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Physiology for Engineers > Midterm Review 3/3 > Flashcards

Midterm Review 3/3 Flashcards

1
Q

Describe the endothelial cells.

A
  • Linked together by continuous tight junctions that prevent free diffusion into brain
  • Unlike other capillaries in body with fenestration (large slit pores between adjacent endothelial cells)
  • Also have thick basement membrane under endothelial cells
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2
Q

What substances easily pass through the blood brain barrier

A

uncharged molecules, lipid-soluble molecules, lipid-soluble gases (CO2, O2, and anesthetics), drugs (caffeine, nicotineT, heroin)

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3
Q

True/False: the blood-brain barrier is very permeable to water

A

True

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4
Q

What causes the blood-brain barrier to be compromised?

A

meningitis and bacteria cause inflammation

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5
Q

What are the parts of the neuron?

A

Cell body, dendrites, axon, and presynaptic terminal

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6
Q

What does the cell body of the neuron contain?

A

nucleus, ER, etc

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7
Q

What are the dendrites of a neuron?

A

receptors that bind to neurotransmitters

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8
Q

What is the function of the axon?

A

The message-sending portion of the neuron, carries action potential to the next neuron

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9
Q

How does AP travel in myelinated axons?

A

through the nodes of Ranvier

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10
Q

What is the function of glial cells?

A

supportive to help the neurons (assistants) bathes them in healing solutions

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11
Q

True/False: Glial cells can not proliferate throughout life.

A

False: they proliferate throughout life (unlike neurons)

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12
Q

What is the function of oligodendrocytes?

A
  • Form myelin sheath in CNS axons
  • Schwann cells form myelin sheath in peripheral nerves
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13
Q

What are the Nodes of Ranvier and what do they do?

A

rich in positive sodium ions and they jump from one node to the next (makes it a lot faster to have that action propagate down the axon.

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14
Q

What happens if we have a problem with the nodes of ranvier or the myelin sheath?

A

The person would be weak and not be able to walk well

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15
Q

What is the presynaptic terminal and what happens?

A

where axons terminate and where neurotransmitters are released which diffuse across synaptic cleft,
bind to receptors on postsynaptic membrane, electrical signal is converted to chemical signal (neurotransmitter release), triggers AP

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16
Q

What are the excitatory neutrotransmitters?

A
  • Glutamate (major excitatory neurotransmitter)
  • Acetylcholine
  • Epinephrine
  • Histamine (generally excitatory effects)
  • Dopamine (both Excitatory and Inhibitory)
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17
Q

What are some of the inhibitory neurotransmitters?

A
  • GABA (Gamma-aminobutyric acid) (most common
    one in nervous system)
  • Serotonin
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18
Q

What is action potential?

A

transient, regenerative,
electrical impulse in which the membrane
potential rapidly rises to a more positive peak

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19
Q

True/False: Normal resting voltage of AP is negative

A

True

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20
Q

What happens at the junction between two neurons?

A

AP causes neuron to release chemical neurotransmitter (which either excites or hinders next neuron from firing its own AP)

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21
Q

What do the efferent nerves do?

A

Allows brain to communicate with periphery (e=away from brain)

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22
Q

What do the afferent nerves do?

A

Allows periphery (e.g. organs, muscles) to
communicate with brain
(a= to brain)

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23
Q

Action potential has ____ depolarization and ____ repolarization.

A

Rapid depolarization and slow repolarization

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24
Q

What happens when an electrical stimulus of nerve or muscle cell causes membrane potential to become more + than threshold voltage?

A

triggers AP

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25
Q

Depolarizing stimulus
requires certain
____ and ____.

A

requires certain
intensity (magnitude)
and duration

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26
Q

When a cell fires an AP, how soon can it fire another one?

A

Cell needs time to recover

27
Q

What is the absolute refractory period?

A

Second response is not
possible regardless of
strength/duration of
stimulus due to Na+ channel inactivation

28
Q

How long does the absolute refractory period last?

A

Lasts from initiation of AP to when repolarization is
almost complete

29
Q

What is the relative refractory period?

A

Second response can be
elicited but requires a greater stimulus (in strength or duration)

30
Q

Why is action potential so important?

A

Because it lets the body talk to the brain and the brain talk to the body

31
Q

What happens during saltatory conduction?

A

current flows from node to node, very efficient system

32
Q

What is a motor unit?

A

Motor neuron with
cell body in spinal cord have long axons that branch with target muscle

33
Q

How is synaptic nerve transmission terminated?

A

Large amount of acetylcholinesterase in muscle basement membrane

34
Q

What are the three types of muscle?

A

Skeletal, cardiac (heart), smooth (intestines, bladder)

35
Q

What is the basic function of muscles?

A

to generate force or movement in response to physiological stimulus

36
Q

Muscles turn a chemical or electrical command
into a ____ response.

A

mechanical

37
Q

What triggers muscle contraction?

A

rise in free cytosolic calcium concentration

38
Q

True/False: All muscle types have the same contraction trigger.

A

True

39
Q

What is sarcolemma and why is it important?

A

plasma membrane and it allows communication with muscle cels

40
Q

True/False: A single muscle cell responds to a single neuron, but, a single neuronal axon may bifurcate to
innervate several muscle cells (motor unit)

A

True

41
Q

What is the big muscle bundle broken down into?

A

myosin and actin

42
Q

What two myofilaments are responsible for contraction?

A

myosin and actin

43
Q

What happens during a muscle contraction?

A
  • Myosin heads bind to actin, forming cross bridges, then detach from actin
  • Energy is derived from ATP hydrolysis
  • Therefore needs to be regulated or myocyte
    would be depleted of ATP
  • In all 3 muscle types, ↑ Ca++ initiates and allows
    cross-bridges to continue
44
Q

Where is glycogen stored and what is it used for?

A

in muscle cells and can be used for energy

45
Q

Usually, the muscle uses ____ metabolism.

A

aerobic

46
Q

True/False: You body can function using anaerobic metabolism if you are lifting heavy weight.

A

True

47
Q

What chemical makes you feel sore after a workout?

A

lactate

48
Q

What do T-tubules do?*

A

Penetrate muscle at junctions of A and I bands (a highway that allows the calcium to go from the sarcoplasmic reticulum to the T-tubule and then go deeper into the muscle to provide calcium for muscle contraction)

49
Q

What is the sarcoplasmic reticulum?

A

Storage site of intracellular calcium

50
Q

How does excitation-contraction coupling work in skeletal muscles?

A
  • Action potential begins at motor end plate
  • Travels along cell membrane and down T-tubules
  • Depolarization of T-tubule activates voltage-gated
    L-type Ca++ channels
  • Ca++ released from sarcoplasmic reticulum
  • Activates troponin C which starts cross-bridge cycling
51
Q

How is ach inactivated?

A

by acetylcholinesterase (stops muscle activity)

52
Q

What fibers make up skeletal muscle?

A

slow and fast twitch fibers

53
Q

Describe slow-twitch fibers.

A
  • Smaller, thinner fibers, surrounded by capillaries to provide oxygen
  • Red due to ↑myoglobin to bind oxygen
  • Rely on oxidative metabolism for energy (low glycogen level)
  • Provide endurance for minutes to hours (quadriceps in marathoners)
54
Q

Describe fast-twitch fibers.

A
  • Abundant glycogen for rapid energy release by glycolytic pathway
  • Less mitochondria, less myoglobin, less extensive blood supply for oxygen
  • Give great amount of power for a few seconds to a minute or so
  • Gastrocnemius (calf muscle used in jumping), fatigue quickly
55
Q

Are slow twitch muscle fibers aerobic or anaerobic?

A

aerobic

56
Q

Are fast twitch muscle fibers aerobic or anaerobic?

A

anaerobic

57
Q

True/false: the amount of fast/slow twitch muscle fibers can change with training or age.

A

True

58
Q

Compare and Contrast slow and fast twitch muscle fibers.

A

Slow: oxidative (red muscle), small diameter, high myoglobin content, high capillary density, many mitochondria, low glycolytic enzyme content
Fast: Glycolytic (white muscle), large diameter, low myoglobin content, low capillary density, few mitochondria, high glycolytic enzyme content

59
Q

How can fast, slow and intermediate twitch be identified?

A

biopsy

60
Q

True/False: In any muscle there will be a mixture of slow and fast fibers.

A

True

61
Q

Motor units containing ___ fibers will be recruited first to power normal contractions.

A

slow

62
Q

___ fibers help out when particularly forceful contraction is required.

A

Fast

63
Q

All 3 muscle types terminate contraction through ____ re-uptake into sarcoplasmic reticulum

A

calcium

64
Q

How is calcium removed from the cytoplasm?

A

by either extruding
calcium across cell membrane or sequester within intracellular compartments
- Use Na-Ca exchanger or Calcium pump at plasma membrane
- Calcium re-uptake by SERCA-type calcium pump
- Voltage gates

Physiology for Engineers (15 decks)

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