Blood vessels and lymphatics

• What is Interstitial fluid?


  Fluid that is found in spaces surrounding cells
• What can happen to interstitial fluid

  It can be forced out of blood vessels at the arterial end of capillaries due to hydrostatic pressure

  It can be reabsorbed into the blood vessels at the venous end of the capillaries through oncotic or osmotic pressure
• What is the main role of the lymphatic system?


  To prevent a build up of interstitial fluid by absorbing it and returning it to the venous system
• What is the structure and related function of lymph vessels?

  They have very thin walls made of endothelium - this allows them to absorb the interstitial fluid - known as lymph fluid once in the lymphatic system

  They have many valves within their vessels - prevents back flow of fluid as the lymph system doesn't have its own pump so it relies on the structures surrounding it to return it to the venous system in the neck
• What surrounding structures can help with the lymph fluid return?

  Muscles - contraction of muscles can push the lymph fluid through the vessels

  Arteries - as the heart pumps the arteries contract and can help the movement of lymph fluid

  Thoracic draw - as you breathe a pressure difference is created which can help draw the fluid through the lymph vessels
• With what structures are various lymph vessels associated?

  Superficial lymph vessels are associated with veins

  Deep lymph vessels are normally associated with arteries
• Where does the lymph drain into the venous system?

  In the neck, at the junction between the internal jugular and the subclavian veins
• What can be found along lymphatic vessels?

  Lymph nodes
• What is the function of lymph nodes?

  They act as filters within the immune system

  They contain T and B lymphocytes which recognise antibodies and create an immune response
• Other than creating an immune response, what are lymph nodes involved in?

  The spread of cancer
• What is the process of metastasis


  When malignant cells from primary tumours, detach and are picked up by lymphatic vessels and transported to the lymph nodes where they form a secondary tumour
• How can you predict where cancer will spread?

  If you know where the major lymph vessels and lymph nodes are, you can tell where a malignant cell would travel to to form a secondary tumour

  Also, it is important to know that organs and regions might not drain into the closest lymph node - lymphatic vessels have their own system and pathway
• What is a palpable node?

  A superficial node that, when enlarged, becomes palpable
• What are three groups of nodes that can become palpable and where are they located?

  Cervical nodes - lie in a chain on either side of the neck

  Axillary - lie in the fatty tissue packing the axilla

  Inguinal - lie in the superficial fascia just below the inguinal ligament in the groin
• Name the three different node areas

  Where are the nodes.

  A)

  B)

  C)

  
• What is the order of circulation?


  1. Elastic arteries
  2. Muscular arteries
  3. Capillaries
  4. Venules
  5. Medium veins
  6. Large veins
  7. Continuous capillary
  8. Fenestrated capillary
• Describe the structure of an elastic artery, from outermost layer to innermost 


  • Tunica externa
  • Tunica media
  • Tunica intima
  • internal elastic layer
  • endothelium
• Describe the structure of a muscular artery, from outermost layer to innermost

  • Tunica externa
  • Tunica media
  • Tunica intima
  • Edothelium
• Describe the structure of an arteriole, from outermost layers to innermost

  • tunica media - smooth muscle cells
  • Basal lamina - basement membrane
  • Endothelium
• Describe the structure of a continuous capillary, from outermost layers to innermost

  • Basal lamina
  • Endothelium cells
• Describe the structure of a large vein, from outermost layer to innermost


  • Tunica externa
  • Tunica media
  • Tunica intima
  • Endothelium
• Describe the structure of a medium sized vein, from outermost layer to innermost

  • tunica externa
  • tunica media
  • tunica intima
  • endothelium
• Describe the structure of a venule, from outermost layer to innermost

  • Tunica externa
  • Endothelium
• Describe the structure of a fenestrated capillary, from the outermost layer to innermost 


  • Basal lamina - basement membrane
  • endothelium cells - contains pores - determined 'leaky'
• Describe the differences in structure between veins and arteries


  Within the tunica intima, both contain;

  • endothelium
  • subendothelium layer

  But arteries also contain an internal elastic membrane

  Within in the tunica media, both contain;

  • Smooth muscle and elastic fibres

  But arteries also contain an external elastic membrane

  Within the tunica externa, both contain;

  • Collagen fibres
  • vaso vasorum

  Only veins contain valves - prevent backflow of blood

  
• Describe the tunica intima


  • innermost layer, creates the lumen
  • lined with simple squamous epithelium - endothelium
  • deep to the endothelium is the basal lamina - the basement membrane
  • In larger arteries, there is also an internal elastic membrane to provide additional support and stretch
• Describe the tunica media


  • concentric layers of smooth muscles
  • varying amounts of elastin fibres
  • Thickest layer in arteries, thicker than in veins
  • Contains sympathetic vasomotor nerve fibres - controls blood pressure/flow
  • vasoconstriction - decreases lumen size
  • vasodilation - relaxation
• Describe the tunica externa (adventitia)


  • sheath of longitudinally oriented connective tissue - mostly type 1 collagen fibres and elastin
  • Can be thicker than the tunica media in some arteries
  • contains nerve fibres, lymphatic vessels (and elastic fibres in larger veins)
  • Contains vaso vasorum
• Describe structure and fucntion of the vaso vasorum 


  • network of small blood vessels in the largest vessels - eg the aorta, brachiocephalic and coronary arteries
  • Branch profusely in the externa and outer part of the media
  • Nourish the outer layers and respond to nutrient needs
• Describe the structure and function of elastic arteries


  • large, thick walled arteries near the heart
  • More elastin than other vessels - most in the tunica media
  • Large lumen, low resistance - conducting arteries - conduct the blood from the heart to the the rest of the body
• Name the major blood vessels in this diagram

  A)

  B)

  C)

  D)

  A) A

  B) B

  C) C

  D) D

  E) E

  F) F

  G) G

  H) H

  I) I

  J) J

  
• Describe the structure and function of muscular arteries


  • Thickest tunica media layer
  • In tunica media - have more smooth muscle and less elastic tissue than elastic arteries
  • More active in vasoconstriction
  • regulates blood flow
  • controls distribution to tissues
  • Accommodates to increase in diameter
  • when a principle artery is occluded, collateral muscular arteries will carry blood to the region
  • Can contract to prevent haemorrhage
• Name the upper limb arteries

  The name of the same artery will change depending on the area that the artery is going through.

  A) A

  B) B

  C) C

  D) D

  
• Define arterial anastomosis


  Arterial anastomses provide alternative pathways for blood to supply target areas where the primary arterial pathway is obstructed
• Where can anastromoses be found

  Around all joints
• Name the arteries of the hand and where they are derived from

  • In the hand the deep and superficial palmer arches are derived from both the ulnar and radial arteries
  • The arterial anastomosis ensures supply to the hand and fingers in any position of the upper limb

  A) A

  B) B

  C) C

  D) D

  
• Name the large abdominal arteries

  Ignore the higher arteries branching from the aorta for now

  A) A

  B) B

  C) C

  D) D

  E) E

  F) F

  G) G

  H) H

  
• What is a common trio amongst large arteries, why is this important to know?

  • An artery, vein and nerve
  • Eg - in the groin, the femoral artery lies with its vein medially and the femoral nerve laterally
  • This is important when taking blood or inserting arterial canulae
• Name the arteries of the lower limb (above the knee)

  The picture is landscape

  A) A

  B) B

  C) C

  D) D

  E) E

  F) F

  G) H

  H) I

  
• Name the arteries in the lower limb (below the knee)

  The picture is landscape

  A) A

  B) B

  C) C

  D) D

  E) E