Anatomy of Arteries in Peripheral Vascular System

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Questions and Answers

What is the primary function of the smooth muscle tone in arterioles?

To contribute to the propagation of blood flow

To determine systemic vascular resistance (correct)

To facilitate diffusion of oxygen and carbon dioxide

To regulate blood pressure

What is the characteristic of the endothelial lining in capillaries?

It facilitates rapid diffusion of oxygen and carbon dioxide (correct)

It has a diameter of 20 to 100 μm

It has a thick layer of smooth muscle

It is highly elastic

What is the result of anastomoses between branching networks of smaller arteries when an artery is obstructed?

Formation of collateral circulation (correct)

Formation of new capillaries

Increased blood pressure

Reduced blood flow to the affected area

What is the diameter of capillaries?

7 to 8 μm Signup and view all the answers

What type of arteries are the coronary and renal arteries?

Medium-sized muscular arteries Signup and view all the answers

What is the primary function of the elastic recoil in large- and medium-sized arteries?

To contribute to the propagation of blood flow and arterial pulsatile flow Signup and view all the answers

What is the function of the vasa vasorum in the media layer of an artery?

To provide blood supply to the media Signup and view all the answers

What is the initial step in the development of atherosclerosis?

Injury to vascular endothelial cells Signup and view all the answers

What is the function of the adventitia in an artery?

To provide a barrier against the external environment Signup and view all the answers

What occurs when atheromatous plaque forms in the coronary arteries?

Acute myocardial infarction Signup and view all the answers

What is the role of mononuclear phagocytes in the development of atherosclerosis?

To mature into macrophages and ingest lipids Signup and view all the answers

What is the purpose of the internal elastic membrane?

To separate the intima from the media Signup and view all the answers

What is the composition of the media layer of an artery?

Smooth muscle cells with elastic properties Signup and view all the answers

What is the consequence of atheromatous plaque formation in the carotid arteries?

Stroke Signup and view all the answers

Where is the femoral artery palpable in the legs?

Just below the inguinal ligament, midway between the anterior superior iliac spine and the symphysis pubis Signup and view all the answers

What is the posterior tibial artery protected by?

An interconnecting arch between its two chief arterial branches Signup and view all the answers

What is a potentially life-threatening condition that can result from occlusion of the mesenteric arteries?

Acute mesenteric ischemia Signup and view all the answers

Where is the popliteal artery located?

Deep in the knee, behind the femur Signup and view all the answers

Where is the dorsalis pedis artery located?

On the dorsum of the foot just lateral to the extensor tendon of the big toe Signup and view all the answers

Where is the brachial artery located in the arm?

At the bend of the elbow just medial to the biceps tendon Signup and view all the answers

Which artery is not palpable in the abdomen?

All of the above Signup and view all the answers

What is the primary function of the celiac trunk?

To perfuse the liver, gallbladder, and pancreas Signup and view all the answers

Which artery perfuses the jejunum and ileum?

Superior mesenteric artery Signup and view all the answers

What is the purpose of the two vascular arches in the hand?

To doubly protect circulation to the hand and fingers from arterial occlusion Signup and view all the answers

Which part of the large intestine is perfused by the inferior mesenteric artery?

Descending and sigmoid colon Signup and view all the answers

What percentage of circulating blood flow can veins contain?

Two-thirds Signup and view all the answers

What is the function of the unidirectional valves in peripheral veins?

To promote venous return to the heart Signup and view all the answers

Which veins drain into the portal vein?

Veins from the abdominal viscera Signup and view all the answers

What is the consequence of the weaker wall structure of leg veins?

Irregular dilatation, compression, and ulceration Signup and view all the answers

What is the role of the hepatic artery in the liver?

To supply oxygenated blood to the liver Signup and view all the answers

Where do veins from the arms, upper trunk, and head drain?

Into the superior vena cava Signup and view all the answers

What percentage of venous return from the lower extremities is carried by the deep veins?

90% Signup and view all the answers

Which superficial vein originates on the lateral side of the foot?

Small saphenous vein Signup and view all the answers

What is the function of the one-way valves in the deep, superficial, and perforating veins?

To prevent pooling and venous stasis Signup and view all the answers

Which lymphatic duct drains fluid from the right side of the head, neck, thorax, and right upper limb?

Right lymphatic duct Signup and view all the answers

What is the primary function of the lymphatic system?

To drain lymph fluid from body tissues and return it to the venous circulation Signup and view all the answers

Where do the superficial veins receive relatively poor tissue support?

In the subcutaneous tissues of the leg Signup and view all the answers

What is the name of the vein that joins the femoral vein of the deep venous system below the inguinal ligament?

Great saphenous vein Signup and view all the answers

What helps to propel blood upward against gravity in the venous system?

Contraction of the calf muscles Signup and view all the answers

Study Notes

Structure of Arteries

Arteries consist of three concentric layers of tissue: intima, media, and adventitia.
Intima is the innermost layer, a single continuous lining of endothelial cells.
Media is composed of smooth muscle cells with elastic properties.
Adventitia is the outer layer, containing connective tissue, nerve fibers, and vasa vasorum.

Atherosclerosis

Atherosclerosis is a chronic inflammatory disease initiated by injury to vascular endothelial cells.
Injury leads to atheromatous plaque formation, triggered by circulating cholesterol particles (LDLs) and proteoglycans from the extracellular matrix.
LDLs undergo oxidative modification, leading to a local inflammatory response and attracting mononuclear phagocytes.
Phagocytes mature into macrophages, ingest lipids, and become foam cells that develop into fatty streaks.

Effects of Atherosclerosis

Thrombi in coronary arteries can result in acute myocardial infarction.
Thrombi in carotid arteries can dislodge and travel to the brain, resulting in stroke.

Arterial Branching

Arteries vary in size and anatomy according to their distance from the heart.
Large, highly elastic arteries (e.g., aorta, common carotid, and iliac arteries) course into medium-sized muscular arteries (e.g., coronary and renal arteries).
Medium-sized arteries divide into small arteries (<2 mm in diameter) and arterioles (20-100 μm in diameter).
Arterioles are responsible for systemic vascular resistance, a major component of blood pressure.

Capillaries

Capillaries are the smallest blood vessels, with a diameter of a single red blood cell (7-8 μm).
Capillaries have an endothelial cell lining, but no media, facilitating rapid diffusion of oxygen and carbon dioxide.
Anastomoses between branching networks of smaller arteries can increase in size to form collateral circulation, perfusing structures distal to an occlusion.

Arterial Pulses

Arterial pulses are palpable in arteries close to the body surface.

Pulses in the Arms and Hands

Locate pulsations in the brachial artery at the bend of the elbow just medial to the biceps tendon.
Find pulsations in the radial artery on the lateral flexor surface.
Identify pulsations in the ulnar artery on the medial flexor surface (although overlying tissues may obscure pulsations).
Two vascular arches within the hand interconnect the radial and ulnar arteries, protecting circulation to the hand and fingers from arterial occlusion.

Pulses in the Abdomen

Locate pulsations of the aorta in the epigastrium.
Celiac trunk supplies blood to the esophagus, stomach, proximal duodenum, liver, gallbladder, pancreas, and spleen (foregut).
Superior mesenteric artery supplies blood to the small intestine (jejunum, ileum, cecum), large intestine (ascending and transverse colon, right splenic flexure) (midgut).
Inferior mesenteric artery supplies blood to the large intestine (descending and sigmoid colon, proximal rectum) (hindgut).

Pulses in the Legs

Palpate pulsations in the femoral artery just below the inguinal ligament, midway between the anterior superior iliac spine and the symphysis pubis.
Find pulsations in the popliteal artery, an extension of the femoral artery that passes medially behind the femur, palpable just behind and deep in the knee.
Identify pulsations in the posterior tibial (PT) artery, which lies behind the medial malleolus of the ankle.
Locate pulsations in the dorsalis pedis (DP) artery on the dorsum of the foot just lateral to the extensor tendon of the big toe.

Importance of Arterial Pulses

Despite a rich collateral network, occlusion of the mesenteric arteries can result in acute mesenteric ischemia, a potentially life-threatening condition.

Characteristics of Veins

Thin-walled and highly distensible, allowing them to contain up to two-thirds of circulating blood flow
Nonthrombogenic endothelium in the venous intima
Unidirectional valves in peripheral veins promote venous return to the heart
Media contains circumferential rings of elastic tissue and smooth muscle that change vein caliber in response to minor changes in venous pressure

Venous Return

Veins from the arms, upper trunk, and head and neck drain into the superior vena cava
Veins from the abdominal wall, liver, lower trunk, and legs drain into the inferior vena cava
Veins from the abdominal viscera drain into the portal vein, which supplies ~75% of blood flow to the liver
Blood from the portal vein flows into the hepatic sinusoids, then drains into the hepatic veins that empty into the inferior vena cava

Leg Veins

Susceptible to irregular dilatation, compression, ulceration, and invasion by tumors due to weaker wall structure
Require special attention due to their vulnerability

Venous System

Deep veins of the legs carry approximately 90% of the venous return from the lower extremities and are well supported by surrounding tissues.
Superficial veins are subcutaneous and have relatively poor tissue support.
The great saphenous vein originates on the dorsum of the foot, passes anterior to the medial malleolus, and joins the femoral vein below the inguinal ligament.
The small saphenous vein begins on the lateral side of the foot, passes upward along the posterior calf, and joins the deep venous system in the popliteal fossa.

Blood Flow and Valves

Competent one-way valves in the deep, superficial, and perforating veins propel blood toward the heart, preventing pooling, venous stasis, and backward flow.
Contraction of the calf muscles during walking serves as a venous pump, propelling blood upward against gravity.

Lymphatic System

The lymphatic system is an extensive vascular network that drains lymph fluid from body tissues and returns it to the venous circulation.
Lymphatic capillaries originate in extracellular spaces, collecting tissue fluid, plasma proteins, cells, and cellular debris via their porous endothelium.
The right lymphatic duct drains fluid from the right side of the head, neck, thorax, and right upper limb, emptying into the junction of the right internal jugular and subclavian veins.
The thoracic duct collects lymph fluid from the rest of the body, emptying into the junction of the left internal jugular and subclavian veins.
Lymph fluid is filtered through lymph nodes interposed along the way.

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Description

Learn about the structure and layers of arteries, including the intima, media, and adventitia, and understand the role of atherosclerosis in vascular disease.