Human Anatomy - Cardiovascular System - Blood Vessels and Hemodynamics (PDF)

7 Human Anatomy Chapter 14: The Cardiovascular System: Blood Vessels and Hemodynamics 1 Part I STRUCTURE AND FUNCTION OF BLOOD VESSELS 2 5 main types of blood vessels ◼ Arteries – carry blood AWAY from the heart ◼ Arterioles...

7 Human Anatomy Chapter 14: The Cardiovascular System: Blood Vessels and Hemodynamics 1 Part I STRUCTURE AND FUNCTION OF BLOOD VESSELS 2 5 main types of blood vessels ◼ Arteries – carry blood AWAY from the heart ◼ Arterioles ◼ Capillaries – site of exchange ◼ Venules ◼ Veins – carry blood TO the heart 3 4 Basic structure of blood vessel ◼ The wall of a blood vessel consists of three layers, or tunics ❑ Tunica interna (innermost) ◼ Inner lining, Endothelium continuous with endocardial lining of heart ❑ Tunica media (middle) ◼ Muscular and connective tissue layer ◼ Smooth muscle regulates diameter of lumen ❑ Tunica externa (outermost) ◼ Elastic and collagen fibers ◼ Modifications account for 5 types of blood vessels and their structural/ functional differences 5 6 Arteries ◼ Three layers of typical blood vessel ◼ Thick muscular-to-elastic tunica media ◼ High compliance – walls stretch and expand in response to pressure without tearing ❑ Vasoconstriction – decrease in lumen diameter ❑ Vasodilation – increase in lumen diameter ◼ Elastic arteries and muscular arteries 7 Elastic Arteries ◼ Largest arteries ◼ Largest diameter but walls relatively thin ◼ Function as pressure reservoir ❑ Help propel blood forward while ventricles relaxing ❑ Also known as conducting arteries – conduct blood to medium-sized arteries 8 Muscular Arteries ◼ Tunica media contains more smooth muscle and fewer elastic fibers than elastic arteries ◼ Walls relatively thick ◼ Capable of great vasoconstriction/ vasodilatation to adjust rate of blood flow ◼ Also called distributing arteries 9 Arterioles ◼ Abundant microscopic vessels ❑ Metarteriole: the terminal end of the arteriole ❑ Metarteriole has precapillary sphincter which monitors blood flow into capillary ◼ Sympathetic innervation and local chemical mediators can alter diameter and thus blood flow and resistance ◼ Also called resistance vessels – resistance is opposition to blood flow ❑ Vasoconstriction can raise blood pressure 10 Arteries, Capillaries, and Venule 11 Capillaries ◼ Smallest blood vessels connect arterial outflow and venous return ◼ – flow from metarteriole through capillaries and into postcapillary venule ◼ Also called Exchange vessels – primary function is exchange between blood and interstitial fluid ❑ lack both a tunica media and a tunica externa ❑ capillary walls are composed of only a single layer of endothelial cells and a basement membrane 12 ◼ Capillary beds – a network of capillaries that arises from single metarteriole ❑ Vasomotion – intermittent contraction and relaxation of the smooth muscle of metarterioles and the precapillary sphincters ❑ Thoroughfare channel – bypasses capillary bed ◼ Portal vein – blood passes through second capillary bed (details in slides 83-86) ❑ Hepatic or hypophyseal 13 14 15 Capillary lack tunica media and tunica externa Three types of Capillaries 1. Continuous ❑ Endothelial cell membranes from continuous tube 2. Fenestrated ❑ Have fenestrations or pores 3. Sinusoids ❑ Wider and more winding(pores) ❑ Unusually large fenestrations 16 Venules ◼ Thinner walls than arterial counterparts ◼ Postcapillary venules – smallest venules; ❑ Form part of microcirculatory exchange unit with capillaries ◼ Muscular venules have thicker walls with 1 or 2 layers of smooth muscle 17 Veins ◼ In general, very thin walls in relation to total diameter; Not designed to withstand high pressure ◼ Same 3 layers ❑ Tunica interna thinner than arteries ❑ Tunica media thinner with little smooth muscle ❑ Tunica externa thickest layer ◼ Valves – folds on tunica interna forming cusps ❑ Aid in venous return by preventing backflow ◼ Types of veins ❑ Anastomotic veins ❑ Superficial veins ❑ Deep veins 18 Venous Valves 19 Vascular anastomoses ◼ Vessels communicating with each other ◼ Veins have more than arteries ◼ Form alternative pathways or collateral channels ◼ Protect organs from being supplied by just one route ❑ Poor anastomoses & therefore vulnerable: central artery of retina, kidneys, spleen, bone diaphyses ◼ Vasa vasorum ❑ Means vessels of the vessels ❑ Blood supply to vessel itself ❑ Smallest vessels don’t need 20 21 Artery All system arteries branch from the Aorta ◼ Ascending aorta – first portion ◼ Aortic arch ◼ Descending aorta ❑ Thoracic aorta– within the thorax ❑ Abdominal aorta – within the abdomen 28 29  Aorta ◼ Ascending aorta ❑ Right and left coronary arteries ❑ Originate from base of aortic sinus ◼ Aortic arch ❑ Brachiocephalic trunk – first branch ◼ Right common carotid ◼ Right subclavian ❑ Left common carotid a– second branch ❑ Left subclavian a -- third branch ◼ Descending aorta ❑ Thoracic and abdominal aortas 30 31 32 33 Head and Neck ◼ Internal carotid a ◼ External carotid a ◼ Vertebral a ◼ Basilar a– formed by the fusion of the vertebral arteries 34  Head and Neck ◼ Cerebral arterial circle (Circle of Willis) ❑ Posterior cerebral a ❑ Posterior communicating a ❑ Middle cerebral a ❑ Anterior cerebral a ❑ Anterior communicating a Functions: supplying most of brain, equalizing blood pressure to the brain, and providing alternate routes for blood flow to the brain. 35 36 Upper limb From left and right subclavian arteries ◼ Axillary a – continuation of the subclavian ❑ Shoulder, thoracic and scapular muscles, and humerus ◼ Brachial a – continuation of the axillary ❑ arm ◼ Ulnar a– branch of the brachial ❑ Medial part of forearm, wrist and hand ◼ Radial a – branch of the brachial ❑ Lateral part of forearm, wrist and hand 37 Upper Limb ◼ Axillary a – continuation of the subclavian ◼ Brachial a– continuation of the axillary ◼ Ulnar a– branch of the brachial ◼ Radial a– branch of the brachial 38 Thoracic and abdominal regions From thoracic aorta and abdominal aorta ◼ Intercostal a ◼ Celiac trunk – to stomach, spleen, pancreas, duodenum, esophagus, and liver ◼ Superior mesenteric a – to the small intestine and proximal large intestine ◼ Suprarenal a – to the adrenals ◼ Renal a – to the kidneys ◼ Gonadal a – Testicular or Ovarian ◼ Inferior mesenteric a – to the distal large intestine 39 Thoracic and abdominal region 40 41 42 43 Pelvis and lower limbs ◼ Common iliac a – branches from the inferior end of the abdominal aorta ◼ Internal iliac a – to pelvic structures ◼ External iliac a – to the leg ◼ Femoral a – to the thigh ◼ Popliteal a – to the popliteal region ◼ Anterior tibial a – to the crural region ◼ Posterior tibial a – to the sural region ◼ Fibular a – to the fibular region 44 Pelvis and lower limbs 45 Veins – head and neck ◼ Brachiocephalic v – into sup vena cava ◼ Subclavian v – lateral branch of brachiocephalic ◼ Internal jugular v – medial branch into the brachiocephalic vein ◼ External jugular v – external vein of the neck that returns blood to the subclavian ◼ Sinuses – drain blood from the cranium ❑ Superior sagittal ❑ Inferior sagittal sinus ❑ Transverse, etc 47 48 49 Vagus nerve 50 Upper limb ◼ Axillary v – it is a continuation of the subclavian S◼ Brachial v – continuation of axillary S◼ Basilic v– medial and empties into the brachial S◼ Cephalic v – lateral and empties into the axillary ◼ Median v ◼ Ulnar v ◼ Radial v 51 ◼ Deep vein vs. superficial vein 53 52 Thorax ◼ Azygos – unpaired branch into the superior vena cava. Drains the right side of the thorax. ◼ Hemiazygos, and accessory hemiazygos – 2 sets of multiple veins that empty into the azygos and drain the left side of the thorax. ◼ Intercostals v 54 55 Abdominal veins ◼ Hepatic and hepatic portal v ❑ Superior mesenteric v ❑ Splenic v ◼ Renal v ◼ Gonadal v – testicular or ovarian ❑ Right side empties into inferior vena cava ❑ Left side joins with left renal ◼ Common iliac v – two branches that fuse to become inferior vena cava 56 57 Hepatic portal system ◼ Hepatic portal vein – going to the liver ◼ Liver ◼ Hepatic vein – from the liver to inferior vena cava 58 59 60 Hepatic portal circulation ◼ Portal circulation is a set of vessels that begins and ends with capillary networks. ◼ It returns blood from gastrointestinal organs and the spleen (from superior mesenteric vein and splenic vein) to the sinusoids of liver ◼ Blood in sinusoids drain to hepatic vein and return to the inferior Vena cava 61 62 Lower limb ◼ Internal iliac v ◼ External iliac v ◼ Femoral v ◼ Great saphenous v – medial; into the femoral vein ◼ Popliteal v ◼ Small saphenous v – lateral and posterior; into the popliteal ◼ Anterior tibial v – branch into the popliteal ◼ Posterior tibial v – branch into the popliteal ◼ Fibular v 63 64 Pulmonary Circulation ◼ Pulmonary trunk ◼ Pulmonary artery ◼ Pulmonary vein 66 67 Chapter 15: The Lymphatic System and Immunity 68 Overview of Lymphatic system structure and function ◼ Components of the Lymphatic System ❑ Lymph ◼ once interstitial fluid enter into lymphatic vessels, it is called lymph ❑ Lymphatic vessels ❑ Structures and organs containing lymphatic tissue ❑ Red bone marrow ◼ Functions of the lymphatic system 1. Drain excess interstitial fluid 2. Transport dietary lipid 3. Carry out immune responses 69 Components of the Lymphatic System 70 Lymphatic vessels and lymph circulation ❑ Vessels begin as lymphatic capillaries ◼ Closed at one end ❑ Unite to form large lymphatic vessels ◼ Resemble veins in structure but thinner walls and more valves ❑ Passes through lymph nodes ◼ Encapsulated organs with masses and B and T cells ❑ Lymphatic trunks - named for the region from which they collect lymph ❑ Lymphatic ducts 71 Lymphatic capillaries ◼ Slightly large diameter than blood capillaries ❑ Found everywhere except the CNS, bone marrow, eyes and a part of the spleen ❑ More permeable than blood capillaries, thus larger molecules can enter such as protein ◼ Unique one-way structure ❑ Permits interstitial fluid to flow in but not out ◼ Small intestine has lacteal for dietary lipid uptake (details in digestive system) ❑ Chyle is lymph with lipids 72 Lymphatic Capillaries 73 Lymph trunks and ducts ◼ Lymphatic trunks - named for the region from which they collect lymph ❑ Principal trunks are the lumbar, intestinal, bronchomediastinal, subclavian and jugular ◼ Two Lymphatic ducts ❑ Thoracic duct - begins as cisterna chyli, collects lymph from the left side of head, neck, chest, left arm and entire body below the ribs to drain into the left subclavian vein ❑ Right lymphatic duct - drains the upper right side of the body and drains into the right subclavian vein 74 Routes for drainage of lymph 75 76 Formation and flow of lymph ◼ Excess filtered fluid – about 3L/day – drains into lymphatic vessels and become lymph ◼ Important function of lymphatic vessels to return lost plasma proteins to blood stream ◼ Sequence of fluid flow: ❑ Blood capillaries (blood) →interstitial space (interstitial fluid) →lymphatic capillaries (lymph) →lymphatic vessels (lymph) →lymphatic ducts (lymph) →junction of the internal jugular and subclavian veins (blood) 77 Formation and flow of lymph ◼ Contain valves, ensure the one-way movement of lymph ◼ Same 2 “pumps” aiding venous return also used ❑ Skeletal muscle pump – milking action ❑ Respiratory pump – pressure changes during breathing 78 Relationship of the Lymphatic System to the Cardiovascular System 79 Lymphatic tissues and organs ◼ Two groups based on function 1. Primary lymphatic organs ❑ Sites where stem cells divide and become immunocompetent ❑ Red bone marrow and thymus 2. Secondary lymphatic organs ❑ Sites where most immune response occurs ❑ Lymph nodes, spleen, lymphatic nodules 80 Thymus ◼ T lymphocytes become competent here ◼ Thymus shrinks with age from 70g in infants to 3g in old age 81 Lymph nodes ◼ Surrounded by a capsule ◼ Contains B and T lymphocytes ◼ Lymph nodes function as a filter ❑ Foreign substances trapped ❑ Destroyed by macrophages or immune response of lymphocytes ◼ When the number of microbes is too high, the node enlarges and becomes tender 82 Structure of a Lymph Node 83 84 Principle lymph nodes ◼ Head and neck ❑ Submandibular nodes: nose, mouth, chin, cheeks ❑ Cervical nodes: neck and posterior head ◼ Upper limbs ❑ Axillary nodes: shoulder, upper limb, chest (mammary gland) ◼ Abdomen and Pelvis ❑ Intestinal nodes: intestine ❑ Iliac nodes: Pelvis and gluteal regions ◼ Lower limbs ❑ Inguinal nodes: lower limb and perineal regions 85 Lymphatic nodules ◼ Not surrounded by a capsule. Most small and solitary. ❑ Mucosa-associated lymphatic tissue (MALT) ◼ Scattered throughout lamina propria of mucous membranes lining GI, urinary, reproductive tract and respiratory tract ◼ Some larger – tonsils, Peyer’s patches, appendix ❑ Tonsils: palatine, lingual, pharyngeal ❑ Peyer’s patches: aggregated lymphatic follicles 86 Copyright: pearson education 87 Figure 20.5 Normal tonsil Spleen ◼ Largest lymphatic mass in the body ❑ Lymphatic tissue (White pulp)– ◼ B cells and T cells carry out immune function ❑ Red pulp – ◼ Macrophages remove ruptured, worn out or defective blood cells ◼ Storage of up to 1/3 of body’s platelet supply ◼ Production of blood cells during fetal life ◼ Stores up to 200 ml of blood in adult 89 Structure of the Spleen 90