M14-15

• Pulmonary Vessels


  Transport blood from right ventricle of heart through lungs & back to the left atrium

  
• Systemic Vessels


  Transport blood from left ventricle through all parts of body and back to right atrium

  
• Major Functions of Circulatory System


  • Carries blood
  • Exchanges nutrients, waste products, and gases with tissues
  • Transports substances
  • Helps regulate blood pressure
  • Directs blood flow to the tissues
• Three Layers of Blood Vessel Walls / Tunics

  • Tunica Intima
  • Tunica Media
  • Tunica Adventitia
• Tunica Intima


  Innermost layer; composed of endothelium consisting of simple squamous epithelium, basement membrane & small amount of connective tissue
• Tunica Media


  Middle layer; consists of smooth muscles cells arranged circularly around the blood vessel
• Tunica Adventitia


  Outermost layer; composed of dense connective tissue adjacent to the tunica media; tissue becomes loose connective tissue toward the outer portion of blood vessel wall
• Three Main Types of Blood Vessels

  • Arteries
  • Capillaries
  • Veins
• Arteries


  Carry blood away from the heart; usually oxygenated
• Elastic Arteries


  • Largest diameter & have thickest walls; composed of greater portion of elastic tissue & smaller portion of smooth muscle (ex: aorta & pulmonary trunk); stretch when the ventricles pump blood
  • Function: elastic recoil prevents blood pressure from falling rapidly & maintains blood flow while ventricles are relaxed
• Muscular Arteries


  • Medium-sized (distributing arteries), relatively thick & tunica intima has thin elastic connective tissue; contain smooth muscle tissue to control blood flow to different body regions
  • Vasoconstriction – contraction of smooth muscle, decreases blood vessel diameter & blood flow
  • Vasodilation – relaxation of smooth muscles, increases blood vessel diameter & blood flow
• Arterioles


  Transport blood from small arteries to capillaries; smallest arteries adapted for vasodilation & vasoconstriction
• Capillaries


  Blood flow here from arterioles; where the diffusion or exchange of gases, substances, and other waste products of occurs between the blood & tissue fluid
• Precapillary Sphincters


  Smooth muscles cells located at the origin of capillary branches that regulate the amount of blood flow through various sections of the network
• Veins


  Carry blood toward the heart; usually deoxygenated; increase in diameter & decrease in number as progressing toward the heart

  
• Venules


  Diameter slightly larger than capillaries; composed of endothelium resting on a delicate connective tissue layer; all tunics are present
• Valves


  Similar in shape to semilunar valves consisting of folds in tunica intima, forming two flaps; many valves also in medium-sized veins & lower limbs
• Blood Vessels of System Circulation: ARTERIES

  • Aorta
  • Brachiocephalic Artery
  • Internal & External Carotid Arteries
  • Vertebral Arteries

  
• Aorta


  Where arteries of systemic circulation branch directly or indirectly; considered in three parts: Ascending Aorta, Aortic Arch, Descending Aorta
• Branches of Descending Aorta

  • Thoracic Aorta
  • Abdominal Aorta
• Visceral Arteries (Thoracic Aorta)


  • Posterior Intercostal Arteries
  • Superior Phrenic Arteries
• Parietal Arteries (Thoracic Aorta)


  • Inferior Phrenic Arteries
  • Lumbar Arteries
  • Median Sacral Artery
• Unpaired Branches (Abdominal Aorta)

  • Celiac Artery
  • Superior Mesenteric Artery
  • Inferior Mesenteric Artery
• Paired Branches (Abdominal Aorta)


  • Renal Arteries
  • Suprarenal Arteries
  • Testicular Arteries/Ovarian Arteries
• Brachiocephalic Artery


  Extends a short distance & then branches at the level of clavicle to form: Right Common Carotid Artery, Right Subclavian Artery

  
• Internal Carotid Arteries


  Pass through carotid canals & contribute to the cerebral arterial circle (circle of Willis), supply blood to most of the brain
• Carotid Sinus


  Located at its base which contains baroreceptors
• External Carotid Arteries


  Have branches that supply the structures of neck, face, nose, & mouth
• Vertebral Arteries


  Branch from subclavian arteries; supply blood to spinal cord, vertebra, muscles & ligaments of neck & some blood to the brain

  
• Basilar Artery


  Forms in union of vertebral arteries; located along anterior, inferior surface of brainstem; gives off branches that supply blood to pons, cerebellum, & midbrain; contributes to circle of Willis
• Arteries of the Upper Limbs


  • Axillary Artery
  • Brachial Artery
  • Ulnar Artery
  • Radial Artery
• Arteries of the Pelvis and Lower Limbs


  • Femoral Artery
  • Popliteal Artery
  • Anterior & Posterior Tibial Artery
  • Dorsalis Pedis Artery
  • Fibular Artery / Peroneal Artery
• Femoral Triangle


  Important access point for medical procedures & where pulse in femoral artery can be palpated; located in superior & medial area of thigh
• Superior Vena Cava


  Returns deoxygenated blood from head, neck, thorax, & upper limbs to right atrium
• Inferior Vena Cava


  Returns deoxygenated blood from the abdomen, pelvis, & lower limbs to right atrium
• Veins of the Head & Neck


  • External Jugular Veins
  • Internal Jugular Veins
  • Brachiocephalic Veins
• Femoral Artery


  • Branches off from external iliac artery
  • Supplies the thigh
• Popliteal Artery


  • Supplies the knee
  • Located in popliteal space
• Anterior & Posterior Tibial Artery


  • Supply blood to the leg and foot
• Dorsalis Pedis Artery


  • Rises from anterior tibial artery
  • Supplies the ankle