Human Physiology – From Cells to Systems PDF

Human Physiology – From Cells to Systems | 9e Lauralee Sherwood 1 Introduction to Physiology and Homeostasis © Cengage Learning 2016. 2016 All Rights Reserved. 1.1 Introduction to Physiology • Physiology is the study of the functions of living things – Focuses on the underlying mechanisms of bod...

Human Physiology – From Cells to Systems | 9e Lauralee Sherwood 1 Introduction to Physiology and Homeostasis © Cengage Learning 2016. 2016 All Rights Reserved. 1.1 Introduction to Physiology • Physiology is the study of the functions of living things – Focuses on the underlying mechanisms of body processes • Physiology is closely related to anatomy – the study of the structure of the body – Structure and function are inseparable © Cengage Learning 2016. All Rights Reserved. 1.2 Levels of Organization in the Body • The body is structurally organized into a total functional unit – Chemical – Cellular – Tissue – Organ – Body system – Organism © Cengage Learning 2016. All Rights Reserved. Levels of Organization in the Body (a) Chemical level: a molecule in the membrane that encloses a cell (b) Cellular level: a cell in the stomach lining (c) Tissue level: layers of tissue in the stomach wall (d) Organ level: the stomach (e) Body system level: the digestive system (f) Organism level: the whole body © Cengage Learning 2016. All Rights Reserved. The Chemical Level • Various atoms and molecules make up the body – Atoms: mostly oxygen, carbon, hydrogen, and nitrogen – Molecules of life: proteins, carbohydrates, fats, and nucleic acids (genetic material, such as deoxyribonucleic acid, or DNA) © Cengage Learning 2016. All Rights Reserved. The Cellular Level • Cells are the basic units of life – Have basic and specialized functions – Are progressively organized into tissues, organs, body systems, and finally the whole body • Organisms can be single-celled or multicellular – Cell differentiate in complex multicellular organisms © Cengage Learning 2016. All Rights Reserved. Basic Cell Functions • Obtaining food and O2 • Performing energy-generating chemical reactions • Eliminating wastes • Synthesizing proteins and cell components • Moving materials throughout the cell • Responding to the environment • Reproducing © Cengage Learning 2016. All Rights Reserved. Specialized Cell Functions • Secrete digestive enzymes that break down ingested food • Retain and eliminate substances accordingly • Produce intracellular movement • Generate and transmit electrical impulses that relay information © Cengage Learning 2016. All Rights Reserved. The Tissue Level • Tissues are groups of cells with a similar structure and specialization – Muscle tissue: skeletal, cardiac, and smooth – Nervous tissue: initiate and transmit electrical impulses – Epithelial tissue: exchange materials between the cell and environment – Connective tissue: connects, supports, and anchors various body parts © Cengage Learning 2016. All Rights Reserved. The Four Primary Tissue Types Organ: Body structure that integrates different tissues and carries out a specific function Stomach Epithelial tissue protection, secretion, absorption Connective tissue structural support © Cengage Learning 2016. All Rights Reserved. Muscle tissue movement Nervous tissue communication, coordination, control Exocrine and Endocrine Glands Surface epithelium Surface epithelium Surface epithelium Connecting cells lost during development Secretory endocrine gland cell Duct cell Pocket of epithelial cells Blood vessel Secretory exocrine gland cell (c) Endocrine gland (a) Invagination of surface epithelium during gland formation (b) Exocrine gland © Cengage Learning 2016. All Rights Reserved. The Organ Level • An organ is a unit made up of several tissue types – Consists of two or more types of primary tissue organized to perform particular functions © Cengage Learning 2016. All Rights Reserved. The Body System Level • A body system is a collection of organs that performs related functions – Organs interact to accomplish a common activity essential for survival • Eleven systems: – Circulatory, digestive, respiratory, urinary, skeletal, muscular, integumentary, immune, nervous, endocrine, and reproductive © Cengage Learning 2016. All Rights Reserved. Components of the Body Systems Circulatory system Digestive system Respiratory system Urinary system Skeletal system Muscular system heart, blood vessels, blood mouth, pharynx, esophagus, stomach, small intestine, large intestine, salivary glands, exocrine pancreas, liver, gallbladder nose, pharynx, larynx, trachea, bronchi, lungs kidneys, ureters, urinary bladder, urethra bones, cartilage, joints skeletal muscles © Cengage Learning 2016. All Rights Reserved. Components of the Body Systems Integumentary system skin, hair, nails Immune system lymph nodes, thymus, bone marrow, tonsils, adenoids, spleen, appendix, and, not shown, white blood cells, gut-associated lymphoid tissue, skin-associated lymphoid tissue Nervous system brain, spinal cord, peripheral nerves, and, not shown, special sense organs © Cengage Learning 2016. All Rights Reserved. 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, associated ducts Female: ovaries, oviducts, uterus, vagina, breasts The Organism Level • Body systems are packaged into a functional whole body – Each body system depends on the proper functioning of other systems – Many complex body processes depend on the interplay among multiple systems © Cengage Learning 2016. All Rights Reserved. 1.3 Concept of Homeostasis • Cells in a multicellular organism – Cannot live and function without other body cells – Most are not in direct contact with the surrounding external environment in which an organism lives – Life-sustaining exchanges are made through the internal environment – the fluid that surrounds the cells © Cengage Learning 2016. All Rights Reserved. The Internal Environment • Body cells are in contact with a privately maintained internal environment – Intracellular fluid (ICF): fluid collectively contained within all body cells – Extracellular fluid (ECF): fluid outside the cells • Plasma, the fluid portion of blood • Interstitial fluid, which surrounds and bathes the cells © Cengage Learning 2016. All Rights Reserved. Components of the ECF Extracellular fluid Cell Interstitial fluid Plasma Blood vessel © Cengage Learning 2016. All Rights Reserved. Body Systems Maintain Homeostasis • Homeostasis – A dynamic, and relatively stable state in the internal environment – Body cells can live and function only when the ECF is compatible with their survival • Chemical composition and physical state of this internal environment must be maintained within narrow limits © Cengage Learning 2016. All Rights Reserved. The Interdependence of Cells, Body Systems, and Homeostasis Maintain Body systems Homeostasis Is essential for survival of Make up Cells © Cengage Learning 2016. All Rights Reserved. Homeostatically Regulated Factors • • • • • Concentration of nutrients Concentration of O2 and CO2 Concentration of waste products Changes in pH Concentrations of water, salt, and other electrolytes • Volume and pressure • Temperature © Cengage Learning 2016. All Rights Reserved. Body Systems: Circulatory and Digestive • Circulatory system (heart, blood vessels, and blood) – Transports materials from one part of the body to another • Digestive system (mouth, esophagus, stomach, intestines, and related organs) – Breaks down food into small nutrient molecules that can be absorbed © Cengage Learning 2016. All Rights Reserved. Body Systems: Respiratory and Urinary • Respiratory system (lungs and major airways) – Gets O2 from and eliminates CO2 to the external environment • Urinary system (kidneys and associated structures) – Removes excess water, salt, acid, and other electrolytes from the plasma and eliminates them in the urine © Cengage Learning 2016. All Rights Reserved. Body Systems: Skeletal • Skeletal system (bones and joints) – Provides support and protection for soft tissues and organs – Serves as a storage reservoir for calcium – Enables the body and its parts to move – Bone marrow is the source of all blood cells © Cengage Learning 2016. All Rights Reserved. Body Systems: Muscular and Integumentary • Muscular system (skeletal muscles) – Moves bones attached to skeletal muscles • Voluntary movements range from fine motor skills to powerful movements – Generates heat and maintains body temperature • Integumentary system (skin and related structures) – Serves as an outer protective barrier – Important in regulating body temperature © Cengage Learning 2016. All Rights Reserved. Body Systems: Immune • Immune system (white blood cells and lymphoid organs) – Defends against foreign invaders such as bacteria and viruses and against body cells that have become cancerous – Helps in replacing injured or worn-out cells © Cengage Learning 2016. All Rights Reserved. Body Systems: Nervous and Endocrine • Nervous system (brain, spinal cord, nerves, and sense organs) – Controls and coordinates body activities that require swift responses • Endocrine system (all hormone-secreting glands) – Regulates activities that require duration rather than speed, such as growth © Cengage Learning 2016. All Rights Reserved. Body Systems: Reproductive • Reproductive system (male and female gonads and related organs) – Essential for perpetuating the species – Not essential for homeostasis © Cengage Learning 2016. All Rights Reserved. Maintaining Homeostasis, Part I BODY SYSTEMS Made up of cells organized according to specialization to maintain homeostasis See Chapter 1. Information from the external environment relayed through the nervous system O2 CO2 Urine containing wastes and excess water and electrolytes Nutrients, water, and electrolytes Feces containing undigested food residue Sperm leave male Sperm enter female NERVOUS SYSTEM Acts through electrical signals to control rapid responses of the body; also responsible for higher functions e.g., consciousness, memory, and creativity See Chapters 4,5, 6,and 7. Regulate RESPIRATORY SYSTEM Obtains O2 from and eliminates CO2 to the external environment; helps regulate pH by adjusting the rate of removal of acid-forming CO2 See Chapters 13 and 15. URINARY SYSTEM Is important in regulating the volume, electrolyte composition, and pH of the internal environment; removes wastes and excess water, salt, acid, and other electrolytes from the plasma and eliminates them in the urine See Chapters 14 and 15. DIGESTIVE SYSTEM Obtains nutrients, water, and electrolytes from the external environment and transfers them into the plasma; eliminates undigested food residues to the external environment See Chapter 16. REPRODUCTIVE SYSTEM Is not essential for homeostasis, but essential for perpetuation of the species See Chapter 20. Exchanges with all other systems EXTERNAL ENVIRONMENT CIRCULATORY SYSTEM Transports nutrients, O2, CO2, wastes, electrolytes, and hormones throughout the body See Chapters 9,10, and 11. © Cengage Learning 2016. All Rights Reserved. Maintaining Homeostasis, Part II ENDOCRINE SYSTEM Acts by means of hormones secreted into the blood to regulate processes that require duration rather than speed e.g., metabolic activities and water and electrolyte balance See Chapters4,18,and 19. INTEGUMENTARY SYSTEM Serves as a protective barrier between the external environment and the remainder of the body; the sweat glands and adjustments in skin blood flow are important in temperature regulation See Chapters12 and 17. IMMUNE SYSTEM Defends against foreign invaders and cancer cells; paves the way for tissue repair See Chapter 12. MUSCULAR AND SKELETAL SYSTEMS Support and protect body parts and allow body movement; heat-generating muscle contractions are important in temperature regulation; calcium is stored in the bone See Chapters 8,17,18,and 19. Exchanges with all other systems Body systems maintain homeostasis Keeps internal fluids in Keeps foreign material out HOMEOSTASIS A dynamic steady state of the constituents in the internal fluid environment that surrounds and exchanges materials with the cells See Chapter 1. Factors homeostatically maintained: • Concentration of nutrient molecules See Chapters16,17,18,and 19. • Concentration of O2 and CO2 See Chapter 13. • Concentration of waste products See Chapter 14. • pH See Chapter 15. • Concentration of water, salts, and other electrolytes See Chapters14,15,18,and 19. •Temperature See Chapter 17. •Volume and pressure See Chapters10,14,and 15. Protects against foreign invaders Enables the body to interact with the external environment Homeostasis is essential for survival of cells CELLS Need homeostasis for their own survival and for performing specialized functions essential for survival of the whole body See Chapters1,2,and 3. Need a continual supply of nutrients and O2 and ongoing elimination of acid-forming CO2 to generate the energy needed to power life-sustaining cellular activities as follows: Food + O2 CO2 + H2O + energy See Chapters13,15,16,and 17. Cells make up body systems © Cengage Learning 2016. All Rights Reserved. 1.4 Homeostatic Control Systems • What is a homeostatic control system? – An interconnected network of body components – Operates to maintain a given factor in the internal environment at a relatively constant optimal level © Cengage Learning 2016. All Rights Reserved. How Does the Control System Maintain Homeostasis? • To maintain homeostasis, the control system must be able to: – Detect deviations from normal – Integrate this information with other information – Make adjustments to restore the factor to normal © Cengage Learning 2016. All Rights Reserved. Classes of Homeostatic Control Systems • Intrinsic (local) controls – Built into an organ • Extrinsic (systemic) controls – Initiated outside an organ to alter the organ’s activity © Cengage Learning 2016. All Rights Reserved. Negative Feedback • Opposes an initial change and is widely used to maintain homeostasis – Change in a controlled variable triggers a response that drives the variable in the opposite direction of the initial change, thus opposing the change • Example: controlling room temperature © Cengage Learning 2016. All Rights Reserved. Deviation in controlled variable (detected by) Sensor (informs) Integrator (negative feedback shuts off system responsible for response) (sends instructions to) Effector(s) (brings about) Compensatory response (results in) Controlled variable restored to normal (a) Components of a negative- feedback control system © Cengage Learning 2016. All Rights Reserved. * Fall in room temperature below set point Thermometer Thermostat (negative feedback) Furnace Heat output Increase in room temperature to set point (b) Negative-feedback control of room temperature © Cengage Learning 2016. All Rights Reserved. * Fall in body temperature below set point Temperature-monitoring nerve cells Temperature control center (negative feedback) Skeletal muscles (and other effectors) Heat production through shivering and other means Increase in body temperature to set point (c) Negative-feedback control of body temperature © Cengage Learning 2016. All Rights Reserved. * Positive Feedback • Output enhances or amplifies a change so that the controlled variable continues to move in the direction of the initial change – Less common than negative feedback but is important in some instances • Example: childbirth © Cengage Learning 2016. All Rights Reserved. Feedforward Mechanisms • Initiate responses in anticipation of a change • Infrequently used • Example: – Insulin levels increase while a meal is in the digestive tract as an anticipatory response © Cengage Learning 2016. All Rights Reserved. Disruptions in Homeostasis • Can lead to illness and death – Pathophysiology: abnormal functioning of the body associated with disease – When a homeostatic disruption becomes so severe that it is no longer compatible with survival, death results © Cengage Learning 2016. All Rights Reserved. Points to Ponder • What factors must be homeostatically maintained, and which body systems contribute to maintaining each of these factors? • What are the components of a homeostatic control system? • Why is negative feedback important physiologically? © Cengage Learning 2016. All Rights Reserved.