Membrane Physiology: Chapter 3 Flashcards
What are the 3 types of membranes?
Freely permeable membrane
Selectively permeable membrane
Impermeable membrane
What is the purpose of plasma membrane?
Separation
Regulation
Communication
Structural
How do different molecules move across the membrane?
Chemical
Size
Need
What type of layer is the plasma membrane?
Phospholipid bilayer
What are the functional classes of membrane proteins?
Anchoring proteins
Recognition proteins
Enzymes
Receptor proteins
Carrier proteins
Channels
What are the two components of plasma membrane?
Integral: transport proteins
Peripheral: enzymes, cell-to-cell links
Can integral membrane proteins signal cascade?
Yes; extracellular signaling molecules bind receptors and elicit intracellular responses
What are the roles of membrane receptors?
Contact signaling: touching and recognition of cells
Chemical signaling: interaction between receptors and ligands to alter the activity of cell proteins
G protein-linked receptors: release of internal second messenger
What happens when contact signaling is lost?
Tumors occur
What are g protein coupled receptors? What do they do?
Convert extracellular signals to intracellular responses
Ligand - receptor - g protein - enzyme - 2nd messenger
What is glycocalyx? What is it’s function?
Extracellular glycoprotein
Protection - layers for recognition
What does cholesterol help with?
Determining fluidity in membrane
Are lipid rafts localized?
No; stable platforms for cell-signaling molecules (cascade triggered)
What determines whether a substance can passible permeate a membrane?
Concentration gradient
Lipid solubility of a substance
Channels of appropriate size
Carrier proteins
Explain simple diffusion
Directly through membrane without channel or carriers
What is facilitated diffusion?
Use carrier proteins that exhibit specificity, are saturable and can be regulated in terms of activity and quantity
What is carrier mediated facilitated diffusion?
Diffusion via proteins carriers specific for one chemical; binding substances causing shape change
What is channel mediated facilitated diffusion? What are 2 types?
Doesn’t change shape
Mostly ions are selected on basis of size and charge
Leaky, gated
What determines diffusion rate for leaky channels?
Concentration rate
What determines diffusion rate for chemically gated channels?
Neurotransmitters
What determines diffusion rate for voltage gated channels?
Charge in and out of membrane determines if it’s open or closed
What determines diffusion rate for mechanically gated channels?
Distortion
Where does water go during osmosis?
Water goes toward solute, balance
What is osmotic flow?
Movement fo water driven by osmosis
