membranes

Question 1

function of membranes

Answer 1

control exchange between body compartments (entry/exit of substances into cell)

Question 2

What does the membrane consist of

Answer 2

Phospholipid bilayer, phospholipid head which is hydrophilic = on outside and fatty tail =hydrophobic= on inside
proteins embedded

Question 3

What molecules can move through the membrane easily

Answer 3

small lipid soluble molecules

Question 4

What do membrane proteins do

Answer 4

allow control of movement of molecules in/out of cell, by controlling protein synthesis you control access

Question 5

What does the cell membrane of capillaries do

Answer 5

control exchange between the plasma and interstitial fluid

Question 6

Is there more sodium inside or outside the cell

Answer 6

outside

Question 7

Is there more calcium inside or outside of cell

Answer 7

outside ( and relatively low amount of both in/out compared to sodium)

Question 8

More potassium inside or out of cell

Answer 8

inside (makes cell negative)

Question 9

more chloride in/out of cell

Answer 9

outside (nacl)

Question 10

define diffusion

Answer 10

substance move randomly down a concentration gradient until even (gas and liquids) due to energy in particles

Question 11

define osmosis

Answer 11

movement of water through a semi-permeable membrane down a concentration gradient (water itself moves)

Question 12

osmosis vs diffusion

Answer 12

both down a concentration gradient
both passive
diffusion is substance moving, osmosis is about solvent
osmosis is through a partially permeable membrane

Question 13

define osmolarity

Answer 13

number of particles in a solution Osm/l (per litre) = solute osmotic concentration per volume solvent

Question 14

define osmostic pressure

Answer 14

pressure needed to oppose osmosis = number of particles per unit volume of fluid

Question 15

what is an aquaporin

Answer 15

membrane channel that transports water and controls water intake, only water not solutes

Question 16

define osmolality

Answer 16

expression of solute osmotic concentration per mass solvent = Osm/kg

Question 17

What is the rate of diffusion dependent on (4)

Answer 17

-membrane permeability to solute (lipid solubility or proteins present, size of molecule)
- diffusion distance (thickness of membrane)
-transmembrane gradients (ions= voltage gradient)
- membrane surface area (bigger=better)

Question 18

iso/hyper/hypo osmotic

Answer 18

isosmotic = solutions both have same concentration of dissolved solutes (same osmotic pressure)
hyperosmotic= one solution has higher concentration of solutes , so has an increased osmotic pressure
hypoosmotic = one solution has lower concentration of dissolved solutes so has decreased osmotic pressure

Question 19

what does tonicity depend on

Answer 19

osmolarity of solution and osmolality of cell, biological term relating to solution relative to living cells. tonicity has no units

Question 20

osmolarity vs tonicity

Answer 20

osmolarity compares 2 solutions whereas tonicity compares solution and a cell , so has no units ( usually in reference to blood )

Question 21

what happens if a red blood cell is in a hypertonic solution

Answer 21

water will leave the cell and cause it to shrivel up

Question 22

how does transport of respiratory gases occur

Answer 22

simple diffusion as they are lipophilic

Question 23

how does pneumonia affect gas exchange

Answer 23

pneumonia causes swelling of alveoli walls so membrane thickens so diffusion is harder = hypoxia

Question 24

what can passive diffusion be divided into

Answer 24

simple and facilitated

Question 25

simple diffusion + examples

Answer 25

substance is lipid soluble so can diffuse directly through lipid bilayer e.g. steroid hormones, fatty acids, O2 and co2

Question 26

facilitated diffusion + examples

Answer 26

molecules need specific protein transporters to form a diffusion pathway, limited by number of proteins and can be affected by competitive inhibition

Question 27

channel vs carriers vs pumps (proteins)

Answer 27

channel = won’t saturate, all/nothing (is either open or closed) no ATP needed
carrier = will saturate, can be used in active transport
pumps = require energy, against conc. gradient, graded
pumps and carriers are same thing

Question 28

types of carriers

Answer 28

uniporter = transports one type of ion
symporter = more than one type of molecule transported simultaneously in same direction
antiporter = more than one type of ion/molecule transported simultaneously in opposite directions

Question 29

types of ion channels

Answer 29

ungated (leak)- always open, small but continuous movement of an ion , maintains resting membrane potential
voltage-gated = selective, narrow pore , 4 sub-units, changes in membrane potential causes gate structure to change, muscle contraction and nerve
ligand-gated channels = larger, less selective, 5 subunits, controlled by signal molecules from ECF or IC signals
mechano-gated = affected by deformation of membrane (stretch/pressure) may cause pain

Question 30

active transport + two types

Answer 30

active transport = requires carrier protiens and uses ATP to move molecules against gradient
primary = protein use ARP to flip substance through membrane against con. gradient
secondary = energy required to establish conc. gradient which cause transport of species

Question 31

example of primary active transport

Answer 31

proton pump in stomach transports H ions from blood into stomach against electrochemical gradient

Question 32

example of secondary active transport

Answer 32

movement of glucose and amino acids into intestine