Chapter 19 Blood Vessels and Circulation

Where are chemoreceptors located?

Carotid bodies, aortic bodies and on the ventrolateral surfaces of the medulla oblongata

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

Carry blood with absorbed nutrients from the digestive organs to the liver for processing. Primary vessel- hepatic portal vein

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

Celiac trunk, superior mesenteric artery, and the inferior mesenteric artery

Define edema

An abnormal condition that occurs if the CHP rises or the BCOP decreases, fluid moves out of the blood capillaries and builds up in the peripheral tissues

Identify the compensatory mechanisms that respond to blood loss

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 two veins that carry away blood from the stomach

The left and right gastroepiploic veins

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

The stomach, inferior portion of the esophagus, spleen, liver, gallbladder, and proximal portion of the small intestine

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

The superior vena cava (collects blood from head, chest, and upper limbs) and the inferior vena cava (collects blood from all structures inferior to the diaphragm)

Describe the distribution of total blood volume in the body

The systemic venous system contains nearly 2/3 of total blood volume (64%) The remaining contribution is in the heart (7%) pulmonary circulation (9%) and systemic capillaries (7%)

Explain the function of baroreceptor reflexes

They respond to changes in blood pressure; Baroreceptors are located in the walls or carotid sinuses and aortic arch-monitor the degree of stretch in 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

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

Left ventricle-> ascending aorta->aortic arch->thoracic aorta->abdominal aorta->right common iliac->right external iliac->right femoral-> right deep femoral-> right hip joint

Identify the major branches of the inferior vena cava

Lumbar veins, Gonadal veins, Hepatic veins, Renal veins, Adrenal veins, and Phrenic veins

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

MAP formula- Diastolic pressure + pulse pressure/3 MAP equals 70 + (125-70) /3 70 + 18.3 88.3 mm Hg

Define tissue perfusion

The blood flow through the tissues that is sufficient to deliver adequate oxygen and nutrients

Describe the respiratory pump

A mechanism by which a reduction of pressure in the thoracic cavity during inhalation assists venous return to the heart

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

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

Which is greater, arterial pressure or venous pressure?

Arterial pressure

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 Blood flow is directly proportional to arterial pressure (increased pressure= increased blood flow)& inversely proportional to peripheral resistance (increased resistance = decreased blood flow)

Describe the changes in cardiac output and blood flow during exercise

Cardiac output increases and blood flow to skeletal muscles increase at the expense of blood flow to less essential organs. Unless compensatory vasoconstriction occurs in the less essential organs, vasodilation in skeletal muscles would cause a dangerous decrease in blood flow and blood pressure throughout the body during exercise

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

Name the arterial structure in the neck region that contains baroreceptors

Carotid sinus

Describe circulatory shock, progressive shock, and irreversible shock

Circulatory shock- involves a series of interlocking positive feedback loops that begin when blood loss exceeds about 35 percent of total blood volume Progressive shock- initial stage characterized by positive feedback loops that accelerate tissue damage Irreversible shock- the fatal stage that occurs if the positive feedback loops initiated during progressive shock are not broken

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

Epinephrine ( E) and norepinephrine (NE) from the adrenal medullae

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 the 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

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

External jugular vein

Identify the veins that combine to form the brachiocephalic vein

External jugular, internal jugular, vertebral, and subclavian veins

Describe a capillary

Small blood vessel between an arteriole and a venule, thin walls permit exchange between blood and interstitial fluid by diffusion

Describe 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 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 reenters the systemic circuit

List the five general classes of blood vessels

Arteries, arterioles, capillaries, venules, and veins

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

Name the first two branches of the common iliac artery

Internal iliac artery and external iliac artery

A blockage of which branch of the aortic arch would interfere with blood flow to the left atrium?

Left subclavian artery

Under what general conditions would fluid move into a capillary?

(reabsorption) Whenever blood colloid osmotic pressure (BCOP) is greater than capillary hydrostatic pressure (CHP)

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

An increase in vessel diameter

The plantar venous arch carries blood to which three veins?

Anterior tibial, posterior tibial, and fibular (peroneal) veins

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

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

At what sites in the body are fenestrated capillaries located?

Choroid plexuses of the brain and the capillaries of the hypothalamus, pituitary gland, pineal gland, and thyroid gland. Also located along absorptive areas of the intestinal tract and at filtration sites in the kidneys

Identify the two types of capillaries with a complete endothelium

Continuous capillary and fenestrated capillaries

Distinguish among efferent vessels, afferent vessels and exchange vessels

Efferent vessels are veins that carry blood away from the heart (arteries) Afferent vessels carry blood toward the heart (veins) Exchange vessels interconnect the smallest arteries and smallest veins (capillaries) thin walls allow exchange of nutrients, dissolved gases and wastes between blood and surrounding fluid

Why are valves located in veins but not in arteries?

In the atrial 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

Neural and endocrine regulatory mechanisms influence which factors?

Influence heart rate, stroke volume, peripheral resistance, and venous pressure

Name the three branches of the internal carotid artery

Ophthalmic artery (supplies the eyes), Anterior cerebral artery (supplies frontal & parietal lobes of brain) Middle cerebral artery (supplies the midbrain and lateral surfaces of the cerebral hemispheres)

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

Right atrium

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

Right forearm-> right brachial->right axillary-> right subclavian-> right brachiocephalic-> superior vena cava-> right atrium

Identify the branches of the external carotid artery

Superficial temporal, maxillary, occipital, facial, lingual, and external carotid arteries

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

Superior mesenteric, inferior mesenteric, and splenic veins

Compare a ventricular septal defect with tetralogy of Fallot

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

Identify the largest artery in the body

The aorta

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

The existence of dual (superficial and deep) venous drainage in the neck and limbs

Briefly describe general patterns of blood vessel organization

The peripheral distributions of arteries and veins on the left and right sides are generally identical (except near the heart, largest blood vessels connect) A single vessel may have several names as it crosses specific anatomical boundaries, making anatomical descriptions accurate Tissues and organs are generally serviced by several arteries and veins

What factors are involved in the formation of varicose veins?

The pooling of blood due to gravity and the failure of venous valves

Compare the oxygen content in the two circulatory circuits

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

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

Tibial and fibular veins(form the popliteal vein) and the small saphenous vein (joins popliteal vein)

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

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, The ductus arteriosus persists as the ligamentum arteriosum, umbilical vessels and ductus venosus persist throughout life as fibrous cords

List the factors that contribute to total peripheral resistance

Vascular resistance, viscosity, and turbulence

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

Vasoconstriction would decrease the blood flow and blood pressure at the kidneys. The kidney releases EPO and renin, EPO increases the rate of red blood cell formation which leads to an increase in blood volume. The release of renin would lead to an increase in the level of angiotensin II that would bring about increased blood pressure and increased blood volume

Explain the equation R (infinity sign) 1/r(to the 4th power)

Vessel radius (r) and resistance ( R ) in this equation demonstrate that a small change in luminal vessel diameter produces a large change in resistance

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

Name the veins that drain the Dural sinuses of the brain

Internal jugular veins

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

It allows time for diffusion between the blood and the surrounding intestinal fluid

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

Reduces the CO2 levels

What is the function of hemangioblasts?

Remodel blood islands first into capillary networks and then into larger arterial and venous networks

What is the function of chemoreceptor reflexes?

Respond to changes in carbon dioxide, oxygen, or pH levels in blood and cerebrospinal fluid (CSF) The 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 the pH and oxygen levels meanwhile decreases the carbon dioxide levels

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

Right subclavian artery and the right common carotid artery

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

Right ventricle -> pulmonary trunk -> right and left pulmonary arteries-> pulmonary arterioles-> alveoli-> pulmonary venules-> pulmonary veins-> left atrium

Describe the structure and function of the cerebral arterial circle (Circle of Willis)

Ring shaped anastomosis that encircles the infundibulum of the pituitary gland It creates pathways in the cerebral circulation so that if blood flow is interrupted in one are, other blood vessels can continue to perfuse the entire brain with blood

Name the immediate and long term problems related to hemorrhage

Short term - maintain adequate blood pressure and peripheral blood flow Long term- to restore normal blood volume

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

The aorta. If the pressure were higher in the inferior vena cava than the aorta, blood would flow in the reverse direction

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

The inferior vena cava