Ch 3 Lec 9

Question 0

What do sensory neurons do?

Answer 0

send messages from sensory receptors to the central nervous system.

Question 1

Neuron

Answer 1

nerves cells that serve as the basic building block of the nervous system.

Question 2

What do motor neurons do?

Answer 2

send messages from the central nervous system to
• smooth muscles
• skeletal muscles
• cardiac muscle=

Question 3

What are three parts of each neuron?

Answer 3

• Cell body
• Dendrites
• Axon

Question 4

What are functions of cell body(soma)?

Answer 4

• contains biochemical structures required to keep the neuron alive
• contains a nucleus that caries genetic information that determines cell development and function

Question 5

What do dendrites do?

Answer 5

Receive messages from neighboring neurons and them to the cell body

Question 6

What does axon do?

Answer 6

conducts (doing a particular process )electrical impulses away from the cell body towards neurons, muscles, or glands

Question 7

What are five functions of Glial cells?

Answer 7

• surround neurons and secure them in place
• manufacture nutrient chemicals that neurons require
• form myelin sheaths around some axon (facilitating the transmission of message by neurons)
• absorb toxins and waste materials
• in the peripheral nervous system they help regenerate damaged neurons

Question 8

What is Blood-brain barrier(BBB)?

Answer 8

mechanism responsible for impeding the passage of toxic substances from the blood to the brain.

Question 9

Why is BBB functional?

Answer 9

Because of the particular structure of cerebral blood vessels.
But does not stop the passage of all large molecules(e.g. glucose(葡萄糖))

Question 10

Axonal conduction

Answer 10

When a neural impulse is transmitted along the length of an axon.

Question 11

What is resting potential?

Answer 11

• The electrical charge of a neuron at a point when it is not firing a neural impulse.
• Due to differences in charge between the intracellular fluid and extracellular fluid(separated by the neuronal membrane)

Question 12

Neuronal membrane is selectively permeable(allows water or gas pass through) to ions, what are main positive and negative ions?

Answer 12

main positive ions: sodium and potassium

main negative ions: chloride and proteins

Question 13

Action potential

Answer 13

• A sequence of changes in the electrical charge across the axonal membrane
• This occurs after the axon has reached its firing threshold.

Question 14

Depolarization

Answer 14

the shift from negative to positive voltage

Question 15

What are two sub-period of refractory period?

Answer 15

• Absolute refractory period

* Relative refractory period

Question 16

• Absolute refractory period

* Relative refractory period

Answer 16

• The period of time, after the initiation of a action potential, during which a second action potential cannot be initiated.
• The time during which the initiation of an action potential can be initiated but requires higher-than-normal levels of stimulation.

Question 17

All-or-none law

Answer 17

Action potentials only occur at a uniform and maximum intensity(刺激的强弱只产生有反应和无两种情况)

Question 18

• 1.Action potential threshold

* 2.Graded potentials

Answer 18

• 1.The voltage inside the axon mush change from -70 to about -50 in order to make an action potential to be triggered.
• 2.Changes in the resting potential do not reach the -50