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BIO 241: Anatomy & Physiology II > Blood Vessels > Flashcards

Flashcards in Blood Vessels Deck (66)
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What are the layers of a blood vessel?

  1. Tunica Adventitia
  2. Tunica Media (only in arteries)
  3. Tunica Intima


What are the characteristics of the tunica Intima?

Contains the:

  1. Endothelium - simple squamous cells w/ basement membrane
  2. Internal Elastic Lamin - connective tissue to Tunica Media


What are the characteristics of the Tunica Media?


  1. smooth muscle - circular muscle that contracts and squeezes lumen (vasoconstriction or vasodilation for relaxation)

    1. Elastin fibers - for stretch & recoil


What are the characteristics of the Tunica Adventitia?

Outer most layer of the blood vessel


  1. Elastin
  2. Smooth muscle


What are the general properites of arteries?

  1. Contractility
  2. Extensability / Elasticity


What is the general property of arteries, contractility?

  1. Vasoconstriction/Vasodilation controlled by smooth muscle
  2. Controlled by Autonomic nervous system (sympathetic only)
    • Increase frequency of stimulation = increase in norepinephrine = vasoconstriction
    • Decrease frequency of stimulation = decrease in norepinephrine = vasodilation


What is the general property of arteries, Extensibility/Elasticity?

  1. The ability to stretch and recoil
    • allows for pressure changes
      • Vasoconstriction = pressure increase
      • Vasodilation = pressure decrease


How does the Elasticity/Extensibility of Arteries create a pressure reservoir?

Stretch and recoil of arteries allows them to store potential energy (Stretch) and convert it to Kinetic energy (recoil)

  1. During Systole
    • Blood surges into the aorta and causes stretch
  2. During Diastole
    • Drop in blood pressure causes elastin fibers to recoil and push blood forward


What are the types of arteries?

  1. Elastic (large) - conducting artery
  2. Muscular (medium) - distributing artery
  3. Resistance (small)


What are the characteristics of Elastic Arteries?

The LARGE arteries

  1. the blood pressure reservoirs
  2. conducting arteries because they conduct blood away from heart
  3. Lots of smooth muscle to generate force
  4. Less contractility then medium arteries because the circumference of the large arteries is much larger


What are the characteristics of Muscular arteries?

Distributing arteries b/c they distribute to body

  1. Lots of smooth muscle
    • Greater contractility
      • Control where blood is distributed
      • Can cut off blood flow to get it where it's needed (Blood shunting)
  2. Collateral Circulation
    • A preferred route for blood but there are alternative routes to get to the same tissue (anastomoses)


What are the characteristics of the small arteries?

More smooth muscle than elastic arteries

  • like Medium arteries so they can completely shut off blood flow


What are the characteristics of arterioles?

Branching off from small arteries leads to Arterioles which eventually lead to Capillary Bed

  1. Do not have ELASTIN
  2. 1 to 5 layers of smooth muscle
    • The most contractility for vasoconstriction/vasodilation
      • blood shunting to regulate blood flow to tissue


What are the characteristics of capillaries?

  1. Microscopic in size
  2. Distribution in some areas higher than others (skeltal muscle)
  3. Only contains Tunica Intima layer for Exchange
    • Simple squamous cells allow for diffusion w/ interstitial fluid


What are pre-capillary sphincters?

Localized/tissue level control of blood shunting

  1. Just before a arteriole reaches a capillary bed
  2. vasoconstriction/dilation to control blood flow to the capillary bed


What is vasomotion?

blood flow through capillary bed

  1. stop and go motion
  2. sphincter open/closing
  3. at rest occurs 5x/min, during exercise will occur faster ~15x/min


What are the types of capillaries?

  1. Continuous
  2. Fenestrated
  3. Sinusoids


What are the characteristics of continuous capillaries?

  1. Simple squamous cells that overlap
  2. skeletal muscle, lungs, connective tissue
  3. normal capillary


What are the characteristics of Fenestrated capillaries?

arrangement just like continuous capillary but the cells are perforated

  • the perforations are holes through the cell that connect one side of cell to the other side
  • For filtration (think kidneys)


What are the characteristics of Sinusoid capillaries?

Large gaps between the cells

  • most permeable
  • where you need to screen blood for (spleen -screen for pathogens and damaged RBCs and liver - screens for damaged RBCs)


What are the characteristics of Venules/Veins?

  1. Same Basic tunics as arteries (tunica adventitia, tunica media, tunica intima) BUT:
    • Tunica media is much thinner (don't need as much muscle
  2. Larger Lumen
    • Doesn't hold shape due to thinner wall
  3. Very distensible
    • For blood pooling
  4. Valves
    • to prevent back flow


How does Blood pressure influence blood flow?  What are the blood pressures of the arteries vs capillaries vs veins?

Blood flows from area of high pressure to area of low pressure


Arterial Pressure > Capillary Pressure > Veinous Pressure


Explain the concept of blood reservoirs and what role veins play in it?

Majority of blood in body (~60%) is in the veinous system at any given time because of the larger lumen

  1. Skin, liver, spleen

This blood can be shuttled to needed areas during exercise

  1. Vasoconstriction cuts off blood flow to the veins in these areas and forces more blood straight back to heart 
  2. Gets more blood oxygenated and pumped to skeletal muscle


What are the main mechanisms of capillary exchange?

  1. Diffusion
  2. Vesicular Transport
  3. Bulk Flow


What is the method of capillary exchange, diffusion?

  1. occurs directly though the simple squamous cells
  2. follows concentration gradients


What is the method of capillary exchange, vesicular transport?

AKA Transcytosis

  1. Molecule will fuse with cell membrane (invaginates)
  2. forms vessicle which carries molecule to other side
  3. vessicle fuses w/ cell membrane on other side
  4. releases contents on other side of cell


What is bulk flow?

Method of capillary exchange for filtration/reabsorption

STARLINGs Law of the Capillaries (BULK FLOW)

  1. Blood hydrostatic pressure
    • Pressure of fluid pushing against blood vessel walls
  2. BHP drops as blood flows from arteriole through capillary to veinous end
    • Arteriole BHP = 30 mmHg
    • Capillary bed BHP = 20 mmHg
    • Veinous end BHP = 10 mmHg
  3. Blood contains solutes that contribute to osmotic pressure
    • the solutes attract water into capillary
  4. Interstitial fluid has osmotic pressure pulling water out of capillary
    • IF Osmotic pressure = 8 mmHg



What is the Net filtration Pressure of capillary exchange (Starling's Law of Capillaries)?

Net Filtration Pressure

  1. Blood Hydrostatic Pressure (in arterial end) + Interstitial Fluid Osmotic Pressure (Outward force) = 30 mmHg + 8 mmHg = 38 mmHg
  2. Blood Coloid Osmotic Pressure + Interstitial Fluid Hydro Pressure (inward Force) = 28 mmHg + 0 mmHg) = 28
  3. Net Forces = 38- 28 = 10 mmHg pushing out in the arterial end

The only thing that changes as blood flows through blood vessel (artery, capillary, vein) is the Blood hydrostatic pressure

  • The net forces are going to change as blood flows through because of this change

At arterial end = fluid moving out (FILTRATION)

At Capillary = Net Pressure is 0 mmHgAt Veinous end = fluid moving in (REABSORPTION)


What occurs to the fluid that is pushed through the capillary into the interstial fluid during bulk flow?

85% of fluid that got pushed out in arterieal end gets reabsorbed in the veinous end

the other 15% gets pushed into lymphatic system


What determines bulk flow filtration or reabsorption?

Outward Forces

  1. Blood Hydrostatic Pressure (BHP)
    • Arterial End = 30 mmHg
    • Venous End = 10 mmHg
  2. Interstitial Osmotic Pressure (IOP)
    • 8 mmHg

Inward Forces

  1. Interstitial Fluid Hydrostatic Pressure (IFHP)
    • 0 mmHg
  2. Blood Colloid Osmotic Pressure (BCOP)
    • 28 mmHg