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Introduction to Physiology and Homeostasis Physiology • Physiology is the study of how how living organisms function Chapter 1 Assumptions in Physiology • The same chemical and physical laws that apply to the inanimate world govern processes in the the living body. • The laws describe how how an organism lives using information from biology, chemistry, physics, and mathematics – Not concerned with that part of life which cannot be explained by science – On the street explanations are in terms of meeting a bodily need – Physiologic explanations emphasize how how something occurs and how how its occurrence contributes to the maintenance of normalcy i.e. the homeostatic condition known as life Organization of the Body • Levels of organization – Chemical • An organism is ultimately a set of highly organized, elegantly interacting, organic organic molecules • Molecules composed of atoms – Cellular • Cells are basic unit of life • Cells must perform certain functions to maintain “live” status – Each cell contributes to the continued existence and possible demise of the organism – Must obey basic laws of thermodynamics – Cells exist at expense of surrounding environment Organization of the Body (a) Chemical level: a molecule in the membrane that encloses a cell (b) Cellular level: a cell in the stomach lining • Levels of organization (c) Tissue level: layers of tissue in the stomach wall – Cells make up • Tissue – Tissues make up (d) Organ level: the stomach • Organ – Organs make up (e) Body system level: the digestive system • Body system – Body systems make up • Organism (f) Organism level: the whole body Fig. 1-1, p. 3 Basic Functions of Living Cells 1. Obtain nutrients and oxygen from surrounding environment 2. Perform chemical reactions that provide energy for the cell a. Food + O2 CO2 + H2O + energy 3. Eliminate carbon dioxide and other wastes to surrounding environment 4. Synthesize needed cellular components Basic Functions of Living Cells 4. Control exchange of materials between cell and its surrounding environment 5. Monitor, detect and respond to change surrounding environment 6. Reproduction a. Exception: Nerve cells and muscle cells lose their ability to reproduce during their early development Specialized Cell Functions • Multicellular organisms – cells also perform specialized functions that contribute to the life of the organism – Specialized functions are modifications of some basic function • e.g. Digestive enzymes • Basic functions = individual cell survival • Specialized functions = survival of organism Tissues • Groups of cells with similar structure and specialized function • Four primary types of tissues – Muscle tissue – Nervous tissue – Epithelial tissue – Connective tissue Tissues • Muscle tissue – Specialized for contracting which generate tension and produce movement – Skeletal muscle – Moves the skeleton – Cardiac muscle – Pumps blood out of the heart – Smooth muscle – Encloses and controls movement of contents through hollow tubes and organs Tissues • Nervous tissue – Consists of cells specialized for initiating and transmitting electrical impulses – Found in brain, spinal cord, and nerves • Epithelial tissue – Consists of cells specialized for exchanging materials between the cell and environment – Structures: Epithelial sheets & secretory glands Tissues Organs • Connective tissue – Connects, supports, and anchors various body parts – Distinguished by having relatively few cells dispersed within an abundance of extracellular material – Examples: Tendons, bone, blood • Two or more types of primary tissues that function together to perform a particular function or functions • Example: Stomach • Inside of stomach lined with epithelial tissue • Wall of stomach contains smooth muscle • Nervous tissue in stomach controls muscle contraction and gland secretion • Connective tissue binds all the above together Organ: Body structure that integrates different tissues and carries out a specific function Surface epithelium Stomach Duct cell Secretory exocrine gland cell Connective tissue: Muscle tissue: Epithelial tissue: Protection, secretion, Structural support Movement and absorption Nervous tissue: Communication, coordination, and control Fig. 1-2, p. 4 (a) Exocrine gland Fig. 1-3a, p. 4 Body Systems Surface epithelium Secretory endocrine gland cell Blood vessel • Groups of organs that perform related functions and interact to accomplish a common activity essential to survival of the whole body • Do not act in isolation from one another • Human body has 11 systems (b) Endocrine gland Fig. 1-3b, p. 4 Body Systems 1. 2. 3. 4. 5. 6. Circulatory System Digestive System Respiratory System Urinary System Skeletal System Muscular System 7. Integumentary System 8. Immune System 9. Nervous System 10. Endocrine System 11. Reproductive System Circulatory system heart, blood vessels, blood Digestive system: Respiratory system mouth, pharynx, nose, pharynx, esophagus, larynx, trachea, stomach, bronchi, lungs small intestine, large intestine, salivary glands, exocrine pancreas, liver, gallbladder Urinary system kidneys, ureters, urinary bladder, urethra Skeletal system Muscular system bones, skeletal muscles cartilage, joints Fig. 1-4a, p. 6 Homeostasis • Defined as maintenance of a relatively stable internal environment (EXTRACELLULAR FLUID) – The internal enviroment is the EXTRACELLULAR FLUID • Each cell’s activity somehow contributes to maintenance of a relatively stable internal environment • Each cell’ Each cell’s activity somehow contributes to upset of internal environment • Homeostasis is maintained by multifaceted, interacting, “mechanisms” mechanisms” Nervous system Integumentary system Immune system skin, hair, nails lymph nodes, thymus, brain, spinal cord, bone marrow, tonsils, peripheral nerves, and, not shown, adenoids, spleen, special sense appendix, and, organs not shown, white blood cells, gut-associated lymphoid tissue Endocrine system all hormone-secreting tissues, including hypothalamus, pituitary, thyroid, adrenals, endocrine pancreas, gonads, kidneys, pineal, thymus, and, not shown, parathyroids, intestine, heart, skin, adipose tissue Reproductive system Male: testes, penis, prostate gland, seminal vesicles, bulbourethral glands, and associated ducts Female: ovaries, oviducts, uterus, vagina, breasts Fig. 1-4b, p. 6 Homeostatic Control Systems • In order to maintain homeostasis, control system must be able to – Detect deviations from normal in the internal environment that need to be held within narrow limits – Integrate this information with other relevant information – Make appropriate adjustments in order to restore factor to its desired value – In introductory physiology one studies and attempts to learn the mechanisms involved in these multifaceted, interacting control systems mechanisms involved in these multifaceted, interacting control systems which function to maintain homeostasis – In introductory physiology, study is organized by systems for the In introductory physiology, study is organized by systems for the convenience of the learner • In nature the systems interact automatically and in a hierarchy that results in In nature the systems interact automatically and in a hierarchy that results in survival of the organism