Cell Physiology 1

Question 1

What are the components of the cell membrane?

Answer 1

1. phospholipid bilayer. 2. membrane proteins. 3. membrane carbohydrates.

Question 2

What is the phospholipid bilayer?

Answer 2

continuous layer around the cells. has carbs on external surface, proteins in the bilayer. its a barrier to water soluble substances (solutes that can easily dissolve in water). it lets lipid soluble molecules and small molecules like o2 and co2 pass though freely by simple diffusion.

Question 3

What are the different kinds of membrane proteins?

Answer 3

a. transport proteins b. receptor proteins. c. enzymes d. joining proteins e. identifying proteins.

Question 4

What are transport prots and what do they do? What are the two kinds?

Answer 4

they allow certain molecules to pass through the bilayer. so they allow passive transport that doesnt use energy, and secondary active transport. channel prots and carrier prots.

Question 5

What do channel proteins do?

Answer 5

channel-mediated facilitated diffusion (passive transport using channels) of specific ions and water (osmosis). so forms a pore/channel in the membrane so that selected ions/mols can pass through. can be gated - opens and closes when signalled or non-gated - always open.

Question 6

What do carrier proteins do?

Answer 6

allow carrier-mediated facilitated diffusion (passive transport using carriers) or active transport. bind to solute and help carry it across the membrane.

Question 7

What are receptor proteins?

Answer 7

binding sites for signaling molecules ie ligands/chemical messengers like hormones and neurotransmitters. eg. glucose uptake - insulin binds to receptor on mm or adipose tissue and triggers more glucose transporters which increase glucose mvmt into blood from cells.

Question 8

What are enzymes?

Answer 8

prots that control chemical reactions on outer or inner surfaces.

Question 9

What are joining proteins?

Answer 9

anchor cell membrane o cytoskeleton or an adjacent cell. so join cells together. a. junctional prots btwn cells forming desmosomes, tight junctions, gap junctions. b. extracellular fibers

Question 10

What are identifying proteins?

Answer 10

ex. major histocompatibility complex prots. are on the surface of all cells except for rbcs. they ID cell as self, so help immune syst. reco. foreign substances. will attack foreign bodies.

Question 11

What are membrane carbohydrates?

Answer 11

glycoproteins and glycolipids on the exterior of bilayer. allow cells to reco other types of cells. ie sperm recognizes egg.

Question 12

How does membrane transport affect homeostasis?

Answer 12

homeo relies on the ability of cells to maintain the composition of the intracellular and extracellular fluid and to move solutes and solvents across the cell membrane. so needing to maintain equilibrium and letting cells go where they need to go.

Question 13

What is the difference btwn a solute and a solvent?

Answer 13

a solute is the substance dissolved in a solution (ions and molecules). a solvent is the substance that the solute is dissolved in ie water.

Question 14

What are the two types of membrane transport (just list)?

Answer 14

passive transport, and active transport.

Question 15

What is passive transport?

Answer 15

transport that doesnt require any energy (no ATP). its always mvmt down a concentration gradient, so solutes and solvents move from high to low. the greater the diff in conc (ie one side solute conc super high and one side super low), the more molecules that want to move (bc they want to be in equilibrium).

Question 16

What are the types of passive transport (just list)?

Answer 16

simple diffusion, channel-mediated facilitated diffusion, carrier-mediated facilitated transport/diffusion, osmosis (solvent mvmt), bulk flow.

Question 17

What is simple diffusion?

Answer 17

passive transport where solutes - specifically lipid soluble and small molecules like gases o2 and co2 - diffuse directly through the lipid bilayer. so down their conc grad from high to low.

Question 18

What is channel-mediated facilitated diffusion?

Answer 18

passive transport where ions diffuse past bilayer bc of access granted by channel proteins. so solute moves freely through opening created by the channel.

Question 19

What is carrier-mediated facilitated diffusion/transport?

Answer 19

passive or active transport where large, charged, or water soluble molecules diffuse through bilayer by binding to carrier protein that takes them so other side. so solute must bind to protein to pass.

Question 20

What is osmosis?

Answer 20

water/solvent diffuses across semipermeable membrane due to water difference. so water moves bc theres a diff in water lvl on either side. water moves down its conc grad so form high to low (diffusion) via channels or across memb bilayer.

Question 21

What is a dilute solution?

Answer 21

high [H2O], low [solute]

Question 22

What is a concentrated solution?

Answer 22

low [H2O], high [solute]

Question 23

What is osmotic pressure?

Answer 23

the pressure required to prevent water from moving across the semipermeable membrane due to osmosis (ie water wanting to go down its conc grad). so the pressure that S2 needs to exert to keep S1s water from coming over.

Question 24

What is osmotic pressure determined by?

Answer 24

solute concentration. if its pure water (ie no solutes) there is no OP. the greater the solute conc the greater the OP.

Question 25

Where does water move depending on the OP?

Answer 25

water moves from low OP to high OP, bc low OP= high water conc and high OP= low water conc, and we know that water diffuses from high to low concentration.

Question 26

What is the OP if both solutions are pure water?

Answer 26

OP is 0 bc there is no conc grad for water mols and therefore no pressure is required to prevent water mvmt. water is still moving but there is no net mvmt.

Question 27

What is the OP if both solutions have the same concentration of solutes?

Answer 27

the OP of both solutions is equal but not zero. so theres still pressure bc there;s solute, but its the same amount.

Question 28

If the OP is high what is the concentration of the solution?

Answer 28

high OP = high [solute], low [h2o]. bc more pressure is needed to prevent water from other solution going down conc grad into this solution.

Question 29

If the OP is low what is the concentration of the solution?

Answer 29

low OP = high[h2o], low [solute]. bc minimal pressure is needed bc water wants to go from high to low so doesnt want to come into this solution where the water is already high.

Question 30

What is tonicity and what does it depend on?

Answer 30

the response of a cell immersed in a solution. depends on solute conc (and permeability of memb to solute).

Question 31

What are the classifications of tonicity (just list)?

Answer 31

hypotonic, hypertonic, and isotonic

Question 32

What is a hypotonic solution?

Answer 32

cell is a 'hungry hippo' and takes in too much water causing it to swell. this happens bc the ECF has lower OP then the ICF (cell). and we know water moves from low OP to high OP, in other words from high [h2o] to low [h2o]. too much swelling can cause a rupture = lysis (in rbcs called hemolysis).

Question 33

What is a hypertonic solution?

Answer 33

cell is 'hyper and sweats' so loses too much water causing it to shrivel/shrink. this happens bc the ICF (cell) has low OP and the ECF has high OP, in other words the water goes down its conc grad from high conc in cell to low conc outside.

Question 34

What is a isotonic solution?

Answer 34

'same' where theres no change bc the ECF and ICF have equal osmotic pressures. most cells in human body have solute concentrations that are equal to a 0.9% saline solution.

Question 35

What are the practical uses of tonicity to reduce a brain edema?

Answer 35

edema is swelling in the brain, so if we inject a 10% sucrose solution which is hypertonic, the swelling will decrease in the cells bc the OP is higher outside the cell, so water will want to move to it.

Question 36

What is bulk flow?

Answer 36

passive transport thats the mvmt of fluid and solutes due to a pressure gradient (high pressure to low pressure). uses hydrostatic pressure.

Question 37

What is hydrostatic pressure?

Answer 37

the pressure of a fluid pressing against a hard surface.

Question 38

What is an active transport process?

Answer 38

require energy (ATP) to move ions/molecules against their concentration gradient (low to high).

Question 39

What are the types of active processes (just list)?

Answer 39

active transport, and vesicular transport.

Question 40

What is active transport? list its two types?

Answer 40

substances move against their conc grad, always protein carrier-mediated. type one is primary active transport. type two is secondary active transport.

Question 41

What is primary active transport?

Answer 41

a molecular pump breaks down ATP and uses it directly so that it can actively transport ions against their conc grads. example is the Na/K ATPase pump which pumps 3 Na out of the cell and 2 K into the cell per ATP (against their gradients). this forms a conc grad for Na/electron concentration gradient bc now theres even more Na outside cell and even more K inside cell which makes inside the cell negative and outside positive. Summary: pump uses ATP, moves 3 Na and 2 K against conc grad, establishes Na conc grad.

Question 42

What is secondary active transport?

Answer 42

example; glucose absorption by nterocytes. step 1: conc grad established by ATPase pump which uses atp directly (so cant do secondary transport without primary) so use of atp is indirect in secondary. step 2: Na binds to a carrier protein bc it wants to go down its conc grad, and glucose hitches a ride onto that carrier protein and they are cotransported into the cell. (Na going down its conc grad allows glucose to be transported in against its conc grad)

Question 43

What is vesicular transport?

Answer 43

substance is surrounded by a membrane within the cell that moves across the memb ie a vesicle. vesicle mvmt across memb is fueled by atp.

Question 44

What are the types of vesicular transport (list)?

Answer 44

endocytosis, and exocytosis.

Question 45

What is endocytosis?

Answer 45

movement into a cell. two diff kinds; phagocytosis - large items into cell ie bacteria. pinocytosis - fluids into cell.

Question 46

What is exocytosis?

Answer 46

movement out of the cell. vesicles contain hormones, nt, enzymes, etc. fuse with cell memb releasing contents into ECF.