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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
What is the cardiac skeleton made up of?
dense irregular connective tissue; fibrous rings, fibrous triangles, and fibrous IV septum
26
What are the fibrous rings made up of?
collagen bundles mingled with elastin
27
What are the fibrous triangles made up of and where are they located?
connective tissue located between atrioventricular valve openings and the base of the aorta
28
What is the fibrous IV septum made up of?
collagen fibers
29
What is a myocyte?
a cardiac muscle cell
30
What is a myofiber?
a bundle of myocytes
31
What are myofibrils?
bundle of contractile proteins (actin and myosin)
32
What is the sarcomere?
the functional unit of a myocyte from Z-line to Z-line
33
What is the sarcolemma?
the cell membrane of a myocardial structure
34
What is the function of the sarcolemma?
maintains ion gradients
35
What is the sarcolemma impermeable to and selectively permeable to?
impermeable to Na and Ca, selectively permeable to K
36
How to ions move across the sarcolemma?
by some type of carrier which depends on the electrical driving force and concentration gradient
37
What is a t-tubule?
invaginations of the sarcolemma into the cell
38
What do t-tubules contain?
extracellular fluid
39
What is the function of t-tubules?
they allow rapid conduction of impulses to activate contractile elements
40
What does the sarcoplasmic reticulum do?
it regulates intracellular calcium movement it is for Ca storage and release
41
What is the cisterna of the sarcoplasmic reticulum?
the communication unit of the sarcoplasmic reticulum to receive electrical signals coming from the t-tubules
42
What type of junctions are in an intercalated disc?
gap junctions, desmosomes, and fascia adherens
43
What is the function of gap junctions in intercalated discs?
they allow the transfer of chemical signals between cells
44
What is the function of desmosomes in intercalated discs?
their filaments extend into the cytoplasm and attach cells together
45
Where are the actin filaments of the myocardial structure anchored?
in the fascia adherens
46
What are chordae tendinae made out of?
collagen and elastic fibers covered with endothelium
47
What is the function of chordae tendinae?
they arise from papillary muscles to secure cusps to the septal wall to prevent aversion of the valves
48
What are the components of the right atrium?
vena cavae, coronary sinus, azygous vein, auricle with pectinate muscles, interatrial septum, fossa ovalis
49
What are the components of the right ventricle?
tricuspid valve, fibrous skeleton, papillary muscles, trabeculae carneae, moderator band, supraventricular crest, infundibulum, outflow tract area, pulmonic valve, main pulmonary artery
50
What are the components of the left atrium?
Pulmonary veins, auricle with petinate muscles
51
What are the components of the left ventricle?
Shape and relative wall thickness, left A-V or mitral apparatus, papillary muscles, interventricular septum
52
What are the components of the aorta?
Aortic valve with sinuses of valsava, coronary ostia, origin, ascends to right, arches to left and descends left of midline
53
What are the components of the coronary arteries?
Right – distribution varies with species; left – circumflex and interventricular branches
54
Where is the sinoatrial node located?
in the right atria where impulses are originated
55
What is the SA node known as?
the cardiac pacemaker
56
What does the SA node determine?
heart rate
57
Where is the atrioventricular node located?
between the right atria and right ventricle
58
What is the function of the AV node?
it allows ventricles to fill
59
What is the function of the bundle of his?
to send the electrical impulse from the AV node to the interventricular septum
60
What is the function of the purkinje system?
enhance rapid conduction and allow for synchronous contraction of the ventricles
61
What maintains the normal resting potential of the cardiac cell membrane?
passive outward current, Na/K ATPase pump
62
When does equilibrium of the cardiac cell membrane occur?
when chemical concentration gradient is pulling K out and the electrical force is holding K in
63
What defines the electrochemical gradient for K?
the Nernst equation
64
What does is the Nernst equation?
defines the relation between ion concentration gradient and membrane potential forces
65
What is the function of Na and Ca membrane channels?
Na and Ca must enter rapidly for normal depolarization
66
What happens to the membrane as it depolarizes?
it becomes less negative
67
What is this diagram representative of?
The fast response action potential of a myocyte
68
What is happening in phase 0?
activation of the myocyte via the action potential; Na moves in
69
What is happening in phase 1?
a brief period of overshoot and repolarization, Ca moves into the cell
70
What is happening in phase 2?
Ca stops entering the cell, the plateau of action potential
71
What is happening in phase 3?
K moves out of the cell and repolarization begins
72
What is repolarization of the myocyte in the fast response action potential controlled by?
K leaking out and Na/K ATPase pump
73
What is happening in phase 4?
the myocyte has returned to resting action potential
74
What is this diagram showing?
the slow response action potential
75
What is happening in phase 0?
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
What is happening in phase 2?
k channels opening, more K leaving, makes cell more negative, repolarization
77
What is happening in phase 3?
Ca channels closing, no positives Ca entering, makes cell negative, repolarization
78
What is happening in phase 4?
Spontaneous diastolic depolarization; Ca comes in to bring more Ca in

Histology (36 decks)

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