Lessson 3: Nervous System & Neurons

Question 1

Describe the CNS and PNS

Answer 1

-CNS: Brain and spinal cord, protected by meninges, skull, vertebrae
-PNS: all other neurons, serves limbs and organs, sensory and motor branches

Question 2

What two categories can the PNS be divided into?

Answer 2

-Somatic (voluntary contrations in skeletal sys)
-Exceptions are reflexes and shivering
-Autonomic: Involuntary processes (Digestion, sweating, smooth muscle contractions, blood circulation)

Question 3

How if the autonomic system divided?

Answer 3

-Sympathetic: Dominates in dangerous situations, (fight or flight), increase of heartbeat, bp, etc.
-Autonomic: Dominate in quiet situations, conserves energy so heartbeat is slowed, bp is lowered, etc.

Question 4

What is a neuron?

Answer 4

Nerve cell capable of carrying nerve impulses

Question 5

What do dendrites do?

Answer 5

Receive electrical stimulation from other neurons

Question 6

What does an axon do?

Answer 6

Carries nerve impulse away from the cell body

Question 7

What do axon terminals do?

Answer 7

Send electrical impulses to other neurons

Question 8

What are the three types of neurons?

Answer 8

-Sensory neurons
-Motor neurons
-Interneurons

Question 9

What do sensory neurons do?

Answer 9

Receive sensory info and sends it as a nerve impulse to CNS

Question 10

What do motor neurons do?

Answer 10

Take info from CNS to effectors (Muscles, glands, other organs)

Question 11

What are interneurons?

Answer 11

They link the motor and sensory neurons

Question 12

What non-neural cell makes myelin sheaths for the axons in the CNS?

Answer 12

Oligodendrocytes

Question 13

What non-neural cell makes myelin sheaths for the axons in the PNS?

Answer 13

Schwann Cells

Question 14

What is a myelin sheath?

Answer 14

-80% lipid and 20% protein
-Protect axons and speed up nerve impulses

Question 15

Is the inside of the neuron more positive or negative compared to the outside?

Answer 15

Negative

Question 16

Explain the Na/K pump

Answer 16

-Maintains the charge
-More Na on outside and more K inside
-Pump works against gradient (pumps 3 Na OUT and 2 K In)
-Causes cell to become more negative

Question 17

What is action potential?

Answer 17

-Large stimulus reaches cell body and changes the membrane voltage
-Causes domino effect where impulse moves down neuron (node to node)
-At the end of the neuron, neurotransmitters are released to another neuron and it repeats

Question 18

What is resting potential at?

Answer 18

-70 mV