CH. 21: Comprehensive Circulatory System: Blood Vessels, Heart, and Blood Flow Regulation

What is the primary function of the circulatory system?

To carry blood to tissues and facilitate the exchange of substances necessary for homeostasis.

What are the two main types of blood vessels in the circulatory system?

Pulmonary vessels and systemic vessels.

What is the role of pulmonary vessels?

To transport blood from the right ventricle through the lungs to the left atrium.

What is the function of systemic vessels?

To transport blood from the left ventricle through the body to the right atrium.

What substances does the circulatory system transport?

Hormones, immune system components, nutrients, gases, waste products, and enzymes.

How does the circulatory system help regulate blood pressure?

By controlling the degree or volume of blood flow to tissues.

What are the three types of blood vessels?

Arteries, capillaries, and veins.

What is the tunica intima?

The innermost layer of blood vessels, consisting of endothelial cells and a basement membrane.

What is the tunica media?

The middle layer of blood vessels, composed of smooth muscle cells and elastic fibers.

What is the tunica externa?

The outer layer of blood vessels made of connective tissue.

What is vasoconstriction?

The contraction of smooth muscle in blood vessels, decreasing lumen size and blood flow.

What is vasodilation?

The relaxation of smooth muscle in blood vessels, increasing lumen size and blood flow.

What are elastic arteries?

The largest arteries with more elastic tissue than muscle, allowing for elastic recoil.

What are muscular arteries?

Arteries that have thick walls made of smooth muscle, allowing regulation of blood supply.

What are arterioles?

Small arteries that transport blood to capillaries and can undergo vasoconstriction and dilation.

What is the structure of capillaries?

Capillaries have a wall consisting of a single layer of endothelial cells and a basement membrane.

What are continuous capillaries?

Capillaries with narrow intercellular clefts, less permeable to large molecules.

What are fenestrated capillaries?

Capillaries with numerous fenestrae, allowing high permeability, found in places like the intestines.

What are sinusoidal capillaries?

Capillaries with large diameters and fenestrae, allowing large molecules to cross, found in the liver.

What are precapillary sphincters?

Muscle fibers that regulate blood flow into capillary networks.

What is an arteriovenous anastomosis?

A specialized connection allowing blood to flow directly from arterioles to small veins, bypassing capillaries.

What are venules?

Small veins that drain capillary networks and have walls with endothelial cells and some smooth muscle.

What are the classifications of veins?

Venules, small veins, medium veins, and large veins.

What characterizes large veins?

They have a thin tunica intima and a predominant tunica externa.

What are portal veins?

Veins that connect two capillary networks without a pumping mechanism, such as the heart.

What is the hepatic portal vein?

A portal vein that carries nutrient-rich blood from gastrointestinal capillaries to the liver.

What is the hypothalamo-hypophyseal portal system?

A portal system between the hypothalamus and the anterior pituitary gland.

What is the renal nephron portal system?

A portal system within the urine-producing structures of the kidneys.

What structures are found in all veins greater than 2 mm in diameter?

Valves formed by folds in the intima that create two overlapping flaps.

Where are more valves found in veins?

In the veins of the lower extremities compared to the upper extremities.

What are vasa vasorum?

Blood vessels that supply the walls of arteries and veins, penetrating from the exterior.

What type of nerve fibers primarily innervate most blood vessels?

Unmyelinated sympathetic nerve fibers that cause vasoconstriction.

Which blood vessels are innervated by parasympathetic fibers?

The vessels of the penis and clitoris.

What is pulmonary circulation?

The system of vessels that carries blood from the right ventricle to the lungs and back to the left atrium.

What does the pulmonary trunk carry?

Deoxygenated blood from the right ventricle.

What are the two pulmonary veins responsible for?

Carrying oxygenated blood from each lung to the left atrium.

What is systemic circulation?

The system of vessels that carries blood from the left ventricle to body tissues and back to the right atrium.

What are the three parts of the aorta?

Ascending aorta, aortic arch, and descending aorta.

What arteries branch from the aortic arch?

Brachiocephalic artery, left common carotid artery, and left subclavian artery.

What do the common carotid arteries branch into?

Internal carotid arteries (supply the brain) and external carotid arteries (supply the neck and face).

What is the carotid sinus?

A dilation at the bifurcation point of the common carotid arteries that contains baroreceptors.

What do the right and left vertebral arteries supply?

They enter the cranial cavity and join to form the basilar artery, supplying the pons and cerebellum.

What is the function of the cerebral arterial circle (circle of Willis)?

It provides collateral circulation to the brain.

What are the major arteries of the upper limb?

Subclavian artery, axillary artery, and brachial artery.

What arteries arise from the brachial artery?

Ulnar and radial arteries, which supply the forearm.

What do the digital arteries supply?

The fingers and thumb.

What are the visceral branches of the thoracic aorta responsible for?

Supplying portions of the thoracic organs such as lungs and esophagus.

What are the parietal branches of the thoracic aorta responsible for?

Supplying portions of the thoracic wall through intercostal arteries.

What do the anterior intercostal arteries derive from?

Internal thoracic arteries.

What do the posterior intercostal arteries come off of?

Directly from the descending aorta.

What is the function of the superior phrenic arteries?

They supply the diaphragm.

What tissues do the internal thoracic arteries supply?

Diaphragm, mediastinum, pericardium, and anterior thoracic wall.

What do the thyrocervical trunk arteries supply?

The inferior neck and shoulder.

What does the deep brachial artery supply?

The arm and humerus.

What is the role of the basilar artery?

It supplies the cerebellum and pons.

What do the anterior and posterior communicating arteries connect?

They connect the anterior cerebral artery with the posterior cerebral artery.

What is the primary function of the thoracic aorta?

To supply blood to the thoracic organs and tissues.

What are the two main types of branches of the abdominal aorta?

Visceral branches (serving organs) and parietal branches (serving the body wall).

Name a major unpaired branch of the abdominal aorta.

Celiac trunk.

What tissues does the celiac trunk supply?

Stomach, liver, spleen, and pancreas.

Which artery supplies the small intestine and colon?

Superior mesenteric artery.

What is the function of the inferior mesenteric artery?

To supply blood to the descending colon and rectum.

What paired branches supply the kidneys?

Renal arteries.

What are the gonadal arteries responsible for?

Supplying blood to the testes in males and ovaries in females.

What does the internal iliac artery supply?

Pelvic organs such as the urinary bladder, rectum, uterus, and vagina.

What are the branches of the internal iliac artery?

Visceral branches and parietal branches.

What tissues are drained by the external jugular vein?

Superficial surface of the posterior head and neck.

What is the primary function of the internal jugular vein?

To drain blood from the cranial cavity and the anterior head, face, and neck.

What major veins return deoxygenated blood to the right atrium?

Superior vena cava and inferior vena cava.

What is the role of the median cubital vein?

It connects the cephalic vein to the basilic vein and is often used for blood draws.

Which artery becomes the femoral artery?

External iliac artery.

What does the popliteal artery supply?

The knee and leg.

What are the digital arteries responsible for?

Supplying blood to the digits of the foot.

What tissues does the deep femoral artery supply?

Thigh, knee, and femur.

What is the significance of the anterior tibial artery?

It supplies blood to the knee and leg.

What do the suprarenal arteries supply?

The adrenal glands.

What does the term 'visceral branches' refer to?

Branches of arteries that supply organs.

What is the function of the inferior phrenic artery?

To supply the adrenal gland and the inferior surface of the diaphragm.

What is the role of the lumbar arteries?

To supply the lumbar vertebrae and back muscles.

What does the term 'parietal branches' refer to?

Branches of arteries that supply the body wall.

What tissues are drained by the brachiocephalic vein?

Blood from the head, neck, and upper limbs.

What is the primary function of the coronary sinus?

To drain blood from the heart wall through cardiac veins.

What is the function of the external iliac artery?

To supply blood to the lower limbs.

What drains blood from the posterior abdominal wall?

The ascending lumbar veins, which are continuous with the hemiazygos on the left and the azygos on the right.

How does blood from the abdomen and pelvis return to the heart?

Through the inferior vena cava.

What veins drain the pelvis and lower limbs?

The internal iliac veins join the external iliac veins to form the common iliac veins.

What is the function of the hepatic portal system?

It carries blood from most abdominal viscera to the liver.

What does the hepatic portal vein carry?

Blood rich with nutrients collected from the intestines, which may also contain toxic substances.

What is biotransformation in the liver?

The process by which toxic substances can be broken down by hepatocytes or made water-soluble for excretion by the kidneys.

Which veins form the hepatic portal vein?

The superior mesenteric vein, splenic vein, and gastric veins.

What does the inferior mesenteric vein drain?

The large intestine.

What is the longest vein in the body?

The great saphenous vein.

Where does the great saphenous vein originate?

Over the dorsal and medial side of the foot.

What does the small saphenous vein drain?

The superficial posterior leg and lateral side of the foot.

What are the two groups of veins in the lower limb?

Deep and superficial veins.

What do deep foot veins become?

The paired anterior and posterior tibial veins.

What is the role of blood pressure in the circulatory system?

It is the measure of force exerted by blood against the blood vessel walls, driving blood movement.

What is laminar flow?

Streamlined flow where the interior of the blood vessel is smooth and of equal diameter.

What is turbulent flow?

Interrupted flow that occurs when the rate of flow exceeds critical velocity.

What method is used to measure blood pressure indirectly?

The auscultatory method using a sphygmomanometer and stethoscope.