Arteries and Veins Anatomy PDF

# Introduction of anatomy ## Sinusoids - Similar to capillaries but have the following features: - Large irregular lumens. - Wall contains pores and is surrounded by incomplete basement membrane. - Present in the liver, spleen and bone marrow. ## Capillary or Sinusoid? - **Capillary:*...

# Introduction of anatomy ## Sinusoids - Similar to capillaries but have the following features: - Large irregular lumens. - Wall contains pores and is surrounded by incomplete basement membrane. - Present in the liver, spleen and bone marrow. ## Capillary or Sinusoid? - **Capillary:** Continuously lined with blood cells. - **Sinusoid:** Direct contact between blood and hepatocytes (liver cells). ## Arteriovenous shunt - Between small arteries and accompanying veins. ## Capillaries - Microscopic vessels that form a network immediately following arterioles and connecting them with the venules. - Wall is formed of one layer of cells surrounded by continuous basement membrane with no muscle layer. - Uniform, narrow diameter and form anastomotic networks in all tissues called capillary bed. ## End Arteries - Do not anastomose with adjacent arteries. - Obstruction will lead to death (necrosis) of the tissues supplied by them. - Examples: - Central retinal artery - Renal artery - Splenic artery - Central branches of cerebral arteries - Pulmonary arteries ## Veins - Carry blood from all regions of the body to the heart. - Carry deoxygenated blood except the pulmonary and umbilical veins, which carry oxygenated blood. - Classified into superficial and deep veins, according to the relation to deep fascia. ## Factors which help venous return: - **From upper part of the body:** drained mainly by gravity - **From lower part of the body:** - **From lower limb:** - Venous valves - Arterial pulsations - Muscular contractions (muscle pump) - Deep fascia surrounding the muscle groups - Negative intrathoracic pressure drawing blood from the abdomen, head and neck into thorax. ## Blood Vessels ### Arteries - Carry blood from the heart to other regions of the body. - Carry oxygenated blood except the pulmonary and umbilical arteries, which carry deoxygenated blood. - Classified according to their size and structure into: large, medium-sized and small arteries. ### Arterial Anastomosis - **Definition:** Connection between the arteries, which is present mainly around the joints. - **Functions:** - Increases the blood supply to some organs e.g. stomach. - Equalizes pressure in the communicating arteries. - Maintains the blood flow to an area or part of the body if its main artery is obstructed. ### Types of arterial anastomoses: - **End to End Anastomosis:** - Two ends of 2 arteries are connected together forming an arch. - Example: Anastomosis in the hand and foot. **Image Description:** The image shows labeled diagrams of a capillary, a fenestrated capillary, a sinusoidal capillary (discontinuous capillary), and a magnified view of a capillary and sinusoid. The image also includes information about capillaries and sinusoid, as well as an illustration of the arteriovenous shunt. The image has various labels identifying different parts of the vessels and the function of the shunt.