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Histology > Unit 4 - Cardiac properties, structure, and electrical activation > Flashcards

Unit 4 - Cardiac properties, structure, and electrical activation Flashcards

1
Q

What are the layers of the heart?

A

epicardium, myocardium, and endocardium

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2
Q

What is the structure of the epicardium?

A

a serous layer of mesothelial cells that line the pericardial cavity with a loose connective tissue layer underneath

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3
Q

What is the loose connective tissue layer of the epicardium made up of?

A

elastic fibers, blood vessels, nerves, and ganglia fat cells

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4
Q

What is the myocardium?

A

cardiac muscle

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5
Q

What is the myocardium made up of?

A

bundles of cardiac muscle cells with a central nucleus and intercalated discs

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6
Q

What is the function of intercalated discs?

A

they join the ends of myocardial cells together

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7
Q

What are mycardial cells surrounded by?

A

a network of connective tissue with a dense capillary network, lymphatic vessels and autonomic nerve fibers

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8
Q

What is the endocardium?

A

endothelium that lines the ventricles and atria

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9
Q

What are the three layers of the endocardium?

A

endothelium (continuous), subendothelial layer, and subendocardium

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10
Q

What is the supendothelial layer of the endocardium made up of?

A

dense irregular connective tissue

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11
Q

What is the subendocardium layer of the endocardium made up of?

A

loose collagen and elastic fibers, blood and lymph vessels, can have fat cells, and conduction system fibers in some areas

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12
Q

What type of structures are valves and what are they made up of?

A

endocardial structures made up of subendocardial folds with an endothelial cover

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13
Q

What do valves connect to?

A

the cardiac skeleton

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14
Q

What is the atrial side of the atrioventricular valves called (histologically)?

A

stratum spongiosum

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15
Q

What is stratum spongiosum made up of?

A

loose elastic and collagen and small vessels

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16
Q

What is the ventricular side of atrioventricular valves called (histologically)?

A

Stratum fibrosum

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17
Q

What is the stratum fibrosum made up of?

A

mostly collagen

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18
Q

What does the stratum fibrosum connect with?

A

fibrous rings and chordae tendinae

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19
Q

What is the histoological structure of the semilunar valves?

A

circular orientation - central collagen fibers

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20
Q

Where is the SA node located?

A

near the cranial vena cava and right auricle

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21
Q

Where is the AV node located?

A

on the right side of ventral inner atrial septum ventral to the coronary sinus

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22
Q

What are SA nodes and AV nodes made up of?

A

thin branching muscle cells with few myofibrils and no intercalated discs

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23
Q

What is another name for the fibrous base?

A

the cardiac skeleton

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24
Q

What is the function of the cardiac skeleton?

A

the insertion site of atrial and ventricular muscle fibers, the attachment site of cardiac valves, and separates atria and ventricles

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25
Q

What is the cardiac skeleton made up of?

A

dense irregular connective tissue; fibrous rings, fibrous triangles, and fibrous IV septum

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26
Q

What are the fibrous rings made up of?

A

collagen bundles mingled with elastin

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27
Q

What are the fibrous triangles made up of and where are they located?

A

connective tissue located between atrioventricular valve openings and the base of the aorta

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28
Q

What is the fibrous IV septum made up of?

A

collagen fibers

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29
Q

What is a myocyte?

A

a cardiac muscle cell

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30
Q

What is a myofiber?

A

a bundle of myocytes

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31
Q

What are myofibrils?

A

bundle of contractile proteins (actin and myosin)

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32
Q

What is the sarcomere?

A

the functional unit of a myocyte from Z-line to Z-line

33
Q

What is the sarcolemma?

A

the cell membrane of a myocardial structure

34
Q

What is the function of the sarcolemma?

A

maintains ion gradients

35
Q

What is the sarcolemma impermeable to and selectively permeable to?

A

impermeable to Na and Ca, selectively permeable to K

36
Q

How to ions move across the sarcolemma?

A

by some type of carrier which depends on the electrical driving force and concentration gradient

37
Q

What is a t-tubule?

A

invaginations of the sarcolemma into the cell

38
Q

What do t-tubules contain?

A

extracellular fluid

39
Q

What is the function of t-tubules?

A

they allow rapid conduction of impulses to activate contractile elements

40
Q

What does the sarcoplasmic reticulum do?

A

it regulates intracellular calcium movement it is for Ca storage and release

41
Q

What is the cisterna of the sarcoplasmic reticulum?

A

the communication unit of the sarcoplasmic reticulum to receive electrical signals coming from the t-tubules

42
Q

What type of junctions are in an intercalated disc?

A

gap junctions, desmosomes, and fascia adherens

43
Q

What is the function of gap junctions in intercalated discs?

A

they allow the transfer of chemical signals between cells

44
Q

What is the function of desmosomes in intercalated discs?

A

their filaments extend into the cytoplasm and attach cells together

45
Q

Where are the actin filaments of the myocardial structure anchored?

A

in the fascia adherens

46
Q

What are chordae tendinae made out of?

A

collagen and elastic fibers covered with endothelium

47
Q

What is the function of chordae tendinae?

A

they arise from papillary muscles to secure cusps to the septal wall to prevent aversion of the valves

48
Q

What are the components of the right atrium?

A

vena cavae, coronary sinus, azygous vein, auricle with pectinate muscles, interatrial septum, fossa ovalis

49
Q

What are the components of the right ventricle?

A

tricuspid valve, fibrous skeleton, papillary muscles, trabeculae carneae, moderator band, supraventricular crest, infundibulum, outflow tract area, pulmonic valve, main pulmonary artery

50
Q

What are the components of the left atrium?

A

Pulmonary veins, auricle with petinate muscles

51
Q

What are the components of the left ventricle?

A

Shape and relative wall thickness, left A-V or mitral apparatus, papillary muscles, interventricular septum

52
Q

What are the components of the aorta?

A

Aortic valve with sinuses of valsava, coronary ostia, origin, ascends to right, arches to left and descends left of midline

53
Q

What are the components of the coronary arteries?

A

Right – distribution varies with species; left – circumflex and interventricular branches

54
Q

Where is the sinoatrial node located?

A

in the right atria where impulses are originated

55
Q

What is the SA node known as?

A

the cardiac pacemaker

56
Q

What does the SA node determine?

A

heart rate

57
Q

Where is the atrioventricular node located?

A

between the right atria and right ventricle

58
Q

What is the function of the AV node?

A

it allows ventricles to fill

59
Q

What is the function of the bundle of his?

A

to send the electrical impulse from the AV node to the interventricular septum

60
Q

What is the function of the purkinje system?

A

enhance rapid conduction and allow for synchronous contraction of the ventricles

61
Q

What maintains the normal resting potential of the cardiac cell membrane?

A

passive outward current, Na/K ATPase pump

62
Q

When does equilibrium of the cardiac cell membrane occur?

A

when chemical concentration gradient is pulling K out and the electrical force is holding K in

63
Q

What defines the electrochemical gradient for K?

A

the Nernst equation

64
Q

What does is the Nernst equation?

A

defines the relation between ion concentration gradient and membrane potential forces

65
Q

What is the function of Na and Ca membrane channels?

A

Na and Ca must enter rapidly for normal depolarization

66
Q

What happens to the membrane as it depolarizes?

A

it becomes less negative

67
Q

What is this diagram representative of?

A

The fast response action potential of a myocyte

68
Q

What is happening in phase 0?

A

activation of the myocyte via the action potential; Na moves in

69
Q

What is happening in phase 1?

A

a brief period of overshoot and repolarization, Ca moves into the cell

70
Q

What is happening in phase 2?

A

Ca stops entering the cell, the plateau of action potential

71
Q

What is happening in phase 3?

A

K moves out of the cell and repolarization begins

72
Q

What is repolarization of the myocyte in the fast response action potential controlled by?

A

K leaking out and Na/K ATPase pump

73
Q

What is happening in phase 4?

A

the myocyte has returned to resting action potential

74
Q

What is this diagram showing?

A

the slow response action potential

75
Q

What is happening in phase 0?

A

Slow depolarization of the cell, action potential is generated, slower than fast response because Ca is mediating the process; 3 Ca in, 1 K out

76
Q

What is happening in phase 2?

A

k channels opening, more K leaving, makes cell more negative, repolarization

77
Q

What is happening in phase 3?

A

Ca channels closing, no positives Ca entering, makes cell negative, repolarization

78
Q

What is happening in phase 4?

A

Spontaneous diastolic depolarization; Ca comes in to bring more Ca in

Histology (36 decks)

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