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Chapter 1 The Study of Body Function Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 1-1 Chapter 1 Outline Introduction to Physiology Scientific Method Homeostasis The Primary Tissues Muscle Tissue Nervous Tissue Epithelial Tissue Connective Tissue Organs and Systems Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 1-2 Human Physiology Physiology: study of how body works to maintain life Pathophysiology: how physiological processes are altered in disease or injury Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 1-3 Scientific Method 1-4 Scientific Method 1. Form a testable hypothesis about observations 2. Conduct and analyze experiments to test hypothesis 3. Draw conclusions about whether or not results support hypothesis 4. Develop a theory = general statement explaining natural phenomena that is based on proven hypotheses Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 1-5 Testing of Hypotheses Involves: Experimental and control groups Quantitative measurements performed blindly Analysis of data using statistics Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 1-6 Using Scientific Method to Develop New Drugs When a new drug is suggested by experiments: Its effectiveness and toxicity is tested first in tissue culture, rats, mice Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 1-7 Using Scientific Method to Develop New Drugs If effective and safe, clinical trials performed Phase I Trials: Toxicity and metabolism tested in healthy human volunteers Phase II Trials: Effectiveness and toxicity tested in target population Phase III Trials: Widespread test of drug in diverse population Phase IV Trials: Drug is tested for other potential uses Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 1-8 Homeostasis 1-9 Homeostasis Is maintenance of a state of dynamic constancy In which conditions are stabilized above and below a physiological set point By negative feedback loops Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 1-10 Negative Feedback Loops Sensor: Detects deviation from set point Integrating center: Determines response Effector: Produces response Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 1-11 Homeostasis continued Regulatory mechanisms: Intrinsic control is built into organ being regulated Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 1-12 Homeostasis continued Regulatory mechanisms: Extrinsic control comes from outside of organ E.g. body temperature is controlled by antagonistic effects of sweating and shivering Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 1-13 Regulatory Homeostasis continued mechanisms: Extrinsic control comes from outside of organ E.g. hormones control blood glucose levels Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 1-14 Homeostasis continued Regulatory mechanisms: Positive feedback is rare because it amplifies changes It is involved in producing blood clots In females it is used to create the LH surge that causes ovulation Positive feedback between the uterus and oxytocin secretion occurs during labor Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 1-15 Homeostasis continued Regulatory mechanisms: Negative feedback loops control blood pressure Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 1-16 Negative Feedback Hormonal Control of Blood Glucose Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 1-17 The Primary Tissues (includes muscle, nervous, epithelial and connective tissues) 1-18 Muscle Tissue 1-19 Muscle Tissue Specialized for contraction 3 types: skeletal, cardiac, smooth Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 1-20 Skeletal Muscle Is striated; voluntary Each fiber: Forms by fusion of embryonic myoblasts Allowing it to become large and multinucleated Is individually controlled Lines up in parallel with other fibers to form bundles Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 1-21 Myocardial Cardiac Muscle celIs: Are short, striated and involuntary Are branched to form a continuous fabric Have intercalated discs between cells that provide mechanical and electrical interconnections Are not individually controlled Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 1-22 Smooth Muscle Is not striated; is involuntary Found in many organs, tissues Controlled by ANS Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 1-23 Nervous Tissue 1-24 Nervous Tissue Consists of neurons and supporting or glial cells Neurons are specialized for conducting electrical signals Have a cell body, dendrites and axon Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 1-25 Nervous Tissue continued Cell body contains nucleus; is metabolic center Dendrites: highly branched extensions off cell body Receive inputs from other neurons Axon: single, long extension off cell body Conducts nerve impulses to other cells Supporting/Glial cells provide physical and functional support for neurons 5X more abundant than neurons Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 1-26 Epithelial Tissue 1-27 Epithelial Tissue Lines and covers body surfaces Consists of cells that form membranes and glands Regularly replaced Squamous epithelial cells are flattened Columnar epithelial cells are taller than wide Cuboidal epithelial cells are cube-shaped Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 1-28 Epithelial Tissue continued Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 1-29 Epithelial Tissue continued Simple membranes are one cell thick Specialized for transport Stratified has a number of layers Specialized for protection Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 1-30 Epithelial Tissue continued Non-keratinized stratified squamous consists of living cells (Fig 1.13) Keratinized stratified squamous has outer layer of dead cells Cells contain water-resistant keratin Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 1-31 Epithelial Tissue continued Cells are joined by junctional complexes, which increase strength and create barrier Separated from underlying tissue by basement membrane Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 1-32 Exocrine Glands Derived from epithelial cells Secrete onto epithelium via ducts Can be simple tubes or clusters called acini Whose secretion is controlled by surrounding myoepithelial cells Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 1-33 Connective Tissue 1-34 Connective Tissue Has lots of extracellular material deposited in space between its cells Includes connective tissue proper, cartilage, bone and blood Loose connective tissue consists of collagen (fibrous proteins) and tissue fluid E.g. dermis of skin Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 1-35 Connective Tissue Proper Dense fibrous connective tissue is packed with fibers of collagen Can be regularly arranged as in tendons Or irregularly oriented as in capsules, sheaths (Fig 1.16) Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 1-36 Connective Tissue - Adipose Specialized for fat synthesis, breakdown and storage Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 1-37 Connective Tissue - Cartilage Specialized for support, protection Made of chondrocytes and elastic extracellular material Serves as precursor for bone Forms articular surfaces for joints Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 1-38 Connective Tissue - Bone Formed as concentric layers of calcified material Contains 3 cell types: Osteoblasts: boneforming cells Osteocytes: trapped, inactive osteoblasts Osteoclasts: the bone resorbing cells Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 1-39 Organs and Systems 1-40 Organs Are anatomical and functional units made of two or more primary tissues Systems are groups of organs working together to maintain homeostasis Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 1-41 Skin—The Largest Organ Has an outer layer of protective cornified epidermis Next layer is dermis, which contains connective tissue, glands, blood vessels, nerves Inner layer is hypodermis, which contains fat Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 1-42 Stem Cells Most cells in organs are highly specialized or differentiated Many organs retain small populations of adult stem cells These are less differentiated; can become many cell types E.g. bone marrow stem cells can give rise to all of the different blood cell types Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 1-43 Stem Cells continued Hair follicle stem cells can form the hair shaft, root sheath, sebaceous glands and epidermis Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 1-44 Body-Fluid Compartments Body has intracellular and extracellular compartments Intracellular is inside cells Extracellular is outside cells Separated by cell’s outer membrane Extracellular is composed of blood plasma and interstitial fluid Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 1-45