Cardiavascular Histology Flashcards Preview

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Flashcards in Cardiavascular Histology Deck (55)
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1

Cardiac tunics

Endocardium
Myocardium
Epicardium

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Endocardium

-Innermost layer, lining the atria and the ventricles
-components: endothelium, subendothelial CT
- Continuous with the tunica of the blood vessels entering and leaving the heart
- Subendocardium is layer located between the endocardium and the myocardium
- contains nerves and purkinje fibers (subendocardial fibers)

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A layer located between the endocardium and the myocardium

Subendocardium

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The subendocardium contains

nerves and purkinje fibers (subendocardial fibers)

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Purkinje fibers

-Large, specialized cardiac muscle cells

- Carry impulses to ordinary cardiomyocytes

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Myocardium

Consists of cardiac muscle cells

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Epicardium

-External surface is covered by simple squamous epithelium (mesothelium)
- Mesothelium overlies fibroelastic CT containing adipose cells, nerves, and coronary vessels

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The epicardium's external surface is covered by

simple squamous epithelium (mesothelium)

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What is mesothelium

-The simple squamous epithelium covering the external surface of the epicardium

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The cardiac Skeleton

-Dense collagenous CT
- Myocardial fibers originate and insert into the cardiac skeleton

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Wall of all blood vessels except the capillaries are characterized by

three layers (tunics)

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Components of the tunica intima

-Endothelium and its basal lamina
- found in all arteries and arterioles
- endothelial cells produce von Willebrand's factor VIII

- Subendothelial CT
- found in all elastic and muscular arteries and some arterioles

- Internal elastic membrane
- incomplete in elastic arteries but thick and complete in muscular arteries

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The tunica media is mad up of

-circular smooth muscle tissue and fibroblasts
- contains collagen and elastic fibers

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Tunica media contains

collagen and elastic fibers

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The tunica Adventitia

- outermost layer
- lacking in arterioles
- consists of loose areolar tissue
- contains irregular fibroelastic tissue with adipocytes
-has small vessels (vasa vasorum) and nerves (nervi vasorum)

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The tunica adventitia is not present in

Arterioles

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The tunica adventitia consists of

loose areolar tissue

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Tunica adventitia contains

irregular fibroelastic tissue with adipocytes

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What is the vasa vasorum and neri vasorum

-small vessels and nerves that are present in the tunica adventitia

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What are the conducting arteries

the more elastic arteries

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What are the distributing arteries

The more muscular arteries

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Pressure ____ as arteries leave the heart and become progressively smaller

drops

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Elastic arteries

-Conducting arteries
- Stretch during systole and recoil during diastole
- tunica media consists of layers of elastic fibers organized into elastic laminae:
- 40 layers in newborn to 70 layers in older adult
- CT is interspersed between the elastic laminae
- Include: Aorta, pulmonary trunk, large branches of aorta

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The elastic arteries include

-Aorta
- pulmonary Trunk
- Large branches of the aorta

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Tunica media of elastic arteries consist of

-layers of elastic fibers organized into elastic laminae
- 40 layers in newborn to 70 layers in older adults
- CT is interspersed between the elastic laminae

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Muscular Arteries

- Distributing arteries
- Tunica media consists of smooth muscle that responds to autonomic stimulation and hormones:
- Thickness of smooth muscle layer decreases as diameter becomes smaller
- Gradual transition form elastic artery to muscular artery
-Include: All named arteries of the body except the elastic arteries

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The tunica media of muscular arteries

consists of smooth muscle that responds to autonomic stimulation and hormones:
- thickness of smooth muscle layer decreases as diameter becomes smaller
- Gradual transition from elastic artery to muscular artery

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Muscular arteries include

all named arteries of body except for the elastic arteries

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The smooth muscle cells of the tunica media in muscular arteries produce

elastic, reticular, and collagenous fibers

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Arterioles

-Small arteries
- Tunica media consists of one to three layers of smooth muscle cells
- Mean arterial pressure depends on proper tone of smooth muscles in arterioles (peripheral resistance arterioles)
- Thickness of smooth muscle layer decreases as diameter becomes smaller
- Gradual transition from elastic artery to muscular artery
- Give rise to metarterioles which have a discontinuous layer of smooth muscle tissue