EX1; Excitable Cells; Ions/Transport Flashcards Preview

AU14 Physiology > EX1; Excitable Cells; Ions/Transport > Flashcards

Flashcards in EX1; Excitable Cells; Ions/Transport Deck (49):
1

What three types of cells are considered excitable cells

neurons
sensory cells
most muscle cells

2

What categorizes an excitable cell

their physiologic functions rely critically on electrical events in their plasma membrane

3

What three things categorize a mechanism of cell-to-cell (intercellular) communication

very rapid
allow precise timing of signals between cells
allow complex patterns of communication between cells

4

This is a mechanism for sensing environmental changes (light, sound, temp, etc.)

stimuli from environment; electrical events in receptor cells

5

This is a mechanism for triggering intracellular events

electrical events in cells; intracellular changes that are either rapid or can accumulate over time

6

This is the activation to initiate an event

excitation

7

What are the three major components of excitation

extracellular fluid
intracellular fluid
membrane

8

What is the composition of extracellular fluid

primarily ions, proteins, and other molecules
high NaCl concentration

9

What is the composition of intracellular fluid

ions, much higher concentrations of proteins, other molecules
high KCl concentration

10

This allows cells to communicate with one another

the differences between the inside (KCl) and outside (NaCl) of cells

11

What is the composition of the membrane

phospholipid bilayer and proteins (equal amount), small (~5%) carbohydrates

12

This characteristic of cell membranes is essential to excitation

permeability

13

What is the permeability of a membrane to an ion an index of

the ability of the ion to cross the membrane; if the ions can readily cross the membrane, then the membrane has a high ion permeability

14

Changes in the permeability that are these two things are essential to excitation in cells

ion-specific
exquisitely timed

15

This is random diffusion down an electrical or concentration gradient; organic molecules or ions

simple diffusion

16

These type of molecules diffuse rapidly through the membrane which is 50% lipid; solubility in lipid is high

non-polar organic molecules; O2, CO2, fatty acids, steroids

17

Does the diffusion of non-polar organic molecules require energy?

No; no energy is required

18

These type of molecules cross membranes via channels which are proteins, often several subunits and generally specific for that molecule

ions

19

This is the amount of a substance crossing a surface per unit of time

flux

20

Diffusion between two compartments is always what

bi-directional; 1 to 2 and 2 to 1

21

This is the difference between the two unidirectional fluxes

net-flux

22

When net-flux is zero, the system is referred to be in a state of what

diffusion equilibrium

23

What are the two types of mediated transport

facilitated diffusion
active transport

24

This type of mediated transport has no energy requirement; a membrane protein serves as a carrier to translocate a molecule across a membrane

facilitated diffusion

25

This type of mediated transport requires energy; a molecule is bound to a transporter (pump) and it moves up the concentration and/or electrical gradient

active transport

26

What two things does energy effect involving active transport

the affinity of the transporter for the ligand on one side of the membrane more than the other
rate of transporter conformational change

27

What is the energy source of the primary active-transport model

hydrolysis of ATP

28

What is the primary-active transport model

hydrolysis of ATP
transporter becomes phosphorylated
changes affinity for solute (ligand)
increases transport rate

29

What is the secondary-active transport model

uses energy in ion concentration gradient across membrane
transporter has 2 binding sites

30

What three factors determine the rate of flux

number of transporters in the membrane
extent of transporter saturation
rate of transporter conformational change

31

What are three types of channels

ligand-sensitive (chemically regulated)
voltage sensitive (voltage regulated)
mechanosensitive

32

What are the three basic steps in mediated transport

ligand binds to transporter
transporter undergoes conformational change
ligand is released on other side of membrane

33

This is the bulk flow of water across a membrane; shrinking or swelling

osmosis

34

Water is polar and therefore diffused down its concentration gradient through these channels

aquaporins

35

This is the total solute concentration in a solutaion

osmolarity
1.0 osmol = 1.0 mol solute
(1.0 mol NaCl = 2.0 osmols)

36

What is the osmolarity of extracellular fluid

300 mOsm

37

300 mOsm of non-penetrating solutes; no change in cell volume is what type of solution

isotonic

38

< 300mOsm of non-penetrating solutes; cell swells, is what type of solution

hypotonic

39

> 300 mOsm of non-penetrating solutes; cell shrinks, is what type of solution

hypertonic

40

300 mOsm of non penetrating solutes plus penetrating solutes is what type of solution

isoosmotic

41

< 300 mOsm of non penetrating solutes plus penetrating solutes is what type of solution

hypoosmotic

42

> 300 mOsm of non penetrating solutes plus penetrating solutes is what type of solution

hyperosmotic

43

True or False
A solution can be hyper osmotic and isotonic at the same time

True

44

This is engulfment of fluid and particles from the extracellular space

endocytosis

45

This is engulfment of small particles with or without small volume of ECF; performed by all cell types

pinocytosis

46

This is engulfment of large particles or cellular debris; performed by specialized cells

phagocytosis

47

This is the export of material from a cell

exocytosis

48

What is the purpose of exocytosis

replaces membrane patches internalized through endocytosis

49

What is the mechanism of release of molecules synthesized within cells

secretion