The Human Body

1. The Human Body An Overview

2. Anatomy • From Latin tomy (to cut) and ana (apart) • It’s the study of structure and shape of the body and its parts • Two types: • Gross anatomy: large structures, easily observable • Microscopic anatomy: small structures only visible with microscope

3. Gross Anatomy

4. Microscopic anatomy

5. Levels of Structural Organization

6. Structural complexity • Six levels of complexity • Chemical level • Atoms: smallest building blocks of matter • Molecules: combinations of atoms to make water, sugars, and proteins • Atoms combine to form molecules Nitrogen

7. Cellular level • Molecules combine to form cells, which vary in size and shape, reflecting different functions of body

8. Tissue level • Similar types of cells group to form tissues • Four basic tissue types: • Epithelial tissue (skin, membranes) • Connective tissue (tendons, cartilage, ligaments and bone) • Muscular tissue (muscles) • Neural tissue (spinal cord, brain matter)

9. Organ level • Tissue or multiple tissues that form a structure that performs a specific function • Ex: small intestine is made out of all four tissue types

10. Organ system level • Group of organs that cooperate to accomplish a common purpose • Ex: digestive system includes esophagus, stomach, small and large intestines, and more • Total of 11 organ systems • How they work = physiology!

11. Organismal level • Highest level of organization • Human organisms have similar organ systems and chimpanzees, but very different organ systems than mosquitoes

12. Physiology • Studies functions (how it works) of human body and its parts • Anatomists observe structures while physiologists employ experimentation

13. Organ systems • Integumentary system • External covering of the body (skin) • Protects deeper tissue from injury or infection • Synthesizes vitamin D • excretes salts and urea in perspiration • helps regulate body temperature • contains pain, temperature, and pressure receptors for environmental cues

14. Muscular system • Muscles of body • Contract or shorten to move skeleton • Maintains posture • Produces heat

15. Skeletal system • All bones, cartilages, ligaments and joints make up skeletal system • Protects and supports body organs • Provides muscle attachment for movement • Forms blood cells (hematopoiesis) in bone marrow • Provides and stores minerals

16. Nervous system • Brain, spinal cord, nerves, and sensory receptors • Speedy control system that responds to external stimuli • Light • Sound • Temperature changes • Pain • Pressure • Central nervous system (brain and spinal cord) assesses information and responds by activating appropriate effector (muscles or glands)

17. Endocrine system • A series of glands that slowly control body by producing and releasing hormones for growth, metabolism, and reproduction • Pituitary gland • Thyroid gland • Parathyroid glands • Adrenal glands • Thymus • Pancreas • Pineal gland • Ovaries (females) • Testes (males)

18. Cardiovascular system • Heart and blood vessels • Work together to transport materials in blood • Nutrients • Hormones • Oxygen • Carbon dioxide • Waste

19. Lymphatic system • Lymphatic vessels, lymph nodes, spleen, and tonsils • Returns fluid leaked from blood back to blood vessels • Lymph nodes (and others) help cleanse blood and store cells involved in immunity

20. Respiratory system • Lungs, nasal passages, pharynx, larynx, trachea, and bronchi • Supplies oxygen • Removes carbon dioxide

21. Digestive system • Mouth, esophagus, stomach, small and large intestines, liver, pancreas, and rectum • Breaks down food • Deliver products to blood for dispersal to body • Undigested food leaves body through anus as feces • Reclaim water for bodily use

22. Urinary(excretory) system • Kidneys, ureters, bladder, urethra • Rids body of waste products • Nitrogen-containing urea and uric acid from breakdown of proteins and nucleic acids • Maintains body’s water and salt/electrolyte balance • Regulates acid-base balance of blood

23. Reproductive system • Males: scrotum, penis, accessory glands, and ducts • Females: ovaries, uterine tubes, uterus, and vagina • Sole purpose is to produce offspring

24. Major Organs

25. Life Functions • Organ systems work together to promote health and well-being of entire body. Must be able to provide eight functions necessary for living. A healthy body must … HINT: these are all VERBS!

26. Maintain boundaries • The “inside” remains distinct from the “outside.” • Examples include • a cell’s environment maintained by the cell membrane • the integumentary system protecting organs from desiccating (drying out), from bacteria and viruses, from heat and sunlight, and from chemicals

27. Move • Muscle movement is necessary for • Locomotion: getting us from one place to another, or for moving muscle for safety (hot stove) • Movement of substances: getting blood, food, and urine through their proper organs

28. Respond or be irritated • Ability to sense changes (from stimuli) and react to them • Ex: is automatically removing hand from broken glass (painful stimulus) that cuts – involuntary response • Ex: when decrease in oxygen levels detected (mountains), response is to increase breathing rate to obtain more oxygen

29. Digest • Breakdown of nutrients and absorption into blood for delivery to all body cells

30. Metabolize • Chemical reactions within body cells to • Produce energy in form of ATP (adenosine triphosphate) • Make body structures like bones and muscles • Regulated mainly by hormones secreted by glands of endocrine system testosterone

31. Excrete • Eliminate excreta (waste) from digestions and metabolic reactions • Urine • Feces

32. Reproduce • Produce future generations… • of identical cells in cell division (repair or growth) • of entire organism

33. Grow • Increasing cell size and number • Must make more cells faster than cells die

34. HINT: these are all NOUNS! Survival needs • In order to maintain the eight functions for living, the human body must have the following items: • Nutrients • Chemicals for energy and cell building • Carbohydrates • Proteins • Lipids • Vitamins • Minerals

35. Oxygen • Required for chemical reactions • Cellular respiration

36. Water • 60-80% of body weight • Necessary for metabolic reactions

37. Basal body temperature • 98.6°F or 37°C • Atmospheric pressure • Standard atmospheric pressure (on earth at sea level is 760 mmHg or 29.92 inHg)

38. Homeostasis • Maintenance of a stable internal environment = a dynamic state of equilibrium • Homeostasis must be maintained for normal body functioning and to sustain life • When needs are being adequately met, body is functioning smoothly, body demonstrates homeostasis • All organ systems partake in maintaining homeostasis

39. Homeostatic imbalance – a disturbance in homeostasis sets off chain reaction of events • Stimulus • Produces change in variable • Detection • Change is detected by receptor • Input • Information is sent from receptor to control center • Output • Control center decides what action or response should be taken • Response • Action or response feeds back to influence magnitude of stimulus and returns variable to homeostasis

40. Overview of Homeostasis

41. The body communicates chiefly through nervous and endocrine systems • Nervous uses electrical signals delivered by nerves • Endocrine system uses blood borne hormones • Factor being regulated is called the variable

42. All homeostatic control mechanisms have at least three components • Receptor • Responds to changes in the environment (stimuli) • Sends information to control center via afferent pathway • Afferent approaches control center • Control center • Determines set point at which variable should be maintained • Analyzes information • Determines appropriate response • Effector • Provides a means for response to the stimulus • Desired response flows along efferent pathway • Efferent exits control center

43. Most homeostatic control mechanisms are negative feedback mechanisms • Negative feedback • Includes most homeostatic control mechanisms • Shuts off the original stimulus, or reduces its intensity • Works like a household heating system with set point of 72°F • If it’s too cold, will heat it up by turning on heater • If it’s too warm, will shut off heater until it levels off

44. Hypothalamus, located in brain, regulates body temperature

45. If stimulus produces desired effect, and body needs it to increase in action, a positive feedback results • Positive feedback • Increases the original stimulus to push the variable even farther away from set point • In the body this only occurs in blood clotting, birth of a baby, breastfeeding, and protein digestion • Cut on hand = stimulus (wasn’t there prior and is not part of body set-point) • Factor in blood starts to form blood clots • Body wants MORE blood clots so positive feedback mechanism takes over • MORE blood clotting factors are in play until wound heals

46. Homeostasis is SO important that most disease is a result of homeostatic imbalance • As we age, body organs become less efficient, and internal conditions less stable • Events put us at increased risk for illness and produce changes associated with aging • Ex: elastin in connective tissue of skin makes it able to resume shape after stretching, like a rubber band • As we age, elastin production decreases and/or breaks down, so skin loses ability to resume shape

48. Anatomical Language • Can’t always describe body as left and right or top and bottom because so many protrusions and bends. Have specific terminology to describe locations of the body. • Exact terms are used for • Positions • Directions • Regions • Structures

49. Positions • Initial point of reference is always the standard position called anatomical position regardless of position body happens to be in (like sitting) • Body standing erect • Feet parallel • Arms hanging at sides, palms facing forward • Two major positions: • Anterior – front of body in anatomical position • Posterior – back of body in anatomical position

50. Regions • Anterior body landmarks • See page 13 of book (don’t need to know for test)