BLOOD VESSELS

• Blood vessels outside the heart

  • Pulmonary vessels
  • Systemic vessels
• Pulmonary vessels


  Transport blood from the right ventricle of the heart through the lungs and back to the left atrium
• Systemic vessels


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

  
• Blood vessel functions


  • Carry blood
  • Exchange nutrients, waste products, gases within tissues
  • Transport substances
  • Regulate blood pressure
  • Direct blood flow to tissues

  
• Arteries


  • Carry blood away from heart
  • Thick with a lot of elastic tissue
• Veins


  • Carry blood toward heart
  • Thick with less elastic tissue

  
• Capillaries


  • Exchange occurs between blood and tissue fluids
• Blood flow


  1. Arteries to arterioles

  2. Arterioles to capillaries

  3. Capillaries to venules

  4. Venules to small veins

  5. Veins return to heart

  
• Blood vessel wall layers

  • Tunica intima (innermost)
  • Tunica media (middle)
  • Tunica adventitia (outermost)

  
• Tunica intima


  • Simple squamous
• Tunica media


  • Smooth muscle with elastin and collagen fibers
• Tunica adventitia


  • Connective tissue
• Types of arteries


  • Elastic arteries
  • Muscular arteries

  
• Elastic arteries


  • Largest in diameter
  • Thickest walls
  • Example - aorta and pulmonary trunk

  
• Muscular arteries


  • Medium to small size
  • Thick in diameter
  • Contain smooth muscle cells
  • Can control blood flow to body regions

  
• Capillaries


  • Blood flows from arterioles into capillaries
  • Capillaries branch to form networks
  • Blood flow is regulated by smooth muscle cells, precapillary sphincters

  
• Types of veins


  • Small veins
  • Medium sized veins
  • Large veins
• Small veins


  • All 3 tunics are present
• Medium sized veins


  • Collect blood from small veins and deliver to large veins
• Large veins


  • Contain valves
• Pulmonary circulation


  Blood vessels that carry blood from right ventricle to lungs and back from left atrium of heart

  
• Pulmonary trunk


  Carries blood from right ventricle towards lung
• Pulmonary veins


  Exit lungs and carry O2 rich blood to left atrium
• Systemic circulation


  Carries blood from the left ventricle to the tissues of the body and back to the right atrium

  
• Parts of the aorta

  • Ascending
  • Aortic arch
  • Descending
• Ascending aorta


  Passes superiorly from left ventricle
• Aortic arch


  Contains 3 major arteries which carry blood from aorta to head and upper limbs

  
• Descending aorta


  Extends through thorax and abdomen to pelvis
• Further parts of the aorta

  • Thoracic
  • Abdominal
• Thoracic aorta


  Part of descending aorta that extends through thorax to diaphragm
• Abdominal aorta


  Descending aorta that extends from diaphragm where it divides at the common iliac arteries

  
• Brachiocephalic artery


  • First branch off aortic arch
  • Supplies blood to right side of head and neck

  
• Left common carotid artery

  • 2nd branch off aortic arch
  • Supplies blood to the left side of head and neck

  
• Left subclavian artery


  • 3rd branch off aortic arch
  • Supplies blood to left upper limbs

  
• Right common carotid artery

  • Branches off brachiocephalic artery
  • Supplies blood to right side of head and neck

  
• Right subclavian artery


  • Branches off brachiocephalic artery
  • Supplies blood to right upper limbs

  
• Cerebral arterial circle


  Provides alternative blood supply to brain

  
• Axillary arteries


  Continuation of subclavian in the axilla (armpits)

  
• Brachial arteries


  • Continuation of axillary artery that extends into the arm
  • Where blood pressure measurements are taken

  
• Ulnar arteries


  • Branch of brachial artery
  • Near elbow