topic 9: cardiovascular system

cardiovascular system

is a transport system that carries blood and lymph to and from the tissue fo the body. It includes the heart, blood vessels, and lymphatic vessels.

pulmonary circulation and systemic circulation

two circuits distribute blood to the body:

pulmonary circulation

conveys blood from the heart to the lungs and from the lungs to the heart.

systemic circulation

conveys blood from the heart to other tissues of the body and back to the heart.

musculature of cardiac muscle

for contraction to propel the blood

conduction system

for initiation and propagation of rhythmic depolarizations, which results in rhythmic cardiac muscle contraction. This system is formed by modified cardical muscle cells (Purkinje fibers), which generate and conduct electrical impulses rapidly through the heart.

coronary vasculature

consists of 2 coronary arteries and cardiac veins

epicardium, visceral layer of serous pericardium

adheres to the outer surface of the heart. It consists of single layer of mesothelial cells and underlying connective and adipose tissue.

myocardium

consiting of cardiac muscle, is the principal component of the heart. Does the contractile work of the heart, thickness varies according to workload.

atria

Thinner than the ventricles because it delivers blood only to adjacent ventricles, a process that requires relatively low pressure

ventricles

Substantially thicker because of the higher pressure required to pump the blood through the pulmonary and systemic circulations.

inner layer, middle layer, deeper layer

endocardium layers (3)

inner layer

endothelium and subendothelial connective tissue

middle layer

connective tissue and smooth muscle cells

deeper layer

subendocardial layer; location of the conducting system of the heart/purkinje fibers

fibrosa, spongiosa, ventriculars

3 layers of heart valves

fibrosa

Forms the core of the valve and contains fibrous extensions from the dense ireggular CT.

spongiosa

Loose connective tissue located on the atrial or blood vessel side of each valve. It acts as a shock absorber to dampen vibrations associated with closing the valve.

auricularis

spongiosa on the atrial side of the AV (tricuspid and mitral)

arterialis

spongiosa located on the blood vessel side

ventricularis

Dense connective tissue with many layers of elastic fibers. In AV valves, they continues into the chordae tendineae.

tunics

walls of arteries are composed of three layers called ?

tunica intima

innermost layer of the vessel

tunica media

middle layer

elastic membrane

layer of elastin that separates tunica media from tunica adventitia

tunica adventitia

outermost connective tissue layer

vaso vasorum

present in large arteries and veins, which functions to supply blood to the vascular walls themselves and remove waste products.

nervi vasorum (vascularis)

vasoconstrictor nerves , autonomic nerves that control contraction of the smooth muscle in vessel walls.

elastic arteries

have multiple sheets of eslastic lamellae in their walls.

large arteries or elastic arteries

Serve as conduction tubes and facilitate continuous and uniform movement of blood along the tube.

tunica intima, tunica media

2 large arteries or elastic arteries sub category

CT

collagen and elastic fibers

Cell type

smooth muscle cells

tunica media

thickest layer

tunica media

Consists of elastin, smooth muscle cells, Collagen fibers, and ground substance (proteoglycans)

elastin

fenestrated sheets or lamellae that facilitates the diffusion of substances within the arterial wall.

vascular smooth muscle cells

synthesize collagen, elastin, and other molecules of ECM.

tunica media

no fibroblasts

tunica adventitia

relatively thin ct

tunica adventitia

Collagen fibers and elastic fibers form a loose areolar connective tissue

tunica adventitia

Collagen fibers help prevent the expansion of the arterial wall beyond physiological limits during systole

tunica adventitia

Principal Cells: fibroblasts and macrophages

tunica adventitia

Vaso vasorum, nervi vasorum

muscular arteries

have more smooth muscle and less elastin in the tunica media than do elastic arteries.

tunica media

Smooth muscle cells Contains collagen and little elastic fibers No fibroblast Prominent internal and external elastic membrane.

tunica adventitia

Relatively thick (about the same thickness as tunica media) Fibroblasts, collagen fibers, elastic fibers, adipocytes Principal EC component: collagen

small arteries and arterioles

Distinguished from one another by the number of smooth muscle cell layers in the tunica media

microcirculation

Capillaries form blood vascular networks that allow fluids containing gases, metabolites, and waste products to move through their thin walls.

sinusoids

classification of capillaries

continuous capillary

o Typically found in connective tissue; cardiac, skeletal, smooth muscles; skine; lungs; exocrine glands; CNS. Characterized by uninterrupted vascular endothelium that rests on a continuous basal lamina.

fenestrated capillary

o Characterized by the presence of numerous circular openings known as fenestrations that provide channels across the capillary wall.

sinusoids

o Discontinuous capillary o Found in spleen, liver, and bone marrow

Venules, small veins, medium veins, large veins

4 types of veins

venules

diameter: 0.1mm

postcapillary

characterized by the presence of pericytes undifferentiated mesenchymal stem cells that form

connections w/ endothelial cells.

muscular

distinguished by postcapillary venules by the

presence of a tunica media.

small veins

diameter: <1mm

small veins

continuation of muscular veins

medium veins

diameter: 10mm

medium veins

represent most of the named veins

large veins

diameter: >10mm

large veins

superior and inferior vena cava. hepatic portal vein