7.2 Part 2

Veins: Function

• Veins generally carry deoxygenated blood from the body to the heart, where it can be sent to the lungs.
• The pulmonary veins are an exception, carrying oxygenated blood from the lungs to the heart.
• Capillaries consist of a single layer of endothelium and facilitate nutrient and gas exchange with tissues.

Types of Veins: Structural and Functional

• Postcapillary Venules: Receive blood from capillaries and empty into venules, with lower pressure than capillaries or tissues.
• Venules: Continue to move blood away from capillaries and eventually unite to form veins. They contain valves preventing retrograde blood flow.
• Veins: The major vessels of the venous system, responsible for returning blood to the heart.

Types of Veins: Anatomical Location

• Superficial veins: Located under the skin (subcutaneous).
• Deep veins: Located underneath the deep fascia, often accompanying major arteries.

Superficial Veins: Upper Limb

• Hand: Superficial palmar arch.
• Forearm: Cephalic vein, Basilic vein, and Median (cubital) forearm vein.
• Median cubital vein: Clinically significant for venipuncture (blood drawing) and intravenous cannulation.
• Arm: Cephalic vein and Basilic vein.

Superficial Veins: Lower Limb

• Foot: Dorsal planter arch.
• Leg: Great and small saphenous vein.
• Thigh: Great saphenous vein.

Varicose Veins: Lower Limb

• Dilated segments of veins associated with valvular incompetence (inefficient valves).
• Incompetent valves allow blood to flow from the deep venous system to the superficial system.
• Can cause cosmetic issues, aching, or itching.
• Treatment options include vein ligation.

Deep Veins: Lower Limb and Deep Vein Thrombosis (DVT)

• Deep veins lie underneath the deep fascia, accompanying major arteries.
• Deep vein thrombosis (DVT): Blood clot formation within deep veins of the lower limb, causing blockage.
• Symptoms of DVT: pain, swelling, and tenderness in the affected limb.
• Pulmonary embolism: A major complication of DVT where the thrombus dislodges and travels to the lungs, potentially preventing blood from returning to the heart.

Functions of Veins

• Veins typically carry deoxygenated blood from the body to the heart.
• Pulmonary veins are an exception; they carry oxygenated blood from the lungs to the heart.
• Capillaries consist of a single layer of endothelium, which allows for efficient nutrient and gas exchange with tissues.

Types of Veins (Structural/Functional)

• There are three main types of veins:
  • Postcapillary venules: Receive blood from capillaries and empty into venules. Their pressure is lower than capillaries and surrounding tissues.
  • Venules: Connect with postcapillary venules and continue moving blood away from capillary beds. Many venules join to form a vein. They have valves that prevent backflow of blood.
  • Veins: The major vessels of the venous system, responsible for returning blood to the heart.

Types of Veins (Anatomical Location)

• Veins are categorized into two types based on their location:
  • Superficial veins (subcutaneous): Located near the skin's surface.
  • Deep veins: Located deeper within the body, often accompanying arteries.

Superficial Veins (Upper Limb)

• Veins of the upper limb are divided into deep veins (accompanying arteries) and superficial veins.
• Hand: Superficial palmar arch.
• Forearm: Cephalic vein, Basilic vein, and Median (cubital) forearm vein.
  • Median cubital vein: Clinically relevant for venipuncture (blood drawing) and intravenous cannula insertion.
• Arm: Cephalic vein and Basilic vein.

Superficial Veins (Lower Limb)

• Veins of the lower limb are also categorized into deep and superficial veins.
• Foot: Dorsal planter arch.
• Leg: Great and small saphenous vein.
• Thigh: Great saphenous vein.

Varicose Veins (Lower Limb)

• Varicose veins are dilated segments of veins associated with valvular incompetence.
• They result from incompetent valves, allowing blood flow from deep to superficial venous systems.
• Initially presenting as cosmetic issues, they can cause aching or itching.
• Treatment options include vein ligation.

Deep Veins (Lower Limb and DVT)

• Deep veins are located beneath the deep fascia of the lower limb, alongside major arteries.
• Deep vein thrombosis (DVT) is the formation of blood clots within the deep veins of the lower limbs, obstructing blood flow.
• DVT causes pain, swelling, and tenderness in the affected limb.
• The primary complication of DVT is pulmonary embolism: Dislodged thrombus travels to the lungs, blocking blood flow and potentially leading to death.

Summary

• Veins generally carry deoxygenated blood towards the heart.
• Veins are classified based on function (postcapillary venules, venules, veins) and location (superficial and deep).
• Varicose veins occur in the superficial veins and are caused by valvular incompetence.
• Deep vein thrombosis (DVT) occurs in the deep veins and can lead to pulmonary embolism.

Test your knowledge on the function, structure, and types of veins in the human body. This quiz covers important aspects of superficial and deep veins, along with the role they play in the circulatory system. Dive into the details of venous return and associated anatomical locations.