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HB2 Midterm > Week 1 > Flashcards

Week 1 Flashcards

1
Q

What makes up the epimysium?

A

tough, connective tissue

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2
Q

What is contained within the perimysium?

A

the arteries, veins, and nerves associated with skeletal muscle fibers

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3
Q

What covers the myofibrils?

A

the endomysium

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4
Q

What do muscle fascicles contain?

What do those contain?

A

muscle fibers

sarcolemma with T tubules, sarcoplasmic reticulum, multiple nuclei

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5
Q

What are the functional units of striated muscle and what do they contain?

A
  • sarcomeres

- thin filament (with actin and regulatory troponin and tropomyosin) and thick filaments (myosin)

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6
Q

What are Z discs?

A

where both actin and myosin bind to for structure

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7
Q

Where is the M line located?

A

the middle of the sarcomere

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8
Q

What is the I band?

A

areas of the sarcomere where only thin filaments are present

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9
Q

What is the A band?

A

where thick and thin filaments overlap, and is responsible for the dark striations on muscle

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10
Q

What is the H-zone?

A

the ‘bare zone’ where only myosin is located

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11
Q

Explain the process of cross-bridge cycling.

A
  1. system in rigor, with myosin head bound to actin
  2. ATP binds myosin, giving a conformational change and making myosin release from the actin
  3. ATP hydrolyzed to ADP and myosin head cocks forwards (towards the + end)
  4. P released and myosin binds to the actin (the power stroke)
  5. ADP is released and the system returns to rigor
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12
Q

What are the 3 sources of energy for muscle contraction?

A
  1. creatine~P
  2. glycogen
  3. FA in the presence of O2
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13
Q

What are type I muscle fibers aka?
Which pathway do they use?
What are the relative amounts of myoglobin, mitochondria, and glycogen?

A
  • slow twitch
  • aerobic pathways/oxidative
  • lots of myoglobin, lots of mitochondria, less glycogen
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14
Q

What are type II muscle fibers aka?
Which pathway do they use?
What are the relative amounts of myoglobin, mitochondria, and glycogen?

A
  • fast twitch
  • anaerobic/glycolytic
  • fewer mitochondria, abundant glycogen, fewer myoglobin
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15
Q

In an ATPase stain, how do the muscle fibers stain?

A
  • slow twitch are light tan

- fast twitch are dark brown

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16
Q

In an NADH stain, how do the muscle fibers stain?

A
  • slow twitch are darker

- fast twitch are lighter

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17
Q

Which type of muscle fiber has a higher rate of fatigability?

A

fast twitch/type II

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18
Q

Where does a large majority of the heart’s ATP come from?

A

free FA and aerobic metabolism

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19
Q

What is the cell membrane in a myocyte aka?

A

sarcolemma

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20
Q

What is the cytoplasm of a myocyte aka?

A

sarcoplasm

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21
Q

What is the ER of a myocyte aka?

A

the sarcoplasmic reticulum

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22
Q

How do cardiac myocytes attach to one another?

What does this contain?

A
  • intercalated discs

- desmosomes and gap junctions

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23
Q

What is the equation for osmolarity?

A

pi = Cg(RT)
C = molar solute concentration
g = van’t Hoff
add RT and convert to physical pressure

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24
Q

What does effective osmolarity depend on?
What is it?
What is it aka?

A
  • the reflection coefficient theta
  • the tendency for something to pass through a membrane and thereby reduce the effective osmotic gradient
  • tonicity
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25
Q

What is the reflection coefficient for things that do not permeate the membrane?
What is it for something that is freely permeable?

A

0

1

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26
Q

What is the equation for tonicity?

A

pi = theta x Cg(RT)

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27
Q

Where does water move?

A

a hypotonic solution has a smaller effective osmolarity than a cell, causing water to move into the cell

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28
Q

How do you calculate the clinical estimation of plasma osmolality?

A

P = 2[Na] + [glucose]/18 + [blood urea nitrogen]/2.8

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29
Q

What is definition of dehydration?

A

plasma Na levels over 145 mM/L

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30
Q

Where can you see an increase in the osmolal gap?

A

when there are solutes in the plasma that are usually not there, such as in alcohol poisoning

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31
Q

What are the narrowly controlled variables?

A

mean arterial pressure/BP, temperature, hematocrit, PO2, PCO2, pH, fasting glucose, osmolarity, [Na], [K], [Ca], [HCO3]

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32
Q

What is the usual comparator in the human body?
What does it do?
What is this an example of?

A
  • the CNS
  • it gets fed info from the sensor about controlled variables and figures out what to do to fix it
  • a negative feedback loop
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33
Q

What is the general value for hypotension?

A

90/60

34
Q

What is the general value for hypertension?

A

140/90

35
Q

What is the value for a fever?

A

100.4

36
Q

What ion is higher in the extracellular fluids- Na or K?

A

Na

37
Q

What ion is higher in the intracellular fluids- Na or K?

A

K

38
Q

Where are cell bodies for motor fibers located?

What kind of signals do they send?

A
  • anterior horn of the spinal cord

- efferent signals

39
Q

Where are cell bodies for sensory fibers located?

Where do they enter the spinal cord?

A
  • the dorsal root ganglion in the PNS

- the posterior root

40
Q

What nerves do posterior rami give rise to?

A

nerves that innervate the intrinsic muscles of the back and the skin overlying that region

41
Q

What nerves do anterior rami give rise to?

A

nerves that innervate the anterior and lateral trunk, as well as the extremities

42
Q

What are the dermatomes in the brachial plexus?

A

C5, C6, C7, C8, and T1

43
Q

What do free nerve endings mediate?

A

pain and temperature sensation

44
Q

Which things cross to the contralateral side just after entering the spinal cord?

A

pain and temperature

45
Q

Where is the T4 dermatome?

A

the level of the nipples

46
Q

Where is the T10 dermatome?

A

the level of the belly button

47
Q

What would a diminished knee jerk reaction tell you?

A

there is likely a problem with sensory fibers coming from the muscle or motor fibers going to the muscle

48
Q

What would an increased knee jerk reaction tell you?

A

likely a problem with the spinal cord or higher descending influences on the associated gamma motor neurons

49
Q

What are the branches of the aorta?

A
  1. brachiocephalic artery
  2. left common carotid artery
  3. left subclavian artery
50
Q

What responds to brain injury by dividing?

What is this aka?

A

astrocytes

gliosis

51
Q

What are the functions of astrocytes?

A
  • gliosis
  • end feet make barriers
  • structural support
  • metabolize some neurotransmitters
  • buffer electrolytes
52
Q

What do ependymal cells do?

A

line the ventricles and central canal in the brain

53
Q

What do microglia do?

A

enter the CNS from the vascular system and act as the major mechanism of immune defense

54
Q

What do oligodendrocytes do?

A

each one insulates many axons in the CNS

55
Q

What do Schwann cells do?

A

each one insulates only a portion of one axon in the PNS

56
Q

Explain the process of neuromuscular transmission.

A
  1. action potential in nerve reaches the end
  2. action potential triggers voltage-sensitive Ca channels, causing Ca to enter the cell because of the electrochemical graident
  3. Ca causes the pre-formed synaptic vessicles to exocytose their chemical message
  4. neurotransmitter reaches the receptor of the next cell, usually a GPCR or ligand-gated ion channel
  5. ion channel opened and Na flows in while K flows out down gradients
  6. depolarization of motor end plate and propagation of action potential in muscle
  7. neurotransmitter in the cleft gets removed, either by degradation or re-uptake
57
Q

What is NOT present in the motor end plate?

A

voltage-gated Na channels

58
Q

Describe skeletal muscle EC coupling.

A
  1. depolarization of the membrane
  2. voltage sensitive Ca channel has a conformational change
  3. the Ca channel (physically linked to the membrane with a foot protein) causes the SR Ca release channel (ryanodine receptor) to open
  4. Ca enters the cytoplasm and binds troponin C for cross-bridge cycling
  5. Ca transported back to the SR via the SR Ca ATPase pumps (Serca)
59
Q

Describe cardiac EC coupling.

A
  1. depolarization of the membrane
  2. voltage gated Ca channels open allowing influx of Ca
  3. Ca that entered binds to the SR Ca release channel (ryanodine receptor) [Ca induced Ca release!!!]
  4. Ca enters the cytoplasm and binds to troponin C for cross-bridge cycling
  5. Ca transported back to the SR via the SR Ca ATPase pumps (Serca)
60
Q

What is the difference between skeletal and cardiac EC coupling?

A

In cardiac muscle, Ca enters thru the channel.
In skeletal muscle, there is a foot protein in between the Ca channel and ryanodine receptor and that initiates Ca release .

61
Q

How can you remove Ca from the cytoplasm?

A
  1. SR Ca ATPase (Serca)
  2. Na/Ca exchanger
  3. sarcolemmal Ca ATPase
62
Q

What are the 2 ways to increase force in skeletal muscle?

A
  1. temporal summation of twitches (slowly increases the Ca concentration)
  2. recruitment of additional motor units
63
Q

What things do smooth muscles not have that are present in striated muscles?

A
  • no T tubules
  • no sarcomeres or striations
  • no troponin
  • involuntary
64
Q

In smooth muscle, what happens after intracellular Ca levels increase?

A

Ca binds to calmodulin. This increases activity of myosin light chain kinase (MLCK), which phosphorylates the myosin light chains. Myosin ATPase activity is increased leading to cross-bridge cycling and development of force

65
Q

What are the ways smooth muscle can be activated?

A
  1. depolarization from neuron at synapse
  2. hormones/neurotransmitters make IP3 to cause Ca release from SR
  3. hormones/neurotransmitters open ligand-gated Ca channels
66
Q

What does the endomysium surround?

A

the myofiber

67
Q

What surrounds the fasicle?

A

perimysium

68
Q

When you first apply stimulus to a muscle, what happens?

What is this aka?

A
  • there is force development but no change in length

- isometric contraction

69
Q

What does muscle shortening depend on?

A

whether you can overcome the tension or not

70
Q

How long does the isometric phase last?

A

until you can generate enough force to overcome the resistance

71
Q

What is muscle preload?

What does it determine?

A
  • the force applied to a relaxed muscle before stimulation

- resting length

72
Q

What determines passive force in skeletal muscles?

A

structural proteins associated with Z lines

73
Q

What determines passive force in cardiac muscles?

A

elastic forces

74
Q

Why is passive force in cardiac muscle important?

A

prevents overfilling or deformation of the heart

75
Q

What is the inital length of the cardiac muscle fibers synonymous with?

A

end diastolic volume

76
Q

What is the tension in cardiac muscle fibers synonymous with?

A

stroke volume

77
Q

What is afterload?

A

the load or resistance a muscle must contract against (the thing you are trying to lift)

78
Q

What is the aortic pressure?

A

the primary afterload that the normal heart must contract against to eject blood

79
Q

What is afterload called in the heart?

How do you calculate it?

A

-wall stress

P (ventricular pressure) x r (radius of the ventricle)/thickness of ventricular wall

80
Q

What is another term for contractility when speaking about heart muscles?

A

ionotropy

81
Q

Explain the concept of contractility.

A

In cardiac muscles, the Ca concentration determines the strength of contraction, not the length of the sarcomere

HB2 Midterm (5 decks)

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