Chapter 19: blood vessels and circulation

Neural and endocrine regulatory mechanisms influence which factors?

Neural and endocrine regulatory mechanisms influence heart rate, stroke volume, peripheral resistance, and venous pressure.

Identify the largest artery in the body

The largest artery in the body is the aorta.

Identify two veins that carry blood away from the stomach

The left and right gastro-epiploic veins carry blood away from the stomach.

Identify the six structures that are vital to fetal circulation but cease to function at birth, and describe what becomes of these structures.

The six structures vital to fetal circulation are two umbilical arteries, one umbilical vein, the ductus venosus, the foramen ovale, and the ductus arteriosus. After birth, the foramen ovale closes and persists as the fossa ovalis, a shallow depression; the ductus arteriosus persists as the ligamentum arteriosum, a fibrous cord; and the umbilical vessels and ductus venosus persist throughout life as fibrous cords.

Name the three branches of the internal carotid artery

The three branches of the internal carotid artery are the ophthalmic, anterior cerebral, and middle cerebral arteries.

Identify the three veins that merge to form the hepatic portal vein

The three veins that merge to form the hepatic portal vein are the superior mesenteric, inferior mesenteric, and splenic veins.

Name the two arteries formed by the division of the brachiocephalic trunk.

The two arteries formed by the division of the brachiocephalic trunk are the right common carotid artery and the right subclavian artery.

Compare the oxygen content in the two circulatory circuits

The two circulatory circuits of the cardiovascular system are the pulmonary circuit and the systemic circuit. The pulmonary circuit carries deoxygenated blood from the right ventricle to the lungs and returns oxygenated blood to the left atrium. The systemic circuit carries oxygenated blood to the organs and tissues of the body and returns deoxygenated blood to the right atrium.

Name the two large veins that collect blood from the systemic circuit.

The two large veins that collect blood from the systemic circuit are the superior vena cava and the inferior vena cava.

List the five general classes of blood vessels.

The five general classes of blood vessels are arteries, arterioles, capillaries, venules, and veins.

Identify the major branches of the inferior vena cava

The major branches of the inferior vena cava are the lumbar, gonadal, hepatic, renal, adrenal, and phrenic veins.

Trace the path of a drop of blood from the left ventricle to the right hip joint.

left ventricle S ascending aorta S aortic arch S thoracic aorta S abdominal aorta S right common iliac S right external iliac S right femoral S right deep femoral S right hip joint.

Name the arterial structure in the neck region that contains baroreceptors

The arterial structure in the neck region that contains baroreceptors is the carotid sinus.

Identify the branches of the external carotid artery.

The branches of the external carotid artery are the superficial temporal, maxillary, occipital, facial, lingual, and external carotid arteries.

Describe the distribution of total blood volume in the body.

The systemic venous system and systemic arterial system contain 64 and 13 percent of the total blood volume, respectively. The remaining volume is contained in the heart (7%), pulmonary circulation (9%), and systemic capillaries (7%).

Identify the two types of capillaries with a complete endothelium

The two types of capillaries with a complete endothelium are continuous capillaries and fenestrated capillaries.

List the unpaired branches of the abdominal aorta that supply blood to the visceral organs.

The unpaired branches of the abdominal aorta that supply blood to the visceral organs are the celiac trunk, superior mesenteric artery, and inferior mesenteric artery.

Identify the veins that combine to form the brachiocephalic vein

The veins that combine to form the brachiocephalic vein are the external jugular, internal jugular, vertebral, and subclavian veins.

What factors are involved in the formation of varicose veins?

Varicose veins are sagging, swollen superficial veins in the thighs and legs. They result from the pooling of blood due to gravity and the failure of venous valves.

How does the kidney respond to vasoconstriction of the renal artery?

Vasoconstriction of the renal artery would decrease both blood flow and blood pressure at the kidney. In response, the kidney would release EPO and renin. EPO increases the rate of red blood cell fomation, which leads to an increase in blood volume. The release of renin would lead to an increase in the level of angiotensin II. The angiotensin II would bring about increased blood pressure and increased blood volume.

How is blood pressure maintained in veins to counter the force of gravity?

Assisted by the presence of valves in the veins, which prevent backflow of the blood, the contraction of the surrounding skeletal muscles squeezes venous blood toward the heart.

A blockage of which branch of 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.

Describe a capillary

A capillary is a small blood vessel, located between an arteriole and a venule, whose thin wall permits exchange between blood and interstitial fluid by diffusion.

Besides containing valves, cite another major dierence between the arterial and venous systems

A major anatomical difference between the arterial and venous systems is the existence of dual (superficial and deep) venous drainage in the neck and limbs.

What effect does an increase in the respiratory rate have on CO2 levels?

An increase in the respiratory rate reduces CO2 levels.

Which would reduce peripheral resistance: an increase in vessel length or an increase in vessel diameter?

An increase in vessel diameter would reduce peripheral resistance. (An increase in vessel length would increase peripheral resistance.)

Define blood flow, and describe its relationship to blood pressure and peripheral resistance

Blood flow is the volume of blood flowing per unit of time through a vessel or group of vessels; it is directly proportional to arterial pressure (increased pressure results in increased blood flow) and inversely proportional to peripheral resistance (increased resistance results in decreased blood flow).

What is the function of chemoreceptor reflexes?

Chemoreceptor reflexes respond to decreasing pH and oxygen levels and to increasing CO2 levels in the blood and cerebrospinal fluid (CSF) by adjusting cardiovascular and repiratory activity. These reflexes stimulate responses by the cardiovascular centers to increase blood pressure through vasoconstriction and increased cardiac output and stimulate responses by the respiratory centers to increase the respiratory rate, which increases pH and oxygen levels and decreases CO2 levels.

Where are chemoreceptors located?

Chemoreceptors are located in the carotid bodies, in the aortic bodies, and on the ventrolateral surfaces of the medulla oblongata.

Describe the pattern of fetal blood flow to and from the placenta

Deoxygenated blood flows from the fetus to the placenta through a pair of umbilical arteries, and oxygenated blood returns from the placenta in a single umbilical vein. The umbilical vein then drains into the ductus venosus within the fetal liver.

Describe the changes in cardiac output and blood flow during exercise.

During exercise, cardiac output increases, and blood flow to skeletal muscles increases at the expense of blood flow to less essential organs. Unless compensatory vasoconstriction occurs in "less essential" organs, such as those of the digestive system, vasodilation in skeletal muscles would cause a potentially dangerous decrease in blood pressure and blood flow throughout the body during exercise.

Define edema

Edema is an abnormal accumulation of interstitial fluid in peripheral tissues.

Distinguish among efferent vessels, afferent vessels, and exchange vessels.

Efferent vessels (arteries) carry blood away from the heart, afferent vessels (veins) carry blood to the heart, and exchange vessels (capillaries) exchange nutrients, dissolved gases, and wastes between the blood and interstitial fluid.

At what sites in the body are fenestrated capillaries located?

Fenestrated capillaries are located where solutes as large as small peptides move freely into and out of the blood. These sites include endocrine glands, the choroid plexus of the brain, absorptive areas of the intestine, and filtration areas of the kidneys.

Under what general conditions would fluid move into a capillary?

Fluid moves into a capillary (reabsorption) whenever blood colloid osmotic pressure (BCOP) is greater than capillary hydrostatic pressure (CHP).

Briey describe general patterns of blood vessel organization.

General patterns of blood vessel organization include 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; and (3) tissues and organs are usually serviced by several arteries and veins.

What is the function of hemangioblasts?

Hemangioblasts remodel blood islands first into capillary networks and then into larger arterial and venous networks.

In a healthy person, where is blood pressure greater: in the aorta or in the inferior vena cava? Explain

In a healthy person, blood pressure is greater in the aorta than in the inferior vena cava. If the pressure were higher in the inferior vena cava than in the aorta, blood would flow in the reverse direction.

Explain the equation R ∝ 1/r 4

The equation R α 1/r4 states that resistance (R) is inversely proportional to the fourth power of the vessel radius (r). This means that a small change in vessel diameter results in a large change in resistance.

Name the first two branches of the common iliac artery

The first two branches of the common iliac artery are the internal iliac artery and the external iliac artery.

A blood clot that blocks the popliteal vein would interfere with blood flow in which other veins?

The plantar venous arch delivers blood to the anterior tibial, posterior tibial, and fibular (peroneal) veins.

The plantar venous arch carries blood to which three veins?

The plantar venous arch delivers blood to the anterior tibial, posterior tibial, and fibular (peroneal) veins.

Whenever Thor gets angry, a large vein bulges in the lateral region of his neck. Which vein is this?

Thor's bulging vein is his external jugular vein.

Define tissue perfusion

Tissue perfusion is blood flow to tissues that is sufficient to deliver adequate oxygen and nutrients.

Calculate the mean arterial pressure for a person whose blood pressure is 125/70.

Using the formula MAP = diastolic pressure + (pulse pressure)/3, MAP equals 70 + (125 - 70)/3, which equals 70 + 18.3, or 88.3 mm Hg.

Why is it beneficial for capillary pressure to be very low?

Very low capillary pressure is beneficial because it allows time for diffusion between the blood and the surrounding interstitial fluid.

Identify the conditions that would shift the balance between hydrostatic and osmotic forces

Any condition that affects either blood pressure or osmotic pressures in the blood or tissues will shift the balance between hydrostatic and osmotic forces.

Which is greater: arterial pressure of venous pressure?

Arterial pressure is much higher than venous pressure because it must push blood a greater distance and through progressively smaller and thinner vessels.

Explain the function of baroreceptor reflexes

Baroreceptor reflexes respond to changes in blood pressure. The baroreceptors—located in the walls of the carotid sinuses and aortic arch—monitor the degree of stretch at those sites. When blood pressure increases, the cardiac centers decrease cardiac output and the vasomotor center is inhibited, resulting in vasodilation; when blood pressure decreases, the cardiac centers increase cardiac output and the vasomotor center is stimulated, resulting in vasoconstriction.

What are blood islands, and from which cells do they form?

Blood islands are aggregations of embryonic cells scattered within the yolk sac that form blood vessels and blood cells. During embryonic development, these islands give rise to hematopoietic stem cells and hemangioblasts.

Describe autoregulation as it relates to cardiovascular function

Cardiovascular autoregulation involves local factors changing the pattern of blood flow within capillary beds in response to chemical changes in interstitial fluids.

Describe circulatory shock, progressive shock, and irreversible shock.

Circulatory shock occurs when blood loss exceeds about 35 percent of the total blood volume. Circulatory shock involves a series of positive feedback loops that are initiated after homeostasis has been disrupted. Progressive shock is the next stage after circulatory shock. It, too, is a series of positive feedback loops that accelerate tissue damage. Irreversible shock is the fatal stage that occurs if the positive feedback loops initiated during progressive shock are not broken.

Identify the compensatory mechanisms that respond to blood loss.

Compensatory mechanisms that respond to blood loss include an increase in cardiac output, a mobilization of venous blood reservoir, peripheral vasoconstriction, and the release of hormones that promote the retention of fluids and the maturation of erythrocytes.

Identify the hormones responsible for short-term regulation of decreasing blood pressure and blood volume

Epinephrine and norepinephrine from the adrenal medullae provide short-term regulation of decreasing blood pressure and blood volume.

Describe the roles of the natriuretic peptides

Excessive stretching of the right atrium during diastole causes the release of atrial natriuretic peptide (ANP). Excessive stretching of the ventricles during diastole causes the release of brain natriuretic peptide (BNP). The roles of these peptides are to trigger responses whose combined effects act to decrease blood volume and blood pressure. As blood volume and blood pressure decrease, natriuretic peptide production ceases.

Why are valves located in veins but not in arteries?

In the arterial system, pressures are high enough to keep the blood moving away from the heart and through arteries and capillaries. In the venous system, blood pressure is too low to keep the blood moving back toward the heart. Valves in veins prevent blood from flowing backward whenever the venous pressure drops.

Grace is in an automobile accident, and her celiac trunk is ruptured. Which organs will be affected most directly by this injury?

Rupturing the celiac trunk would most directly affect the stomach, inferior portion of the esophagus, spleen, liver, gallbladder, and proximal portion of the small intestine.

Describe the structure and function of the cerebral arterial circle

The cerebral arterial circle (also known as the circle of Willis) is a ring-shaped anastomosis that encircles the infundibulum of the pituitary gland. Its anatomical arrangement creates alternate pathways in the cerebral circulation, so that if blood flow is interrupted in one area, other blood vessels can continue to perfuse the entire brain with blood.

Describe the function of the hepatic portal system, and name its primary vessel

The function of the hepatic portal system is to carry blood with absorbed nutrients from the digestive organs to the liver for processing. The primary vessel of the hepatic portal system is the hepatic portal vein.

Name the immediate and long-term problems related to hemorrhage

The immediate, short-term problem during hemorrhage is to maintain adequate blood pressure and peripheral blood flow; the long-term problem is to restore normal blood volume.

Which vessel collects most of the venous blood inferior to the diaphragm?

The inferior vena cava collects most of the venous blood inferior to the diaphragm.

Name the veins that drain the dural sinuses of the brain.

The internal jugular veins drain the dural sinuses of the brain.

Describe the pulmonary circuit

The pulmonary circuit transports blood from the right ventricle through the pulmonary arteries, capillaries in the lungs, and pulmonary veins and returns it to the left atrium.

Describe the respiratory pump

The respiratory pump is a mechanism by which a reduction of pressure in the thoracic cavity during inhalation assists venous return to the heart.

Which chamber of the heart receives blood from the systemic circuit?

The right atrium receives blood from the systemic circuit.

describe the systemic circuit

The systemic circuit transports blood through the arteries, capillaries, and veins of the body from the left ventricle to the right atrium. Blood returning to the heart from the systemic circuit must complete the pulmonary circuit before it re-enters the systemic circuit.

List the factors that contribute to total peripheral resistance.

Total peripheral resistance reflects a combination of vascular resistance, vessel length, vessel luminal diameter, blood viscosity, and turbulence.

Compare a ventricular septal defect with tetralogy of Fallot

Ventricular septal defects are abnormal openings between the left and right ventricles. Tetralogy of Fallot includes a ventricular septal defect plus three other heart defects: a narrowing of the pulmonary trunk, a displaced aorta, and an enlarged right ventricle with corresponding thickened right and left ventricles.

Trace the path of a drop of blood from the right forearm to the right atrium.

right forearm S right brachial S right axillary S right subclavian S right brachiocephalic S superior vena cava S right atrium.

Trace a drop of blood through the lungs, beginning at the right ventricle and ending at the left atrium

right ventricle S pulmonary trunk S right and left pulmonary arteries S pulmonary arterioles S alveoli S pulmonary venules S pulmonary veins S left atrium.