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

2. Objectives: Chapter 1 • Explain the Principle of Complimentarity • Name the different levels of structural organization and explain their relationships. • List the 11 organ systems of the body, identify major organs and give the major functions of each system. • Define homeostasis and explain its importance to living organisms • Define negative and positive feedback mechanisms, explain how each works to maintain homeostasis and give an example of each. • Describe anatomical position. • Locate and name the major body cavities, subdivisions of and the membranes within them.

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

4. 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

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

6. 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

7. 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

8. The 11 Major body systems

9. Hair Nails Skin (a) Integumentary System Forms the external body covering, and protects deeper tissues from injury. Synthesizes vitamin D, and houses cutaneous (pain, pressure, etc.) receptors and sweat and oil glands. Figure 1.3a

10. Bones Joint (b) Skeletal System Protects and supports body organs, and provides a framework the muscles use to cause movement. Blood cells are formed within bones. Bones store minerals. Figure 1.3b

11. Skeletal muscles (c)Muscular System Allows manipulation of the environment, locomotion, and facial expression. Main- tains posture, and produces heat. Figure 1.3c

12. Brain Nerves Spinal cord (d) Nervous System As the fast-acting control system of the body, it responds to internal and external changes by activating appropriate muscles and glands. Figure 1.3d

13. Pineal gland Pituitary gland Thyroid gland Thymus Adrenal gland Pancreas Testis Ovary (e) Endocrine System Glands secrete hormones that regulate processes such as growth, reproduction, and nutrient use (metabolism) by body cells. Figure 1.3e

14. Heart Blood vessels (f) Cardiovascular System Blood vessels transport blood, whichcarries oxygen, carbon dioxide,nutrients, wastes, etc. The heart pumpsblood. Figure 1.3f

15. Red bone marrow Thymus Lymphatic vessels Thoracic duct Spleen Lymph nodes (g) Lymphatic System/Immunity Picks up fluid leaked from blood vessels and returns it to blood. Disposes of debris in the lymphatic stream. Houses white blood cells (lymphocytes) involved in immunity. The immune response mounts the attack against foreign substances within the body. Figure 1.3g

16. Nasal cavity Pharynx Bronchus Larynx Trachea Lung (h) Respiratory System Keeps blood constantly supplied with oxygen and removes carbon dioxide. The gaseous exchanges occur through the walls of the air sacs of the lungs. Figure 1.3h

17. Oral cavity Esophagus Liver Stomach Small intestine Large intestine Rectum Anus (i) Digestive System Breaks down food into absorbable units that enter the blood for distribution to body cells. Indigestible foodstuffs are eliminated as feces. Figure 1.3i

18. Kidney Ureter Urinary bladder Urethra (j) Urinary System Eliminates nitrogenous wastes from the body. Regulates water, electrolyte and acid-base balance of the blood. Figure 1.3j

19. Mammary glands (in breasts) Prostate gland Ovary Penis Ductus deferens Testis Uterine tube Scrotum Uterus Vagina (l) Female Reproductive System (k) Male Reproductive System Overall function is production of offspring. Testes produce sperm and male sex hormone, and male ducts and glands aid in delivery of sperm to the female reproductive tract. Ovaries produce eggs and female sex hormones. The remaining female structures serve as sites for fertilization and development of the fetus. Mammary glands of female breasts produce milk to nourish the newborn. Figure 1.3k-l

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

21. Digestive system Takes in nutrients, breaks them down, and eliminates unabsorbed matter (feces) Respiratory system Takes in oxygen and eliminates carbon dioxide Food O2 CO2 Cardiovascular system Via the blood, distributes oxygen and nutrients to all body cells and delivers wastes and carbon dioxide to disposal organs Blood CO2 O2 Urinary system Eliminates nitrogenous wastes and excess ions Heart Nutrients Interstitial fluid Nutrients and wastes pass between blood and cells via the interstitial fluid Integumentary system Protects the body as a whole from the external environment Feces Urine Figure 1.2

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

23. 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

24. 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

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

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

27. Survival Needs • Water • Most abundant chemical in the body • Site of chemical reactions • Normal body temperature • Affects rate of chemical reactions • Appropriate atmospheric pressure • For adequate breathing and gas exchange in the lungs

28. Homeostasis • Maintenance of a relatively stable internal environment despite continuous outside changes • A dynamic state of equilibrium

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

30. 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

31. 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)

32. 1 IMBALANCE Stimulusproduceschange invariable. BALANCE IMBALANCE Figure 1.4, step 1

33. 2 Receptor Receptordetectschange. 1 IMBALANCE Stimulusproduceschange invariable. BALANCE IMBALANCE Figure 1.4, step 2

34. 3 Input: Informationsent along afferentpathway to controlcenter. ControlCenter Afferentpathway 2 Receptor Receptordetectschange. 1 IMBALANCE Stimulusproduceschange invariable. BALANCE IMBALANCE Figure 1.4, step 3

35. 4 Output:Information sent alongefferent pathway toeffector. 3 Input: Informationsent along afferentpathway to controlcenter. ControlCenter Afferentpathway Efferentpathway 2 Receptor Effector Receptordetectschange. 1 IMBALANCE Stimulusproduceschange invariable. BALANCE IMBALANCE Figure 1.4, step 4

36. 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

37. 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)

38. 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

39. 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

40. Positive Feedback • The response enhances or exaggerates the original stimulus • May exhibit a cascade or amplifying effect • Usually controls infrequent events e.g.: • Enhancement of labor contractions by oxytocin (Chapter 28) • Platelet plug formation and blood clotting

41. 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)

42. Anatomical Position • Standard anatomical body position: • Body erect • Feet slightly apart • Palms facing forward

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48. Regional Terms • Two major divisions of body: • Axial • Head, neck, and trunk • Appendicular • Limbs • Regional terms designate specific areas

49. Body Planes • Plane: Flat surface along which body or structure is cut for anatomical study

50. Body Planes • Sagittal plane • Divides body vertically into right and left parts • Produces a sagittal section • Midsagittal (median) plane • Lies on midline • Parasagittal plane • Not on midline