Chapter 21: Peripheral Vascular and Lymphatic System

Peripheral Vascular System

Its main functions are to: 

• Deliver oxygen and nutrients to tissues. 

• Remove carbon dioxide and metabolic waste. 

• Maintain adequate circulation to the arms, legs, and other tissues. 

• Return blood to the heart. 

Arteries

Carry blood away from the heart

Higher pressure

Thick, muscular, and elastic

Generally do not have valves along the peripheral vessels

Reduced blood supply to tissues

Peripheral arterial disease

Veins

Return blood toward the heart

Lower pressure

Thinner and more distensible

Many have valves to prevent backflow

Poor return of blood to the heart

Chronic venous insufficiency or DVT

Capillaries

tiny blood vessels where the exchange of oxygen, nutrients, fluids, and waste occurs between blood and tissues.

Deep veins

Carry most of the blood returning from the legs; include the femoral and popliteal veins

Superficial veins

Located closer to the skin; include the great and small saphenous veins

Perforating veins

Connect superficial veins to deep veins and help direct blood toward the deep system

How blood returns to the heart

1. Skeletal muscle contraction: Leg muscles squeeze the veins and push blood toward the heart. 

2. Breathing: Pressure changes in the chest and abdomen help move blood toward the heart. 

3. Venous valves: Prevent blood from flowing backward. 

Inmobility

When a person sits or lies in one position for a long time, the calf muscles do not contract as frequently. Blood can pool in the veins, increasing the risk of venous stasis and DVT.

Lymphatic System

1. Return excess fluid and proteins from the tissues to the bloodstream. 

2. Support immune defense against infections and other harmful substances. 

3. Absorb certain dietary fats from the small intestine. 

Lymph

fluid collected from the spaces between the body's cells.

Lymphatic vessels

• Begin as tiny, open-ended capillaries in the tissues. 

• Collect excess interstitial fluid. 

• Join into larger vessels. 

• Contain valves that help keep lymph moving in one direction. 

• Eventually drain into the venous circulation near the subclavian veins. 

Lymph nodes

Their functions include: 

• Filtering lymph. 

• Trapping microorganisms and other foreign material. 

• Supporting immune responses through lymphocytes. 

When an infection or inflammation occurs, nearby lymph nodes may become enlarged or tender. 

Spleen

Filters blood, removes old red blood cells, stores blood cells, and supports immune responses

Tonsils

Help defend against pathogens entering through the respiratory and gastrointestinal tracts

Thymus

Supports T-lymphocyte development, especially during childhood

Peripheral Arterial Disease (PAD)

occurs when arteries supplying the limbs become narrowed or obstructed, commonly because of atherosclerosis.

Important risk factors include: 

• Smoking. 

• Diabetes mellitus. 

• Hypertension. 

• Elevated cholesterol. 

• Obesity. 

• Physical inactivity. 

• Chronic kidney disease. 

• Family history of cardiovascular disease. 

Atherosclerosis

involves the buildup of fatty plaques in artery walls. The narrowing reduces blood flow and limits the amount of oxygen delivered to tissues.

Intermittent claudication

muscle pain or cramping caused by inadequate blood flow during activity.

Common characteristics: 

• Usually affects the calf, although other muscle groups may be involved. 

• Begins during walking or exercise. 

• Improves with rest. 

• Often occurs after a relatively predictable walking distance. 

Ischemic rest pain

Rest pain occurs when arterial circulation is severely reduced. 

Possible findings: 

• Pain at rest, especially at night. 

• Pain that worsens when the leg is elevated. 

• Pain that improves when the foot is lowered or dangled. 

• Cool skin. 

• Diminished or absent pulses. 

• Poorly healing wounds. 

Six Ps of acute arterial ischemia

1. Pain 

2. Pallor 

3. Pulselessness 

4. Paresthesia: Tingling or altered sensation. 

5. Poikilothermia: The affected limb becomes unusually cool. 

6. Paralysis: Loss of movement or weakness. 

Chronic Venous Insufficiency

when the veins have difficulty returning blood toward the heart. Venous valves may become incompetent, allowing blood to flow backward and pool in the lower extremities.

Risk factors 

• Prolonged standing or sitting. 

• Obesity. 

• Multiple pregnancies. 

• Increasing age. 

• Varicose veins. 

• Previous DVT. 

• Reduced mobility. 

Varicose veins

are enlarged, dilated, and tortuous superficial veins. 

They occur when increased venous pressure and incompetent valves allow blood to pool in the veins. 

Possible symptoms include: 

• Aching. 

• Heaviness. 

• Cramping. 

• Burning. 

• Swelling. 

• Fatigue in the legs. 

arterial disease

Blood cannot adequately reach tissues

Venous disease

Blood does not return efficiently to the heart

Deep Vein Thrombosis (DVT)

occurs when a blood clot forms in a deep vein, commonly in the lower extremity.

The clot interferes with venous blood flow and may cause inflammation and swelling.

Venous stasis

Blood flow slows down

Prolonged bed rest

Hypercoagulability

Blood is more likely to clot

Cancer or certain clotting disorders

Endothelial injury

The vessel lining is damaged

Surgery or trauma

Virchow's triad

describes three major factors that promote clot formation.

Lymphedema

swelling caused by impaired lymphatic drainage, resulting in the accumulation of protein-rich fluid in the tissues.

Arterial ulcers

• Often occur on the toes, heels, or pressure points. 

• May have a dry, pale base. 

• Usually have well-defined edges. 

• May be very painful. 

• May occur with cool skin and diminished pulses. 

Venous ulcers

• Often occur near the medial ankle. 

• May have irregular edges. 

• Often appear shallow and moist. 

• May occur with edema, varicose veins, and brown skin discoloration. 

• Pain may worsen with prolonged standing and improve with elevation. 

Neuropathic ulcers

These are associated with loss of protective sensation, often due to diabetes-related neuropathy.

They commonly develop at pressure points and may go unnoticed because the patient cannot feel pain normally.