57 terms

Chapter 21: Blood Vessels & Circulation

The blood vessels that play the most important role in regulating blood pressure and blood flow to a tissue are the
a) arteries
b: artirioles
Cardiovascular function is regulated by all of the following except
a)local factors
b)neural factors
c)endocrine factors
d)venous return
e) capillaries
Baroreceptors that function in the regulation of blood pressure are located in the
a) lv
b) brain stem
c) carotid sinus
d) common ilac artery
e) pulmonary trunk
The two-way exchange of substances between blood and body cells occurs only through
d) a,b, and c
Large molecules such as peptides and proteins move into and out of the blood stream by way of
a) continuous capillaries
b) fenestrated capillaries
c) thoroughfare channels
d) metarterioles
The local control of blood flow due to the action of precapillary sphincters is
a) vasomotion
b) auto regulation
c)selective resistance
Blood is transported through the venous system by means of
a) muscular contractions
b)increasing blood pressure
c) the respiratory pump
d) a and c
The most important factor in vascular resistance is
a)the viscosity of the blood
b) the diameter of the lumen of blood vessels
c) turbulence due to irregular surfaces of blood vessels
d) the length of the blood vessels
Net hydrostatic pressure forces water _____ a capillary; net osmotic pressure forces water ____ a capillary.
The two arteries formed by the division of the brachiocephalic trunk are the
a) aorta and internal carotid
b) axillary and brachial
c) external and internal carotid
d) common carotid and subclavian
The unpaired arteries supplying blood to the visceral organs include
a) the adrenal, renal, and lumbar arteries
b) the iliac, gonadal and femoral arteries
c) the celiac, left gastric, and superior and inferior mesenteric arteries
The vein that drains the dural sinuses of the brain is the
a) cephalic vein
b)great saphenous vein
c) inferior vena cava
d) azygos vein
What are the primary forces that cause fluid to move
a) out of a capillary at its arterial end and into the interstitial fluid?
b) into the capillary at its venous end from the interstitial fluid
a) capillary hydrostatic pressure forces fluid out of the capillary at the arteriole end
b) blood colloid osmotic pressure causes the movement of fluid back into the capillary at its venous end
What cardiovascular changes occur at birth?
When an infant takes its first breath, the lungs expand and pulmonary vessels dilate. The smooth muscles in the ductus arteriosus contract due to the increased venous return from the lungs, iscolating the pulmonary and aortic trunks, and blood begins flowing through the pulmonary circuit. As pressure rises in the left atrium, the valvular flap closes the foramen ovale, completing the vascular remodeling.
A major difference between the arterial and venous systems is that
a) arteries are usually more superficial than veins
b) in the limbs there is dual venous drainage
c) veins are usually less branched compared to arteries
d) veins exhibit a much more orderly pattern of branching in the limbs
e) veins are not found in the abdominal cavity
Which of the following conditions would have the greatest effect on peripheral resistance?
a) doubling the length of a vessel
b) doubling the diameter of a vessel
c) doubling the viscosity of the blood
d) doubling the turbulence of the blood
e) doubling the number of white cells in the blood
Which of the following is greater?
a) the osmotic pressure of the interstitial fluid during inflammation
b) the osmotic pressure of the interstitial fluid during normal conditions
c) neither is greater
Relate the anatomical differences between arteries and veins to their functions.
Artery walls are generally thicker and contain more smooth muscle and elastic fibers, enabling them to resist and adjust to pressure generated by the heart. Venous walls are thinner; the pressure in veins is less than that in arteries. Arteries constrict more than veins do when not expanded by blood pressure, due to a greater degree of elastic tissue. Finally, the endothelial lining of an artery has a pleated appearance because it cannot contract and so forms folds. The lining of a vein looks like a typical endothelial layer.
Why do capillaries permit the diffusion of materials, whereas arteries and veins do not?
Capillary walls are thin, so distances for diffusion are short. continuous capillaries have small gaps between adjacent endothelial cells that permit the diffusion of water and small solutes into the surrounding interstitial fluid but prevent the loss of blood cells and plasma proteins. Fenestrated capillaries contain pores that permit very rapid exchange of fluids and solutes between interstitial fluid and plasma. The walls of arteries and veins are several cell layers thick and are not specialized for diffusion.
How is blood pressure maintained in veins to counter the force of gravity?
Contraction of the surrounding skeletal muscles squeezes venous blood toward the heart. This mechanism, the muscular pump, is assited by the presence of valves in the veins, which prevent backflow of the blood. The respiratory pump, which results from the increase in internal pressure of the thoracic cavity during exhalation, pushes venous blood into the right atrium.
How do pressure and resistance affect cardiac output and peripheral blood flow?
Cardiac output and peripheral blood flow are directly proportional to blood pressure. Blood pressure is closely regulated by a combination of neural and hormonal mechanisms. The resistance of the vascular system opposes the movement of blood, so blood flow is inversely proportional to the resistance. Sources of peripheral resistance include vascular resistance, viscosity, and turbulence.
Why is blood flow to the brain relatively continuous and constant?
The brain receives arterial blood via four arteries that form anastomes within the cranium. An interruption of any one vessel will not compromise the blood flow to the brain.
compare the effects of the carioacceleratory and cardioinhibitory centers on cardiac output and blood pressure.
The cardioacceleratory and vasomotor centers are stimulated when general sympathetic activation occurs. The result is an increase in cardiac output and blood pressures. When the parasympathetic division is activated, the cardioinhibitory center is stimulated, reducing cardiac output.
Bob is sitting outside on a warm day and is sweating profusely. Mary wants to practice taking blood pressures and he agrees to play the patient. Mary finds that Bob's blood pressure is elevated even though he is resting and has lost fluid from sweating. She reasons that fluid loss should lower blood volume and thus blood pressure. Why is Bob's blood pressure high instead of low?
Fluid loss lowers blood volume, leading to sympathetic stimulation, which elevates blood pressure.
People with allergies commonly take antihistamines with decongestants to relieve their symptoms. The container warns that individuals who are being treated for high blood pressure should not take the medication. Why not?
Antihistamines and decongestants are sympathomimetic drugs; they have the same effects on the body as does stimulation of the sympathetic nervous system. In addition to the desired effects of counteracting the symptoms of the allergy these medications can produce an increased heart rate, increased stroke volume, and increased peripheral resistance, all of which will contribute to elevating blood pressure. In a person with hypertension, these drugs would aggravate this condition, with potentially hazardous consequences.
Iolene awakens suddenly to the sound of her alarm clock. Realizing that she is late for class, she jumps to her feet, feels light headed, and falls back on her bed. What probably caused this reaction? Why doesn't this happen all the time?
When Jolene stood up rapidly, gravity caused her blood volume to move to the lower parts of her body away from the heart, decreasing venous return. The decreased venous return resulted in a decreased end-diastolic volume (EDV), leading to a decreased stroke volume and cardiac output. In turn, blood flow to the brain decreased so the diminished oxygen supply caused her to be light-headed and feel faint. This reaction doesn't happen all the time because as soon as the pressure drops due to inferior movement of the blood, baroreceptors in the aortic arch and carotid sinus trigger the baroreceptor reflex. Action potentials are carried to the medulla oblonga where appropriate responses are integrated. In this case, we would expect an increase in peripheral resistance to compensate for the blood pressure. If this doesn't compensate enough for the drop, then an increase in heart rate and force of contraction would occur. Normally, these responses occur so quickly that changes in pressure following changes in body position go unnoticed.
What are the 5 general classes of blood vessels?
Arteries, arterioles, capillaries, venules, and veins.
A cross section of tissue shows several small, thin-walled vessels with very little smooth muscle tissue in the tunica media. Which type of vessel are these?
The blood vessels are veins. Arteries and arterioles have a large amount of smooth muscle tissue in a thick, well developed tunica media.
Why are the valves located in veins, but not in arteries?
In the arterial system, pressures are high enough to keep the blood moving forward. In the venus system, blood pressure is too low to keep the blood moving on toward the heart. Valves in veins prevent blood from flowing backward whenever the venous pressure drops.
Where in the body would you find fenestrated capillaries?
Fenestrated capillaries are located where fluids and small solutes move freely into and out of the blood, including endocrine glands, the choroid plexus of the brain, absorptive areas of the intestine, and filtration areas of the kidneys.
Identify the factors that contribute to total peripheral resistance
Total peripheral resistance reflects a combination of vascular resistance, vessel length, vessel diameter, blood viscosity, and turbulence.
In a healthy individual, where is blood pressure greater; at the aorta or at the inferior vena cava.
In a healthy individual, blood pressure is greater in the aorta than at the inferior vena cava. Blood, like other fluids, moves along a pressure gradient from areas of high pressure to areas of low pressure. If the pressure were higher in the inferior vena cava than the aorta, the blood would flow backward.
While standing in the hot sun, Sally begins to feel light-headed and faints. Explain what happened.
While a person stands for periods of time, blood pools in the lower limbs, which decreases venous return to the heart. In turn, cardiac output decreases so less blood reaches the brain, causing light-headedness and fainting. A hot day adds to this effect, because the loss of body water through sweating reduces blood volume.
Mike's blood pressure is 125/70. What is his mean arterial pressure?
Mike's mean arterial pressure is approx 88.3mm Hg; 70 + (125-70)/3=70+18.3=88.3.
Describe the actions of vasodilators and local vasodilators
Vasodilators promote the dilation of precapillary sphincters; local dilators act at the tissue level to accelerate blood flow through their tissue origin.
How would applying slight pressure to the common carotid artery affect your heart rate?
Pressure on the common carotid artery would decrease blood pressure at the baroreceptors in the carotid sinus. This decrease would cause a decreased frequency of action potentials along the glossopharyngeal cranial nerve (IX) to the medulla oblongata and more sympathetic impulses would be sent to the heart. The net result would be an increase in the heart rate.
What effect would the vasoconstriction of the renal artery have on blood pressure and blood volume?
Vasoconstricton of the renal artery would decrease both blood flow and blood pressure at the kidney. In response, the kidney would increase the amount of renin it releases, which in turn would lead to an increase in the level of angiotensin II. The angiotensin II would bring about increased blood pressure and increased blood volume.
Why does blood pressure increase during exercise? 736
Blood pressure increases during exercise because
1. cardiac output increases
2. resistance in visceral tissues increases
Name the immediate and long-term problems related to the cardiovascular response to hemorrhaging.
The immediate problem during hemorrhaging is the maintenance of adequate blood pressure and peripheral blood flow; the long-term problem is the restoration of normal blood volume.
Explain the role of aldosterone and the ADH in long-term restoration of blood volume
Bot aldosterone and ADH promote fluid retention and reabsorption at the kidneys, preventing further reductions in blood volume.
Identify the two circuits of the cardiovascular system
The two circuits of the cardiovascular system are the pulmonary circuit and the systemic circuit.
Identify the three major patterns of blood vessel organization seen in the pulmonary and systemic circuits of the cardiovascular system.
The three major patterns are the following
1. The peripheral distributions of arteries and veins on the body's left and right sides are generally identical except near the heart where the largest vessels connect to the atria or ventricles
2. a single vessel may have several names as it crosses specific anatomical boundaries, making accurate anatomical descriptions possible
3. tissues and organs are usually serviced by several arteries and veins
Name the blood vessels that enter and exit the lungs, and indicate the relative oxygen content of the blood in each.
The pulmonary arteries enter the lungs carrying deoxygenated blood, and the pulmonary veins leaving the lungs carrying oxygenated blood.
Trace the path of a drop of blood through the lungs, beginning at the RV and ending at the LA.
RV--> Pulmonary trunk --> L&R pulmonary arteries --> pulmonary arterioles -->alveoli --> pulmonary venules --> pulmonary veins --> LA
A blockage of which branch from the aortic arch would interfere with blood flow to the left arm?
A blockage of the left subclavian artery would interfere with blood flow to the left arm.
Why would compression of the common carotid arteries cause a person to lose consciousness?
Compression of the common carotid arteries would reduce blood pressure at the carotid sinus and cause a rapid reduction in blood flow to the brain, resulting in a loss of consciousness. An immediate reflexive increase in heart rate and blood pressure would follow.
Grace is in an automobile accident, and her celiac trunk is ruptured. which organs will be affected most directly by this injury?
Rupture of the celiac trunk would most directly affect the stomach, spleen, pancreas, and liver.
Whenever Tim gets angry, a large vein bulges in the lateral region of his neck. Which vein is this?
The vein that is bulging is the external jugular vein.
A thrombus that blocks the popliteal vein would interfere with blood flow in which other veins?
A blockage of the popliteal vein would interfere with blood flow in the tibial and fibular veins (which form the popliteal veing) and the small saphenous vein (which joins the popliteal vein)
Identify components of the cardiovascular system that are affected by age.
Blood, heart, and blood vessels.
Define thrombus.
A thrombus is a stationary blood clot within the lumen of a blood vessel.
Define aneurism.
An aneurysm is the ballooning out of a wakened arterial wall resulting from sudden pressure increases.
Describe what the cardiovascular system provides for all other body systems.
The cardiovascular system provides other body systems with oxygen, hormones, nutrients, and white blood cells while removing carbon dioxide, and metabolic wastes; it also transfers heat.
What is the relationship between the skeletal system and the cardiovascular system?
The skeletal system provides calcium needed for normal cardiac muscle contraction, and it protects developing blood cells in the bone marrow. The cardiovascular system provides calcium and phosphate for bone deposition, delivers erythropoietin to bon marrow, and transports parathyroid hormone and calcitonin to osteoblasts and osteoclasts.
Name the three vessel that carry blood to and from the placenta
Two umbilical arteries supply blood to the placenta and one umbilical vein returns blood from the placenta. The umbilical vein then drains into the ductus venous within the fetal liver.
A blood sample taken from the umbilical cord contains high levels of oxygen and nutrients, and low levels of carbon dioxide and waste products. In this sample from an umblilical artery or form the umbilical vein? Explain.
This blood sample was taken from an umbilical vein, which carries oxygenated nutrient-rich blood from the placenta to the fetus
Name the structures in the fetal circulation that cease to function at birth. What becomes of these structures?
Structures specific to the fetal circulation include two umbilical arteries, and umbilical vein, the ductus venous, the forman ovale, and the ductus arteriosus. In the newborn, the foramen ovale closes and persist as the fossa ovalis, a shallow depression the ductus arteriosis persists as the ligamentum arteriosum, a fibrous cord; and the umbilical vessel and ductus venosus persist throughout life as fibrous cord.