An Orientation to the Human Body

1. An Orientation to the Human Body Anatomy & Physiology I Chapter 1

2. Overview of Anatomy & Physiology • Anatomy: The study of form (structure) • Subdivisions: • Gross Anatomy - study of structures that can be seen with the naked eye • Neuroanatomy – study of nervous system structure • Microscopic Anatomy – study of structures that are too small to see with the naked eye • Cytology – study of cells • Histology – study of tissues

3. Overview of Anatomy & Physiology • Physiology: The study of function at many levels • Subdivisions are based on organ systems • neurophysiology (physiology of nervous system) • endocrinology (physiology of hormones) • pathophysiology (mechanisms of disease)

4. The Human Body L e v e l s o f O r g a n I z a t I o n

5. Levels of Structural Organization All living things are organized. • Atoms • Molecules • Organelles • Cells • Tissue • Organ • Organ System • Organism

6. Atoms Molecule Chemical levelAtoms combine to form molecules. 1

7. Organelle Atoms Molecule Smooth muscle cell Cellular levelCells are made up ofmolecules. 2 Chemical levelAtoms combine to form molecules. 1

8. Organelle Atoms Molecule Smooth muscle cell Cellular levelCells are made up ofmolecules. 2 Chemical levelAtoms combine to form molecules. 1 Smooth muscle tissue Tissue levelTissues consist of similartypes of cells. 3

9. Organelle Atoms Molecule Smooth muscle cell Cellular levelCells are made up ofmolecules. 2 Chemical levelAtoms combine to form molecules. 1 Smooth muscle tissue Tissue levelTissues consist of similartypes of cells. 3 Blood vessel (organ) Smooth muscle tissue Connective tissue Epithelialtissue Organ levelOrgans are made up of different typesof tissues. 4

10. 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 Organ system levelOrgan systems consist of differentorgans that work together closely. 5

11. 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

12. Levels of Structural Organization (cont’d.) • Atoms – the smallest units (building blocks) of matter. • Molecules – make up organelles and other cellular components • macromolecules – proteins, carbohydrates, fats, DNA • Organelles – microscopic structures in a cell that carry out its individual functions • Cells– smallest unit of life

13. Levels of Structural Organization (cont’d.) • Cells • The smallest units of an organism that carry out all the basic functions of life • Perform all activities necessary to maintain life • Metabolism, digestion, assimilation, excretion, reproduction

14. Levels of Structural Organization (cont’d.) • Tissues • A mass of similar cells and cell products that form discrete region of an organ and performs a specific function Four Tissue Classes • Epithelial: covers and protects • Connective: binds and supports other tissues • Muscle: movement • Nervous: connects sensory structures to motor structures

15. Levels of Structural Organization (cont’d.) • Organs • Structure composed of two or more tissue types that work together to carry out a particular function • Cells integrated into tissues • Serve a common function • Examples • Brain • Heart • Lungs • Pancreas

16. Levels of Structural Organization (cont’d.) An Organ System is a group of organs • Protection, support, and movement Integumentary - Skeletal - Muscular • Coordination and control Nervous - Endocrine • Circulation Cardiovascular - Lymphatic • Nutrition and fluid balance Respiratory - Digestive - Urinary • Production of offspring Reproductive

17. The Human Body O r g a n S y s t e m s

18. 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.

19. 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.

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

21. 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.

22. 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.

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

24. 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.

25. 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.

26. 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.

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

28. 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.

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

30. 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

31. Metabolism and Its Regulation ( H o m e o s t a s I s )

32. Metabolism • All the life-sustaining chemical reactions that occur within body cells • Types of metabolism • Anabolism – reactions that build (synthesize) larger, more complex structures from simpler substances. • Similar to building a pearl necklace from individual pearls. • In cells, anabolic reactions require ATP for energy. • Catabolism – reactions that breakdown larger, more complex substances to simpler substance. • Similar to removing each individual pearl from a pearl necklace • Catabolic reactions, like glycolysis, release energy. This energy can be used in cells to make ATP.

33. Homeostasis • stable internal conditions regardless of external conditions • fluctuates within limited range around a set point • Homeostatic Control Mechanisms– Mechanisms that help to maintain homeostasis • The body has hundreds of homeostatic mechanisms, including mechanisms to control: • Body temperature, blood sugar, blood pH, water balance, blood pressure, electrolyte balance, etc. • When these mechanisms don’t work normally, the result can be disease, dysfunction or death.

34. Homeostatic Control Mechanisms • Involve continuous monitoring and regulation of many factors (variables) • Nervous and endocrine systems accomplish the communication via nerve impulses and hormones • Usually involves negative feedback loop • Negative feedback loops have 3 components • Receptor • Control Center • Effector

35. Negative Feedback • Body senses a change and activates mechanisms to reverse it • The response reduces or shuts off the original stimulus • Examples: • Regulation of body temperature and blood pressure (two nervous system mechanism) • Regulation of blood volume by ADH (an endocrine mechanism)

36. Components of Negative Feedback Loop • Receptor (sensor) • Monitors the environment and responds to stimuli (changes in controlled variables) • Reports changes to the control center • Control center • Determines the set point at which the variable is maintained • Receives input from receptor when variable is out of range • Determines appropriate response; delivers instructions to the appropriate effector

37. Components of Negative Feedback Loop • Effector • Receives signal (command) from control center • Provides the means to respond • Response acts to reduce or enhance the stimulus (feedback)

38. 1 IMBALANCE Stimulusproduceschange invariable. BALANCE IMBALANCE

39. 2 Receptor Receptordetectschange. 1 IMBALANCE Stimulusproduceschange invariable. BALANCE IMBALANCE

40. 3 Input: Informationsent along afferentpathway to controlcenter. ControlCenter Afferentpathway 2 Receptor Receptordetectschange. 1 IMBALANCE Stimulusproduceschange invariable. BALANCE IMBALANCE

41. 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

42. 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

43. 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)

44. Negative Feedback Control of Blood Pressure • Sitting up in bed causes a drop in blood pressure in the head and upper thorax • Receptors in the arteries near the heart alert the control center in the brainstem • Control center in the brainsends nerve signals to the heart (effector) • The effector (the heart) receives a command signal to increases the heart rate. This returns the blood pressure to normal • Failure of this to feedback loop may produce dizziness in the elderly

45. Control of Blood Pressure Person rises from bed Blood pressure rises to normal; homeostasis is restored Blood drains from upper body, creatinghomeostatic imbalance Cardiac center accelerates heartbeat Baroreceptors above heart respond to drop in blood pressure Baroreceptors send signals to cardiac center of brainstem

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

47. 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 • Platelet plug formation and blood clotting

48. Positive Feedback Loops • Self-amplifying cycle • leads to greater change in the same direction • feedback loop is repeated – change produces more change • Normal way of producing rapid changes • occurs with childbirth, blood clotting, protein digestion, fever, and generation of nerve signals 3 Brain stimulates pituitary gland to secrete oxytocin 4 Oxytocin stimulates uterine contractions and pushes fetus toward cervix 2 Nerve impulses from cervix Transmitted to brain 1 Head of fetus pushes against cervix

49. 1 Break or tearoccurs in bloodvessel wall. Positive feedbackcycle is initiated.

50. 1 Break or tearoccurs in bloodvessel wall. Positive feedbackcycle is initiated. 2 Plateletsadhere to siteand releasechemicals.