Chapter 6 Interactions Between Cells And The Extracellular Environment

Question 1

What are selectively permeable membranes?

Answer 1

Just certain substances can go through

Question 2

What is carrier mediated transport?

Answer 2

Facilitated diffusion

Active transport through a membrane = requires ATP and can be primary and secondary

Question 3

What is non-carrier mediated transport

Answer 3

Diffusion (passive transport)

Osmosis

Question 4

Diffusion

Answer 4

Movement of solute along its concentration gradient (for simple and facilitated diffusion) - from regions of higher concentration to region of lower concentration

Question 5

Simple diffusion

Answer 5

Movement of molecules from one location to another

Question 6

Facilitated diffusion

Answer 6

Carrier-mediated

Is assisted by another molecule

Question 7

Net diffusion

Answer 7

Movement in both direction but the net diffusion follows the concentration gradient until the gradient no longer exist = equalibrium

Question 8

What affects the rate of diffusion?

Answer 8

1. Concentration difference
2. Membrane permeability
3. Temperature
4. Mass of the solute molecule
5. Surface area of the membrane
6. Medium through which solute must pass
7. Distance

Question 9

Diffusion through the bilayer

Answer 9

Right through the membrane

Non-polar substances diffuse easily

Small polar molecules can diffuse easily

Question 10

Diffusion through channels

Answer 10

Channels are proteins

Channels selectively allow certain substances to pass

Can be open or gated

Electrochemical gradient must exist

Question 11

Why do substance move in and out of cells

Answer 11

In order to maintain homeostasis and perform physiological functions

Question 12

What process is the diffusion of water

Answer 12

Osmosis

Question 13

What are aquaporins

Answer 13

Channel proteins that allow water to pass through

Question 14

Osmotic pressure

Answer 14

Pressure require to prevent the flow of water - region with higher solute concentration

Question 15

Total body water percentages

Answer 15

67% ICF

33% ECF:
20% blood plasma
80% ISF

Question 16

What makes a solution

Answer 16

Solvent + solute

Question 17

What is toncity

Answer 17

The effect of a solution on osmotic movement of water

Question 18

isotonic

Answer 18

equal osmotic pressure inside and outside the cell

Question 19

hypertonic

Answer 19

higher osmotic pressure in the external solution

Question 20

Hypotonic

Answer 20

lower osmotic pressure in the external solution

Question 21

different types of carrier-mediated transport

Answer 21

faciliated diffusion
active transport
endothelial transport
endocytosis
exocytosis

Question 22

What is Faciliated diffusion

Answer 22

diffusion along the concentration gradient; assisted by another molecule
passive transport - doesn´t require ATP

Question 23

What is active transport and what types

Answer 23

1. Transport of solute against its concentration gradient 2. Requires ATP

Primary transport - in membrane integrated pump

Secondary transport - Ion concentration gradient is used as the energy source to move a second solute;

Question 24

Sodium Potassium pump

Answer 24

3 Na+ out and 2 K+ in = inside of cell more negative

Question 25

What is epithelial transport and what pathways are there

Answer 25

Transport of substances across epithelial cells

Pathways:

1. Praracellular pathway - substance moves between adjacent (german angrenzend) cells of epithelium
2. Transcellular pathway - substance moves in through apical or basolateral membrane, through cytoplasm and exits through opposite membrane

Question 26

endocytosis

Answer 26

membrane forms vesicle, including small amount of ECF - brings that fluid + extracellular substances into the cell

Question 27

exocytosis

Answer 27

membrane vesicle joins membrane and releases cellular products into ECF

Question 28

membrane potential

Answer 28

difference in charge across the cell membrane - cause by different factors

Question 29

What is the concentration of Potassium and Sodium

Answer 29

Na+ 12mM inside the cell, 145 mM outside the cell

K+ 150 mM inside the cell, 5 mM outside the cell

Question 30

What equation is used to work out membrane potential

Answer 30

by Nernest Equation => Eion = 61/Z log(Cout/Cin)
Z: valence of the ion (available electrons)
Cout: extracellular concentration of ion
Cin: intracellular concentration of ion

Question 31

What is a resting membrane potential

Answer 31

membrane potential of a cell not producing electrical impulses - determined by relative concentrations of ions inside and outside the cell

Question 32

What is cell signalling and what 4 ways can signals travel

Answer 32

chemical communication in between cells
4 different transport ways of signal:
1. Paracrine signal - signal to nearby cell
2. Endocrine signal - related to hormones, travel through bloodstream to distant target
3. Synaptic signal - neurons release neurotransmitter to regulate usually nearby target cells
4. Diffusion

Question 33

signal receptors in the cell membrane

Answer 33

for hydrophilic signals - require second messenger - another substance that enters cytoplasm with signal

Question 34

signal receptors in the cytoplasm or nucleus

Answer 34

for hydrophobic (non-polar) signals

Question 35

What is the difference between anions and cations

Answer 35

Anions - negatively charged

Cations - positively charged

Question 36

What is potassiums equilibrium potential

Answer 36

-90 mV