Review Lessons 5-7

Question 1

What are the two systems of the nervous system called? What does each contain?

Answer 1

Central Nervous System: brain & spinal cord

Peripheral Nervous System: nerves – carry signals into & out of CNS

Question 2

What are the two types of cells?

Answer 2

Neurons: transmit nerve impulses
Neuroglia: support & nourish neurons

Question 3

What are the three parts of a neuron?

Answer 3

Cell body, dendrite, axon

Question 4

What are the three types of neurons classified according to function?

Answer 4

Sensory: takes nerve impulses from sensory receptors to CNS
Interneuron: in CNS; receive input from sensory neurons before integration
Motor: takes impulse away from CNS to an effector

Question 5

What are the three types of neurons classified according to structure.

Answer 5

According to structure neutrons are classified as unipolar, bipolar and multipolar.

Question 6

How is the myelin sheath formed?

Answer 6

Formed by Schwann cells (neuroglia)which wrap themselves around the axon many times

Question 7

What do these Schwann cells contain that make the sheath protective and insulating?

Answer 7

Their plasma membrane contains lipids; neurilemma

Question 8

What is the name for an area of myelinated axon missing the sheath?

Answer 8

Node of Ranvier

Question 9

Which axons are covered by the myelin sheath?

Answer 9

Usually long axons

Question 10

What is the difference between resting and action potential?

Answer 10

Resting: axon is not conducting an impulse; inside negative compared to outside; unequal distribution of ions
Action: axon is conducting an impulse = rapid change in polarity
●2 gated channels must open:
●1st: Na+ gate opens: Depolarization – Na+ flows into axon, and inside charge changes from neg. to pos.
●2nd: K+ gate opens: Repolarization – K+ flows out of axon, and inside changes back to negative

Question 11

What makes up a synapse?

Answer 11

Presynaptic membrane (axon terminal)
Synaptic cleft
Postsynaptic membrane (dendrite)

Question 12

How is a nerve impulse transmitted across a synapse

Answer 12

Impulse reaches axon terminal
Stimulation of synaptic vesicles to merge with presynaptic membrane
Neurotransmitters released into synaptic cleft, diffuse to postsynaptic membrane, bind with receptor proteins
Response of postsynaptic neuron

Question 13

What are the three functions of the nervous system?

Answer 13

Forms a communication network throughout the body
Allows response to external stimuli
Coordinates internal system to maintain homeostasis