Physiology of nerves (powerpoint) - DONE

Question 1

What are the two major regulatory systems in the body?

Answer 1

• the nervous system

- the endocrine system

Question 2

Endocrine system:

Answer 2

• regulates relatively slow

- long-lived responses

Question 3

The nervous system

Answer 3

• regulates fast

- short-term responses

Question 4

The types of neurons:

Answer 4

• anaxonic neurons
• bipolar neurons
• unipolar neurons
• multipolar neurons

Question 5

Neuroglia found in PNS:

Answer 5

• Schwann cells

- Satellite cells

Question 6

Neuroglia found in CNS:

Answer 6

• Oligodendrocytes
• Astrocytes
• Microglia
• Ependymal cells

Question 7

Satellite cells:

Answer 7

• surround neuron cell bodies in ganglia

- regulate O2, CO2, nutrient, and neurotransmitter levels around neurons in ganglia

Question 8

Schwann cells:

Answer 8

• surround all axons in PNS
• responsible for myelination of peripheral axons
• participate in repair process after injury

Question 9

Oligodendrocytes:

Answer 9

• myelinate CNS axons

- provide structural framework

Question 10

Astrocytes:

Answer 10

• maintain blood-brain barrier
• provide structural support
• regulate ion, nutrient, and dissolved gas concentrations
• absorb and recycle neurotransmitters
• form scar tissue after injury

Question 11

Microglia:

Answer 11

• remove cell debris, wastes and pathogens by phagocytosis

Question 12

Ependymal cells:

Answer 12

• line ventricles (brain) and central canal (spinal cord)

- assist in producing circulating, and monitoring of cerebrospinal fluid

Question 13

NaK-ATPase

Answer 13

pumps 3Na+ out for 2K+ pumped in

Question 14

Ohm´s law

Answer 14

I=E/R

Question 15

When a channel opens, it has a fixed resistance ->

Answer 15

Thus, each channel has a fixed current

Question 16

What do we use the patch-clamp technique for?

Answer 16

Using the patch-clamp technique, we can measure the current through individual channels

Question 17

Graded potential:

Answer 17

A change in potential that decreases with distance:

- localized depolarization or hyperpolarization

Question 18

Action potential:

Answer 18

• Appears when region of excitable membrane depolarizes to treshold.

Question 19

What are the steps involved in action potential?

Answer 19

• membrane depolarization and sodium channel activation
• sodium channel inactivation
• potassium channel activation
• return to normal permeability

Question 20

What follows all-or-none principle?

Answer 20

The generation of action potential follows all-or-none principle.

Question 21

For how long does the refractory period last?

Answer 21

Refractory period lasts from time action potential begins until normal resting potential returns.

Question 22

Continuous propagation:

Answer 22

spread of action potential across entire membrane in series of small steps

Question 23

Salutatory propagation:

Answer 23

action potential spreads from node to node, skipping internal membrane.

Question 24

Voltage-gated Na+ channels

Answer 24

• have two voltage sensitive gates
• at rest one is closed and the other one is open
• when the membrane becomes depolarized enough the second gate will open
• after a short time, the second gate will shut

Question 25

Voltage-gated K+ channels

Answer 25

• have only one gate

- the gate is activated by depolarization

Question 26

Which voltage-gated channel, between Na+ and K+, is much slower to respond to the depolarization?

Answer 26

voltage-gated K+ channels

Question 27

γ aminobutyric acid

Answer 27

= GABA
- two known receptors for GABA
* both initiate hyper polarization in the post synaptic membrane
^GABA_A receptors allows an influx of Cl- ions
^GABA_B receptors allows an efflux of K+ ions

Question 28

What does most chemical stimuli result in?

Answer 28

an influx of cations

* this causes a depolarization of the membrane potential

Question 29

At least one transmitter opens an anion influx. This results in _________

Answer 29

a hyperpolarization

Question 30

EPSP

Answer 30

If the transmitter opens a cation influx, the resulting depolarization is called an Excitatory Post Synaptic Potential (EPSP).
* These individual potentials are subthreshold.

Question 31

IPSP

Answer 31

If the transmitter opens an anion influx, the resulting hyper polarization is called an Inhibitory Post Synaptic Potential (IPSP).
* All these potentials are additive

Question 32

Myelination I

Answer 32

• In the CNS, myelin is formed by oligodendrocytes.

- One oligodendrocyte can contribute to the myelin sheath of several axons.

Question 33

Myelination II

Answer 33

• In the PNS, myelin is formed by Schwann cells.

- Each Schwann cell associates with only one axon, when forming a myelin internode.