Cardiovascular System Histology Flashcards

Flashcards based on lecture notes for reviewing the histology of the cardiovascular system.

What does the circulatory system consist of?

Blood, a central pump (the heart), blood distribution (arterial) and collection (venous) networks, and a system for exchange of nutrient and waste products between blood and extravascular tissue (microcirculation).

What are the functions of the cardiovascular system?

Maintenance of adequate blood flow (cardiac output), delivery of oxygen, nutrients, hormones, electrolytes and water to peripheral tissues, removal of carbon dioxide (CO2) and other metabolic waste products, maintenance of normal thermoregulation, maintenance of normal glomerular filtration rate (GFR) and urine output.

What are the four chambers of the heart?

Right atrium (RA), right ventricle (RV), left atrium (LA), left ventricle (LV)

What are the three layers of the heart, from inside to outside?

Endocardium, myocardium, and epicardium.

What is the endocardium?

Inner lining of the heart and the valves; equivalent to the tunica intima of blood vessels.

What are the three layers of the endocardium?

Endothelium, basal lamina (connective tissue), and subendocardium.

What are Purkinje fibers?

Modified cardiomyocytes in the subendocardium that function in impulse conduction.

Which two nodes generate the impulses for myocardial contraction?

Sinoatrial node (SA) and atrioventricular node (AV).

What is the cardiac skeleton?

Provides structural support to the heart; consists of dense connective tissue that encircle the base of the pulmonary trunk, aorta, and AV valves.

Describe cardiomyocytes.

Involuntary striated muscle arranged in sarcomeres with a central single nucleus.

What structures are found in intercalated discs?

Gap junctions and anchoring junctions.

What is the epicardium?

Outer surface of the heart; visceral pericardium.

Describe the endocardium in summary.

Endothelial lining of the heart chambers and surface of the valves; the subendocardium contains a thin layer of connective tissue and the Purkinje fibers.

Describe the myocardium in summary.

Cardiac muscle mass - involuntary striated muscle.

Describe the epicardium in summary.

Single layer of flattened epithelial cells (mesothelium) supported by connective tissue, including fat; represents the visceral layer of the pericardial sac.

What are the three types of arteries?

Elastic arteries, muscular arteries, and arterioles.

What are the three types of capillaries?

Continuous, fenestrated, and discontinuous/sinusoidal.

What are the three tunics of vessels?

Tunica intima, tunica media, and tunica adventitia/externa.

What are vasa vasorum?

Small blood vessels that supply nutrients and oxygen to the tunica adventitia of large arteries and veins.

What are nervi vasorum?

Vascular nerves which innervate arteries and veins, controlling vasodilation and vasoconstriction.

What is the role of vascular endothelium?

Plays a role in hemostasis, modulates perfusion, and plays a role in inflammation.

What is the tunica intima of an elastic artery made of?

Endothelium + loose connective tissue.

What does the tunica media of an elastic artery consist of?

Consists largely of repeating elastic lamellae.

Where are the elastic arteries located, and what's their function?

Located closer to the heart; uses elastic recoil to store energy from the heart's contraction.

What is the tunica intima of a muscular artery made of?

Endothelium + loose connective tissue.

What is the function of muscular arteries?

Muscular arteries contract and expand to control blood flow.

How many layers of smooth muscle cells are in the arterioles? What is the effect on blood pressure?

1-3 layers of smooth muscle cells; greatest effect on blood pressure.

What is a metarteriole?

Terminal vessel with precapillary sphincters that regulate flow to the capillary bed.

What are capillaries?

Thin-walled tubules of mesenchymal origin; site of exchange between blood and surrounding tissue.

What are pericytes?

Mesenchymal-like cells that wrap around the endothelium of capillaries and venules; help maintain homeostatic and hemostatic functions.

Where are continuous capillaries found?

Muscle, brain, bone, lung, etc. E.g. Blood-brain and blood-testis barriers.

Where are fenestrated capillaries found?

Intestinal villi, choroid plexus, ciliary process, glomerular capillaries.

Where are discontinuous capillaries found?

Hepatic and splenic sinusoids.

What role do podocytes play in the Bowman's capsules (nephrons)?

Help prevent proteins and other large molecules from being filtered; their foot processes (pedicels) extend and wrap around the capillaries of the glomerulus to form the filtration slits.

Describe discontinuous capillaries (sinusoids).

Enlarged and irregular lumen; discontinuous and fenestrated lining endothelium; basal lamina may be absent.

What are venules?

Very 'leaky' vessels with no smooth muscle; leukocyte diapedesis possible here.

What are the valves in veins?

Projections into the lumen of the tunica intima, covered by endothelial cells with a core of elastic fibers.

How can veins be distinguished from arteries?

Large, wide lumen, thin walls in comparison to same-size arteries; valves present; thin tunica media; thick tunica adventitia.

What are lymphatic vessels?

Complementary to the cardiovascular system; transport lymph throughout the lymphatic system; valves are present.