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Chapter 1

Chapter 1. The Human Body: An Orientation: Part A. Overview of Anatomy and Physiology. Anatomy : The study of structure of the body Subdivisions : Gross or macroscopic (e.g., regional, surface, and systemic anatomy) Microscopic (e.g., cytology and histology)

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Chapter 1

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  1. Chapter 1 The Human Body: An Orientation: Part A

  2. Overview of Anatomy and Physiology • Anatomy: The study of structure of the body • Subdivisions: • Gross or macroscopic (e.g., regional, surface, and systemic anatomy) • Microscopic (e.g., cytology and histology) • Developmental (e.g., embryology)

  3. Overview of Anatomy and Physiology • Essential tools for the study of anatomy: • Anatomical terminology • Observation • Palpation • Auscultation

  4. Overview of Anatomy and Physiology • Physiology: The study of function of the body at many levels • Subdivisions are based on organ systems (e.g., renal, digestive, cardiovascular physiology)

  5. Overview of Anatomy and Physiology • Essential tools for the study of physiology: • Ability to focus at many levels (from systemic to cellular and molecular) • Basic physical principles (e.g., electrical currents, pressure, and movement) • Basic chemical principles

  6. Principle of Complementarity • Anatomy and physiology are inseparable. • Function always reflects structure • What a structure can do depends on its specific form

  7. Levels of Structural Organization • Chemical: atoms and molecules (Chapter 2) • Cellular: cells and their organelles (Chapter 3) • Tissue: groups of similar cells (Chapter 4) • Organ: contains two or more types of tissues • Organ system: organs that work closely together • Organismal: all organ systems

  8. Organelle Atoms Molecule Smooth muscle cell Cellular levelCells are made up ofmolecules. 2 Chemical levelAtoms combine to form molecules. 1 Smooth muscle tissue Cardiovascularsystem Tissue levelTissues consist of similartypes of cells. 3 Heart Bloodvessels Blood vessel (organ) Smooth muscle tissue Connective tissue Epithelialtissue Organ levelOrgans are made up of different typesof tissues. 4 Organismal levelThe human organism is made upof many organ systems. Organ system levelOrgan systems consist of differentorgans that work together closely. 6 5 Figure 1.1, step 6

  9. Overview of Organ Systems • Major organs and functions of the 11 organ systems

  10. Digestive system • Nervous system • Respiratory system • Cardiovascular system • Lymphatic system • Urinary system Organ Systems • Muscular system • Skeletal system • Integumentary system • Endocrine system • Reproductive system

  11. Organ Systems Interrelationships • All cells depend on organ systems to meet their survival needs • Organ systems work cooperatively to perform necessary life functions

  12. Necessary Life Functions • Boundary: Maintaining boundaries between internal and external environments • Plasma membranes • Skin • Movement: (contractility) • Of body parts (skeletal muscle) • Of substances (cardiac and smooth muscle)

  13. Necessary Life Functions • Responsiveness: The ability to sense and respond to stimuli • Withdrawal reflex • Control of breathing rate • Digestion: • Breakdown of ingested foodstuffs • Absorption of simple molecules into blood

  14. Necessary Life Functions • Metabolism: All chemical reactions that occur in body cells • Catabolism and anabolism • Excretion: The removal of wastes from metabolism and digestion • Urea, carbon dioxide, feces

  15. Necessary Life Functions • Reproduction: • Cellular division for growth or repair • Production of offspring • Growth: Increase in size of a body part or of organism

  16. Survival Needs • Nutrients: • Chemicals for energy and cell building • Carbohydrates, fats, proteins, minerals, vitamins • Oxygen: • Essential for energy release (ATP production)

  17. Survival Needs • Water: • Most abundant chemical in the body • Site of chemical reactions • Body temperature: • Affects rate of chemical reactions • Atmospheric pressure: • For adequate breathing and gas exchange in the lungs

  18. Homeostasis • It is the maintenance of a relatively stable internal environment despite continuous changes both inside and out • A dynamic state of equilibrium

  19. Homeostatic Control Mechanisms • Involve continuous monitoring and regulation of many factors (variables) • Nervous and endocrine systemsaccomplish the communication via nerve impulses and hormones

  20. Components of a Control Mechanism • Receptor (sensor) • Monitors the environment • Responds to stimuli (changes in controlled variables) • Control center • Determines the set point at which the variable is maintained • Receives input from receptor • Determines appropriate response

  21. Components of a Control Mechanism • Effector • Receives output from control center • Provides the means to respond • Response acts to reduce or enhance the stimulus (feedback)

  22. 4 Output:Information sent alongefferent pathway toeffector. 3 Input: Informationsent along afferentpathway to controlcenter. ControlCenter Afferentpathway Efferentpathway 2 Receptor Effector 5 Receptordetectschange. Responseof effectorfeeds backto reducethe effect ofstimulusand returnsvariable tohomeostaticlevel. 1 IMBALANCE Stimulusproduceschange invariable. BALANCE IMBALANCE Figure 1.4, step 5

  23. Negative Feedback • The response reduces or shuts off the original stimulus • Examples: • Regulation of body temperature (a nervous mechanism) • Regulation of blood volume by ADH (an endocrine mechanism)

  24. Control Center (thermoregulatory center in brain) Information sent along the afferent pathway to control center Information sent along the efferent pathway to effectors Efferent pathway Afferent pathway Receptors Temperature-sensitive cells in skin and brain Effectors Sweat glands Sweat glands activated Response Evaporation of sweat Body temperature falls; stimulus ends Stimulus Body temperature rises BALANCE Stimulus Body temperature falls Response Body temperature rises; stimulus ends Receptors Temperature-sensitive cells in skin and brain Effectors Skeletal muscles Afferent pathway Efferent pathway Shivering begins Information sent along the efferent pathway to effectors Information sent along the afferent pathway to control center Control Center (thermoregulatory center in brain) Figure 1.5

  25. Negative Feedback: Regulation of Blood Volume by ADH • Receptors sense decreased blood volume • Control center in hypothalamus stimulates pituitary gland to release antidiuretic hormone (ADH) • ADH causes the kidneys (effectors) to return more water to the blood

  26. Positive Feedback • The response enhances or exaggerates the original stimulus • Enhancement of labor contractions by oxytocin (Chapter 28) • Platelet plug formation and blood clotting

  27. 1 Break or tearoccurs in bloodvessel wall. Positive feedbackcycle is initiated. 3 2 Releasedchemicalsattract moreplatelets. Plateletsadhere to siteand releasechemicals. Positivefeedbackloop Feedback cycle endswhen plug is formed. 4 Platelet plugforms. Figure 1.6, step 4

  28. Homeostatic Imbalance • Disturbance of homeostasis • Increases risk of disease • Contributes to changes associated with aging • May allow destructive positive feedback mechanisms to take over (e.g., heart failure)

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