Cardiovascular System and Lymphatics - Study Flashcards

A comprehensive set of question-and-answer flashcards covering vessel structure, capillaries, angiogenesis, arterial/venous differences, heart anatomy and conduction, valves, innervation, and the lymphatic system based on the provided lecture notes.

What is the primary function of the circulatory system as described in the notes?

To transport and homeostatically distribute oxygen, nutrients, wastes, body fluids and solutes, body heat, and immune system components.

What are the three tunics that describe vessel walls?

Tunica intima, tunica media, and tunica adventitia.

How do lymphatic vessel tunics compare to blood vessel tunics?

Lymphatic vessel tunic borders are less distinct than those in blood vessels and their walls are thinner, increasing the risk of rupture in weak walls.

What is the tunica intima and what is it made of?

The inner layer bordering the lumen; made of endothelium with a thin basal lamina. Capillaries are composed only of endothelium.

What is the internal elastic lamina?

A fenestrated layer of elastin that separates the tunica intima from the tunica media in arteries.

What is the tunica media?

The middle layer, mainly vascular smooth muscle; thicker in arteries; in medium arteries there is often an external elastic lamina between the media and adventitia.

What is the tunica adventitia?

The outermost layer, composed primarily of type I collagen and elastic fibers; anchors the vessel to surrounding tissues; thickest in veins and may contain vasa vasorum.

What are the vasa vasorum?

Small blood vessels in large vessels that supply oxygen and nutrients to the vessel walls.

How is the heart’s outer layer different from vessels’ adventitia?

The heart’s outer layer is the epicardium (a serosa with mesothelium) and it lacks an adventitia; the serosa reduces friction.

What is mesothelium?

A simple squamous epithelium that lines serosal cavities (peritoneal, pleural, and pericardial) and forms part of the serosa.

What are the four components of the cardiovascular system, and what is a notable feature of its flow?

Heart, arteries, veins, and capillaries; flow is bidirectional and the system forms a closed loop.

What are the smallest vascular channels in the circulatory system?

Blood capillaries.

What is the composition of blood capillary walls?

An endothelial cell sheet (simple squamous) rolled into a tube with a thin basal lamina.

How are capillary cells connected?

Endothelial cells are connected by junctional complexes (tight and gap junctions).

What is a fenestrated capillary and where are they typically found?

Capillaries with endothelial pores (fenestrae) that may be open or covered by diaphragms; found in kidneys, intestines, and endocrine glands.

Who are pericytes and where are they located?

Small mesenchymal cells scattered along capillaries and postcapillary venules; can differentiate into various cell types after injury.

Name the three types of capillaries and a key feature of each.

Continuous: nonporous endothelium with tight junctions (muscles, brain, nerves); Fenestrated: endothelial pores (rapid exchange in kidneys, intestines, endocrine glands); Sinusoidal: wide lumens, gaps between endothelium, phagocytes present, discontinuous basal lamina.

What are the four transcapillary transport mechanisms?

Fenestrae (diffusion through pores), intercellular clefts, pinocytosis, and diapedesis.

What is angiogenesis and what activates it?

Sprouting of new vessels from existing ones; activated endothelial cells produce matrix metalloproteases (MMPs) to degrade basal lamina; VEGF and FGFs stimulate growth; hypoxia via HIF increases angiogenesis.

What are inhibitors of angiogenesis?

Angiostatin, endostatin, and TIMPs (tissue inhibitors of metalloproteases) inhibit MMP activity.

What is the role of normal angiogenesis and its relevance to cancer therapy?

Normal angiogenesis supports wound healing and tissue regeneration; tumors stimulate angiogenesis to grow; inhibiting angiogenesis can slow tumor growth by depriving it of blood supply.

How do arteries and veins differ structurally?

Arteries have thicker tunica media and more elastic fibers; veins have thinner walls, thicker adventitia, and often contain valves.

What are portal vessels?

Vessels that carry blood from one capillary bed to another without first returning it to the heart.

What are carotid and aortic bodies?

Unencapsulated chemoreceptors near the fork of the carotid or at the aorta that detect O2, CO2, and pH levels through fenestrated/sinusoidal capillaries.

What is the carotid sinus and its function?

An unencapsulated mechanoreceptor at the bifurcation of the common carotid; acts as a baroreceptor, increasing BP leads to signals causing vasodilation and slower heart rate via the glossopharyngeal nerve.

What are arteriovenous (AV) anastomoses and glomera?

Direct connections between arteries and veins that regulate blood flow by smooth muscle contraction; glomera are complex AV shunts in fingers, nail beds, and ears that lack an internal elastic lamina and have more smooth muscle.

What is the role of precapillary sphincters?

Sphincters around metarterioles that regulate blood flow between AV shunts and capillary beds; closed sphincters shunt blood through metarterioles, open sphincters increase capillary perfusion.

What is the vasa vasorum and why is it important?

Vasa vasorum are the vessels of the vessels that supply blood to the walls of large arteries and veins, ensuring nourishment to wall cells that are far from the lumen.

What kind of nerve supply do blood vessels have and where are vasomotor fibers located?

All blood vessel walls (except capillaries and some venules) have nerve supply; unmyelinated vasomotor fibers (sympathetic) arise in ganglia, terminate in media to stimulate contraction; small intra-adventitial ganglia exist in large arteries; myelinated fibers are in adventitia.

What are the main parts of the heart wall and their functions?

Endocardium (inner lining, including endothelium, subendothelial tissue, subendocardium with vessels and conduction system); Myocardium (muscular middle layer responsible for contraction and contains the conduction system); Epicardium (outer serosal layer with mesothelium that reduces friction.

How do atrial and ventricular cardiac muscles differ?

Atrial muscle: smaller cells, atrial natriuretic peptide granules, less extensive T-tubule system, more gap junctions, faster impulse conduction, rhythmic contraction. Ventricular muscle: complex helically wound layers around the ventricles.

What are cardiac valves and their attachments?

Tricuspid (right atrioventricular) with three cusps anchored to papillary muscles by chordae tendineae; Mitral (bicuspid) with two cusps anchored by chordae to papillary muscles; Semilunar valves (aortic and pulmonary) with three cusps and nodules, no chordae.

What is the impulse-generating and conducting system of the heart?

SA node (pacemaker) initiates impulses; AV node; AV bundle of His; right and left bundle branches; Purkinje fibers; conduction coordinates heart rhythm.

Why must impulses travel slowly from the SA node to the AV node?

To ensure the atria contract first and finish their contraction before the ventricles begin to contract.

What is the innervation pattern of the heart and its effect on heart rate?

Autonomic innervation (sympathetic and parasympathetic); sympathetic stimulation increases heart rate, parasympathetic decreases; there are no motor end plates in the heart.

Where do the heart’s lymphatics drain?

Myocardium has abundant lymphatic capillaries that drain into larger lymphatic vessels in the epicardial connective tissue.

What is the route of blood through the heart and lungs?

Veins return blood to the right atrium, pass through the tricuspid valve to the right ventricle, through the pulmonary semilunar valve to the pulmonary arteries to the lungs for gas exchange, then through pulmonary veins to the left atrium, through the mitral valve to the left ventricle, then via the aorta to systemic capillaries.

What is the route of blood through the systemic circulation after capillary exchange?

Blood travels from arteries to arterioles to capillary beds, exchanges oxygen/nutrients and wastes; most fluid re-enters capillaries; blood then moves to venules and veins back to the heart.

What happens when lymphatic vessels are blocked?

Edema due to accumulation of tissue fluid.