Chapter 3 Flashcards
Extracellular material?
EXTRACELLULAR FLUID (ECF): - Interstitial fluid, in tissues - blood plasma, - cerebrospinal fluid CELLULAR SECRETIONS: - intestinal and gastric fluids. - lube, saliva and mucus. EXTRACELLULAR MATRIX (ECM): - most abundant extracellular material. - jellylike - has proteins and carbs (polysaccharides).
Define a cell:
- smallest unit of life
- every cell has a plasma membrane, nucleus and cytoplasm.
- human beings are multi cellular.
Membrane carbohydrates:
GLYCOLIPIDS:
- stability, identification/recognition, adherence, and communication
GLYCOPROTEINS:
involved in identification/recognition, adherence, and communication
GLYCOCALYX:
- provide identification molecules for approaching cells to recognise. Immune system cells use these to recognise if foreign or not. involved in identification/recognition, adherence, and communication
Membrane proteins:
INTEGRAL: embeded in lipid bilayer. - transport, channels or carriers. PERIPHERAL: Sit on top of bilayer. - cell signalling, transport.
functions of membrane proteins:
signal transduction, cell-cell recognition and signalling, enzymes,
Microvilli and cilia
Microvilli: - extensions on cell surface, increase surface area Cilia: - microtubules from centrioles - move substances across cell membrane.
cell junctions:
TIGHT: - zipper - impermiable - digestive tract DESMOSOMES: - Anchoring junctions - found in cells subject to mechanical stress. ie) skin and heart muscle. GAP: - communication junctions - connected to connexons (hollow cylinders composed of proteins). - heart and smooth muscle.
passive transport:
SIMPLE DIFFUSION:
- non polar molecules
FACILITATED:
- protein channel (small polar or charged molecules). Channels are leakage (always open) or gated (controlled).
- protein carrier (large polar molecules).
OSMOSIS:
- small amount of water can pass through membrane due to small size. Water freely passes though proteins called aquaporins.
membrane permiable to water or solutes?
Permeable to both:
- will reach equilibrium
Permeable to water but not solutes:
- volume changes on both sides of membrane.
what’s osmalarity?
total concentration of all particles of a solution.
what’s tonicity?
Ability of a solution to change the shape of a cell by altering its internal volume.
Primary Active transport:
Primary active transport:
- uses ATP directly, which is hydrolized (phosphate group breaks off and is added to carrier.
- moving against concentration gradient
- uses protein carrier
- Na+ K- pump
Sodium potassium pump:
- 3 Na+ ions bind to protein channel.
- ATP provides energy to change shape of channel and drive ions through.
- 1 P group from ATP remains bound to the channel.
- Na+ is then released out of cell.
- new shape of channel has a high affinity for potassium ions. 2 of these bind to the channel.
- This causes a change in shape of the channel and releases P group into the cytoplasm.
- channel now reverts to original shape, and K- ions are released inside cell.
- cycle continues.
Secondary active transport:
- ATP is used indirectly with symport and antiport.
ie) glucose travels against concentration gradient. - Na+ travels back into the cell through a transport protein, simultaneously driving glucose against its concentration gradient into the cell.
- symport - pumps firing in same direction.
- antiport - pumps fire in opposite directions.
Vesicular transport:
(bulk transport, uses ATP):
Exocytosis:
- docking process. In which transport vesicles in the cell binds with the plasma membrane. This occurs by a tsnare (membrane protein) fusing with the vsnare on the vesicle. Upon fusing the fusion pore that has formed opens up and contents are released outside of cell.
- neurotransmitters, hormones and mucus.
