Anatomy and Physiology Answer Key

G during muscle contraction and provides

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Unformatted text preview: oncentration). – Molecules diffuse along their own concentration gradient, independent of other molecules. – Diffusion rates are higher at higher temperatures. – Diffusion rates are faster when the concentration gradient is greater. – Thicker barriers slow diffusion. 3. (a) Channel-mediated facilitated diffusion, i.e through a protein channel in the membrane that creates a hydrophilic pore. (b) Carrier mediated facilitated diffusion, i.e. the molecule is aided across the membrane by a carrier protein specific to the molecule being transported. 4. Aquaporins are protein channels in the membrane 1. Phagocytosis is the engulfment of solid material by endocytosis whereas pinocytosis is the uptake of liquids or fine suspensions by endocytosis. 2. Phagocytosis examples (any of): • Feeding in Amoeba by engulfment of material using cytoplasmic extensions called pseudopodia. • Ingestion of old red blood cells by Kupffer cells in the liver. • Ingestion of bacteria and cell debris by neutrophils and macrophages (phagocytic white blood cells). 3. Exocytosis examples (any of): • Secretion of substances from specialized secretory Concentration gradients are maintained by constant use or transport away of a substance on one side of a membrane (e.g. use of ADP in mitochondria and by production of a substance on one side of a membrane (e.g. production of CO2 by respiring cells). 5. Exocytosis and Endocytosis (page 28) Biozone International 2009 Photocopying Prohibited Anatomy and Physiology Name: Cellular junctions (given) Location: At cell membrane surface, connecting adjacent cells Function: Depends on junction type but basically cell adhesion and communication. Gap junction: Act as communication channels between cells. Tight junction: Prevent leakage of extracellular fluid from layers of epithelial cells. Desmosome: Fasten cells together. Visible under LM: No. specific to water molecules. This is faster (less resistance) than diffusion through the membrane. 6 cells in multicellular orga...
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This document was uploaded on 01/28/2014.

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