2. cell physiology 1

Question 1

the cell membrane has

Answer 1

phospholipid bilayer
membrane proteins
membrane carbohydrates

Question 2

phospholipid bilayer

Answer 2

*continuous layer around the cell
*barrier to water soluble substances – NOT to small molecules (O2 & CO2) and lipid
soluble molecules

Question 3

membrane proteins are:

Answer 3

• transport proteins
• receptor proteins
• enzymes
• joining proteins
• identifying proteins

Question 4

transport protein types:

Answer 4

channels

carrier proteins

Question 5

channels

Answer 5

• form pore in membrane
• selectively permit channelCmediated facilitated diffusion of water &
  specific ions
• Can be:
  1 gated: can open or close – when signaled
  2 nonCgated (= leakage channels): always open

Question 6

carrier proteins

Answer 6

• bind solute + carry it across membrane
• allow protein carrierCmediated facilitated transport OR active
  transport
• e.g. glucose transporters

Question 7

receptor proteins

Answer 7

• can bind specific extracellular molecules (= ligands) e.g. hormones, neurotransmitters (nt)
• e.g. glucose uptake:
  i. insulin binds to receptor on skel. muscle or adipose tissue
  ii. triggers movement of more glucose transporters to cell membrane
  iii. ⇑ glucose movement from blood into cells

Question 8

enzymes

Answer 8

• control chemical reactions on outer or inner surface
• e.g. acetylcholinesterase
• e.g.2: Na+/K+C ATPase C all cells have these

Question 9

joining proteins

Answer 9

• control anchor cell membrane to cytoskeleton or an adjacent cell
  i. junctional proteins between cells forming:
• —- desmosomes, tight junctions, and gap junctions
  ii. extracellular fibers (usually glycoproteins)

Question 10

identifying proteins

Answer 10

• e.g. Major Histocompatibility Complex (MHC) proteins
  o on surface of all cells except rbc
  o identify cell as “self” (part of the body) – not foreign

Question 11

membrane carbohydrates

Answer 11

• glycoproteins and glycolipids

* differs for every cell type C allow cells to recognize type e.g. sperm recognizes egg

Question 12

membrane transport

Answer 12

movement of material between the intra and extra cellular fluids

Question 13

solute

Answer 13

substance dissolved in a solution

Question 14

solvent

Answer 14

substance solute is dissolved in e.g. water

Question 15

types of transport

Answer 15

passive

active

Question 16

passive transport

Answer 16

• no energy required (no ATP)
• movement from a high to low concentration (i.e. down its conc. gradient) * the greater the difference in concentration = the more molecules want to move

Question 17

passive transport types

Answer 17

simple diffusion
facilitated diffusion
facilitated transport
osmosis 
bulk flow

Question 18

simple diffusion

Answer 18

solute movement

*solute diffuses directly through cell membrane bilayer therefore small, lipid soluble (O2, CO2, etc.)

Question 19

facilitated diffusion

Answer 19

solute movement

*ions diffuse through membrane by protein channels

Question 20

facilitated transport

Answer 20

solute movement

• large, charged or water soluble molecules
• diffuse across membrane using a specific carrier protein - must bind to protein to be transported
• eg, glucose into liver or skeletal muscle

Question 21

osmosis

Answer 21

solvent movement

• movement of H2O across a semipermeable membrane (permeable to H2O) due to [H2O] difference (H2O moves down it’s concentration gradient ) by pores (channels) or across the membrane bilayer
• NOTE-
• high [H2O] = low [solute] (dilute solution)
• low [H2O] = high [solute] (concentrated solution)
• [solute] depends on the number of ions of molecules not the type

Question 22

high solute and low solvent

Answer 22

high osmotic pressure

Question 23

low solute and high solvent

Answer 23

low osmotic pressure

Question 24

osmotic pressure

Answer 24

• pressure that must be applied to prevent movement
  of H2O from a pure H2O solution (S1) across a semipermeable membrane into another solution (S2)
  i. if S2 has high [salt] (low [H2O]) then more H2O will move into it ⇒ requires pressure to stop H20 moving into S2
  ——————- Therefore the greater [salt] in solution the greater OP and lower [H2O] ⇒ water will want to move in (down gradient)
  ii. S1 & S2 = pure H2O ⇒ no P required to prevent H2O movement (no gradient) ∴ S1, S2 OP = 0
• OP is used as a measure of the [solute] of a solution o high OP = high [solute] (low [H2O]) + vice
  versa

Question 25

tonicity

Answer 25

o response of a cell immersed in a solution * depends on [solute] (and permeability of cell membrane to solute) o uses: * injecting 10% sucrose solution (hypertonic) will move water to blood stream * e.g. use to ⇓ brain edema (swelling)

Question 26

tonicity classificatinons

Answer 26

hypotonic solution hypertonic solutions isotonic solution

Question 27

hypotonic solution

Answer 27

* ECF has lower OP (higher [H2O]) than ICF (cytosol) * cell swells (takes in water) + may burst * swelling can rupture cell = lysis - ------- if rbc = hemolysis

Question 28

hypertonic solution

Answer 28

* ECF has higher OP (lower | [H2O]) than ICF (cytosol) * cell shrinks (loses H2O)

Question 29

isotonic solution

Answer 29

* ECF and ICF have equal OP * cell neither swells nor shrinks * rbc C all [solutes] within equals a 0.9% saline solution (= normal saline)

Question 30

osmosis role in solute regulation:

Answer 30

o Concentration of solutes in body fluids must be maintained within narrow limits or cells will die *major body fluids: -extracellular fluids (ECFs) -intracellular fluid (ICF)

Question 31

extracellular fluids

Answer 31

``` bood plasma interstitital fluid (ISF) ```

Question 32

osmosis eg e.g. If body loses H2O (e.g. sweat) ⇒ ⇑ [blood] blood OP ⇑ ⇒ fluid moves from tissues to blood

Answer 32

response = thirst and ⇓ renal H2O loss which leads to ⇓ urine production

Question 33

bulk flow

Answer 33

* movement of fluid (+ solutes) due to a pressure gradient (high pressure to low pressure) * hydrostatic pressure = P of a fluid pressing against a surface o e.g. cell membrane, blood vessel wall (= blood pressure) o e.g. Capillary – if blood has higher pressure than ISF, fluid flows out of the capillary (= filtration)

Question 34

active process require

Answer 34

Require energy (ATP)

Question 35

active processes types

Answer 35

active transport and vesicular transport

Question 36

ative transport types

Answer 36

primary active transport | secondary active transport

Question 37

primary active transport

Answer 37

* molecular pumps C ATP breakdown is directly part of transport process * e.g. Na+/K+CATPase Pump – 3 Na+ out of cell and 2 K+ in per ATP

Question 38

secondary active trasport

Answer 38

* cotransport (use of ATP is indirect) * e.g. glucose entry at small intestine – 2 steps: 1. Na+ gradient established by Na+/K+C ATPase (ATP use step) 2. glucose & Na+ both must bind to carrier and are cotransported into the cell ⇒ Na+ moving down its concentration gradient drives in glucose against its concentration gradient (transport step)

Question 39

vesicular transport

Answer 39

substance is surrounded by a membrane within a cell (vesicle)

Question 40

active transport

Answer 40

- substance move against conc. gradient (low to high) | - always protein carrier-mediated

Question 41

vesicular transport types

Answer 41

endocytosis | exocytosis

Question 42

endocytosis

Answer 42

movement into a cell * phagocytosis * pinocytosis

Question 43

phagocytosis

Answer 43

- large items into cell (e.g. bacteria) | - ="cell eating"`

Question 44

pinocytosis

Answer 44

- fluids (+dissolved substances) | - ="cell drinking"

Question 45

exocytosis

Answer 45

– movement out of cell * vesicles containing hormones, enzymes, neurotransmitters, etc. * fuse with cell membrane releasing contents into ECF (triggered by a rise in cytosolic Ca++)