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BIOL1412 > Topic 2: Cell Physiology I > Flashcards

Topic 2: Cell Physiology I Flashcards

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1
Q

what does the ability to maintain homeostasis rely on?

A

-the ability of cells and tissues to…
-carry out specialized functions
-regulate internal conditions
-maintain the composition of ICF and ECF
-move solutes and/or solvents across the membrane
-communicate

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2
Q

what helps the body function when homeostasis is lost?

A

-drug therapies
-diet
-exercise
-help to regulate the dysfunction

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3
Q

what level does the dysfunction of homeostasis occur at?

A

-cellular/tissue level

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4
Q

what is the significance of the cell membrane?

A

-not just a structural boundary
-dynamic and active participant in the cell’s interactions with its environment
-its functions are central to almost every aspect of human physiology
-does so with important structures

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5
Q

what are the important structures of the cell membrane?

A

-phospholipid bilayer
-membrane proteins
-membrane carbohydrates

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6
Q

what is the phospholipid bilayer?

A

-continuous layer around the cell
-barrier to water soluble substances
-allows lipid soluble molecules and small molecules to pass through (O2, CO2, H2O)

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7
Q

why does the phospholipid bilayer act as a barrier to water soluble substances?

A

-hydrophobic tails
-water can move through (small)
-substances that dissolve in water cannot pass

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7
Q

what are the types of membrane proteins?

A

-transport proteins
-receptor proteins
-enzymes
-joining proteins
-identifying proteins

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8
Q

what are the 2 types of transport proteins?

A

-channel proteins
-carrier proteins

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9
Q

what are the characteristics of channel proteins?

A

-form a pore/channel in the membrane
-selected ions/molecules can move freely through it
-selectively permit channel-mediated facilitated diffusion of water and specific ions
-can be gated or non-gated

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10
Q

what does it mean for a channel protein to be gated?

A

-opens and closes when signalled

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11
Q

what does it mean for a channel protein to be non-gated?

A

-always open
-leakage channels

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12
Q

what is the significance of having both gated and non-gated channel proteins?

A

-changes the permeability of a membrane

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13
Q

what are the characteristics of carrier proteins?

A

-bind to a solute (ion/molecule) and help carry it across the membrane
-protein carrier-mediated facilitated diffusion or active transport methods
of transport

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14
Q

what is an example of a carrier protein?

A

-glucose transporters

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15
Q

what are receptor proteins?

A

-can bind to specific extracellular molecules (ligands)
-ligands include hormones and neurotransmitters (carry a physiological function)

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16
Q

what is an example of a physiological process involving receptor proteins?

A

-glucose uptake (by skeletal muscle cells or adipose tissue)
-insulin binds to a receptor on skeletal muscle or adipose tissue
-triggers the movement of more glucose transporters to the cell membrane
-glucose movement from blood into the cells increases as a result

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17
Q

what is the function of enzymes in the cell membrane? what are 2 examples?

A

-control chemical reactions on the outer and inner surface
-ex: acetylcholinesterase
-ex: Na+/K+ - ATPase (all cells have)

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18
Q

what is the function of joining proteins?

A

-anchor the cell membrane to the cytoskeleton or an adjacent cell

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19
Q

what are the 2 types of joining proteins?

A

-junctional proteins (between cells)
-extracellular fibres (usually glycoproteins)

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20
Q

what are examples of junctional proteins between cells?

A

-desmosomes
-tight junctions
-gap junctions

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21
Q

what is an example of a identifying protein?

A

-major histocompatibility complex (MHC) proteins
-on the surface of all cells (except RBCs)
-identify cells as “self”

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22
Q

what are membrane carbohydrates?

A

-glycoproteins and glycolipids
-differ for each cell type
-allow cells to recognize type (ex: sperm recognizes egg)

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23
Q

what is a solute?

A

-substance dissolved in a solution

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24
what is a solvent?
-substance that the solute is dissolved in -ex: water, some lipids, alcohol
25
what are the 2 branches of transport?
-passive transport -active transport
26
what are the basics of passive transport?
-no energy required (no ATP) -movement is from high to low concentration (down the gradient) -the greater difference in concentration, the more molecules that want to move
27
what are the types of passive transport? do they involve movement of the solute or solvent?
-simple diffusion (solute) -channel-mediated facilitated diffusion (solute) -carrier-mediated facilitated diffusion (solute) -osmosis (solvent)
28
what is simple diffusion?
-solute diffuses directly through the cell membrane bilayer -small and lipid molecules will pass -ex: O2, CO2
29
what is channel-mediated facilitated diffusion?
-ions diffuse through the membrane via protein channels -solute does not bind to the protein (moves freely through the opening)
30
what is carrier-mediated facilitated diffusion?
-large charged or water soluble molecules diffuse through the membrane using a specific carrier protein -solute must bind to the protein -ex: glucose movement into the liver or skeletal muscle
31
what is osmosis?
-movement of H2O across a semipermeable membrane (membrane is permeable to H2O) -occurs due to the [H20] difference (moves down the gradient) -occurs via pores/channels or simply across the membrane bilayer
32
what is a dilute solution?
-high [H20] + low [solute]
33
what is a concentrated solution?
-low [H2O] + high [solute]
34
what does [solute] depend on?
-the number of molecules -not the type of molecules
35
what is osmotic pressure?
-the pressure required to prevent the movement of water across a semipermeable membrane due to osmosis
36
how is osmotic pressure determined?
-by the [solute] in a solution -pure water has an osmotic pressure of 0 -the greater the [solute], the greater the osmotic pressure -high osmotic pressure = high [solute]/low [H20] -low osmotic pressure = low [solute]/high [H2O]
37
how does water move in relation to osmotic pressure?
-areas of low osmotic pressure to areas of high osmotic pressure
38
what is an example of how osmotic pressure works?
-you have 2 solutions (S1 + S2) -S1= pure water -S2= high [solute] -the pressure that must be applied to prevent H2O from moving from S1 across to S2 would be the osmotic pressure of S2
39
what would the osmotic pressure of 2 equally concentrated solutions be?
-osmotic pressures would be equal -osmotic pressure would NOT be 0 since solute is in the solution -however, no osmosis would occur
40
what is tonicity?
-the response of a cell immersed in a solution
41
what does tonicity depend on?
-[solute] -permeability of the cell membrane to the solute
42
what are the 3 types of solutions a cell is immersed in?
-hypotonic solution -hypertonic solution -isotonic solution
43
what is a hypotonic solution?
-ECF has a lower osmotic pressure (high [H2O]) compared to ICF (cytosol) -cell will swell (taking in water) -swelling may cause bursting/rupturing = lysis
44
what is the rupture of a red blood cell called?
-hemolysis
45
what is a hypertonic solution?
-ECF has a higher osmotic pressure (low [H2O]) compared to ICF (cytosol) -cell shrinks (losing water)
46
what is a isotonic solution?
-ECF and ICF have equal osmotic pressures -cell neither swells or shrinks
47
what do most cells have for a solute concentration of NaCl?
-have a [] that equals 0.9% which is normal saline -red blood cells are a good example
48
do other forms of saline exist besides the 0.9% NaCl solution?
-NO
49
what is an example of how is tonicity used?
-injecting a 10% sucrose solution (hypertonic) to move water to the blood stream -use to reduce brain edema (swelling)
50
what is osmosis' role in the regulation of solute concentration?
-body fluids [solute] must be maintained within narrow limits or cells will die -for ECFs (blood plasma + ISF) -for ICF
51
what happens when the body loses H2O through sweating?
-the concentration of the blood increases as well as osmotic pressure -this results in fluid movement from the tissues into the blood -dehydration of tissues -causes a response of thirst and a decrease in renal H2O loss (decreased urine production)
52
what is bulk flow?
-movement of fluid (and solutes) due to a pressure gradient (high to low)
53
what is hydrostatic pressure?
-the pressure of a fluid pressing against a surface
54
where is there bulk flow/hydrostatic pressure in the body?
-cell membrane -blood vessel wall (blood pressure) -capillary
55
how does bulk flow/hydrostatic pressure take place in the capillary?
-if blood has higher pressure than ISF, fluid flows out of the capillary (filtration) -if ISF has higher pressure than blood, fluid flows from the ISF into the capillary (absorption)
56
what are active processes of transports?
-require energy (ATP) to move ions/molecules -moves them against their concentration gradient
57
what are the 2 types of active processes?
-active transport -vesicular transport
58
what always mediates active transport?
-a protein carrier
59
what are the 2 types of active transport?
-primary active transport -secondary active transport
60
what is primary active transport?
-molecular pumps that have ATP breakdown directly apart of the transport process -ex: Na+/K+ - ATPase Pump (3 Na+ out, 2 K+ in per ATP used)
61
what is secondary active transport?
-molecules move by cotransport (ATP use is indirect) -ex: glucose absorption by enterocytes (Na+ is important, not K+)
62
what are the 2 steps to glucose absorption by enterocytes?
-Na+/K+ - ATPase establishes a Na+ gradient (ATP use step) -glucose and Na+ both bind to a carrier protein and are moved into the cell -Na+ moves down its concentration gradient and drives glucose in against its concentration gradient (transport step)
63
what is vesicular transport?
-substance is moved in or out of the cell by being surrounded by a membrane (vesicle) within the cell
64
what are the 2 types of vesicular transport?
-endocytosis -exocytosis
65
what is endocytosis?
-movement into a cell -phagocytosis and pinocytosis
66
what is phagocytosis?
-moving large items into a cell -ex: bacteria -cell eating
67
what is pinocytosis?
-moving fluids + dissolved substances into a cell -cell drinking
68
what is exocytosis?
-movement out of the cell -vesicles containing hormones, enzymes, and neurotransmitters, etc -vesicles fuse with the cell membrane and release contents into the ECF -triggered by a rise in cytosolic Ca++

BIOL1412 (15 decks)

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