Nervous system

Question 1

Myelin is produced in the CNS by?

Answer 1

olygodendrocytes

Question 2

Myelin is produced in the PNS by?

Answer 2

schwann cells

Question 3

glia cells role?

Answer 3

support and structure

Question 4

Astrocytes

Answer 4

• from ectoderm

- Nourish neurons; form blood-brain barrier; homeostasis of ions; clear out synapses

Question 5

Ependymal cells

Answer 5

Line brain ventricles; produce CSF

Ependymal cells help form the barrier that holds in and produces CSF, cerebrospinal fluid.

Question 6

Microglia

Answer 6

• from mesoderm from monocytes (NOT ECTODERM)

- Phagocytic cells of CNS; immune function; antigen presentation

Question 7

Oligodendrocytes /Schwann cells

Answer 7

• ectoderm

- Produce myelin in CNS and PNS

Question 8

What is the Resting potential and how is it maintained?

Answer 8

-70mV, ATPase –> 3Na+ out and 2K+ in and gradient

Question 9

Action potential production

Answer 9

• the ATPase maintains high Na outside and high K inside
• when the neuron receives a presynapse, causes depolarization: at threshold of depolarization, Na channels open to let Na in then close at -35mV (absolute refractory period)
• repolarization: K channels open to let K out to then close but cell is in state of
• hyperpolarization: too many K out. to prevent further action potential
• stabilized back to -70mV with ATPase

Question 10

What is the threshold for depolarization?

Answer 10

• 55 mV

Question 11

temporal summation

Answer 11

multiple presyn received by neurons, and integrated in a short amount of time

Question 12

spacial summation

Answer 12

additive effects based on number and location of the incoming signals

Question 13

absolute vs relative refractory period?

Answer 13

absolute: Na channels are closed, no action potential
relative: need a greater stimulation since not at -70

Question 14

Why does Myelin sheath results in faster conductance?

Answer 14

because the signal can hope from node to node of Ranvier, as signal is not dissipated.

Question 15

CNS is composed of?

Answer 15

Brain and spinal cord

Question 16

PNS is composed of

Answer 16

crania and spinal nerves, outside the CNS

Question 17

somatic and autonomic nervous system is part of?

Answer 17

PNS

Question 18

Somatic nervous system

Answer 18

sensory (afferent) –> sensors and motor (efferent) neurons –> effectors

Question 19

autonomic nervous system

Answer 19

involuntary - sympathetic and parasympathetic

Question 20

nerves role?

Answer 20

• collections of neurons in the PNS
• may contain multiple types of info (sensory or motor)
• contain cell bodies in ganglia

Question 21

Tracts role?

Answer 21

• collections of neurons in the CNS that contain only 1 type of info
• contain cell bodies in nuclei

Question 22

interneurons

Answer 22

most numerous, mostly autonomic and reflexes

Question 23

reflexes

Answer 23

direct motor response to sensory input without conscious thought

Question 24

monosynaptic reflex

Answer 24

• single afferent and efferent nerve involved and there is a direct communication between sensory and motor neurons

Question 25

polysynaptic reflex

Answer 25

- multiple afferent and efferent nerves invovled, and there is the interneuron to help facilitate sensory-motor communications, present in the dorsal root ganglion

Question 26

reciprocal inhibition

Answer 26

concurrent relaxation of a muscle with the contraction of another.

Question 27

sympathetic ganglia

Answer 27

short preganglionic axon, ganglia body closer to spinal cord, long postganglionic axon

Question 28

parasympathetic ganglia

Answer 28

long preganglionic axon, ganglia body closer to target effector, short postganglionic axon