provided a survival advantage. The reason why the birds were otherwise similar is because they all came from the same ancestors, but different traits were selected in different environments. What Darwin didn’t know yet was that every generation’s DNA has a few mutations that cause different traits to appear in the offspring (i.e. you may be taller than your parents, or have a different shaped nose, etc.) Any of these mutations that proves to be an advantage for survival can be passed on to offspring through genes. If you add up how many different mutations are possible over the 4.5 Billion-year-old age of the earth, millions of different species can diverge in a tree of life from a single trunk (our common ancestor with all living things). Selection is cumulative. One differing trait does not make an organism a different species from another, but millions of different traits accumulated over 10 million years results in so many different traits, that the two animals can no longer reproduce with each other and are considered different species. Humans’ closest living relatives are Chimpanzees. We are not descendent from them, but they are our cousins. i.e. we share great-great (times 2 million or so)- grandparents with chimps. Over time we’ve gradually adapted to our environment and they’ve adapted to theirs. Evolution’s only goal is to make an organism more fit to survive in his current environment. Those who can adapt survive, those who cannot, go extinct. 99% of all species that have ever lived on Earth are extinct. Mutations over time that increased brain size allowed humans and other sophisticated primates to develop tools and weapons, to build shelters, and to make fire. These adaptations provided us with significant advantages over other animals. Eventually, these adaptations allowed us to travel the continents to different environments and subjected us to new selective pressures, selecting new mutations and traits while the chimps stayed in the jungle with little need for more adaptations. As more & more traits were selected for survival by the environmental conditions (aka selective pressures), these accumulated traits, which include opposable thumbs, walking upright, language, and social structure have allowed humans to survive as a population and have changed us so dramatically from our ape-like ancestors, that we are nearly unrecognizable as apes. Humans, as we know ourselves, can only be found as far back as 200,000 years in the fossil record. Our common ancestor with chimps has been found as a fossil that dates back about 5 million years. Levels of Body Organization (figure 1.7 on powerpoint) Dividing the body into levels from the smallest functional units to the largest (whole person). b. Organism: a totals living form; one individual c. There are 6 Levels of Organization for Anatomy & Physiology i. Chemical Level: Includes atoms, which are the smallest units of matter that participate in chemical reactions and molecules, which are two or more atoms joined together. 1. Examples of atoms necessary to sustain life are Carbon (C), Hydrogen (H), Oxygen (O), Nitrogen (N), Phosphorous (P), Calcium (Ca), and Sulfur (S) 2. Examples of molecules that are necessary to sustain life are deoxyribonucleic acid (DNA), and glucose a. (blood sugar). IV. ii. Cellular Level: Molecules combine to form organelles, which carry out specific functions and combine to form cells, which are the basic structural and functional units of an organism. Cells are the smallest living units in the human body. iii. Tissues: Groups of cells and the materials that surround them working together to perform a specific function. There are four types of tissues in your body: 1. Epithelial Tissue 2. Connective Tissue 3. Muscle Tissue 4. Nervous Tissue iv. Organ Level: Different kinds of tissues join together as Organs and perform specific functions in the body. Examples of organs are the stomach, liver, lungs, heart, and skin. There are many others. v. System Level: A system consists of related organs that work together to perform a particular function. An example is the gastrointestinal system, which employs the esophagus, the stomach, the small and large intestine, the pancreas, liver, gall bladder, and others to function in digestion. vi. Organismal Level: The largest of the levels of organization. All parts of the human body function together to make up the whole organism, or one living person. d. All the levels of organization work together and within each other to make a total organism function. e. Health-Care Professionals often use three non-invasive techniques to gain information about a patient’s body structure and function: i. Palpation: feeling the body with the hands 1. i.e. when taking a pulse, you must feel for the radial artery at the wrist and measure the pulse beats as they occur. ii. Ausculatation: listening to the sounds of the body 1. i.e. when measuring lung sounds and checking the valves of the heart, the examiner uses a stethoscope to auscultate the areas. iii. Percussion: Gently tapping on the body’s surface with the fingers and listening to the echo 1. i.e. checking for enlargement of the spleen, the examiner will tap his/her fingertips over the left 9th intercostals (in between ribs) space while the patient inhales and exhales. The sound resulting from the tapping should be hollow the entire time. Characteristics of the living Human Organism a. Organisms carry on certain processes that distinguish them from non-living things. i. Metabolism: the sum of all chemical processes in the body broken down into 2 phases. 1. Catabolism: The breaking down of complex chemical substances into simpler ones. 2. Anabolism: building complex chemical substances from smaller, simpler ones. 3. Working together, metabolism is the process of utilizing oxygen absorbed by the lungs and nutrients absorbed by digestion to give the body energy to power cellular activities. 4. Metabolism also breaks down large, chemical substances into smaller, chemical components that can be used to build and repair body structures. ii. Responsiveness: The body’s ability to detect and respond to changes in its internal or the external environment. 1. i.e. an increase in body temperature is a change in the internal envorinment, which would cause a sweating response 2. i.e. pulling your hand back from a hot stove would be an example of a reaction to a change in the external environment. 3. this includes homeostasis (see below) iii. Movement: motion of the whole body, individual organs, single cells, and small structures within cells. iv. Development: a. Growth: An increase in body size as a result of an increase in the size of existing cells, the number of cells, or both. 1. Growth can also be a result of an increase of the size of the material between cells (mineral deposits in bone surrounding active bone cells) b. Differentiation: The process a cell goes to develop from an unspecialized to a specialized state. I.e. a stem cell is an unspecialized cell waiting to grow into a cell that has a specific structure and function, such as a liver cell (hepatocyte). vii. Reproduction: The formation of new cells for tissue growth, repair, or replacement or the formation of an entirely new individual. a. evolution: offspring express genetic changes with each generation to better suit their own environment. vii. organization: living beings spend a great deal of energy to maintain order within their own bodies (homeostasis) and as a society. b. V. Homeostasis: The Condition of Equilibrium within the body’s environment. i. States that the cells of many-celled organisms live in a relative state of constancy despite continual changes in the external environment. ii. Homeostasis is a dynamic process, it is always happening as a result of all the body’s processes working together to sustain life. c. Body Fluids i. Dilute, watery substances found inside and surrounding cells. ii. An important aspect of homeostasis is maintaining the volume of and composition of body fluids. iii. Intracellular Fluid (ICF) – the fluid within cells iv. Extracellular fluid (ECF) – the fluid outside cells 1. Interstitial Fluid (ISF) – the ECF that fills the narrow spaces in between the cells of tissues of the body 2. Blood Plasma: the ECF within blood vessels 3. Lymph: ECF within the lymphatic system 4. Cerebrospinal Fluid (CSF) – the ECF that surrounds the brain and spinal cord 5. Synovial Fluid – the ECF within joint capsules 6. Aqueous Humor and Vitreous Body – the ECF within the eye Control of Homeostasis a. Homeostasis is continually being disturbed from the internal and external environment i. External: increase in temperature outside or decrease in oxygen level ii. Internal: decrease in blood glucose iii. Psychological stresses, such as work and school, can also disrupt homeostatic balance. b. Feedback systems: cycles of events in which the status of a body condition of continually monitored, evaluated, changed, remonitored, reevaluated, and so on. i. Each monitored variable (blood pressure, body temperature, blood glucose) is called a controlled condition. ii. Any disruption to a controlled condition is called a stimulus. iii. There three basic components that make up a feedback system 1. Receptor: body structure that monitors changes in a controlled condition. I.e. nerve endings in the skin that sense temperature. 2. Control Center: thew center that sets the range of values within which a controlled condition should be maintained. a. The control center receives and evaluates information from the receptors. Then is decides what is to be done based on that information. b. Output from the control center is typically in the form on nerve impulses, hormones, or other chemical signals. 3. Effector: a body structure that receives output from the control center and carries out the appropriate response. I.e. when your body detects a drop in temperature, the brain acts as the control center and, via the nervous system, tells the skeletal muscles, acting as the effetor, to contract resulting in shivering, which raises the body’s temperature. iv. A group of receptors and effectors communicating with a control center act together to form feedback system. v. If a response reverses the original condition (shivering warms the body in response to a drop in temperature) it is considered a negative feedback system (Fig 1.9 & 1.10 in powerpoint). vi. If a response enhances the original condition, it is considered a positive feedback system (figure 1.12 in powerpoint) 1. During childbirth the mother releases a hormone called Oxytocin. This hormone causes the uterine wall to contract, pushing the fetus toward the cervix. The fetus then distends the cervical wall as it’s moving through. Receptors in the cervical wall send a nerve impulse to the pituitary gland telling it to release more oxytocin, which will cause more uterine contractions. **See animation titled “positive & negative feedback” on website** Homeostatic imbalances i. As long as all the controlled conditions remain within certain narrow limits, feedback systems maintain homeostasis, cells function efficiently and the body stays healthy. However, this normal equilibrium can be disrupted and disorder or disease may occur. ii. Disorder: any derangement or abnormality of function iii. Disease: a specific term for an illness that can be characterized by recognizable set of signs and symptoms. 1. Local Disease: affects one part or a limited region of the body 2. Systemic Illness: affects the entire body or a very large part of it iv. Epidemiology: the science that deals with why, where, how, and when diseases occur and how they are transmitted v. Pharmacology: deals with the effects and uses of drugs in the treatment of disease. vi. Diagnosis: the science and skill of distinguishing one disease from another. 1. Signs & symptoms, medical history, physical exam, advanced imaging, diagnostic tests, and laboratory tests are all used to come to a definitive diagnosis. Anatomical Terminology (figure 1.05 in powerpoint) a. Designed to use a standard of terms for anatomical structures in standard positions to avoid confusion when discussing anatomy and physiology. b. Anatomical Position: Standing upright, facing the observer, with arms at your sides and palms facing forward. i. This is the position assumed when discussing any relationship of anatomical structures. ii. Prone: lying face-down iii. Supine: lying face-up c. Regional Names: the body is divided into regions i. Head: skull and face ii. Neck: supports the head and attaches it to the trunk. iii. Trunk: Chest, abdomen, and pelvis c. VI. d. e. f. iv. Upper limb: the shoulder, armpit, upper arm, elbow forearm, wrist, and hand 1. attached to the trunk v. Lower limb: the buttock, thigh, knee, leg, ankle, and foot. 1. also attached to the trunk 2. Leg: portion of the limb from the knee to the ankle Directional Terms (figure 1.06 in powerpoint): Terms that describe where a body part is relative to another body part. All terms are considered while the body is facing the observer and in anatomical position (see table 1.2 in powerpoint for plural versions of terms). i. Anterior or Ventral: toward the front ii. Posterior or Dorsal: toward the back iii. Superior or Cephalad: toward the head iv. Inferior or Caudal: toward the feet v. Medial: toward the midline of the body vi. Lateral: away from the midline of the body vii. Intermediate: between two structures viii. Ipsilateral: on the same side of the body as another structure ix. Contralateral: on the opposite side of the body as another structure x. Proximal: nearer to where the limb attaches to the trunk or nearer the origination of a structure xi. Distal: further from where a limb attaches itself to the trunk or from the origination of a structure xii. Superficial: toward or on the surface of the body xiii. Deep: Away from the surface of the body xiv. Median: On the midline Planes and Sections (figure 1.07 in powerpoint): i. When you view the inside of the body, you often view it in a section. 1. Section: one flat surface of a three-dimensional object. When studying anatomy, it is important to know which plane the section you are looking at is in. 2. Plane: Flat surfaces that imaginarily pass through the body in a particular direction ii. Frontal or Coronal plane: splits the body into anterior and posterior halves iii. Mid-Sagittal plane: splits the body into left and right halves iv. Parasagittal plane: splits the body into two, uneven left and right portions. v. Transverse plane or “cross section”: Splits the body into superior and inferior portions. Anatomical Names for well known body regions (figure 1.05 in powerpoint) i. Head: cephalic 1. forehead: frontal 2. base of skull: occipital ii. Neck: cervical iii. Armpit: axillary iv. Back: dorsal 1. shoulder blade: scapular 2. spine: vertebral 3. low back: lumbar 4. Buttock: gluteal v. Upper arm: brachial vi. Anterior of elbow: antecubital vii. Posterior elbow: olecranal viii. Forearm: antebrachial ix. Wrist: carpal x. Hand: manual 1. anterior hand: palmar 2. posterior of hand: dorsum Fingers or toes: digital or phalangial Chest: thoracic Trunk: abdominal Breastbone: sternal Groin: inguinal Thigh: femoral Knee: Genu 1. Anterior surface of knee cap: patellar 2. posterior of knee: popliteal xviii. Shin: Leg 1. anterior leg: crural 2. posterior leg: sural xix. Ankle: tarsal xx. Foot: pedal 1. top of foot: dorsum 2. sole of foot: plantar 3. Heel: calcaneal Body Cavities (figure 1.09 in powerpoint): spaces within the body that help protect, support, and separate the body’s internal organs i. Separated from each other by muscles, ligaments, and bones ii. There are two major cavities within the body: the dorsal cavity and the ventral cavity. iii. The Dorsal Cavity is located on the posterior aspect of the body and is split into two parts 1. Cranial Cavity containing the brain 2. Vertebral Canal containing the spinal cord and lined by the meninges (the three layers of tissue that protect the spinal cord) iv. The Ventral Cavity is located on the anterior aspect of the body and is also split into two divisions separated by the diaphragm (a flat, broad muscle splitting the body into to top and bottom parts). 1. The Thoracic cavity is superior and a. Contains the lungs and the heart 2. The Abdominopelvic cavity is inferior a. Contains the intestines, liver, stomach, spleen, gall bladder, kidneys, reproductive organs, and urinary organs. v. The Abdominopelvic region is divided into regions and quadrants 1. Nine Regions set up like a tic-toe-board (figure 1.13a in powerpoint) a. Top right: right Hypochondriac b. Top center: epigastric c. Top left: left hypochondriac d. Middle right: right lumbar e. Middle center: umbilical f. Middle left: left lumbar g. Bottom right: right inguinal h. Bottom center: hypogastric i. Bottom left: left inguinal 2. 4 Quadrants (figure 1.13b in powerpoint) a. right upper b. right lower c. left upper d. left lower vi. Medical Imaging: technology that allows us to visualize inside the body without making incisions 1. Radiography: aka “Plain Film X-Ray” xi. xii. xiii. xiv. xv. xvi. xvii. g. a. 2. 3. A shadow of bones projected onto film i. X-rays produce clear images of bones, but poor images of soft tissues and organs Magnetic Resonance Imaging (MRI) a. Uses magnets to arrange all the body’s protons in an organized fashion. Then, radiowaves read the proton arrangement in the magnetic field and relay that to a computer that creates a picture of what it looks like inside. b. Good for soft tissue, such as muscles, organs, ligaments, tendons, intervertebral spinal discs, etc. Computed Tomography (CT Scan) a. Many X-rays are taken at different angles and the information is evaluated by a computer, which generates an image. b. Good for bones and soft tissues c. More sensitive to bone than X-ray, less sensitive to soft tissue than MRI.