Blood Vessel Structure and Function

 The Blood Vessels 5 main types  Arteries – carry blood AWAY from the heart - Muscular and Elastic  Arterioles - Resistance vessels.  Capillaries – exchange vessels.  Venules: collecting and site for WBC leave  Veins – carry blood TOWARDS the heart 33 Pulmonary and Systemic Circulation - 2 circuits in series  Pulmonary circuit       Right side of heart Receives blood from systemic circulation Ejects blood into pulmonary trunk then pulmonary arteries Gas exchange in pulmonary capillaries Pulmonary veins takes blood to left atrium Systemic circuit       Left side of heart Receives blood from lungs Ejects blood into aorta Systemic arteries, arterioles Gas and nutrient exchange in systemic capillaries Systemic venules and veins lead back to right atrium 34 35 Major Blood Vessels of the Thorax The Major Arteries The Aorta Is the largest artery in the body Arises from the LV Brachiocephalic artery  Divided into 4 parts: 1. Ascending aorta 2. Arch of aorta 3. Descending Thoracic aorta 4. Abdominal aorta 36 Important Branches (In the Thorax):  Ascending Aorta: 1. Right Coronary artery 2. Left Coronary artery  Arch of aorta: 1. Brachiocephalic trunk a. Right Subclavian artery b. Right Common Carotid artery 2. Left Common Carotid Artery 3. Left Subclavian Artery  Descending Thoracic Aorta: Gives various branches 1. Intercostal spaces 2. Diaphragm 3. Pericardium 4. Esophagus 5. Bronchi 37 38 39 40 The Pulmonary Trunk Arises from the RV  Divided into the Right and Left Pulmonary arteries which pass into the corresponding lung  The pulmonary trunk is connected to the arch of aorta by the ligamentum arteriosum. This is the remnant of the ductus arteriosus which shunted blood from the pulmonary trunk to the aorta during fetal life thus bypassing the lung41 The Major Veins (Thoracic)  Blood from the thoracic region is collected by the azygos system: Accessory hemizygous V Hemizygous V Azygos V  The azygos vein eventually arches forwards to enter the superior vena cava which drain into Right Atrium 42 The Brachiocephalic veins: They drain blood from the head, neck and upper limbs. They unite to form the Superior Vena Cava (SVC) which opens into the Right Atrium. The Pulmonary Veins: 4 Veins (2 from each lung) that carry oxygenated blood from the lung to the Left Atrium of the heart. The Inferior Vena Cava (IVC) : This is formed in the abdomen (L5) and its terminal part enters the thorax (through the diaphragmT8) to open into the Right Atrium. 43 44 Major Blood Vessels of the Head and Neck The Major Arteries The Carotid Arteries  The right and left common carotid arteries are responsible for supplying blood to structures in the head and neck (not all)  They ascend superiorly in the neck where they are closely related to the internal jugular vein.  About the level of the upper border of the thyroid cartilage (Adam’s Apple), each artery divides into the External and Internal Carotid arteries  External carotid branches supply almost all structures in the head and neck except the brain …… 45 47 Branches of External Carotid Structures supplied Facial Structures in the face Lingual The tongue Others  The Internal Carotid supplies the brain and various other structure (the eye, the forehead, and part of the nose).  The brain is supplied by the two internal carotid and the two vertebral arteries (branches of subclavian arteries). The four arteries anastomose on the inferior surface of the brain and form the circle of Willis (circulus arteriosus). 48 Circle of Willis 49 50 51 The Subclavian Arteries  The right and left subclavian arteries arch laterally from their origins  At the outer border of the first rib they become the axillary artery  The scalenus anterior muscle divide the artery into 3 parts  They give off several branches (e.g. vertebral artery) that supply various structure in the head (brain), the neck and even the chest. 52 53 The Major Veins All blood from the brain (and related structures) will drain into Sinuses (enlarged veins). These sinuses will eventually drain into the Internal Jugular vein (IJV).  The IJV is formed inside the skull, leave the skull by passing through the jugular foramen and descend through the neck in close relation to the internal carotid and common carotid arteries.  Blood from the neck drain into both IJV and the External Jugular vein (EJV). The IJV will unite with Subclavian vein to form the brachiocephalic vein.  The external jugular (EJV) will drain into the subclavian vein. 54 55 Major Blood Vessels of the Upper Limb The Major Arteries The Axillary Artery  It’s the direct continuation of the Subclavian artery when it passes the lateral border of the first rib  The Pectoralis minor muscle divides the artery into 3 part  Its several branches supply surrounding structures Pectoralis minor Teres major  At the lower border of the Teres major muscle, it becomes the Brachial artery 56 The Brachial Artery  It’s the direct continuation of the Axillary artery when it passes the lower border of the Teres major muscle  Its branches supply surrounding muscles, the humerus and the elbow joint  It terminates at the neck of the radius by dividing into the radial and ulnar arteries  The brachial artery passes medial to the tendon of the biceps muscle where it’s superficial. This is the site for taking the brachial pulse and measuring the blood pressure 57 58 The Radial and Ulnar Arteries  The radial artery passes down on the lateral aspect of the forearm. The ulnar passes on the medial side. They enter the palm where they form the superficial and deep palmar arches.  The radial and ulnar arteries supply structures in the forearm. The two palmar arches supply structures in the hand and fingers.  The radial artery is superficial as it passes over the wrist. It’s here that the radial pulse can be felt. 59 60 The Major Veins  In the upper limb, we have superficial and deep veins.  Most of the deep veins are in the form of two small veins (venae comitantes) accompanying the arteries The superficial veins run just under the skin. They start as a network on the dorsum of the hand to from: 1. Basilic veins unites with the venae comitantes of the brachial artery to form the axillary veins (a large deep vein accompanying the axillary artery) (teres major muscle). 2. Cephalic vein will drain into Axillary vein. 3. Axillary vein becomes the subclavian vein when passing the outer border of the first rib to inter neck 61 Median cubital vein Ante cubital fossa 62 Major Blood Vessels of the Abdomen The Major Arteries The Abdominal Aorta  The abdominal aorta is the continuation of the descending thoracic aorta. It begins where the aorta passes through the diaphragm to enter the abdominal cavity opposite T12  The abdominal aorta (left) is closely related to the vertebral column and the IVC (right)  It terminates opposite L4 by dividing into the two Common Iliac Arteries 63 Structures supplied Branch Celiac trunk Superior Mesenteric artery Lower part of esophagus Stomach Pancreas Spleen Liver and biliary system Proximal part of duodenum Distal part of duodenum Pancreas Jejunum and Ileum Appendix Cecum, Ascending Colon and right ½ of transverse colon Inferior Mesenteric artery Left ½ of transverse colon Descending Colon, Sigmoid Colon Rectum Upper part of Anal Canal Suprarenal arteries Adrenal glands Renal arteries Others Kidneys 65 66 The Major Veins  All Blood from the abdomen drains ultimately into the IVC IVC starts at L5 then it passes upwards close to the abdominal aorta (Right), then passes through the diaphragm at level of T8 to enter the thorax where it open into the RA The blood from the digestive organs (esophagus, stomach, small and large intestines, Pancreas and spleen) drains first into the Portal vein then into 67 liver then hepatic vein then IVC into RA 68 Major Blood Vessels of the Lower Limb The Major Arteries  Each common iliac artery soon divide to give the internal and external iliac arteries  The internal iliac artery supplies structures in the pelvis  The external iliac artery pass into the thigh where it becomes the Femoral artery  The femoral artery gives branches that supply structures in the thigh and the knee joint  When this artery reaches the knee joint it becomes known as the Popliteal artery. The branches of this artery supply structures in the leg and foot 69 71 72 The Major Veins  Here we have deep and superficial veins.  The deep veins are venae comitantes. Some large deep veins correspond to the larger arteries The superficial veins are: a. The Great Saphenous Vein which drains into the femoral vein b. The Small Saphenous vein which drains into the Popliteal vein 73 74