Unit 2: Neuron Structure/Function

Question 1

Two types of nervous tissue cells

Answer 1

Neurons (sends signals)

Neuroglia (cellular division)

Question 2

Astrocytes

Answer 2

Type neuroglial

• help form blood brain barrier
• Allows certain substances to pass while harmful things are kept out

Question 3

Ependymal cells

Answer 3

Type of neuroglial

• creates cerebral spinal fluid
• Located in brain and spinal chord

Question 4

Microglia

Answer 4

Type of neuroglial

• provide protection
• engulf microbes or clear debris from dead cells

Question 5

Oligodendrocytes

Answer 5

Type of neuroglial cell

• In the CNS: produce myelin sheaths

Question 6

Schwann cells

Answer 6

Type of neuroglial

• in the PNS and form the myelin sheaths for PNS Neurons
• Surround the axon and increase the speed of conduction

Question 7

Four characteristics of neurons

Answer 7

• Extreme longevity
• Amitotic (not capable of division)
• High metabolic rate (constant need for oxygen and glucose)
• Irritability (capable of responding to stimulation)

Question 8

Structure of neurons

Answer 8

• Central cell body (axon) and dendrites (axon terminals)

- Entire cell is surrounded by a cell membrane

Question 9

Axon hillock

Answer 9

• Connects the cell body or soma to the axon
• Thickened area
• Also called the trigger zone

Question 10

Axon terminals

Answer 10

Responsible for releasing neurotransmitters into the synapse so that communication can continue between two neurons

Question 11

Myelin sheath

Answer 11

Fatty and insulating material that covers the axons of the neurons

Includes:
Oligodendrocytes
Schwann cells
Nodes of ranvier
Saltatory conduction

Question 12

The synapse

Answer 12

Space or gap between an axon terminal and another neuron effector

Question 13

Neurotransmitter

Answer 13

Released into this synapse and then binds to a specialized receptor

• Chemical that carries the nerve message.
• Released from the axon terminal (not the dendrite)

Question 14

Neuromuscular junction

Answer 14

Name for the synapse between a nerve cell and the skeletal muscle fiber that it supplies

Question 15

Dendrites

Answer 15

Contain receptors for neurotransmitters

Question 16

2 ways to classify neurons

Answer 16

• Number of processes they have

- Direction of action potential conduction

Question 17

Three number of processes

Answer 17

• Multipolar: Many dendrites and one axon
• Bipolar: one dendrite and one axon
• Unipolar: One process from the cell body that divides into 2 processes

Question 18

3 directions of neurons

Answer 18

1. Afferent or sensory neurons: From the body into the CNS
2. Interneurons: connect neurons within the central nervous system
3. Efferent or motor neurons: Convey info out of the CNS into the body

Question 19

Cns

Answer 19

Central nervous system

Question 20

Voltage gated channels

Answer 20

Present on the axon cell membrane, normally kept closed unless there is a change in voltage

Question 21

Depolarization

Answer 21

Charge goes toward positive

Happens when Na+ enters the axon

Question 22

Hyper polarization

Answer 22

Charge goes more negative

This happens when K+ leaves the axon

Question 23

Propagation if action potentials

Answer 23

The action potential travels down the axon, toward the axonal terminals

Question 24

Two types of propagation

Answer 24

Saltatory conduction

Continuous (local) conduction

Question 25

Describe a neuron at rest

Answer 25

Negative charge inside | High concentration of Na+ inside

Question 26

Phase of action potential

Answer 26

Depolarization: Na+, charge goes to +30mV, into axon Repolarization: K+, back down to -70mV, out of axon

Question 27

Action potential

Answer 27

A brief reversal of membrane potential

Question 28

Synaptic transmission

Answer 28

Where one neuron meets the next neuron or where a neuron meets a muscle cell

Question 29

Presynaptic events

Answer 29

Action potential travels down the axon and gets to the axonal terminal

Question 30

Postsynaptic events

Answer 30

Ligand gated channels - Channels for either Na+, K+ or Cl- that are found on the dendrites if neurons

Question 31

Events of presynaptic process

Answer 31

- Action potential arrives - Ca++ channels open - Ca++ enters presynaptic neuron - neurotransmitters released - Neurotransmitter binds to receptors - ligand gated Na+ channels open - removal of neurotransmitters by reuptake

Question 32

Cell body/soma

Answer 32

Contains nucleus of the cell or neuron

Question 33

Nodes of ranvier

Answer 33

Gaps or spaces do not contain myelin and allow the action potential to propagate or move faster

Question 34

Neuron action potential sequence of events

Answer 34

1. Depolarization graded potential occurs in response to a stimulus 2. Na+ channels open 3. Na+ flows into axon 4. -70mV to +30 mV 5. K+ channels open 6. K+ flows out of axon 7. +30 to -70