Module 2 - Nervous Systems Flashcards Preview

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Flashcards in Module 2 - Nervous Systems Deck (28):
1

Sensory neuron vs interneuron vs motor neuron structure

Sensory neuron - long axon
Interneuron - lots of dendrites to collect information and many synaptic terminals (branches off axon)
Motor neuron - many dendrites and 1 long axon from CNS to effector

2

What are Glia? What are the types and their roles?

- supporting cells that are vital for structural integrity and normal function of neurons

Types:
Astrocytes - in the CNS, form the blood-brain barrier and regulate extracellular concentration of ions and neurotransmitters

Oligodendrocytes (CNS) and Schwann cells (PNS) - form myelin sheaths around axons that act as insulators

3

What is the abundance of Glia?

10-50 times more than neurons in the mammalian brain

4

Resting membrane potential Na+ and K+ concentration

ECF - 5mM K+ and 150mM Na+
Cytoplasm - 140mM K+ and 15mM Na+

5

Rate of Na+/K+-ATPase pumping

3 Na+ ions out and 2 K+ ions in

6

What causes the resting membrane potential?

Many open K+ channels and few Na+ channels plus charged proteins inside the cell

7

Hyperpolarisation vs depolarisation

Hyper - inside of membrane becomes more negative as a result of K+ channels opening and K+ flowing out of cell

De - inside of membrane becomes more positive as a result of Na+ channels opening and Na+ ions flowing into the cell

8

Graded vs action potentials

Graded:
- can be hyper- or depolarisation
- vary in magnitude with the strength of stimulus
- local and die out

Action:
- depolarisation only
- reach a certain threshold and is an 'all or nothing' response
- travel along axons

9

Absolute refractory period (ARP) vs relative refractory period (RPR)

ARP - no action potential can be generated on top of the current one as Na+ channels are open and then inactive

RPR - action potential can only be generated to add to the current one if a large stimulus is applied, as some Na+ channels are closed again

10

Saltatory vs. smooth conduction

Saltatory: conduction of AP along axon - AP only needs to be generated at Nodes of Ranvier between Schwann cells along the axons => faster conduction

Smooth: AP generated all the way along due to no myelination

11

Na+ channels vs K+ channels

Na+ channels have 3 stages - Closed, open and inactive, and open very fast
K+ channels have 2 stages - closed and open, and are slower to open

Both open by depolarisation signal

12

What effects the speed of conduction?

- Axon diameter: larger diameter = less resistance = faster conduction
- temperature: increase temp = increase conduction speed
- degree of myelination: increase myelination = decreased loss of electrical signal = increased conduction speed (more effect than axon diameter)

13

Electrical vs chemical synapses

Electrical:
- rare type
- at gap junctions
- direct electrical currents between cells

Chemical:
- common type
- involve release of a neurotransmitter
- neurotransmitter released by presynaptic neuron

14

Excitatory vs inhibitory postsynaptic potential

EPSP - depolarisation in postsynaptic membrane, could lead to another action potential is depolarisation reaches threshold

IPSP - hyperpolarisation at postsynaptic membrane

15

Temporal vs spatial summation

temporal - several EPSP's from the same synapse just after each other

spatial - two or more EPSP's from different synpases

16

Postsynaptic potential vs action potential

Postsynaptic:
- excitatory (EPSP) or inhibitory (IPSP)
- graded
- local
- at the cell body or dendrites

Action:
- depolarisation
- all or nothing
- can be the result of the addition of excitatory postsynaptic potentials
- generated at the axon hillock
- travels along the axon

17

Types of chemical synaptic transmission and related receptor types

Direct:
- neurotransmitter opens ion channels on the postsynaptic membrane
- action via ligand-gated ion channels
Receptors: ion channel receptors

Indirect:
- neurotransmitter binds to a receptor on the postsynaptic membrane
- activates a signal transduction pathway
- involves a second messenger
Receptors: GPCR's

18

4 ways to remove neurotransmitters from synaptic cleft

- Broken up by enzymes such as acetylcholinesterase (super fast, enzyme sits in cleft ready to take action)
- Diffusion (too slow for the necessary control)
- recycled by selective uptake of transporters such as NET and SERT back into the presynaptic neuron where they return to vesicles (different transport proteins for each neurotransmitter)
- Taken up by astrocytes which mop up the left overs

19

What animals don't have a nervous system?

Sponges

20

CNS vs PNS

CNS
- brain
- spinal cord

PNS
- cranial nerves (12 pairs in mammals)
- spinal nerves (31 pairs in mammals)

21

Somatic vs autonomic nervous system

Both part of PNS

Somatic - voluntary control e.g. motor neurons

Autonomic
- mostly involuntary control e.g. heart rate
- 3 divisions: sympathetic, parasympathetic and enteric

22

Sympathetic vs parasympathetic vs enteric divisions of autonomic nervous system from PNS, and response/s of activation

Enteric - nerves to gut, very complex

Sympathetic:
- fight or flight
- bronchi dilate
- heart rate increases
- increase converstion of glycogen to glucose
- adrenaline secretion
- digestion inhibitation
- nerves arise from thoracic or lumber (middle) regions of spine
- short pre-ganglia fibre and long post-ganglia fibre

Parasympathetic:
- rest and digest
- calming
- often has opposite response to the sympathetic division
- nerves arise from cervical or sacral (top and bottom) regions of spine
- long pre-ganglia fibre and short post-ganglia fibre

23

Roles of cerebrospinal fluid

- protects the CNS
- clear fluid in subarachnoid space (between the skull and cortex)
- 4 ventricles and central canal
- supply nutrients and hormones
- remove waste
- blocks flow in hydrocephalus

24

Grey vs white matter inc. location in brain and spinal cord

Grey matter:
- dendrites, cell bodies and unmyelinated axons
- outside of brain
- inside of spinal cord

White matter:
- myelinated axons
- inside of brain
- outside of spinal cord

25

Where are new neurons derived from?

adult stem cells

26

What determines how long the refractory period goes for?

How long it takes for the voltage-gated sodium channels to reactivate at the end of an action potential

27

4 ways that neurotransmitters affect postsynaptic cells

- causing molecular changes in the cells
- affecting ion-channel proteins
- initiating signal transduction pathways in the cells
- altering the permeability of the cells

28

How is the activity of acetylcoline in a synapse terminated?

It is degraded by a hydrolytic enzyme on the postsynaptic membrane