Lecture 3 - Excitable Membranes

Question 1

What is the structure of the plasma membrane?

Answer 1

fluid mosaic model

Question 2

What makes up the fluid mosaic model?

Answer 2

-phospholipid bilayer
-cholesterol
-transmembranal proteins

Question 3

What is the polar section of a phospholipid?

Answer 3

polar hydrophilic head

Question 4

What is the non-polar section of a phospholipid?

Answer 4

non-polar hydrophobic fatty acid chains (tail)

Question 5

peripheral membrane protein
-where
-what looks like
-function

Answer 5

-inside membrane
-small not across the full membrane
-attachment + shape changes

Question 6

integral membrane proteins
-where
-what looks like
-function

Answer 6

-across the full membrane
-channel, pump…
-transport + communication

Question 7

cytoskeleton
-where
-what looks like
-function

Answer 7

-underneath the plasma membrane
-small, attached to other proteins
-anchors + receptors

Question 8

carbohydrates
-specific name
-where
-what looks like
-function

Answer 8

-glycocalyx
-outside of the cell
-thin, looks like little trees
-cell-cell recognition

Question 9

cholesterol
-where
-what looks like
-function

Answer 9

-embedded in the membrane
-it looks like a steroid structure
-stabilization

Question 10

4 functions of the plasma membrane

Answer 10

1. communication
2. selective
3. physical barrier
4. cell recognition

Question 11

6 functions of the plasma membrane proteins?

Answer 11

1. enzyme activity
2. transport
3. receptors
4. cell-cell recognition
5. intracellular joining
6. attach to ECM

Question 12

3 types of junctions formed between cells

Answer 12

1. desmosomes
2. gap junctions
3. tight junctions

Question 13

tight junctions + where

Answer 13

-impermeable
-no random diffusion
+ blood-brain barrier

Question 14

desmosomes + where

Answer 14

-attach
-anchor
-structure
+ cardiac muscle tissue, bladder tissue, and epithelia

Question 15

gap junctions + where

Answer 15

-channel
-communicate
-specialize
+ all cells of solid tissue

Question 16

how much of the brain is used to maintain the Na+/K+ ATPases pump?

Answer 16

40%

Question 17

How is the electrochemical gradient challenged? (2)

Answer 17

1) slow leaking ions
2) stimulation of muscle

Question 18

3 types of endocytosis

Answer 18

1) pinocytosis
2) receptor-mediated
3) phagocytosis

Question 19

what is the process of exocytosis?

Answer 19

t-snare on receptor + v-snare of vesicle attach on membrane to release outside

Question 20

what molecules can travel past the membrane by simple diffusion?

Answer 20

O2 + CO2 + fats + urea + alcohol

Question 21

state 5 features of facilitated diffusion

Answer 21

1) no ATP
2) specific
3) down conc. gradient
4) carrier saturation
5) can be inhibited

Question 22

what and where is the biosynthetic centre?

Answer 22

• large spherical nucleus
  -glandular cytoplasms

Question 23

where is the term tract used?

Answer 23

nerve processes of the CNS

Question 24

where is the term nerve used?

Answer 24

nerve processes of the PNS

Question 25

what are the 3 special features of an axon?

Answer 25

1) extreme longevity
2) amitotic
3) high metabolic rate

Question 26

look at the drawing on the 2nd page + names 1-4 regions

Answer 26

1) receptive
2) initial segment
3) conducting
4) secretory

Question 27

receptive region of the axon
-the name of parts of the cell
-function

Answer 27

-dendrites + cell body
-receive graded potentials

Question 28

initiail segment of the axon
-name parts
-function

Answer 28

-axon hillock
-where the action potential is reached

Question 29

conducting region of the axon
-name parts
-function

Answer 29

-axon + myelin sheath
-propagate the electrical current down the axon

Question 30

2 functional divisions of PNS

Answer 30

-sensory
-motor

Question 31

how is the sensory PNS divided?

Answer 31

-somatic (skin/skeletal)
-visceral (visceral organs to the CNS)

Question 32

how is the motor PNS divided?

Answer 32

-somatic (voluntary movement of muscles)
-autonomic (self-regulated organs)

Question 33

What are the 2 principal cell types of nervous tissue and their definitions?

Answer 33

1) neuroglia
-small cells that wrap around axons

2) neurons
-excitable cells that transmit signals

Question 34

what is the 4 main neuroglia that supports the CNS neurons?

Answer 34

1) astrocytes
2) oligodendrocytes
3) microglial
4) ependymal

Question 35

astrocytes
-definition
-function

Answer 35

-highly branched that connect at capillaries and synaptic endings

-support, exchange, guide, control, respond, influence, process

Question 36

microglial cells
-definition
-functions

Answer 36

-small cells that touch and monitor neurons

-help injury + phagocytize bad stuff

Question 37

ependymal cells
-definition
-functions

Answer 37

-forms permeable membrane between the CSF and tissues

-layer the central cavities of the brain and spinal column

Question 38

oligodendrocytes
-definitions
-functions

Answer 38

• a highly branched fatty cell that wraps around the CNS nerve fibres

-for conduction of electrical impulses

Question 39

What is the 2 major neuroglia in the PNS?

Answer 39

1) Schwann cells
-surround nerve fibres

2) ganglion
-surround neuron cell body

Question 40

What is vital to the regeneration of damaged PN fibres?

Answer 40

Schwann cells

Question 41

What do conduction velocities depend on? (2)

Answer 41

-axon diameter
-myelin sheath

Question 42

What is anterograde transport?

Answer 42

-transport away from the cell body toward the synapse
=mitos + cytoskeleton, membrane parts, nervous tissue

Question 43

what is retrograde transport?

Answer 43

-transport towards the cell body