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242 - 18 & 19 > 18 6-10 > Flashcards

18 6-10 Flashcards

1
Q

Trace the pathway of blood through the heart and vasculature. Start with the L ventricle.

A 
LV -- 
Aortic semilunar valve -- 
Aorta -- 
(systemic circ) -- 
Sup/inf vena cavae + Coronary sinus -- 
RA -- 
Tricuspid valve -- 
RV -- 
Pulmonary semilunar valve -- 
Pulmonary trunk -- 
Lungs -- 
Pulmonary veins -- 
LA -- 
Bicuspid/mitral valve
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2
Q

Left coronary artery

A

Runs towards the L side of the heart then branches into the:

anterior interventricular artery

circumflex artery.

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3
Q

Anterior interventricular artery

A

AKA left anterior decending artery - follows the anterior interventricular sulcus and supplies blood to the interventricular septum and anterior wall of both ventricles.

Known as the “widowmaker”

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4
Q

Circumflex artery

A

Supplies the left atrium and the posterior walls of the left ventricle.

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5
Q

Right coronary artery

A

Courses to the right side of the heart and gives rise to two branches:

Right marginal artery,

Posterior interventricular artery.

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6
Q

Right marginal artery

A

Serves the myocardium of the lateral right side of the heart

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7
Q

Posterior ventricular artery

A

Runs to heart apex and supplies the posterior ventricular walls. At apex, merges with the anterior interventricular artery.

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8
Q

R and L coronary arteries travel..?

A

Within the coronary sulcus and originate off the ascending aorta.

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9
Q

Adenosine?

A

A vasodilator. Can be released by the heart to open up coronary vessels.

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10
Q

What veins feed the coronary sinus?

A

Great cardiac, middle cardiac, small cardiac.

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11
Q

MI

A

Myocardial infarction, aka heart attack. Results from prolonged coronary blockage that leads to cell death.

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12
Q

Myocardial ischemia

A

Decrease in blood flow to the heart.

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13
Q

Angina pectoris

A

Thoracic pain caused by a fleeting deficiency in blood delivery to the myocardium.

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14
Q

AV valves

A

prevent backflow from the ventricles to atria. Relaxed heart = open

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15
Q

Semilunar valves

A

Prevent backflow into the ventricles from the arteries. Relaxed heart = closed

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16
Q

Skeletal vs. Cardiac

A

MECH OF CONTRACT Neurogenic Cardiac

INNERVATION SNS/Voluntary ANS/Involuntary

CALCIUM SR SR+ECF

HORMONE INFLUENCE — Yes-E/NE

SHAPE Long/cylindrical Short/branch

MITOCHONDRIA Few/2% of cell/Anaerobic+aerobic Many/25% of cell/aerobic

ATTACHMENT — Intercalated disc

NUCLEUS Multi-nucleated/Periphery
Uni-nucleated/centrally located

17
Q

How are cardiac and skeletal muscle similar?

A 
Use ATP, 
Actin/myosin, 
Sliding filament theory, 
sarcomeres, 
striated
18
Q

How are cardiac and smooth muscle similar?

A

Both have gap junctions

19
Q

What are the inercellular spaces of cardiac muscle filled with?

A

Loose connective tissue, endomysium.

It is connected to the fibrous cardiac skeleton which acts as a tendon and as an insertion giving cardiac cells something to pull or exert force against.

20
Q

Intercalated discs

A

Junctions that link cells together both mechanically and electrically by: desmosomes (physical bond, prevents adjacent cells from separating during contraction) and gap junctions (electrical - transmits current across heart).

These connections allow cardiac cells to act as a functional syncytium.

21
Q

Briefly describe the events of cardiac muscle cell contraction that are the same as skeletal muscle cell contraction.

A
  1. Depolarization, fast voltage gated Na+ channels open.
  2. Transmission of the depolarization wave down the T tubules (ultimately) causes the SR to release Ca2+ into the sarcoplasm.
  3. Excitation-contraction coupling occurs as Ca2+ (binding to troponin) signals for cross bridge activation and couples the depolarization wave to the sliding of the myofilaments.
22
Q

Briefly describe the events of cardiac muscle cell contraction that are unique to cardiac muscle.

A

Cardiac muscle is unique in the way the SR is stimulated to release Ca2+.

Ca2+ is barred from entering nonstimulated cells, but when Na+ dependent membrane depolarization occurs the voltage change also opens slow Ca2+ channels that allow Ca2+ to enter (10-20%). Once inside, it triggers the Ca2+ sensitive channels in the SR to release the other 80% of the Ca2+ that is needed.

23
Q

3 steps in the action potential of contractile cardiac muscle cells.

A
  1. Depolarization, fast voltage gated channels open.
  2. Plateau phase - Calcium influx through slow Ca2+ channels - cell remains depolarized even though Na+ channels are inactivated (few K+ channels are open yet).
  3. Repolarization - Ca2+ channels iactivate and K+ channels open.
24
Q

What is the significance of the plateau phase?

A

When the sodium channels have inactivated, and repolarization has started, Ca2+ surges in.

This prolongs depolarization and the cells continue to contract.

25
Q

What is the significance of the extended absolute refractory period?

A

Cardiac = 250ms, skeletal = 1-2ms. This prevents sustained tetany contraction in the heart which would stop the heart’s pumping action.

26
Q

Tetany

A

Sustained contraction

Continuous tonic spasm of a muscle; steady contraction of a muscle without distinct twitching.

27
Q

Ischemia

A

Reduced flood flow

28
Q

Hypoxia

A

Decreased oxygen

29
Q

Skeletal muscle are stimulated by a nerve ending, how are cardiac muscles stimulated?

A

Some cardiac cells are self excitable - they can initiate not only their own depolarization, but the rest of the heart as well. (in a spontaneous and rythmic way - automaticity or autorythmicity)

30
Q

Skeletal muscle operates in motor units, how does cardiac muscle operate?

A

As an organ rather than motor unit. Either all the muscles in the heart contract, or none of them do. Happens because of gap junctions - depolarization wave travels from cell to cell.

31
Q

functional syncytium

A

Behaving like a single coordinated unit - acting as a multi-nucleated mass - single functional unit.

32
Q

Intrinsic conduction system

A

Heart’s internal NS

Nodal cells establish and maintain RMP and conduct APs.

33
Q

Cardiac APs last for? Absolute refractory period for? Tension development?

A

Hundreds of ms, 250 ms, 200+ms

Skeletal is 1-2 ms, 1-2 ms, 15-100

242 - 18 & 19 (8 decks)

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