BIO10004 WK7

• Arteries


  Carry blood away from the heart
• Types of arteries


  • Elastic arteries
  • Muscular arteries
  • Arterioles

  
• Elastic arteries


  • Nearest the heart (aorta and pulmonary arteries)
  • Contain much more elastic tissue in the tunica media than muscular arteries
  • Allow them to maintain a relatively constant pressure gradient despite the constant pumping action of the heart

  
• Muscular arteries


  • Medium-sized arteries that draw blood from an elastic artery and branch into small arteries and arterioles
  • Walls contain larger number of smooth muscles, allowing them to contract (vasoconstriction) and expand (vasodilation) depending on peripheral blood demand

  
• Arterioles


  • Considered as the primary resistance vessels as they distribute blood flow into capillary beds
  • Provide approximately 80% of the total resistance to blood flow through the body
  • Constriction increases resistance, decreasing blood flow to downstream capillaries and increasing blood pressure
  • Dilation decreases resistance, increasing blood flow to downstream capillaries and decreasing blood pressure

  
• Parts of the aorta

  • Ascending aorta
  • Aortic arch
  • Descending - Thoracic aorta
  • Abdominal aorta

  
• Aortic arch


  • Section of the aorta between the ascending and descending aorta
  • Main branches supply head, neck and upper limb

  
• Main branches of the aortic arch

  • Brachiocephalic trunk
  • Left common carotid artery
  • Left subclavian artery

  
• Branches of the brachiocephalic trunk

  • Right common carotid artery
  • Right internal carotid artery
  • Right external carotid artery
  • Right subclavian artery
  • Right vertebral artery

  
• Branches of the left common carotid artery

  • Left internal carotid artery
  • Left external carotid artery

  
• Branches of the left subclavian artery

  • Left vertebral artery

  
• Abdominal aorta


  • Continuation of the thoracic aorta
  • Begins at the diaphragm, runs down to where it ends by splitting into two common iliac arteries
  • Supplies oxygenated blood to all of the abdominal and pelvic organs and the legs

  
• Single (unpaired) branches of the abdominal aorta

  • Coeliac artery (trunk)
  • Superior mesenteric artery
  • Inferior mesenteric artery

  
• Paired branches of the abdominal aorta


  • Suprarenal arteries
  • Renal arteries
  • Gonadal arteries

  
• Hypertension


  Also known as high blood pressure, a condition in which the blood vessels have persistently raised pressure

  
• Hypertension


  • Blood pressure is created by the force of blood pushing against the walls of blood vessels (arteries) as it is pumped by the heart
  • The higher the pressure, the harder the heart has to pump
  • A serious medical condition that can increase the risk of heart, brain, kidney and other diseases
  • A major cause of premature death worldwide, with upwards of 1 in 4 men and 1 in 5 women having the condition

  
• Abdominal aortic aneurysm


  • Occurs when a lower portion of the aorta becomes weakened and bulges
  • A ruptured aneurysm can cause massive internal bleeding, which is usually fatal
• The most common symptom of a ruptured aortic aneurysm is sudden and severe pain in the abdomen
• Functions of veins


  • Generally, carry deoxygenated blood from the body to the heart
  • Exception: pulmonary veins carry oxygenated blood from the lungs to the heart
• Capillaries


  Consist of one layer of endothelium, specially adapted to provide a short diffusion distance for nutrient and gas exchange with the tissues
• Types of Veins (structural/functional)

  • Postcapillary Venules
  • Venules
  • Veins

  
• Postcapillary Venules


  Receive blood from capillaries and empty into venules, have lower pressure than capillaries or tissue

  
• Venules


  Continuous with postcapillary venules, move blood away from capillary beds, contain valves that restrict retrograde blood transport
• Veins


  Major vessels of the venous system, final step in return of blood to the heart

  
• Types of Veins (anatomical location)

  • Superficial veins (subcutaneous)
  • Deep veins

  
• Superficial veins of upper limb

  • Grouped into deep veins accompanying arteries, and superficial veins
  • Hand: Superficial palmar arch
  • Forearm: Cephalic, Basilic, Median (cubital) veins
  • Arm: Cephalic, Basilic veins

  
• Median cubital vein


  Clinically relevant for venepuncture and IV cannula

  
• Superficial veins of lower limb

  • Foot: Dorsal plantar arch
  • Leg: Great and small saphenous veins
  • Thigh: Great saphenous vein

  
• Varicose veins


  Dilated segments of vein associated with valvular incompetence, arise from incompetent valves allowing blood flow from deep to superficial veins

  
• Varicose veins (lower limb)


  • Initially cause cosmetic issues, then aching or itching
  • Treatment options include vein ligation

  
• Deep veins (lower limb)


  Located underneath deep fascia, accompany major arteries

  
• Deep vein thrombosis (DVT)


  • Formation of blood clot within deep veins of lower limbs, causing vessel blockage and local pain, swelling, tenderness
  • Main complication is pulmonary embolism - thrombus becomes dislodged and travels to pulmonary circulation, preventing blood return to heart

  
• Heart


  A muscular organ that pumps blood through the arteries and veins, sending oxygen and nutrients to all parts of the body and carrying away carbon dioxide and waste products
• Heart


  • Located in the mediastinum, posterior to the sternum
  • Surrounded by the pericardium, a fibrouserous membrane that covers the heart and great vessel roots
  • Has four chambers: right atrium, right ventricle, left atrium, left ventricle

  
• Function of the heart

  1. Receives deoxygenated blood from the body in the right chambers

  2. Pumps this blood to the lungs for gas exchange

  3. Receives oxygenated blood from the lungs in the left chambers

  4. Pumps this oxygenated blood to the body
• Cardiac chambers


  • Atria are thin-walled chambers that receive blood from the veins
  • Ventricles are thick-walled chambers that forcefully pump blood out of the heart
• Pericardium


  • Fibrouserous membrane
  • Has two layers: fibrous pericardium and serous pericardium
  • Pericardial cavity is the potential space between the two layers, containing a small amount of fluid
• Layers of the heart

  • Endocardium (outer thin layer of fat and connective tissue)
  • Myocardium (cardiac muscle)
  • Epicardium (serous pericardium)

  
• Shape of the heart

  • Conical shape
  • Apex mostly formed by left ventricle
  • Base is the posterior aspect
• Cardiac conduction system


  • Sinoatrial (SA) node (intrinsic pacemaker)
  • Atrioventricular (AV) node
  • AV bundle (bundle of His)
  • Right and left bundle branches
  • Purkinje fibres