Circulatory System (*) Flashcards
The system consisting of the heart, arteries, veins, and microvascular beds is organized as the _______ -________ and _______ _______
pulmonary circulation and the systemic circulation
describe blood flow with pulmonary circulation
In the pulmonary circulation the right side of the heart pumps blood through pulmonary vessels, through the lungs for oxygenation, and back to the left side of the heart.
describe blood flow with systemic circulation
The larger systemic circulation pumps blood from the left side of the heart through vessels supplying either the head and arms or the lower body, and back to the right side of the heart
When the body is at rest, approximately _____% of the blood moves through the systemic circulation, about _____ % through the pulmonary circulation, and _____% through the heart.
70, 18, 12
the human heart has ____ atria and _____ ventricles
2, 2
describe the cardiac conducting system
initiates the electrical impulse for contraction (heartbeat) and spreads it through the ventricular myocardium
what is the function of the sinoatrial node
pacemaker
describe the atrioventricular (AV) node
consist of myocardial tissue that is difficult to distinguish histologically from surrounding cardiac muscle. The AV node is continuous with specialized bundles of cardiac muscle fibers, the AV bundles (of His) that run along the interventricular septum to the apex of the heart, where they branch further as conducting (Purkinje) fibers that extend into myocardium of the ventricles.
what does the endocardium consist of?
endothelium, a thin layer of connective tissue with smooth muscle cells, and a layer of variable thickness lacking smooth muscle called the subendocardial layer.
what are purkinje fibres?
These fibers are cardiac muscle cells joined by intercalated disks but specialized for impulse conduction rather than contraction. With glycogen filling much of the cytoplasm and displacing myofibrils to the periphery, Purkinje fibers typically are more pale staining than contractile cardiac muscle fibers
the _________, is the site of the coronary vessels and contains considerable adipose tissue
epicardium
The ________cells secrete a lubricant fluid that prevents friction as the beating heart contacts the parietal pericardium on the other side of the pericardial cavity
mesothelial
descirbe compliance
how much a compartment will expand if the pressure in that compartment is change. A balloon has a high compliance because a small pressure increase inside the balloon will greatly expand the balloon. A rigid tube has a low compliance because a small pressure increase inside the rigid tube will not result in a significant increase in the volume of the rigid tube.
describe elasticity
tendency to return to initial structure after being distended
Walls of both arteries and veins have three tunics called ?
- intima
- media
- adventitia
An_______ has a thicker media and relatively narrow lumen. A _______ has a larger lumen and its adventitia is the thickest layer.
artery, vein
The intima of veins is often folded to form ______
valves
Capillaries have only an endothelium, with no ________ layer or other tunics.
subendothelial
The _______ arteries contain considerable elastic material and expand with blood when the heart contracts.
largest
not all interstitial fluid formed at capillary beds is drained into venules; the excess is called ___ and collects in thin-walled, irregularly shaped lymphatic vessels
lymph
Arterioles are microvessels with an ___________
intima
In skin blood flow can be varied according to external conditions by _________ -____________, or anastomoses, commonly coiled, which directly connect the arterial and venous systems and temporarily bypass capillaries.
arteriovenous (AV) shunts
describe the venus portal system
one capillary bed drains into a vein that then branches again into another capillary bed. This arrangement allows molecules entering the blood in the first set of capillaries to be delivered quickly and at high concentrations to surrounding tissues at the second capillary bed, which is important in the anterior pituitary gland and liver.
describe the arterial portal system
afferent arteriole → capillaries → efferent arteriole which occur in the kidney.
Capillaries are normally associated with perivascular contractile cells called
pericytes
what are the 3 types of vessels between arterioles and venules?
- continuosu capillaries
- fenestrated capillaries
- sinusoids
descirbe continuous capillaries
the most common type, have tight, occluding junctions sealing the intercellular clefts between all the endothelial cells to produce minimal fluid leakage. All molecules exchanged across the endothelium must cross the cells by diffusion or transcytosis.
describe sinusoids
discontinuous capillaries, usually have a wider diameter than the other types and have discontinuities between the endothelial cells, large fenestrations through the cells, and a partial, discontinuous basement membrane. Sinusoids are found in organs where exchange of macromolecules and cells occurs readily between tissue and blood, such as in bone marrow, liver, and spleen.
fenestrated capillaries
capillaries also have tight junctions, but perforations (fenestrations) through the endothelial cells allow greater exchange across the endothelium. The basement membrane is continuous in both these capillary types. Fenestrated capillaries are found in organs where molecular exchange with the blood is important, such as endocrine organs, intestinal walls, and choroid plexus.
____________capillaries exert the tightest control over what molecules leave and enter the capillary lumen
Continuous
what is the function of fenestrated capillaries?
specialized for uptake of molecules such as hormones in endocrine glands or for outflow of molecules such as in the kidney’s filtration system
what is the function of lymphatic capillaries?
drain interstitial fluid produced when the plasma forced from the microvasculature by hydrostatic pressure does not all return to blood by the action of osmotic pressure
how are lymphatic vessels formed?
by the merger of lymphatic capillaries, but their walls remain extremely thin
