Chapter 20-anatomy
Contrast the functions of elastic arteries, muscular arteries, and arterioles
(a) elastic arteries help propel blood onward while the ventricles are relaxing (b) muscular arteries adjust the rate of blood flow and distribute the blood to organs; (c) arterioles regulate the flow of blood into capillaries.
If a blood pressure is reported as "142 over 95", what are the diastolic and systolic pressures?
142 is systolic 95 is diastolic
Explain the terms tachycardia and bradycardia
a. tachycadia is a rapid heart beat or pulse; bradycardia is a slow heartbeat or pulse
How do hormones regulated blood pressure?
altering cardiac output, changing systemic vascular resistance, or adjusting the total blood volume
What is the relationship between anastomoses and collateral circulation?
an anastomosis is the union of two or more arteries supplying the same body region:collateral circulation is the alternate circulatory route of blood flow to a body part through an anasomosis
What are the primary structural and functional differences between arteries, capillaries, and veins?
arteries: thick walls with smooth muscle and elastic fibers, coduct blood from the heart to the body; capillaries: walls are single-celled with only an endothelium and basement membrane, permit exchange of nutrients and wastes between blood and interstitial fluid; veins: this walls with smooth muscle and elastic fibers with valves, return blood to the heart
Why is less blood pressure needed in pulmonary arteries than systemic arteries?
because pulmonary arteries just pump blood to lungs and systemic arteries pump blood to the rest of the body
How is blood flow directed through a capillary bed?
blood flow can be controlled and regulated by percapillary sphincters and can by-pass the caillary bed via the thoroughfare channel.
Following a drop in blood pressure, how does the baroreceptor reflex return blood pressure to a normal level?
by decreasing parasympathetic stimulation of th eheart, increasing sympathetic stimulation of the heart, stimulating adrenal medullae to increase secretion of epinephrine and norepinephrine and increasing vasoconstriction of vascular smooth muscle.
What types of effector tissues are regulated by the cardiovascular center?
cardiac muscle in the heart, and smooth muscle in blood vessel walls.
What is the main function of the systemic circulation?
carries oxygenated blood to all the body parts from the heart and carries deoxygenated blood back to the heart.
Contrast the structure and function of three types of capillaries.
continiuous capillaries only have intercellular clefts this restricts movement across the walls; fenestrated capillaries contain intercellular clefts and fenestrations thta allow greater exchange of materials; sinusoids have large fenestrations and intercellular clefts and an incomplete basement membrane, which allows the greatest amount of capillary exchange
In an adult which are the only arteries that carry deoxygenated blood? Which are the only veins that carry oxygenated blood?
deoxygenated-pulmonary artery oxygenated-pulmonary vein
How do materials move through capillary walls?
diffusion across capillary wall through either intracellular clefts, fenestrations, or the plasma membrane of the endothelial cells, but for large, lipid insolubale molecules transcytosis via pinocytic vesicles.
State the ways substances enter and leave blood plasma.
diffusion and transcytosis
How do elastic arteries and muscular arteries differ in structure?
elastic arteries: more elastic fibers and less smooth muscle in their tunica media;muscular arteries:more smooth muscle and fewer elastic fibers.
what is the function of elastic fibers and smooth muscle in the tunica media of arteries
elastic fibers allow the walls of the arteries to stretch and recoil in response to changes in blood pressure; smooth muscle regulates the diameter of the lumen.
How do capillary blood pressure and blood colloid osmotic pressure determine fluid movement across the walls of capillaries?
high blood pressure "pushes" fluid out of the capillaries, whereas high blood colloid osmotic pressure "pulls" fluid back into the capillaries
What are the principle inputs to and outputs from the cardiovascular center?
input- brain, proprioceptors, baroreceptors, and chemoreceptors; output:parasympathetic output along vagus nerves, sympathetic and parasympathetic neuorns of the ANS
What is vascular resistance? What factors contribute to it?
opposition of blood flow due to friction between blood and the walls of the blood vessels;factors; size of the lumen, blood viscosity, total blood vessel length
Which activity is occurring in the heart to produce systolic blood pressure? Which heart activity is occurring during diastolic blood pressure?
systole-contraction, dystole-relaxation
What is autoregulation?
the ability of a tissue to automatically adjust its blood flow to match its metabolic demands
Which vessel-the femoral artery or the femoral vein-has a thicker wall? Which has a wider lumen?
the femoral artery has a thicker wall; the femoral vein has a wider lumen
What happens to excess filtered fluid and proteins that are not reabsorbed back into capillaries?
they enter lymphatic capillaries and are eventually returned by the lymphatic system to the bloodstream,
What is the role of chemoreceptors in the regulation of blood pressure?
to inform the cardiovascular center about changes in blood levels of O2 and CO2 and H+
Which type of blood vessel exerts the most control over systemic vascular resistance, and how is it achieved?
vasodilation and vasoconstriction of arterioles are the main regulations of systemic vascular resistance
Explain how venous blood is returned in the heart.
venous return is due to the pressure generated by contraction of the left ventricle, by the skeletal muscle pump (contraction of skeletal muscles in the limb), by the respiratory pump alternation comprassion and decompression of veins during inhalation and exhalation.
