Cells, Tissues, Organs & Organ Systems Of Animals (Part 2) Flashcards
(29 cards)
Composed mainly of phospholipids and proteins, allow certain material to move across them.
Cell membranes
Fluid-mosaic model
Is based on knowledge of the cell membrane
What are the function of the cell membranes?
(a)regulate movement of material, (b)separate the inside of the cell from the outside,(c) separate various organelles within a cell, (d)provide large surface area, (e) are a site for receptors, (f) separate cells from one another
Passive transport
Type of membrane transport that does not require energy to move substances across cell membrane
Examples of passive transport
Simple diffusion, facilitated diffusion, osmosis and filtration
Net movement of molecules or ions form a region of higher concentration to a region of lower concentration
Diffusion
What affects the diffusion rates?
Size, Temperature, Steepness of concentration gradient, charge and pressure
The diffusion of water across a selectively permeable membrane from an area of higher water concentration to an area of lower concentration
Osmosis
Net diffusion of water molecules across a selectively permeable membrane between two fluids with different water concentrations
Osmosis
Isotonic
Equivalent solute concentration
Hypertonic
More water diffuses out of the cells than into them
Hypotonic
Swell up because more water diffuses into the cells than out of them
Requires energy from the cell to move substances from areas of lower concentration to areas of higher concentration
Active transport
Additional processes that move molecules across membranes in bulk include:
Endocytosis and Exocytosis
Endocytosis (3)
Pinocytosis, Phagocytosis, Receptor-mediated endocytosis
Enables the cell to acquire bulk quantities of specific substances, even though those substances may not be very concentrated in the extracellular fluid
Receptor-mediated endocytosis
LDL (Low Density Lipoprotein)
Acts as a ligand and gains entrance to the cell through endocytosis
What causes early atherosclerosis?
In hypercholesterolemia, LDL are few or missing thus a build up of cholesterol results in blood
Means by which hormones, neurotransmitters and digestive enzymes are secreted in animal cells
Exocytosis
Nucleus
Information center
Contains DNA
Directs chemical reactions
Stores genetic information
Nuclear envelope
Contains many pores that allow material to enter and leave the nucleus
Pre-assemby point for ribosomes
Nucleus
Two parts of the cytoplasm of a cell:
Cytomembrane system and fluid cytosol
Cytomembrane system 4 parts:
ER
Golgi Apparatus
Vacuoles
Vesicles
