Blood vessels and hemodynamics

• What are the 3 parts the tunica intima?

  answer below

  A) simple squamous epithelium

  B) basement membrane

  C) internal elastic membrane

  
• what are the 2 parts of the tunica media?

  answer below

  A) circular smooth muscle

  B) External elastic membrane

  
• what is the main part of the tunica externa?

  answer below

  A) elastic and collagen fibers

  
• What stimulates vasoconstriction?

  SNS inervating vascular smooth muscle.

  
• what causes vasospasm?


  injury to artery or arteriole, reducing blood loss

  
• Whats the difference between vasoconstriction and vasospasm?

  Vasoconstriction is the narrowing of blood vessels, while vasospasm is a sudden and intense contraction of blood vessels.

  
• Vasodilation is stimulated by…

  SNS, NO, K, H, lactic acids and chemicals, inflammation
• elastic arteries contain an abundance of elastic fibers in….

  tunica media
• muscular arteries are also called

  distributing arteries
• muscle arteries contain more___ in the tunica media

  smooth muscle
• cappillaries are mostly found in

  in tissue with high metabolic rates (muscles, liver, kidneys, brain)
• how is blood flow regulated within the capillaries?

  by metarterioles, and precapillary sphinctors
• When pre-capillary sphincters close, what is the result?

  thoroughfare channel
• What is vasomotion?

  intermittent blood flow through capillary bed
• true or false - vasomotion occurs 5-10 times every minute. 


  true
• what are the types of capillaries?

  continueous, fenestrated, sinusoid
• characteristics of continous capillaries

  • endothelium interupted only by intracellular cleft.
  • found in skeletal muscle, smooth muscle, CT, lungs
• characteristics of fenestrated capillaries

  • many small holes in endothelial cell membrane
  • found in kidneys, endocrine glands.

  
• characteristics of sinusoid capillaries?

  large lumen

  very large fenestrations, and intercellular cleft

  incomplete basement membrane

  allows proteins and blood cells to pass

  in red bone marrow, liver, spleen
• what is special about venules?

  • thin tunica media
  • porous endothelium
  • allows phagocytic WBC to leave during inflammation
• What is the difference in the tunica media of venuLes?

  No elastic membrane, thinner than arteries
• What is the thickest layer of a vein?

  Tunica externa
• veins are distensible, meaning…

  Adapt to changes in blood pressure and volume
• Venous sinuses have no 


  Smooth muscle in their wall
• 64% of blood volume is in 


  Systemic veins and venules
• What functions as blood reservoirs?

  Capacitance vessels.
• During diffusion, what is unable to pass through?

  Large proteins
• What are lipid-soluble substances?

  O2, CO2, Steroids (pass through endothelial cell membranes)
• What are water soluble substances?

  Glucose, amino acids (pass through fenestrations)
• Is transcytosis efficient?


  No
• What is transcytosis? 


  Moving material one by one through vesicles by endocytosis or exo
• what is an example of transcytosis? 


  Passing large molecules to the fetus through placenta circulation.
• What is involved in bulk flow?

  Filtration and Reabsorption
• Filtration moves fluid from

  Blood to interstitial space
• Reabsorption is promoted by

  Blood colloid osmotic pressure, tissue hydrostatic pressure
• NFP = 


  (BHP + IFOP) - (BCOP - IFHP)
• ___ % filtered fluid is returned to the capillaries by osmosis

  85
• __% extra fluid is returned to lymphatic capillaries, then the blood.

  15
• Every time an artery branches…

  Blood flow is slower.
• Blood flow in the aorta is

  40 cm/sec