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MCAT Biology Review > Chapter 8 Nervous System > Flashcards

Chapter 8 Nervous System Flashcards

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1
Q

Neuron Structure
What are three main components of a neurons? Draw it out.

What is the underlying characterisic for the processces? why is this important?

A
  • Soma - the cell body.
  • Dendrites - send nerve impulses to the soma
  • Axon - send impulses away from the soma
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2
Q

What are different types of neurons?

A
  • Multipolar - multiple processes radiate from the cell body.
  • Bipolar - 2 processes coming out from the soma
  • Unipolar - 1 process coming out of the cell body.
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3
Q

Where do you find bipolar and unipolar neurons?

A
  • Bipolar - the eye

- Unipolar - the grey matter

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4
Q

what is the myelinating cell in the central nervous system and in the peripheral nervous system?

A
  • Schwann cell - the PNC

- Oligodendrocytes - the CNS

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5
Q

What is the naked spot between the schwan cells?

What are these naked spots for?

A

Node of Ranvier

  • These nodes of Ranvier allows the impulses to jump speeding up the rate of signal transduction along the axonb.
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6
Q

What is the technical term for jumping impulses along the axon?

A

Saltatory conduction

- why is it called saltatory? In latin, saltate means hop or jump.

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7
Q

Which area or part of the neuron has the most number of Sodium channels? why is that?

A

the axon hillock is the like the start of the axon. this is there action potentials are fired which make sense for why it has the most number of Sodium channels here.

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8
Q

What are the chemical gradient across the cell membrane?

A
  • High concentration of Na+ and Cl- and Ca+ outside of the cells – so they tend to want to move inward making the inside more possitve for Na, Ca and more negative for Cl-
  • K tend to want to flow out making the cell less possitie.
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9
Q

What is value of the resting membrane potential?

What are the membrane proteins that are responsible for this membrane potential?

A
  • 70 mV
  • The K/Na+ ATPase. Pumping 3 Na+ out and 2 K+ inside the cell using one ATP.
  • Potassium leak channel.
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10
Q

What is the resting potential NEGATIVE value?

A
  • It’s negative because Na+ is pumped outside of the cell against its gradient making in the inside more negaitve.
  • K+ leak channel allows for the outflux of K+ making the inside of the cell even more negative.
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11
Q

If the possium leak channels are blocked, what will happen to the membrane potential?

A

less nagtive

so the magitude of the resting membrane potential will go down.

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12
Q

What would happen to the membrane potential if sodium ions were allowed to flow down their concentration gradient?

A
  • making the inside of the cell less nagtive or even more possitive.
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13
Q

What exacly is an action potential? what does it mean to say that the membrane is polarized? what is depolarization and repolarization?

What governs the depolarization and repolarization?

A
  • An action potential is a disturbance of the resting membrance potential - a wave of membrane depolarization among the axon.
  • At equilibrium, the interior of the cell is negatively charged while the outside is possitively charged, hence the membrance is polarized.
  • Depolarization is when this resting potential is disrupted. Repolarization is when the resting membrane is restored.
  • The movement of ions in and out the cell. Since ions are charged molecules, moveme of ions are controled both by electrical and chemical gradients. Thus, action potential is a electrochemical impulses.
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14
Q

When is the cell membrane hyperpolarized?

A
  • the cell is hyperpolarized when the inside of the cell more nagative.
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15
Q

What is equilibrium potential? What is the equation used to calculate the equilibirum potential?

A

Equilibirum potential is when the net force on the ion is zero. chemical and electrical forces balance each other out.

There is an equation to calculate this.
Nernst Equation:
E eq = RT/ zF ln([x]out/ [x]in)

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16
Q

What is the threshold potential?

A

-50

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17
Q

What is the difference between sodium gated channel and potasium gated channel?

A

Na+ channel opens faster than K+ channel.

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18
Q

At what potential is sodium channel deactivated?

A

+35

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19
Q

True or False. Why or why not?
Myelinated axons can conduct many more action potentials then unmyelinated axons.

What is the rate determining step for action potential?

A
  • refractory period of potassium and sodium channels.
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20
Q

What is a nerve impulse?

A

It’s an action potential that travels … that’s all.

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21
Q

In the most general term, what is an electrical synapses?

A

It’s an junction in which an impulse is transferred from one cell to another cell.

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22
Q

What is the different between absolute and relative refractory?

A
  • During absolute refractory period, the neuron absolutely cannot fire another action potential because the sodium channel is in its inactivated state.
  • During the relative refractor period, the sodium channel is closed but not inactivated thus can be open if given enough potential.
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23
Q

How is the entire nervous system structured? how many brands and what are their functions?

A
  • Then central is for integrating information

- Sensory and motor are part of the PNC - for receiving and sending out information.

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24
Q

What are the effectors in the nervous system?

A

muscle organs etc

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25
Q

What are reflexes? how many neurons and synapses are often involved in reflexes? which nervous system is involved in reflexes?

A
  • reflexes are simple nervous system acitvity that don’t involve interneurons
  • the impulses go from sensory to motor no interneurons for integration of information or anything.
  • so one one synpase. This is also called the monosynaptic reflex arc.
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26
Q

what are the four characteristic of electrical synapses?

A
  • Physical connection between cells _ gap junctions
  • Alwaysexcitatory
  • bidirectional
  • Unregulated
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27
Q

Why is bidirectional not a good ideas?

A
  • conflicting waves of contraction
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28
Q

What is the difference between electrical and chemical synpases?

A
  • In constrast to electrical synapses, chemical synapses are highly regulated, non-physical, unidirectional and can be both excitatory or inhibitory.
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29
Q

Is Acetyl Choline an exhibitory or inhibitory?

A

you can’t answer this because it depends not on neurotransmitter but the ligand gated ion channels

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30
Q

What are interneurons?

A
  • neurons that exist in the CNS
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31
Q

what is the difference between efferent and afferent neurons?

A
  • efferent neurons = existing CNS

- afferent neurons = approach CNS

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32
Q

what are relfexes? example

A

rapid intergration designed to avoid injury

- bladder

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33
Q

What is reciprocal inhibition? Provide an example.

A
  • It’s neuromuscular reflext that inhibit the other muscle group during movement.
  • The concurrent relaxation of the hamstring and contraction of the quadriceps is an example.
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34
Q

What is the central nervous system consisted of?

A

the brain the the spinal cord

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35
Q

What is the peripheral nervous system consisted of?

A

all nerves and sensory structures outside of the brain and the spinal cord.

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36
Q

What are the two divisions in the PNC? what are their functions?

A

PNC is consisted of the somatic and autonomic nervous system.

  • Somatic nervous system control sensation and conscious, deliberate movement.
  • Autonomic nervous system is concerned with digestion, metabolism, circulation, repiration and the involuntary processes. Autonomic nervous system controls processes that are critical to the body and yet can’t be controlled consciously. Ex: your heart beat goes up when you are nervous without your control.
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37
Q

What are the two branches of the autonomic nervous system? and what does each of them do?

A
  • Autonomic nervous system consists of the sympathetic (Fight or flight) and the parasympathetic (Rest and digest) braches.
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38
Q

What happen to different organs when the sympathetic nervous system is activated?

A
  • Digestion is stalled.
  • Urinary is also stalled. Bladder is relaxed.
  • what about respiration? what happen to the bronchial smooth muscle? relax, open airway for more air volume.
  • Cardiovascular? faster heart rate. higher firing rate. increase in blood flow to muscle.
  • Skin; what needed to happen when your body is active? sweating and vasoconstriction
  • release of epinephrine
  • genital: ejaculation/ orgasm
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39
Q

Which hormone is associated with the sympathetic nervous system?

A
  • the epinephrine.
40
Q

What is the direction in the CNS that goes from the most primitive to advance? What is the most primitive part fo the CNS and what does it do?

A

The most primitive part of the CNS is the spinal cord. It controls most of the reflexes.

41
Q

Going up from the spinal cord, what is the next part of the CNS and what does it do?

A

the medulla - control basic vital function, respiration and digestive function.

42
Q

Where in the CNS is repiration controlled by?

A

the medulla

43
Q

Where is the pons and what is its functions?

A

on top of the medulla which is responsible for preparation and other digestive functions.
- The pons control balance and facial movement.

44
Q

what is the part that is right behind the pons and the medulla and what does it do? is there anything connection between this part and the pons?

A

the cerebellum
- control and facillitate smooth body movement.

  • the pons - balance.
45
Q

What is the first part of the brain that is affected by alcohol and intoxication? what is the result of this? how can you spot someone that is drunk?

A
  • the cerebellum is the area of the brain that is first affected by alcohol which is shown in the lack of coordination of movement in drunk individual.
46
Q

Moving up from the medulla, pons and cerebellum, what do you run into and what is its function?

A

The mid brain - responsible for visual and auditory startle reflexes.

47
Q

What part of the brain is reponsible for you being startled by a strange noise or sight of someone?

A

the mid brain

48
Q

Next to the mid brain, what do we have?

A

The diencephelon and the cebreum.

49
Q

What part of the brain is at the center of the brain? not the mid brain.

A

the Diencephelon

50
Q

What is the center resgion of the diencephelon? what is region that is above and below the Diencephelon?

A
  • Thalamus the center.
  • Above the thalamus, epithalamus.
  • Below the thalamus, hypothalamus
51
Q

Where is the endecephelon in the brain? in which region of the endecephelon can you find the pineal gland and the putitary gland?

A

The putitary gland is the lower region of the diencephelon, so it’s in the hypodiencephelon region.

The pineal plan, which is responsible for sleep cycle, is located at the epithalamus.

52
Q

which part of the brain (hint: diencephalon) is responsible for relaying sensory.

A

thalamus

53
Q

what part of the brain is responsible for body homeostasis?

A

the pituitary gland

54
Q

What is the difference between white and grey matter?

A
  • white matter = myelated axon = fast and communication
    (white matter in brain = tract, in the PNS = nerve, the cord = tract)
  • Grey matter = more cell bodies and dendrites for integration of information and not transport of impulses.
55
Q

where can you find grey matter in the CNS and what are they called?

A
  • starting from the PNC … ganglion = pockets of cell bodies at synapses.
  • moving into the spinal cord = the butterfly shape = the horn
  • Moving to the brain surface and deep brain = cortex and nucleus
56
Q

What are the four lobes of the cebrerum/ telencephalon?

A

the frontal, parietal, occipital and temporal.

57
Q

which part of the telencephalon or the cebrerum is responsible for movement and reasoning skills?

A

the frontal

58
Q

which region of the telencephalon is the responsible for taste and sensation?

A

parietal lobe

59
Q

which region of the telenceophalon is responsible for hearing, memories and smell?

A

temporal - time (memories)
near the ear - hearing
smell the last senation.

60
Q

which lobe is responsible for vision?

A

occipital lobe

61
Q

What are the differences between cranial and spinal nerves?

A
  • Cranial nerve - nerves that originate from the brain stem

- Spinal nerve - nerves that go in and out of the spinal cord

62
Q

Vagus nerve - where is it and what does it control or regulate?

A
  • cranial nerve

- control the cardiovascular system and the GI tract

63
Q

Is the Vagus nerve part of the para and sympathetic nervous system and why?

A
  • vagus nerve decreases heart rate and activity of the GI tract –> parasympathetic system.
64
Q

What are five types of sensory receptor in the our body? what does each of them do?

A

-

65
Q

What does mechanoreceptor do?

A
  • Mechano - Mechanical energy

- Sensing touch and pressure

66
Q

What does chemoreceptor do?

A
  • Chemo - Chemical

- Responding to chemical - taste, smell, CO2 or O2

67
Q

What is the receptor the detects pain?

A

Nociceptors

68
Q

What does thermoreceptors detect?

A

They respond to temperature

- There are different receptors for hot and cold and each respond to different temperature range.

69
Q

What does the prefix “Noci” mean?

A 
Noci = noxious = bad
Nocireceptor = pain receptor.
70
Q

What are nocireptors? and what do they respond to?

A
  • Nocireceptors are pain receptor
  • ## They responsd to chemical releasing during injury … in some sense nocireceptors are chemoreceptors.
71
Q

What are the photoreceptors and electromagnetic receptors for? where in the human body can you find the photoreceptors?

A

they derect and respond to the light and electromagnetic waves
- The rentina.

72
Q

What is the difference between difference and absolute threshold?

A
  • Absolute thresshold is the minimum level of stimulation required to activate the receptor.
  • the difference threshold is the smallest difference that can be detected.
73
Q

what is bottom up processing?

A
  • receiving information from the sensory branch and the brain interpret that information.
74
Q

What is a top-down processing?

A
  • Prior knowledge is used for the brain interpretatio of the event.
    Ex: seeing an objects and used the learned knowledge to correctly point out the name of the object.
75
Q

What is sensory adaption?

A

This acts like noise filtering.

The unchanged stimuli are ignored by the receptors. The receptors can be triggered again if the stimulus intensifies.

76
Q

which part of the eye is responsible for adjusting the len in your eyes? in what ways is the lens adjusted?

A
  • Contracting of the side muscle that results in changing the shape and the curvature of the lens.–> Ciliary muscles
  • When the muscles contract, it flattens out the lens. When it relaxes, the lens is curved again.
77
Q

What is the first thing the light needs to run into first before entering the pupil?

A
  • Cornea - a transparent layer
78
Q

so after the light enters the pupil, going through the lens, what is the name of the location that the light is focused on?

A
  • the fovea (focal) centralist (central)
79
Q

What regulates the diameter of the pupil?

A

the Iris

80
Q

If you draw out the eye, what is the colored part of the eye?

A

the iris

81
Q

How is the diameter of the pupil regulated?

A

the ciliary muscle

82
Q

What the outermost structure of the eye? What is its relationship to the lens of the eye?

A
  • Looking from the side dissection of the eye, you will see the outermost part of the eye is a clear, curved structure called the cornea.
  • It does a bit of light bending for the lens.
83
Q

What is the layer that is at the back of the eye consisting of photoreceptors?

A

It’s called the retina

84
Q

so the visual information (fight) is captured by the photoreceptors on the retina, how is that information transferred to the brain? through what structure of the eye?

A
  • the optic nerve
85
Q

where is the blind spot of our eye? what is the medical term for that and why is it called a blind spot?

A

It’s called a blind spot because there aren’t any photoreceptors there. The visual information (the light) is lost if it lands on this blind spot.

The reason that we don’t have any photoreceptors there is because that is where the optic nerve forms. It’s also called the optic disk.

86
Q

why does the retina have three layers of cells?

A

the light is captured by the photoreceptors, which make up the most posterior layer of the retina.
The signal then travel backward, through a bipolar cell, which connects the photoreceptor to neurons that transmit the information to the brain. The axon of these neurons makes up the optic nerve.

87
Q

How many types of photoreceptors are there in the retina? what are their properties?

A

There are two types of photoreceptors.

One is good for vision with bright light (colors) and the other is good for low light conditions (black and white).

Rod – finishing rod (Skinny) is usually gray - black and white, low light

Cone - colorful traffic cone – colors in bright light condition.

88
Q

what type of color receptor do you find at the fovea centralis? where is the fovea centralist anyway?

A
  • centralis == the center where most light that goes through your lens focus at.
  • There is only cone receptors at the fovea centralis. Remember the example where the star would disappear if you stare at it for a while because the cone receptors at the fovea centralist are not activated in low light conditions?
89
Q

Describe the physiology of the rod receptors work. Let start with this:
What happens at the cellular level in the absence of light?

A
  • In the absence of light, the sodium channels are open, thus the rod receptors are depolarized.

Since the cell is depolarized
[the action potential travels to the terminal of the receptor… Ca+ channels are now open, Ca+ rushes into the cell and binds to Ca+ gated channels on the vesicle containing neurotransmitters. ] The neurotransmitters are released to the bipolar cells.

  • If it reaches a bipolar cell that is on, meaning it only works in the presence of light, the neurotransmitters act as an inhibitory signal, which stops the bipolar cell from firing the action potential.
  • Now, if the neurotransmitters reach an off cell, meaning a cell that works in the absence of light – a stimulatory synapse – that bipolar cell will fire an action potential that can go to the brain.
90
Q

How many types of bipolar cells are there in the retina?

A

There are two types; on and off cells.

If a cell is an on cell, it will only work or in this case send the action potential to the neuron only the light is on.

91
Q

For the Rod receptors, What happens when there is light.

A
  • In the presence of the light, the Na channel on the rod receptors are close, thus no neurotransmitters are being released by the Rod cell.
  • Now recall that the neurotransmitters released by the Rod cells inhibit the firing of the off bipolar cells. So in the absence of the neurotransmitters (light), it would actually fire an action potential that is sent to the brain.
92
Q

For a normal cell, are they repolarized or hyperpolarized in their resting state? what about the rod cell in the retina?

A
  • Normal cells are often hyperpolarized in their resting state and only depolarized - the opening of the Na channel - when the action potential arrives.

For the rod cells, however, they are depolarized in their resting state, the absence of light.

93
Q

Is the rod cell depolarized in the dark or in the light?

A

They are depolarized in their “resting state” – the dark.

94
Q

how many compartments is the ear divided into?

What are the components or parts that divide the ear into these compartments?

A

The outer, the middle, and the inner ear.

  • the tympanic membrane (your ear drum) divides the outer and the middle ear.
  • the middle ear – three bones in the empty space
  • the oval window – The inner ear = Semicircular canals and the cochlea.
95
Q

describe the mechanism of hearing? In other words, how does the sound converted into electric signals that sent to the brain?

A

Sound wave captured by the outer year.

Sound wave is the compression wave.

  • the vibration is captured by the tympanic membrane. This vibration is conducted through ossicles (the three bones)
  • The oval window is vibrated at the same frequency of the same.
96
Q

How does the structure of the cochlea allow for the detection of different pitch and loudness?

A
  • the cochlea can be flattened out. The nearest part to the oval window is stiff and can only be moved or detect high-frequency sound. The tip of the cochlea however is very soft and can be easily moved or detect low-frequency sound.
  • The loudness of a sound really is just the amplitude of the vibration.
  • The amplitude of the vibration = the loudness
  • the location of vibration on the cochlea dictates the perceived frequency.
97
Q

what is the vestibular complex for?

A
  • coordination.

- the Vesicular complex consists of three rings. Each ring is situated on each planes.

MCAT Biology Review (13 decks)

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