Heart Flashcards

1
Q

What muscle is the primary component of the myocardium?

A

cardiac muscle

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2
Q

What does the myocardium form? What is it composed of?

A
  • composed of cardiac muscle
  • forms the middle layer of the heart wall
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3
Q

How are cardiac muscle fibers arranged in the middle layer of the heart wall?

A

spiral pattern

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4
Q

What is the function of cardiac muscle cells? What do they produce? State an example.

A

produce hormones (eg. atrial natriuretic peptide) –> regulate blood pressure and electrolyte balance

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5
Q

What is the function of the hormones released by cardiac muscle cells? State their process of working.

A

hormones (eg. atrial natriuretic peptide) are released by cardiac muscle cells into cardiac capillaries.
influence blood pressure and electrolyte balance.

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6
Q

Where is myocardium thickest?

A

left ventricle

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7
Q

Where is myocardium thinnest?

A

atria

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8
Q

What are the three layers of the heart?

A
  • epicardium
  • myocardium
  • endocardium
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9
Q

What is the endocardium? What is it continuous with?

A
  • the inner layer of the heart
  • continuous with the tunica interna of the blood vessels that enter and exit the 4 heart chambers
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10
Q

What is the endocardium composed of?

A

lining of endothelium supported by:
- inner dense subendothelial layers of connective tissue
- outer loose subendothelial layers of connective tissue

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11
Q

Where is the endocardium thicker?

A

Endocardium of the atria is thicker than the endocardium of the ventricles.

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12
Q

What is “endocardium” of the heart similar to in other organs?

A

tunica mucosa

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13
Q

What is “myocardium” of the heart similar to in other organs?

A

tunica muscularis

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14
Q

What is “epicardium” of the heart similar to in other organs?

A

serosa

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15
Q

Why do we have specific names for the layers of the heart?

A

the heart is a special organ, therefore it has its own names.

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16
Q

What does the endocardium have?

A

“tunica mucosa”
1) epithelium: called “endothelium”- simple squamous epithelium lining all circulatory system organs.

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17
Q

What is the epithelium covering all circulatory system organs?

A

endothelium- simple squamous epithelium

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18
Q

What is located beneath the endothelium?

A

2 layers of connective tissue:

1) dense irregular connective tissue (like “lamina propria”
2) loose connective tissue

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19
Q

What is cardiac muscle tissue composed of?

A

cardiac muscle cells!
- cylindrical shaped cells
- centered nucleus
- intercallated disks (integrations between adjacent cells= high proportion of cell junctions= hold cells tightly bound)

CELLS NOT FIBERS!

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20
Q

Why can one NOT call cardiac muscle cells “fibers”?

A

“fibers” are features of skeletal muscle tissue, not cardiac!

**skeletal muscle tissue: **
- very long cells=fibers
- border nucleus

cardiac muscle tissue:
- cylinder shaped cell
- centered nucleus
- intercallated discs (integrations between adjacent cells= high proportion of cell junctions= hold cells tightly bound)

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21
Q

What system do cardiac muscle cells work as?

A

endocrine system cells
(they secrete hormones to regulate blood pressure)

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22
Q

What is the final layer of the heart?

A
  • dense connective tissue
  • pericardium (epithelial covering)
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23
Q

What is the pericardium?

A

an epithelial lining of the heart (surrounding the dense connective tissue)

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24
Q

What does the pericardial cavity seperate?

A

the parietal and visceral layers of the pericardium

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25
Q

What does the pericardial cavity contain?

A

small quantity of pericardial fluid

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26
Q

What are the different layers of the pericardium?

A
  • visceral seous layer
  • parietal serous layer
  • fibrous layer
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27
Q

What is the epicardium?

A

the visceral serous pericardium

28
Q

What is the visceral serous pericardium?

A
  • the outer layer of the heart wall
  • continuous with the parietal serous pericardium at the base of the heart
29
Q

Where is the visceral serous pericardium continuous with the parietal serous pericardium?

A
  • at the base of the heart
  • on the inner surface of the pericardial sac
30
Q

State the position of the visceral and parietal serous pericardium layers.

A

visceral- ‘connected to’ the heart center
parietal- ‘connected’ to teh heart outer layer, after the cavity

31
Q

What is the fibrous pericardium composed of?

A

dense connective tissue

32
Q

State the composition and position of the fibrous pericardium.

A
  • dense connective tissue layer
  • lies beneath the mesothelial cells of the parietal serous pericardium
33
Q

How many layers does the pericardium have? What are they? What are they based on?

A

3 layers (1 fibrous and 2 serous):
fibrous layer- dense irregular connective tissue
parietal serous layer- serosa: mesothelial cells (simple quamous epithelium)
- attached to the fibrous layer
visceral serous layer- serosa: mesothelial cells (simple squamous epithelium)
- attached to the heart itself, also known as ‘epicardium’

34
Q

What makes up the pericardial sac?

A

fibrous pericardial layer and parietal serous pericardial layer

35
Q

What is the “epicardium”? (another name)

A

another name for the visceral serous layer of the heart

36
Q

What are the two names of the outside section of the heart organ itself?

A
  • visceral layer part of the pericardium (whole)
  • epicardium (organ only)

depending if one is looking at the organ itself or whole heart

37
Q

What is fibrous pericardium made up of?

A

dense irregular connective tissue

38
Q

What is serous pericardium made up of? What does it secrete?

A

serosa
- mesothelial cells
- simple squamous epithelium
- has connected tissue underneath
- produces serous secrete

39
Q

Where is the serous secrete made by mesothelial cells of the serous layer secreted to? What is its function

A

pericardial cavity
- between the two serous walls (parietal and visceral layer)
- reduces friction (lubricates) created during heart contractions and relaxations

40
Q

What is the epicardium? Another name? What does it cover? What is it composed of? What underlies it?

A
  • visceral pericardium
  • covers outer surface of the heart
  • single layer of mesothelial cells
  • underlying connective tissue
41
Q

What is the subepicardial connective tissue? What does it contain?

A

contains:
- blood vessels
- nerves
- varying amount of fat

42
Q

How does epicardium compare to typical serosa?

A

It has much more connective tissue beneath the mesothelial cells.

43
Q

What is the name of the bundle of cardiac conduction fibers located in the heart?

A

atrioventricular bundle (bundle of His)

44
Q

Where is the atrioventricular bundle located?

A
  • extends from the atriovetricular node
  • through the subendocardium
  • divides into the right and left bundle branches
45
Q

Where do the branches of the atrioventricular bundle ramify?

A

in the myocardium of the ventricles

46
Q

What is another name used for cardiac conduction fibers?

A

Purkinje fibers

47
Q

How do cardiac conduction fibers compare with cardiac myocytes?

A

cardiac conduction fibers are:
- wider
- shorter

(than cardiac myocytes)

48
Q

What is the structure of cardiac conduction fibers?

A
  • shorter than myocytes
  • wider than myocytes
  • have few myofibrils and myofillaments
  • pale cytoplasm
  • clear zone located centrally around the nucleus
49
Q

What forms the pale cytoplasm in cardiac conduction fibers?

A

few myofibrils and myofilaments

50
Q

What is the function of the ‘cardiac impulse conductive system’?

A

It makes nervous impulses which lead to heart contractions.

51
Q

What is unique about the heart?

A
  • it is not stimulated by the central nervous system
  • it is myogenic
  • autonomous system working on itself
  • the impulse is not made on nervous tissue (neurons, neuroglia cells etc.)
  • the impulse is based on myocytes
52
Q

What is the entire cardiac impulse conduction system based on?

A

myocytes!
(not typical cardiac muscle cells. they are called ‘heart conductive myocytes’)

53
Q

How do heart conductive myocytes compare to typical cardiac muscle cells?

A

heart conductive myocytes are:
- bigger
- paler (not as dark) (fewer myofibrils and myofillaments)

(than typical cardiac muscle cells)

appearance similar to adipocytes (size, colour, etc.)

54
Q

Where is the conductive system positioned?

A

in the ENDOCARDIUM!

55
Q

What is heart rate controlled by? Where is it located?

A

sinoatrial node located in the wall of the right atrium

56
Q

Explain the action of the cardiac impulse conductive system.

A

wave of depolarization spreads from the sinoatrial node through the internodal connective pathway to the atrioventricular node

57
Q

Where is the atrioventricular node located?

A
  • the junction of the atria and the coronary sinus
  • near the right atrioventricular valve
58
Q

What is the cardiac skeleton?

A
  • the base of the heart support
  • where the major blood vessels enter and exit
59
Q

What is the cardiac skeleton composed of?

A

dense irregular connective tissue

depends on the animal and age! (it can mineralize in older organisms)

60
Q

What additional structures are usually present in the cardiac skeleton of dogs?

A

fibrocartilage

61
Q

What additional structures are usually present in the cardiac skeleton of horses?

A

hyaline cartilage

62
Q

What additional structures are usually present in the cardiac skeleton of ruminants?

A

bone

63
Q

What are the functions of the cardiac skeleton?

A
  • strongly attaches valves to the internal heart wall
  • keeps heart valves open (disabling them from changing shape)
  • stabilizes the entire heart structure
  • prevents heart from malfunction (fatal)
  • acts as an electrical insulator (prevents electrical impulses from spreading across the all chambers at the same time (fatal))
64
Q

What type of component is the cardiac skeleton?

A

not stroma!!
heart is not a parenchymal organ! it is tubular!

65
Q

What type of organ is the heart?

A

tubular organ!

NOT PARENCHYMAL!