Focus 8 Flashcards
Three types of reconditioning organs
– Digestive organs
– Kidneys
– Skin
Blood volume moving over time. Directly proportional to pressure gradient
Blood flow (F)
Difference in pressure between two ends of vessel. Determines flowrate
Pressure
Measure of the opposition to flow. Friction
Resistance (R)
Resistance depends on (3)
– Blood viscosity
– Vessel length
– Vessel radius (most important)
Elastic pressure reservoir
Arteries
Resistance vessels
Arterioles
Increase surface area. Thin walls exchange materials
Capillaries
Drains capillary beds
Venules
Blood reservoir. Stretch but no recoil
Veins
Altered to match blood flow to tissue demands
Radius and thus resistance
Partial constriction in arterioles (can override to change flow)
Sympathetic tone
Intrinsic factors causing change in radius
Metabolic*
Heat/cold
Extrinsic factors causing change in radius
– Sympathetic
– hormones
Vasodilation intrinsic controls
v O2
^ CO2
^ H+ (v pH)
^ temperature
Vasoconstriction intrinsic controls
^ O2
v CO2
v H+ (^ pH)
v temperature
Helps keep blood flow constant despite wide variations in mean arterial pressure.
Myogenic factors
^ vessel stretch-> constriction
Endothelial cells release in response to metabolic or myogenic factors
Paracrine chemicals
Types of paracrine chemicals (2)
– Endothelin (vasocon)
– Nitric oxide (vasodi)
– Histamine (vasodi)
Organs that receive larger bloodflow than needed and tolerate temporary reductions
Reconditioning organs
Vasopressin hormone
Increases water retention decrease his urine. Vasoconstrictor
Angiotensin hormone
Vasoconstrictor
Aldosterone hormone
Sodium and water retention, decrease urine. Vasoconstrictor
Tends to push fluids out of capillaries into interstitial fluid
Capillary blood pressure
Tends to pull fluids into capillaries from interstitial fluid
Plasma osmotic pressure
Helps balance ECF normally more fluid is filtered than reabsorbed
Bulk flow
What increases venous return (5)
– Sympathetic vasoconstriction - muscle pump – Penis valves – Respiratory pop – Heart
Where are Baroreceptors located
Aortic arch and carotid sinus
