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Flashcards in Bio Class 7 Deck (66)
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1

_____ send impulse towards soma, while _____ send impulse away from soma

dendrites, axon

2

Nodes of Ranvier

"saltatory conduction"
- propagation of AP along myelinated axons from one node to another, increasing velocity of ap

3

Axon hillock

Connects soma and axon
- ap starts here

4

Schwaan cells

Found in PNS, wrap around axon to form myelin

5

Oligodendrocytes

Found in CNS, wrap around axon to form myelin

6

Myelin

Insulator, increases speed of conduction

7

Soma

Performs basic function of cell

8

Types of neurons

Bipolar, unipolar, multipolar (most popular)

9

Bipolar neuron

Single axon, single dendrite
- direction determined by direction of impulse

10

Unipolar

Single process that divides to form axon and dendrite
- direction determined by direction of impulse

11

Depolarization

Move away from rest in positive direction (-70 to -50)

12

Hyperpolarization

Move away from rest in negative direction (-70 to -90)

13

Repolarization

Returning to rest from hyperpolarization or depolarization

14

Equilibrium Potential

The potential at which there is no driving force on an ion

15

Action Potential Process

Potential starts at -70
Cell depolarizes as Na+ VG channels open (-50)
Reaches Na+ equilibrium potential (+35)
Na+ channel is inactive and K+ VG channel opens
Cell hyperpolarizes
Na+ VG channel shifts to "closed"
K+ channel closes

16

What is the resting membrane potential?

-50 mV

17

Absolute refractory period vs relative refractory period

Absolute
- Na+ channel is inactive, cell is too positive
- impossible to fire a second potential

Relative
- Na+ channel is closed, cell is too negative
- close to K+ eq potential

18

Nerve impulse

Action potential travelling

19

Synapse

Once signal reaches end of neuron, signal goes to different cell or neuron

20

If there is a impulse from A --> B --> , why would the AP go towards C and not A?

Because A is in the refractory period

21

What happens to B and C if A is going through an AP?

Na+ is entering A and the membrane potential of B and C is at -70
- then charge from A reaches B and depolarizes it
- Once B reaches threshold, it'll fire an AP

22

Electrical Synapses vs Chemical synapses

Electrical synapse
1. Gap junctions
2. Unregulated
3. Bidirectional
4. Always excitatory (always causes AP in postsynaptic cell)
*Relatively rare & found in cardiac muscle cells

Chemical synapse
Opposite of electrical synapse
- Presynaptic neuron has neurotransmitters in vesicles that are bound by synapsin (cytoskeleton filaments)
- When VG Ca2+ channel reaches threshold, it breaks down synapsin
- Vesicles are released and neurotransmitters float in synaptic cleft
- Receptors on post-synaptic dendrite will bind to some neurotransmitters
1. Neurons make one type of NT, but respond to many
2. NT in cleft can be recycled or broken down, medication can change amount of time it spends in cleft
3. Response of post-synaptic cleft depends on receptors
4. takes more than one vesicle of neurotransmitters to elicit a significant response on post-synaptic cell

23

EPSP

Excitatory post synaptic potential
- when one vesicle dumps into post-synaptic cleft
- If AP comes and dumps lots of vesicles, it will add up and eventually membrane reaches threshold and causes AP

24

IPSP

Inhibitory Post Synaptic Potential
- Adds up and eventually membrane hyperpolarizes

25

Summation

Adding EPSP and IPSP
1. Spatial - add multiple inputs over wide area
2. Temporal - add frequent impulses from a single source

26

_______ increases intensity in neurons

frequency

27

General System function of neurons:
______ --> _______ --> _______

Sensory input ---> Integration ---> Motor output

Sensory input: sensory neurons, afferent, PNS
Integration: making decision, interneurons, CNS
Motor output: motor neurons, efferent, PNS

28

Reflex

rapid integration to avoid body injury

29

Simple Reflex - urine example

- In walls of bladder, there's receptors that monitor stress & tension
- As bladder fills up with urine, tension builds on the bladder
- the bigger the stretch in the bladder, the more frequent AP
- The sensory neuron senses stretch and in the spinal cord it'll interact with the motor neuron and then cause the bladder to contract

30

Complex reflex - hitting tendon example

When you hit the tendon:
- tendon of quadricep muscle stretches, stimulates sensory neuron
- activates quadricep muscle, causing it to contract and inhibit motor neuron of hamstring, causing hamstring to relax