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PT663 > Cardiovascular Histology > Flashcards

Cardiovascular Histology Flashcards

1
Q

What is the primary function of the heart in the cardiovascular system?

A

The heart is responsible for pumping blood throughout the body.

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2
Q

Name the types of blood vessels in the cardiovascular system.

A

The types of blood vessels include arteries, arterioles, capillaries, veins, and venules.

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3
Q

What two aspects are shown at the bottom of the diagram in relation to blood vessels?

A

The lumen diameter (how wide the vessel is) and the thickness of the vessel walls.

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4
Q

What determines the structure and composition of arteries, arterioles, capillaries, and veins?

A

Their distance from the heart and the pressure they are exposed to.

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5
Q

What are the three layers of the heart called?

A

Endocardium, myocardium, and epicardium.

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6
Q

What are the three layers of blood vessels referred to as?

A

Tunica intima, tunica media, and tunica adventitia.

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7
Q

What is the innermost layer of the heart and blood vessels?

A

Tunica intima in blood vessels and endocardium in the heart.

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8
Q

What is the tunica media and what is it composed of in the heart and vessels?

A

The tunica media is the middle layer, composed of cardiac muscle in the heart and smooth muscle in the vessels.

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9
Q

What is the outermost layer of the heart and blood vessels?

A

Epicardium in the heart and tunica adventitia in blood vessels.

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10
Q

What is the endothelium and where is it located?

A

The endothelium is the innermost lining layer that is one cell thick and is continuous throughout the entire cardiovascular system.

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11
Q

How are the layers of the heart and blood vessels similar?

A

Both have layers that consist of similar components, though they are referred to differently (cardium for the heart, tunics for blood vessels).

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12
Q

What suffix do the layers of the heart have?

A

The layers of the heart have the suffix “cardium.”

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13
Q

What are the two components of the endocardium?

A

The endocardium consists of the endothelium (a one-cell-thick layer) and the subendothelium (a connective tissue layer).

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14
Q

What is the primary composition of the myocardium?

A

The myocardium is primarily composed of cardiac muscle.

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15
Q

What connective tissue structures subdivide cardiac muscle in the myocardium?

A

Endomysium, perimysium, and epimysium subdivide the cardiac muscle.

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16
Q

What is the epicardium and what does it contain?

A

The epicardium is the outer layer of the heart, mostly composed of connective tissue and contains blood vessels, collectively called vasa vasorum.

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17
Q

What is the function of the pericardial layer?

A

The pericardial layer is a sac that contains the heart and secretes fluid to allow the heart to contract in a frictionless environment.

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18
Q

Where do Purkinje fibers reside in the heart?

A

Purkinje fibers reside in the subendothelial layer of the endocardium.

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19
Q

How do Purkinje fibers differ from typical cardiac muscle cells?

A

Purkinje fibers are larger, lighter in color due to higher glycogen content, and have more gap junctions compared to typical cardiac muscle cells.

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20
Q

What is the conduction speed of Purkinje fibers compared to myocardial cells?

A

Purkinje fibers conduct impulses at about 3 to 4 meters per second, while myocardial cells conduct at about 0.5 meters per second.

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21
Q

Why is there an abundance of connective tissue between the atria and ventricles?

A

The connective tissue prevents out-of-order conduction of impulses, ensuring that the atria fill before the ventricles contract.

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22
Q

How does the connective tissue assist in the function of the heart?

A

It compresses the heart chambers during contraction to expel blood, supports heart valves, and provides structural integrity.

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23
Q

What are the primary types of blood vessels in the cardiovascular system?

A

The primary types of blood vessels include arteries, arterioles, capillaries, veins, and venules.

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24
Q

What are the two types of cardiac muscle found in the heart?

A

Cardiac muscle is found in the myocardium (heart muscle layer) and in the major veins (e.g., pulmonary vein, superior and inferior vena cava).

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25
Q

Why is there cardiac muscle present in the major veins?

A

To ensure synchrony of firing so that the beginning parts of the veins contract simultaneously with the heart muscle during blood expulsion.

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26
Q

What are the types of connective tissue associated with cardiac muscle?

A

The connective tissues include perimysium (around fascicles), endomysium (around individual muscle cells), and subendocardial connective tissue.

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27
Q

Why is there a high density of capillaries in the heart muscle?

A

To supply oxygen and nutrients necessary for continuous energy for contraction.

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28
Q

What structural feature distinguishes cardiac muscle cells from skeletal muscle cells?

A

Cardiac muscle cells have intercalated discs, which mark the ends of one cell and the beginning of another.

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29
Q

What is the purpose of the branching structure of cardiac muscle cells?

A

Branching increases connectivity between adjacent cells, allowing for synchronized contraction.

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30
Q

What are desmosomes?

A

Desmosomes are structural adhesions that provide mechanical support between adjacent cardiac muscle cells, helping them stay connected during contraction.

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31
Q

What role do gap junctions play in cardiac muscle?

A

Gap junctions facilitate the rapid transport of ions and allow for synchronous contraction of cardiac muscle cells.

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32
Q

What is the significance of mitochondria in cardiac muscle cells?

A

Mitochondria provide the necessary energy for muscle contraction, supporting the heart’s continuous activity.

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33
Q

What are beta-adrenergic receptors in cardiac muscle cells responsible for?

A

They facilitate increased contractility and heart rate when activated.

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34
Q

How do T-tubules and the sarcoplasmic reticulum function in cardiac muscle?

A

They form a dyad that helps convert electrical signals into calcium release, allowing for muscle contraction.

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35
Q

What is the main difference between triads in skeletal muscle and dyads in cardiac muscle?

A

Cardiac muscle has dyads (one T-tubule and one sarcoplasmic reticulum) rather than triads (two sarcoplasmic reticula and one T-tubule) found in skeletal muscle.

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36
Q

Why is synchronous contraction important in the heart?

A

To ensure all muscle cells within a chamber contract at nearly the same time for effective blood expulsion.

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37
Q

What are the three layers of blood vessels?

A

The three layers are the tunica intima, tunica media, and tunica adventitia.

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38
Q

What comprises the tunica intima?

A

The tunica intima consists of an endothelial layer (one cell thick), a subendothelial layer of connective tissue, and the internal elastic lamina (made of elastic fibers).

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39
Q

What is the function of the internal elastic lamina in blood vessels?

A

The internal elastic lamina serves as a boundary between the tunica intima and the tunica media, allowing for flexibility and support.

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40
Q

What is found in the tunica media?

A

The tunica media contains smooth muscle, collagen fibers, and elastic fibers.

41
Q

How does the amount of collagen and elastic fibers in the tunica media vary?

A

The amounts of collagen and elastic fibers are dictated by the pressure the blood vessel is exposed to.

42
Q

What does the wavy appearance in the tunica media indicate?

A

The wavy appearance is due to relaxed elastic fibers in the internal elastic lamina.

43
Q

What is the tunica adventitia, and what is it composed of?

A

The tunica adventitia is the outermost layer of blood vessels, composed largely of connective tissue and elastic fibers.

44
Q

What is the vaso vasorum?

A

The vaso vasorum is a network of small blood vessels that supply larger blood vessels with nutrients and oxygen.

45
Q

How does the structure of a muscular artery differ from that of other arteries?

A

A muscular artery has fewer elastic fibers in the tunica media and a distinct boundary between the muscle layer and the tunica adventitia.

46
Q

Why is the presence of elastic fibers important in blood vessels?

A

Elastic fibers provide the ability to stretch and recoil, helping to maintain blood pressure and facilitate blood flow.

47
Q

What type of muscle is found in blood vessels?

A

Smooth muscle.

48
Q

How do smooth muscle cells appear histologically?

A

They are spindle-shaped with blue nuclei and form concentric rings around the lumen of the blood vessel.

49
Q

How do smooth muscle layers control the diameter of blood vessels?

A

When smooth muscle contracts, it decreases the diameter of the lumen; when it relaxes, it increases the diameter.

50
Q

What is notable about the connective tissue in smooth muscle compared to cardiac and skeletal muscle?

A

Smooth muscle has less connective tissue and is not as highly organized.

51
Q

What stimuli do smooth muscle cells respond to?

A

Smooth muscle responds to stretch, changes in pressure, hormones, and autonomic sympathetic input.

52
Q

How do smooth muscle cells communicate with one another?

A

They communicate via gap junctions, allowing calcium to flow between adjacent cells for synchronized contraction.

53
Q

Why doesn’t each smooth muscle cell require direct neural synapse for contraction?

A

Smooth muscle contraction can occur more slowly and synchronously through gap junctions, making individual nerve connections unnecessary.

54
Q

What type of autonomic input do smooth muscle cells receive?

A

Smooth muscle receives sympathetic autonomic input but not parasympathetic input.

55
Q

What happens to blood vessels during the fight-or-flight response?

A

Blood vessels supplying skeletal muscles dilate to increase blood flow, while blood vessels supplying skin and internal organs constrict.

56
Q

What is the role of sympathetic input in blood vessel function?

A

Sympathetic input can provide different messages to various regions of blood vessels based on the body’s needs, such as increased blood flow to muscles during stress or danger.

57
Q

What are the primary purposes of arteries?

A

To conduct and distribute blood to the capillaries for exchange.

58
Q

What are the three main types of arteries?

A

Elastic arteries, muscular arteries, and arterioles (including meta-arterioles).

59
Q

What is the primary function of elastic arteries?

A

Elastic arteries are known as conducting arteries that handle the immediate blood flow from the heart.

60
Q

Name three examples of elastic arteries.

A

The aorta, common carotids, and subclavian arteries.

61
Q

What distinguishes the tunica media of elastic arteries?

A

It contains an abundance of elastic fibers (about 50/50 elastic to smooth muscle) to accommodate high pressure.

62
Q

What is the role of elastic fibers in elastic arteries?

A

They allow the arteries to expand and contract, maintaining a constant flow of blood regardless of heart activity.

63
Q

What are muscular arteries known for?

A

They are known as distributing arteries, which distribute blood to various regions of the body.

64
Q

How do muscular arteries differ from elastic arteries in structure?

A

Muscular arteries have fewer elastic fibers and possess both an internal and external elastic lamina.

65
Q

What happens to the distinct layers in smaller muscular arteries?

A

As arteries become smaller, the distinction of layers, including the external elastic lamina, becomes less defined.

66
Q

What is the significance of arterioles in the circulatory system?

A

Arterioles regulate blood pressure and flow by constricting or relaxing, which influences total peripheral resistance.

67
Q

What is the structure of arterioles?

A

Arterioles have a tunica intima and a tunica media that can range from one to five layers of smooth muscle.

68
Q

What are meta-arterioles, and how do they function?

A

Meta-arterioles act as a bypass mechanism, allowing blood to either shunt directly to venules or perfuse into capillary beds based on tissue needs.

69
Q

How do meta-arterioles differ from arterioles in structure?

A

Meta-arterioles have discontinuous smooth muscle, unlike the continuous layer found in true arterioles.

70
Q

What is the relationship between arterioles and blood pressure regulation?

A

Constriction of many arterioles increases total peripheral resistance and blood pressure; relaxation decreases them.

71
Q

In a capillary bed, what roles do arterioles and meta-arterioles play?

A

Arterioles supply blood, while meta-arterioles can direct blood flow to capillaries or bypass them based on the body’s needs.

72
Q

What is the primary function of capillaries in the circulatory system?

A

To facilitate the diffusion of gases, nutrients, and waste with low pressure and slow blood flow.

73
Q

What structural feature allows capillaries to maximize exchange surface area?

A

Capillaries are typically organized in beds, which are collections of many capillaries.

74
Q

What is the diameter of capillaries, and why is it significant?

A

Capillaries have a diameter small enough to allow only one red blood cell to pass at a time, enhancing gas and nutrient exchange.

75
Q

Describe the basic structure of a capillary.

A

Capillaries consist of a single layer of endothelial cells surrounded by a basement membrane.

76
Q

What are pericytes, and what is their function?

A

Pericytes are cells surrounding capillaries that can differentiate into endothelial cells, fibroblasts, or smooth muscle cells as needed.

77
Q

What are the three types of capillaries?

A

Continuous (tight), fenestrated, and discontinuous (sinusoidal) capillaries.

78
Q

What characterizes continuous capillaries?

A

They have tight junctions between endothelial cells, forming a barrier that restricts passage between cells.

79
Q

Where are fenestrated capillaries commonly found, and what is their structure?

A

Found in the kidneys, fenestrated capillaries have pores between endothelial cells but a continuous basement membrane.

80
Q

Describe the structure and location of discontinuous (sinusoidal) capillaries.

A

Discontinuous capillaries have large openings and a discontinuous basement membrane, found in organs like the liver, allowing for the passage of large molecules.

81
Q

What roles do intermediate and actin filaments play in endothelial cells?

A

They facilitate synchronous contraction between adjacent endothelial cells when responding to changes in the vascular environment.

82
Q

How do endothelial cells respond to changes in blood pressure?

A

They can sense stretch and adapt, allowing for synchronized responses throughout the cardiovascular system.

83
Q

What protective function do endothelial cells provide?

A

They form a barrier (like the blood-brain barrier) that selectively allows substances to pass while preventing unwanted material from crossing.

84
Q

What vasoactive substances do endothelial cells secrete, and what are their effects?

A

They secrete nitric oxide (causes vasodilation) and endothelin (causes vasoconstriction), regulating vascular tone.

85
Q

What is prostacyclin, and what is its role in the vascular system?

A

Prostaglandin secreted by endothelial cells that acts as an antiplatelet agent, preventing platelet aggregation under normal conditions.

86
Q

How do endothelial cells respond to injury?

A

They secrete substances that promote inflammation, white blood cell migration, and formation of a platelet plug at the injury site.

87
Q

What is angiogenesis, and what promotes it?

A

Angiogenesis is the formation of new capillaries, promoted by substances secreted by endothelial cells.

88
Q

What are postcapillary venules, and how do they differ from capillaries?

A

Postcapillary venules have an endothelial cell lining and a basement membrane like capillaries, but their endothelial cells can be discontinuous and leaky, allowing for easy fluid exchange.

89
Q

What role do postcapillary venules play in inflammation?

A

They allow for the migration of white blood cells (leukocytes) through diapedesis, facilitating the inflammatory response.

90
Q

Describe the characteristics of muscular venules.

A

Muscular venules have a larger lumen and some smooth muscle presence, allowing for vessel constriction to promote blood flow, but they do not have a continuous smooth muscle layer like arterioles.

91
Q

How do veins differ structurally from arteries?

A

Veins have thinner walls, more flexibility, and may appear misshapen compared to the more robust, circular structure of arteries, due to lower pressure in the venous system.

92
Q

Why do veins require valves, and how do these valves function?

A

Valves prevent backflow of blood, ensuring it moves towards the heart. They open when blood flows through and collapse to prevent reverse flow.

93
Q

What are the three layers found in larger veins, and which is the thickest?

A

The three layers are tunica intima, tunica media, and tunica adventitia. The tunica adventitia is typically the thickest layer.

94
Q

What is the function of the vasa vasorum in veins?

A

The vasa vasorum are small blood vessels that supply nutrients to the walls of larger veins, as the blood inside does not provide enough oxygen.

95
Q

How do the valves in veins help combat the effects of gravity?

A

Valves ensure that blood flows in one direction towards the heart, preventing pooling in the lower extremities due to gravity.

96
Q

What happens when venous valves become incompetent?

A

Incompetent valves can lead to conditions like varicose veins, increased pressure, hemorrhaging, and potentially deep vein thrombosis.

97
Q

What is varicose veins, and what causes it?

A

Varicose veins occur when valves in veins become incompetent, causing increased pressure that can lead to valve rupture and pooling of blood.

98
Q

How does the structure of small to medium veins support their function?

A

Small to medium veins have collagen and elastic fibers in their valves, allowing them to respond appropriately to blood flow and recoil after opening.

99
Q

What is diapedesis in the context of postcapillary venules?

A

Diapedesis is the process by which white blood cells migrate out of the bloodstream and into surrounding tissue, facilitated by the leaky nature of postcapillary venules.

PT663 (22 decks)

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