NS 3410 1st Edition Lecture 3Outline of Last LectureI. TeratomaII. RibosomopathiesIII. Endoplasmic Reticulum Associated Destruction- ERADIV. MitochondriaOutline of Current LectureI. Membrane JunctionsII. Ventral body cavity membranesIII. Passive Membrane TransportIV. Active TransportCurrent LectureI. Membrane Junctions- Most cell types are found in groups that function together to bring about desired outcome-Organelles-Cell-Tissue- group of cells with similar function-Organ-collection of tissues-Organ system- group of organs- Cell junctions -Tight junctions- impermeable junctions that prevent molecules from passing through the intercellular spaceThese notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.-Desmosomes- anchoring junctions that bind adjacent cells together and help form and internal tension-reducing network of fibers-Gap junctions- communicating junctions that allow ions and small molecules to pass from one cell to the next- Tight junctions-If damaged, increased gut permeability (ulcers, inflammation, damage from pancreatic enzymes). Intestinal integrity gets compromised and a lot of minerals are lostII. Ventral body cavity membranes- Parietal serosa lines internal body walls- Visceral serosa covers the internal organs- Serous fluid separates the serosaeIII. Passive Membrane Transport- Does not require energy- Simple diffusion- lipid-soluble solutes go right through the membrane- Carrier-mediated facilitated diffusion- protein carrier specific for one chemical binds and transports particle into membrane- Channel-mediated facilitated diffusion- ions move through a channel into the membrane- Osmosis- water moves through specific channel protein known as aquaporins-Water diffuses from the less concentrated solution (fewer solutes, more water) to the more concentrated solution (more solutes, less water)IV. Active Transport- Requires energy- Phagocytosis- pseudopods engulf solids and bring them into the cell’s interior; macrophages do this- Receptor-mediated endocytosis- receptors internalized and recycled back to membrane- Pinocytosis- fluid-phase endocytosis; plasma membrane infolds, bringing extracellular fluid and solutes into interior of cell- Receptor-Mediated Endocytosis-Target molecules bind to receptors in plasma membrane-Areas coated with ligands form deep pockets in plasma membrane surface-Pockets pinch off, forming endosomes known as coated vesicles-Coated vesicles fuse with primary lysosome to form a secondary lysosome-Ligands are removed and absorbed into the cytoplasm-The lysosomal and endosomal membranes separate-The endosome fuses with the plasma membrane and the receptors are again available for ligand binding- Clathrin-coated pits provide a major role in formation of coated vesicles for receptor-mediated endocytosis- Caveolae are also used in receptor-mediated endocytosis- Exocytosis-Adds components to membranes-Recycles membrane receptors-Secretes substances into extracellular fluid- Process of exocytosis:-Membrane-bound vesicle migrates to the plasma membrane-Proteins at the vesicle surface (v-SNAREs) bind with t-SNAREs (plasma membrane proteins)-The vesicle and plasma membrane fuse and a pore opens up-Vesicle contents are released to cell
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