VENOUS SYSTEM Chapter 13 Cardiovascular System

Venous System Returns blood to the heart after blood and body cells exchange gases, nutrients, and wastes.

Characteristics of Venous Pathways: Begin as capillaries, merge into venules, merge into small veins which merge into larger ones. Form irregular networks, hard to follow, name like arteries are Large veins typically follow parallel to arteries  Renal vein is parallel to renal artery All veins merge into two major pathways:  Superior and Inferior vena cava which dump into Right atrium

Veins from the Brain, Head and Neck External Jugular Veins:  Drain blood from the face, scalp, and superficial regions of neck  Empty into subclavian veins Internal Jugular Veins  Larger than external jug.  unions of the subclavian and external jugular form large brachiocephalic vein  Merge into superior vena cava

Veins from the Upper Limb and Shoulder Basilic Vein  Forearm to middle of the arm and joins brachial vein which forms to make axillary vein Cephalic vein  Hand to shoulder, empties at shoulder into axillary vein which then becomes subclavian.

Vein from the Abdominal and Thoracic Wall Azygos Vein  Drains most of the muscular tissue in the abdominal and thoracic walls and enters superior vena cava

Veins from the Abdominal Viscera Veins usually carry blood directly to the atria of the heart but those that drain the abdominal viscera are exceptions Originate in the capillary networks of the stomach, intestines, pancreas and spleen Carry blood from these organs through a portal vein to the liver.

Hepatic Portal System Includes:  R and L gastric veins from stomach  Superior Mesenteric vein from the small intestine, ascending colon, and transverse colon  Splenic vein from a convergence of several veins draining the spleen, pancreas, and parts of stomach  Largest tributary, inferior mesenteric vein, brings blood from the descending colon, sigmoid colon and rectum.

Hepatic Portal System Cont. 80% of blood flowing to liver comes from capillaries in stomach and intestines and is oxygen poor but rich in nutrients. Hepatic Veins:  After liver is done with blood these veins empty into the inferior vena cava and return blood to general circulation.

Veins from Lower Limb and Pelvis Veins follow same name as arteries and flow backwards of arteries Small Saphenous Vein  Ascends along back of calf and enters popliteal fossa to join the popliteal vein Great Saphenous Veins:  Longest veins in body  Starts at the maleolus and extends upwared along medial side of leg and thigh, joins femoral vein Lower extremities flow into the inferior vena cava before re-entering the heart.

Veins to Know! Brachiocephalic R and L Subclavian R and L Gastric Celiac Splenic Portal R and L Renal Gonadal Sup. And Inf. Mesenteric Lumbar R and L. Common Iliac Vertebral Cephalic Superior and Inferior Vena Cava Azygos Basilic Facial Axillary Brachial Radial Ulnar Internal and External Iliac Femoral Popliteal Anterior Tibial Posterior Tibial External and Internal Jugular Superficial Temporal Great Saphenous Small Saphenous