Lecture 2 : Neurons

Question 1

Saltatory Conduction:

Answer 1

impulse will skip from one node of ranvier to the next node

Question 2

Types of Neurons:

Answer 2

1. Multipolar Neuron: majority of neurons

Question 3

Functional Classification of Neurons:

Answer 3

1. Sensory (afferent) neurons: transmitting impulses TOWARDS the CNS
2. Motor (efferent) neurons: carry impulses AWAY from the CNS towards effectors (muscle/glands)
3. Inter Neuron (association) Neuron: lie between sensory + motor neuron, communicate between the two

Question 4

What does a Neuron need to function?

Answer 4

1. Threshold Stimulus
2. Electrolytes: charged atom (Na+, K+)
3. ATP: cell energy (glucose+oxygen)

Question 5

Resting Membrane Potential:

Answer 5

: Axon has different channels (Na+, K+)
- when axons are not firing

Question 6

Action Potential:

Answer 6

:“nerve impulse”
axon fires, either all or none

1. Threshold stimulus; opening of Na+ channels along axon
2. Depolarization; Na+ diffuses into axon (-70mV > +30mV)
3. Re-polarization; after depolar. K+ channels open and diffuse out of the axon (+30mV > -80mV)
4. Hyperpolarization; loss of K+ from axon = charge went from -70mV to -80mv

Question 7

Na+/K+ Pumps:

Answer 7

:use ATP to pump 3 SODIUMS out of the axon and pump 2 POTASSIUMS into the axon
- basically getting rid of the excess positive charge to drive back down to -70mV

Question 8

What could decrease the amount of glucose
-O2

Answer 8

• Uncontrolled diabetes ~ lethargic
• Asthma, choke, COVID ~ brain death

Question 9

Electrolyte Imbalance:
-conditions dealing w/that^

Answer 9

• Hyponatremia: decrease Na+ in blood = slower rate of conduction
• Hyperkalemia: excess K+ in blood = stop action potentials

Question 10

What would cause lowered blood sodium levels?

Answer 10

• Water loss = electrolyte loss
• Ex: vomiting, diaharrea, excess sweating, blood loss

Question 11

What would cause increase blood potassium levels?

Answer 11

• Too many potassium supplements or kidney malfunctions

Question 12

Axon and or neurons need to have what?

Answer 12

continual glucose and O2 supply

Question 13

Axon terminals:

Answer 13

secrete neurotransmitters

Question 14

Synapse:

Answer 14

junction between an axon and muscle cell, gland, OR dendrite