Human Physiology (Biology 4) Lecture Notes

Human Physiology (Biology 4) Lecture Notes

Updated July 2017 Instructor: Rebecca Bailey

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Chapter 1

Homeostasis

? Anatomy - the study of body structure

? Physiology - the study of body function 1. mechanistic approach a. explain how events occur b. e.g., you shiver because a drop in body T leads to signals for muscle contraction 2. teleological approach a. explain how a function fills a need, "why" b. e.g., you shiver because you need to keep warm 3. both approaches can be useful in understanding concepts

? Levels of Organization - Chemical level 1. atoms and molecules

- Cells 1. the basic unit of living things 2. humans are multicellular 3. several basic functions of all cells a. obtain nutrients and O2 b. make usable energy, Food + O2 CO2 + H2O + energy c. eliminate wastes d. synthesize needed molecules e. respond to environmental changes f. control exchange of materials with the environment g. transport molecules h. reproduce 4. in multicellular organisms, cells specialize

- Tissues 1. group of cells with similar structure and function a. plus extracellular material

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2. 4 major types a. muscle (1) specialized for contraction and force generation (2) skeletal - movement of body or body parts (3) cardiac - pump blood (4) smooth - movement of organs b. epithelial (1) specialized for exchange between cell and environment (2) 2 general types - sheets and secretory glands (3) sheets are tightly joined cells covering or lining parts of the body (4) glands secrete products (exocrine glands have ducts leading to a body surface, e.g. sweat glands; endocrine glands release products to interstitial fluid and it goes into blood, e.g. adrenal glands) c. nervous (1) specialized for initiating and transmitting electrical impulses (2) brain, spinal cord, nerves d. connective (1) specialized for connecting and supporting (2) found all over body

- Organs 1. group of two or more tissues designed to perform specific functions

- Body System (organ system) 1. group of organs designed to perform particular functions

- Whole Organism 1. group of organ systems

? Homeostasis - a dynamic equilibrium where body conditions are maintained within narrow limits 1. necessary for each cell to survive 2. each cell contributes 3. all cells are in contact with the aqueous (watery) internal environment, connects all cells, exchanges made a. outside cells, inside body

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b. extracellular fluid (1) plasma (fluid in the blood) (2) interstitial fluid (surrounding cells)

- Major factors maintained 1. concentration of nutrient molecules a. cells need energy and building blocks 2. concentration of O2 and CO2 a. O2 used to make usable energy (ATP) b. CO2 made must be removed 3. concentration of waste products a. become toxic at high levels 4. pH a. acidity affects enzyme reactions and nerve cell impulses 5. concentration of water, salt and other electrolytes a. maintaining cell volume b. various functions of electrolytes 6. temperature a. too cold or too much heat harmful to cells 7. volume and pressure a. blood must be at appropriate volume and pressure to be transported around the body

? 11 Major Organ Systems

? Control Mechanisms - body controlled mainly by nervous and endocrine systems - parts of a control system (all interdependent) 1. sensor a. monitors variable (factor being regulated) b. responds to changes (stimuli) by sending input to... 2. integrator a. determines set point (appropriate level of variable) b. compares set point to input c. sends response to... 3. effector a. responds to changes

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- most control systems operate using negative feedback 1. decreases or shuts off original stimulus 2. resists change

- positive feedback 1. enhances original stimulus 2. uterine contractions during childbirth 3. blood clotting

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