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physiology ii > CNS Organization (Lec 1B) > Flashcards

CNS Organization (Lec 1B) Flashcards

1
Q

True or False?

The brain initiates, controls, and coordinates most muscular activity except simple reflexes

A

True

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2
Q

True or False?
The spinal cord is the last CNS structure encountered by most incoming sensory information and first relay station for most motor information.

A

False. The spinal cord is the first CNS structure encountered by most incoming sensory information and the last relay station for most motor information

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3
Q

What is the site of coordination of most reflex arcs?

A

spinal cord

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4
Q

Define the PNS

A

made up of transmission pathways carrying information between the CNS and external/internal environments

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5
Q

Which direction do afferent (sensory) pathways carry information?

A

to the CNS

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6
Q

Which direction do (efferent) motor pathways carry information?

A

away from CNS

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7
Q

What does the PNS include?

A

cranial nerves (12 pairs), spinal nerves (31 pairs), sensory receptors in the ksin and wall of the gut tube as well as in tendons and skeletal muscles, motor end plates between motor neurons and skeletal muscle fibers

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8
Q

True or False?

The ANS is entirely motor

A

true

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9
Q

What are short branched process on an axon called?

A

telodendria

note: telodendria endings are called terminal boutons and contain synaptic vesicles filled with neurtransmitters

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10
Q

True or false?

The axon is the only part of neuron that is ever myelinated

A

true

note: not all axons are myelinated, even though they are covered by Schwan cells

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11
Q

What is a nucleus?

A

aggregation of dendrites and nerve cell bodies in the CNS

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12
Q

What is a ganglion?

A

aggregation of dendrites and nerve cell bodies in the PNS

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13
Q

What is a nerve?

A

bundle of fibers (axons) in the PNS

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14
Q

What is a tract?

A

a bundle of fibers (axons) in the CNS

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15
Q

What is a commissure?

A

tract in the CNS that crosses from one side to the other

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16
Q

True or false?

The CNS consists of structures arising directly from the neural tube

A

true

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17
Q

What is white matter?

A

areas of myelinated axons

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18
Q

What is gray matter?

A

areas of unmyelinated axons, cell bodies, and dendrites

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19
Q

What do white ramus communicans do?

A

carry myelinated pre ganglion fibers

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20
Q

What do gray ramus communicans do ?

A

carry unmyelinated postganglionic fibers back to spinal nerve

21
Q

Describe paravertebral ganglia

A

linked together into a long chain on either side of the vertebral column, site of cell bodies of postganglionic sympathetic nerves, site of synapses between preganglionic myelinated sympathetic neurons and postganglionic non-myelinated sympathetic neurons

22
Q

Describe prevertebral ganglion

A

typically found anterior to abdominal aorta, site of synapses between preganglionic myelinated sympathetic neurons and postganlgionic non-myelinated neurons

23
Q

What is a reflex arc?

A

a pathway that leaves from and returns to the CNS. It consists minimally of a sensory and motor pathway

24
Q

What are the three physiological states of a neuron?

A

resting: -65mv
excited: -45mv
inhibited: -70mv

25
Q

True or false?

Simultaneous firing of only a few synapses can summate to produce an action potential on a postsynaptic neuron

A

False, need simultaneous firing of many synapses on the postsynaptic neuron

26
Q

Where do primary, secondary, and tertiary afferent neurons synapse?

A

primary: posterior horns of spinal cord or sensory nuclei in brain
secondary: thalamus
tertiary: somesthetic areas of cerebral cortex

27
Q

What does the skeletal motor nerve axis refer to?

A

the sequence of structures involved in the transmission of an action potential from the higher brain centers to skeletal muscles, includes: motor cortex of cerebrum, efferent pathways, and skeletal muscles

28
Q

What are the three processing areas of the skeletal motor nerve axis?

A

basal ganglia in the telencephalon, thalamus in the diencephalon, and spinal cord reflexes

29
Q

What type of NT is acetycholine and what secretes it?

A

Excitatory NT. Secreted by pyramidal cells, neurons in basal nuclei, alpha motor neurons, preganglionic neurons of ANS, postganglionic neurons of the parasympathetic nervous system, and some postganglionic neurons of the sympathetic nervous system

30
Q

What type of NT is Norepinepherine and what secretes it?

A

Can either be excitatory or inhibitory NT. Secreted by neurons located in the brain stem and hypothalamus, some neurons located in the pons, and most postganglionic neurons of the sympathetic system

31
Q

What type of NT is Dopamine and what secretes it?

A

Usually an inhibitory NT. Secreted by most neurons originating in the substantial nigra

32
Q

What type of NT is Glycine and what secretes it?

A

Always an inhibitory NT. Secreted by synapses in spinal cord

33
Q

What type of NT is GABA and what secretes it?

A

Always an inhibitory NT. Secreted by many areas in the spinal cord and cerebral cortex

34
Q

What type of NT is Glutamate and what secretes it?

A

Always an excitatory NT. Secreted by many sensory pathways entering the CNS and many areas of cerebral cortex

35
Q

Can dendrites transmit an action potential?

A

No, they use electronic conduction instead

36
Q

What ions is the dendretic membrane partially permeable to?

A

K+ and Cl-

37
Q

True or false?

Dendrites are long and membranes are thin

A

true

38
Q

What causes much of the potential to be lost in dendrites?

A

leakage

39
Q

Describe the difference in signal strength between dendrites and an action potential down an axon

A

Dendrites: signal becomes weaker the further it is from the site of initiation
AP in axon: constantly renewed along the length of the axon and therefore, doesn’t decrease in strength

40
Q

Define electronic conduction.

A

direct spread of electrical current by ion conduction in the dendritic fluids without generating an AP

41
Q

What are two characteristics of a dendrite that result in electronic conduction?

A

few voltage-gated Na+ channels in dendritic membrane and thresholds too high for APs to occur

42
Q

What is the excitatory state of a dendrite?

A

the summated degree of excitatory drive to the neuron

43
Q

Explain the firing rate of a dendrite.

A

As long as the excitatory rate of a neuron remains above threshold for excitation, the neuron will fire repetitively

44
Q

What is synaptic delay?

A

the time it takes to transmit a signal from a presynaptic neuron to a postsynaptic neuron

45
Q

What are the two sources of blood to the brain?

A

Vertebral arteries and internal carotids

46
Q

What is the circle of willis?

A

a pentagonal-shpaed circle of arteries on the ventral surface of the brain that unites the two vertebral and the two internal carotid arteries

47
Q

What are the components of the circle of willis?

A

posterior cerebral arteries, posterior communicating arteries, internal carotids, anterior cerebral arteries, anterior communicating artery

48
Q

What three things do axons contain?

A

Mitochondria, neurofilaments, and neurotubules

physiology ii (19 decks)

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