Week 2 answers

Week 2 answers - Week 2 Answer Key Homeostasis Dynamic...

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Week 2 Answer Key Homeostasis: Dynamic constancy of the internal environment Systems have large surface areas to increase the rate of diffusion Absolute limit to the size of a cell - The higher the surface to volume ratio the more efficient the diffusion - Ex: egg cells are much larger because they have a lot of internal nutrients and are not as dependent on exchange Tissues: Tissues: collections of cells with similar functions and structure ( means weave in Latin) classified into 4 main categories: Epithelial tissue, connective tissue, muscle tissue, and nervous tissue Epithelial: surfaces that have single ( simple epithelium) or multiple (stratified epithelium) layers of a cell that separate compartments - includes skin, linings of lungs, kidneys, intestines Connective Tissue: connects different parts ( does what it says) - Epithelial cells close together while connective tissues is scattered through extracellular matrix - 3 Types of fibers: collagenous fibers, elastic fibers, reticular fibers - Collagen fibers: ex: palm - various transligaments of collagen that prevents the skin form being loose (hard to pinch) - Jell-O made up of connective tissue (Yuck!) - Elastic Fibers: long threads made of a protein elastin, ex: skin on the back of the hands and the lung tissue ( destroyed when you smoke => emphysema b/c lungs can’t recoil as well) - Reticular fibers- thin and very branched- made up of collagen- join connective tissues to adjacent tissue - Adipose tissue- can deposit a lot of fat: main energy storage of body, insulator, also endocrine glands => secrete hormones - Blood: large amounts of intracellular space: white blood cells (immune response) platelets ( involved in blood clotting) Muscle Tissue - Skeletal muscle: striated, very large cells with many nuclei, each one causes a contraction which shortens the muscle - Cardiac muscle: striated and similar to skeletal, different muscle cells attached with junctions, intercalated disk (gap junctions- help relay signals from cell to cell to help synchronize the heartbeat) - Smooth muscle: not striated, involuntary ( autonomic control), makes up walls of internal organs ( arteries, veins, urinary and genial tract) Nervous Tissue: senses stimuli and transmits signals from one part of the body to another - Neurons: dendrites ( input receivers)- synapses here, axon can be long: all the way from spinal chord to pinky toe (see Fig. 40.5) - Glial cells: hold things together (form myelin sheaths, secrete cerebral spinal fluid, from blood-brain barrier)
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Endocrine System Endocrine cells: endo= inside , crine= secretion Signals: travel through blood stream Paracrine: acts locally ( histamine) NS is much faster but can only be sent to target cells, millisecond ( neural transmitters only affect cells with correct receptors) Lecture 2: 9/28/10 Dynamic constancy of Internal Environment Why is this important? Affects proteins ( can degrade or fold wrong if conditions change)
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This note was uploaded on 02/05/2011 for the course BILD 2 taught by Professor Schroeder during the Spring '08 term at UCSD.

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Week 2 answers - Week 2 Answer Key Homeostasis Dynamic...

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