Blood Vessels

1
Blood Vessels

• Arteries vessels that carry blood away from
  heart, surrounded by thick layer of smooth
  muscle, high levels of BP
• Capillaries microscopic thin walled vessels
  connect to the smallest veins and arteries
• Veins vessels that carry blood to heart
  surrounded by thin layer of smooth muscle and are
  flaccid, low levels of BP

2
Vessel Wall Layers

• Tunica interna inner of vessel, direct contact
  with blood, secretes chemicals for dilation and
  constriction of the vessel
• Tunica media middle layer, made of smooth muscle
  and elastic fibers to prevent rupture from BP and
  to aid in vasomotion
• Tunica externa covers vessel and anchors it to
  tissue and other vessels

3
Arteries

• Conducting arteries biggest in the body i.e.
  aorta, carotid. Large amounts of elastic fibers
  allow expansion and contraction with each HB
  normalizing BP
• Distributing arteries smaller branches that
  deliver blood to specific organs
• Resistance arteries very little elastic fiber,
  funnel blood to capillaries, smallest called
  arterioles

4
Veins

• Postcapillary venules smallest veins, more
  porous than capillaries allowing fluid exchange
• Muscular venules have a thin layer of smooth
  muscle
• Medium veins have venous valves acting in the
  skeletal muscle pump that resists retrograde flow
  caused by gravity

5
Veins

• Venous sinuses large thin walled vessels found
  in the heart and brain not capable of vasomotion
• Large veins thin tunica media with thick tunica
  externa made of bundles of smooth muscle, (venae
  cavae, pulmonary veins)

6
Blood Pressure

• Flow amount of blood flowing in an organ, tissue
  or vessel in a given time
• Perfusion volume of blood over time per gram of
  tissue
• Blood pressure the pressure exerted on the wall
  of a vessel (120/80)
• Pulse pressure the difference between systolic
  and diastolic pressures

7
Blood Pressure

• Hypertension chronic high BP of 140/90 or higher
  
• Hypotension chronic low BP can be caused by
  blood loss, dehydration, anemia

8
Resistance

• Blood viscosity the thickness of blood can
  increase or decrease blood flow
• Vessel length friction develops with length
• Vasoconstriction narrowing vessel ? BP
• Vasodilation widening of vessel ? BP
• Laminar flow blood in center of vessel travels
  faster than blood along vessel wall