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BISC306 > Exam 2 > Flashcards

Exam 2 Flashcards

1
Q

The type of muscle fibers that have only a single nucleus, both thick and thin filaments, but no Z discs, are:

a. Skeletal only
b. Cardiac only
c. Smooth only
d. Skeletal and cardiac
e. Smooth and cardiac
f. Skeletal and smooth
g. All three

A

c. Smooth only

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2
Q

One of the reasons you might struggle to lift a heavy object if you tried to lift it with your arm at a fully extended posture is that:

a. In extension, the proximity of Z discs to thick filaments restricts the sliding movement within sarcomeres
b. Full extension results in decreased overlap between thick and thin filaments in the muscle
c. Motor neurons cannot release as much ACh in that posture
d. In that posture, some myosin heads overlap actin in the wrong orientation and tug actin in the wrong direction

A

b. Full extension results in decreased overlap between thick and thin filaments in the muscle

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2
Q

Which sequence correctly lists the changes that allow the thick and thin filaments to slide past one another in skeletal muscle contraction?

a. Attach - pivot - detach - return
b. Pivot - attach - return - detach
c. Attach - detach - pivot - return
d. Return - pivot - attach - return
e. Pivot - attach - detach - return

A

a. Attach - pivot - detach - return

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2
Q

ack & Jill ran up the hill…… Jill’s legs are primarily of fast glycolytic (white) type, while Jack’s are of slow oxidative type (red). Assuming everything else is the same, which one would utilize the most oxygen during the run?

Jack
Jill
Both the same

A

Jack

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3
Q

Which interval would not shrink during shortening of the muscle?

H Zone
A Band
I Band
T Zone

A

A band

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4
Q

T or F: Thin filament is an ATPAse

A

False

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5
Q

Curare is an inhibitory of acetylcholine receptors at the motor end plate. This would result in:

Lack of calcium uptake by the muscle fiber
More acetylcholinesterase production
Inability of the muscle fiber to respond to nervous stimulation
Sustained contraction of the muscle
Increased stimulation of the muscle

A

Inability of the muscle fiber to respond to nervous stimulation

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6
Q

Give the correct sequence of events following the depolarization of transverse tubules in excitation-coupling in cardiac muscle. (1) calcium ion influx through sarcolemma. (2) Thin myofilament slide toward the middle of sarcomeres. (3) Calcium release into sarcoplasm. (4) Actin and myosin attach

1, 3, 4, 2
2, 4, 3, 1
3, 2, 4, 1
2, 1, 3, 4
1, 2, 3, 4

A

1, 3, 4, 2

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7
Q

The power stroke begins when

The actin is attached to the myosin head
The ATP is hydrolyzed by the myosin head
The inorganic phosphate and ADP are released from the myosin
The actin is released by the myosin head

A

The inorganic phosphate and ADP are released from the myosin

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7
Q

Events of excitation contraction coupling, such as the release of calcium from intracellular stores, occur during the period of a muscle twitch

Relaxation
Contraction
Active
Quiescent
Latent

A

Latent

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8
Q

Trace the pathway of deoxygenated blood through the chambers of the heart and circulatory system

A

Vena Cava → Right Atrium → Tricuspid Valve → Right Ventricle → Pulmonary Semilunar Valve → Pulmonary Artery

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9
Q

Which of the following is not a usual result of resistance exercise?

Increase in the efficiency of the respiratory system
Increase in the number of myofibrils within the muscle cells
Increase in the efficiency of the circulatory system
Increase in the number of muscle cells

A

Increase in the number of muscle cells

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10
Q

Summarize the events of the cardiac cycle

A

Artial systole
Completion of ventricle filling
Ventricular systole
Closure of AV valves
Isovolumic contraction
Semilunar valves open
Ventricular ejection
Ventricular relaxation

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11
Q

Trace the pathway of oxygenated blood through the chambers of the heart and circulatory system

A

Pulmonary Circulation → Pulmonary Vein → Left Atrium → Bicuspid Valve → Left Ventricle → Aortic Semilunar Valve → Aorta → Systemic Circulation

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12
Q

Predict the effects of a reduced contractile force of the heart on the duration of the isovolumic contraction phase of the cardiac cycle.

Longer
Shorter
No Change

A

Longer

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13
Q

What would be the effects of hypertension on the duration of the isovolumic contraction phase?

Longer
Shorter
No Change

A

Shorter

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14
Q

Which region of the ECG reflects the plateau phase of ventricular muscle cells’ action potentials?

P-T segment
P-R interval
Q-R segment
S-T segment
T-P interval

A

S-T segment

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15
Q

Ventricular contraction

Begins just after the T wave
Begins just after the Q (of the QRS)
Begins during the first part of the P wave
Begins during the latter part of the P wave
None of these are correct

A

Begins just after the Q (of the QRS)

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15
Q

Which of the following statements regarding the cardiac cycle is correct?

The aortic valve is open during isovolumetric ventricular contraction
The first heart sound is the closing of the semilunar valves
During isovolumetric ventricular relaxation, blood flows from the atria into the ventricles
The atrioventricular valves are open during mid-to-late diastole
The volume of blood leaving the left side of the heart is greater than that leaving the right side

A

The atrioventricular valves are open during mid-to-late diastole

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16
Q

In which situation would the stroke volume be the greatest?

When calcium channel blockers are present
When the force of contraction is decreased
When the venous return is decreased
When the difference between end-diastolic volume and the end-systolic volume is small
When venous return is increased

A

When venous return is increased

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16
Q

Put the phases of the cardiac cycle in the correct order: A. ventricular relaxation; B. opening of semilunar valves; C. start of ventricular systole; D. isovolumetric contraction; E. closure of AV valves; F. completion of ventricular filling; G. ventricular ejection; H. start of atrial systole

A,C,E,D,F,G,H,B
B,C,A,E,F,G,H,D
H,F,C,E,D,B,G,A
B,F,H,C,E,D,G,A

A

H,F,C,E,D,B,G,A

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17
Q

The plateau phase of the action potential in ventricular myocytes results from the opening of voltage-gated _ channels in the plasma membrane of the cell

A

Calcium

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18
Q

T or F: Cardiac muscle cannot undergo tetanus because its absolute refractory period lasts almost as long as the muscle twitch

A

T

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19
Q

If the membranes of the cardiac muscle cells in the SA Node become more permeable to potassium ions,

The membrane will depolarize
The heart rate will increase
The stroke volume will increase
The intracellular concentration of calcium ions will increase
The heart rate will decrease

A

The heart rate will decrease

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20
A 65-yo patient w/hypertension is prescribed a β-adrenergic receptor blocker. Shortly after starting the medication, the patient reports fatigue and reduced exercise tolerance. Which of the following best explains how β-blockers reduce cardiac output? Blockade of β-adrenergic receptors leads to vasodilation, reducing venous return and thereby lowering cardiac output. Inhibition of β-adrenergic receptors decreases myocardial contractility and heart rate, reducing stroke volume and cardiac output. Β-blockers inhibit calcium influx into cardiac myocytes, preventing depolarization and leading to reduced cardiac output. Activation of parasympathetic pathways compensates for β-blocker effects, directly reducing cardiac output.
Inhibition of β-adrenergic receptors decreases myocardial contractility and heart rate, reducing stroke volume and cardiac output.
21
Which are characteristics of type A blood? a: has anti-A antibodies b: has anti-B antibodies c: has surface antigen A on its erythrocytes d: has surface antigen B on its erythrocytes e: has neither surface antigen A nor B on its erythrocytes f: will agglutinate when mixed with type B blood b, c, d, f a, c, d, f a, d, f b, c, f a, c, f
b, c, f
22
Give the formula for net filtration pressure: (HP = hydrostatic pressure. COP = colloid osmotic pressure. b = blood. if = interstitial fluid): NFP = (HPb + HPif) + (COPb + COPif) NFP = (HPif + HPb) - (COPif + COPb) NFP = (HPb - HPif) - (COPb - COPif) NFP = (HPif - HPb) - (COPb - COPif)
NFP = (HPb - HPif) - (COPb - COPif)
23
As blood moves from the arterial end to the venous end of a capillary, net filtration pressure: Decreases, as blood hydrostatic pressure decreases Increases, as blood hydrostatic pressure rises Decreases, as blood colloid osmotic pressure decreases Remains the same, as rises in blood osmotic pressure are offset by declines in tissue osmotic pressure
Decreases, as blood hydrostatic pressure decreases
24
Normally, the hydrostatic pressure difference between capillary fluid and interstitial fluid favors movement of fluid ______ the capillary. The osmotic pressure difference between capillary fluid and interstitial fluid favors movement of fluid ______ the capillary.
Out of, into
25
Atherosclerosis (fat build-up in artery walls, which narrows the arteries) involves a Sustained increase in blood flow that leads to decreases in venous resistance to keep blood pressure constant Sustained decrease in resistance that leads to decreases in arterial pressure to maintain adequate blood flow Sustained decrease in blood flow that leads to increases in arterial diameter to lower resistance and raise pressure Sustained increase in blood pressure that leads to compensatory vasodilation Sustained increase in resistance that leads to increases in arterial pressure to maintain adequate blood flow
Sustained increase in resistance that leads to increases in arterial pressure to maintain adequate blood flow
26
Which of the following changes would most increase the resistance to blood flow in a blood vessel? Doubling the diameter of the vessel Halving the length of the vessel Doubling the length of the vessel Decreasing the hematocrit (measure of red blood cell levels) from 50% to 40% Halving the diameter of the vessel
Halving the diameter of the vessel
27
The force per unit area that blood places on the inside wall of a blood vessel Increases the further the vessel is from the heart Is called the blood pressure Is called the pulse Is greater during diastole
Is called the blood pressure
28
If someone’s blood pressure were listed as 110/65 mmHg, then their mean arterial pressure (MAP) would be (in mmHg) 95 60 80 120 143
80
29
If someone’s blood pressure were listed as 125/75 mmHg, then their pulse pressure would be (in mmHg): 20 40 75 80 50
50
30
Functions of muscle
Movement Stability Protection/support Storage Heat production
31
Why are skeletal muscles multi nuclealted?
Fusing multiple cells together during development
32
Characteristics of skeletal muscle
Thin and thin filaments Sarcomeres in banding pattern Fast-slow contraction
33
Characteristics of smooth muscle
Thin and thin filaments Very slow contraction
34
Characteristics of cardiac muscle
Thin and thin filaments Sarcomeres in banding pattern Slow contraction
35
Fascicles
Thousand of long muscle long cells organized into bundles
35
Why are multi-nucleated cells important?
Metabolic needs are very high and having a multi-nucleated cell helps with ATP production
36
Myoblasts
Embryonic cells which fuse to form singular muscle fibers each contributing a nucleus to a total nuclei system
37
Satelite cells
Myoblasts remaining unfused in adults Can be used to see if tissue damaged
38
Myofibrils
Cables throughout cell compose 80% of muscle fiber volume
39
Myofilaments
Bundles of protein filaments, thin and thin
40
Steps in excitation-contraction coupling
No Dad Vapes And Drinks Cause Twin Towers Collapsed nAChR opens so sodum influx Deplorization reachs threshold Voltage-gated Na Channels open Action potential transmitted to t-tubules Depolrization to Ca channels Calcium influx triggers more calcium efflux Troponin binds to calcium Tropomyosin is moved, exposing binding sites Cross-bridge between actin and myosin are formed
41
Summarize the changes that occur within a sarcomere during contraction Initiation:
Process begins when Ca2+ are released into sarcoplasm. These Ca2+ ions bind to troponin, causing a conformational change in the troponin-tropomyosin complex. This movement exposes the myosin-binding sites on the actin (thin) filaments
42
Cross-bridge formation
Binding sites exposed, the myosin heads can now bind to the actin filaments, forming cross-bridges. Binding occurs ADP and inorganic phosphate are still bound to myosin head
43
Summarize the changes that occur within a sarcomere during contraction
I Can't Peg Dinky Really Rough Initiation Cross-bridge formation Power strike Detachment Recocking mysoin head Repetition of cycle
44
Power stroke
Pi is released, so stronger attachment between myosin and actin. The myosin head then pivots toward the center of the sarcomere, pulling the myosin. This movement is called the power stroke Causes the thin filaments to slide past the thick filaments. ADP is also released
45
Detachment
A new molecule of ATP binds to the myosin head, causing the cross-bridge to detach from the actin
46
Re-cocking of myosin head
The myosin head then hydrolyzes the ATP into ADP and Pi, releasing energy. This energy is used to return the myosin head to its “cocked” position
47
Repetition of the cycle
As long as Ca2+ and ATP is available, cycle continues
48
Z-discs
Actin filaments are anchored, move closer together as they're pulled towards the center of the sarcomere
49
I band
Contains only thin filaments, becomes smaller as the filaments slide further into the A band
50
A band
Contains the entire length of the thick filaments, remains the same width
51
H zone
Region in the center of the A band that contains only thick filaments, becomes smaller and may disappear completely as the thin filaments slide over and overlap more with the thick filaments
52
Explain the length-tension relationship in skeletal muscle contraction
Length-tension relationship: the amount of active tension a muscle fiber develops during contraction can also be altered by changing the length of fiber
53
What is the optimal length of a muscle?
Length at which the fiber develops the greatest isometric active tension
54
Isometric contraction
Muscle tension insufficient to overcome resistance Contraction of muscle and increased tension Muscle length the same E.g., pushing on a wall
55
Isotonic contraction
Muscle tension able to overcome resistance Results in movement Tone same but length changes E.g., swinging a tennis racket
56
Concentric contraction, subtype
Muscle shortens at it contracts E.g., in the biceps brachii when lifting a load
57
Define muscle fatigue
When a skeletal muscle fiber is repeatedly stimulated, the tension the fiber develops eventually decreases even though the stimulation continues
58
Eccentric contraction, subtype
Muscle lengthens as it contracts E.g., in the biceps brachii when lowering a load
59
Causes of muscle fatigue
Decreases in ATP concentration, increase in concentrations of ADP, Pi, Mg2+ , H+ and oxygen free radicals
60
Define the refractory period
Period after an action potential when the heart cells are unable to fire another action potential Ensuring a steady heart rhythm and preventing overstimulation
61
Inotropic factors
Affect strength of contraction
62
Chronotropic factors
Affect rate contraction
63
MAP = ?
diastolic + [(systolic - diastolic)/3]
63
We spend _____ time at diastiole than systole in the heart in general.
More
64
If the artrials are in systole, that means the ventricles are at the end of the ______
Diastole
65
Once the area depolarize, the next step is to _____
Contract (ie atrial systole)
66
QRS shows us
Atrial depolarization and at the same time, the ventricles polarize
67
Right before the P wave marker, you would expect the SA node to
Depolarize
68
Capillary hydrostatic pressure (CHP):
force exerted by the blood confined within blood vessels against the wall of a capillary
69
Blood colloid osmotic pressure (BCOP)
Pressure created by the concentration of colloidal proteins (primarily plasma proteins) in the blood
70
Net filtration pressure
Net effect of these opposing pressures and determines the direction of fluid movement
71
Higher CHP than BCOP results in a ____ NFP
Positive
72
BCOP promotes reabsorption - a higher BCOP than CHP results in a ______ NFP
Negative
73
Oxidative fibers
Use aerobic cellular respiration Allow to continue contracting for long periods Also called fatigue-resistant Extensive capillaries Large numbers of mitochondria
74
Glycolytic fibers
Use anaerobic cellular respiration Large glycogen reserves for anaerobic respiration Tire easily after short time of sustained activity Also termed fatigable
75
Describe the spread of the action potential through the heart’s conduction system
An action potential is generated at the sinoatrial (SA) node. It spreads via gap junctions between cardiac muscle cells throughout the atria to the atrioventricular (AV) nod
76
Summarize the changes that occur within a sarcomere during contraction
76
types of capilaries
continous fenestrated discontinous

BISC306 (2 decks)

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