nervous system

Question 1

Central nervous system (CNS)

Answer 1

-brain plus spinal cord
-composed on interneurons (association neurons)
99% of all neurons in humans

Question 2

Peripheral nervous system (PNS)

Answer 2

-collects information and initiates reponses
1)Sensory(afferent) neurons-impulses from sensory receptors to CNS
2)Motor (efferent) neurons-impulses from CNS to effectors; muscles and glands
-somatic nervous system: motor neurons that stimulate skeletal muscles
-autonomic nervous system: motor neurons that stimulate smooth muscles, cardiac muscles and glands,

Question 3

Sensory(afferent) neurons

Answer 3

Sensory(afferent) neurons-impulses from sensory receptors to CNS

Question 4

Motor (efferent) neurons

Answer 4

Motor (efferent) neurons-impulses from CNS to effectors; muscles and glands
-somatic nervous system: motor neurons that stimulate skeletal muscles
-autonomic nervous system: motor neurons that stimulate smooth muscles, cardiac muscles and glands,

Question 5

somatic nervous system

Answer 5

somatic(conscious control) nervous system: motor neurons that stimulate skeletal muscles

Question 6

autonomic nervous system:

Answer 6

autonomic nervous system: motor neurons that stimulate smooth muscles, cardiac muscles and glands,

Question 7

Neuron structure

Answer 7

Dendrites-branches off
Axon-tube
Neurons are srurrouned by supported nerugolical cells
1) Schwann cells produce myelin sheaths around axons in PNS
2)Oligodendrocytes do the same in the CNS
in PNS bundles of axons form nervres

Question 8

Schwann cells

Answer 8

1) Schwann cells produce myelin sheaths around axons in PNS

Question 9

Oligodendrocytes

Answer 9

Oligodendrocytes produce myelin sheaths around axons in CNS

Question 10

Efferent

Answer 10

Brain to body

Question 11

Afferent

Answer 11

Body to brain

Question 12

Neural functions depend on..

Answer 12

the ability to create and alter electric potential across plasma membrane

Question 14

resting membrane potetntial(RMP)

Answer 14

the electrical gradient between a resting neuron and surrounding environment

Question 15

Inside of Axon

Answer 15

Fixed anions with cells (proteins and nucleic acids) negative charge
membrane more permeable to K+ than to Na+ (leakage channels)
The concentration gradient favors k+ out of cell
electrical gradient: k+ attracted to anions in cell

Question 16

equilibrium point between the concetration and electrical gradient is the

Answer 16

resting membrane potential (-70mV)

Question 17

If sufficient depolarization across the cell membrane is reached -55mV in mammals

Answer 17

A nerve impulse or action potential is produced

Question 18

Action potentials

Answer 18

Action potentials: a rapidly moving change in electrical membrane potential along the axon of a neuron
-action potentials are caused by voltage-gated ion channels two types: Na+ and K+

Question 19

Neuron goes to point A to B

Answer 19

1)Stimulus- gated channels open in response to chemical signals (Action potential beings at -55mV)
2)Voltage-gated Na+ channels now open, allowing NA+ to enter the cell via diffusion (pos outside, neg inside)
3)Na+ ions cancels out RMP (depolarization) Na+ channels close in response
4)Depolarization causes voltage-gate K+ channels to open, K+ moves outside of cell (repolarization). k+ channels close in reponse
5)action potential passes: membrane returns to RMP
Left to right of axon, self-propagating wave (burning fuse)

Question 20

Repolariztion

Answer 20

Does not return cell to RMP. There is now a high concentration of Na+ inside cell and K+ outside. Thus a new action potential is not possible
-NaK pump, pushes Na out of cell and K back in using energy, corrects repolarization
Action potentials are an all-or-nothing event.

Question 21

All action potentials are Qualitatively

Answer 21

alive, just need to get to 30mV

Question 22

Conduction Velocity

Answer 22

Cundciton velocity on an AP is a function of axon diameter and the presence or absence of myelin

Question 23

Synapses

Answer 23

when action potential passes along a neuron is must cross a synapse
-axon terminals contain vesicles of neurotransmitters that relay messages across synapse
1)Action potential opens up calcium channels and trippers the inward diffusion of Ca+ which causes synaptic vesicles to bind with the plasma membrane and then release neurotransmitters into the synapse
2)Neurotransmitters bind to receptor proteins on postsynaptic cell, opening their gated ion channels
3)if the resulting voltage change across the cell reaches -50mV an action potential in the postsynaptic cell is initiated
4)Neurotransmitters are rapidly removed from synaptic cleft by enzymatic digestion and reuptake by the neuron
5) neuron reabsorbs and resynthesizes components into neurotransmitters