Phys: Microcirculation Flashcards
What are the small vessels in the microcirculation system?
-arterioles
-capillaries
-venules
what are the functions of the microcirculation?
-important in the transport of nutrients to tissues
-site of waste product removal
-sit of solute and fluid exchange
Solute and water move across capillary wall via
intercellular cleft
What are the three different capillary structures?
-continuous
-fenestrated
-sinusoidal
What are the differences between the types of capillaries?
continuous
-no pores
fenestrated
-have pores
sinusoidal
-lots of pores with relatively high caliber
Where are continuous capillaries found?
muscle, skin, fat, and nerve tissue (CNS)
m3 receptors activate _______ to cause vasodilation
nitric oxide synthase (NOS)
Lipid soluble substances ____ diffuse across the cell membrane
easily
Lipid insoluble substances have to use ____ to get through the membrane
clefts and channels
The width of the capillary intercellular pores is
6-7 nanometers
In lymph vessels what causes them to contract?
smooth muscle filaments
when interstitial fluid hydrostatic pressure increases, how does that affect lymph flow?
it increases
What system is important in preventing edema?
lymphatic system
Lymph is derived from?
interstitial fluid that flows into the lymphatics
what is capillary hydrostatic pressure?
tends to force fluid outward through the capillary membrane
what pressures cause net filtration?
capillary pressure and interstitial fluid pressure
decreasing arteriole resistance and increasing venous pressure causes..
increase in capillary hydrostatic pressure
Positive Interstitial pressure opposes
capillary hydrostatic pressure
what is Plasma colloid osmotic pressure?
pulls water into the capillary
What conditions cause a decrease in plasma colloid osmotic pressure?
cirrhosis, nephrosis, and dilutional
-any diseases that cause a decrease in protein in the body
What is interstitial fluid colloid osmotic pressure?
promotes filtration causing osmosis of fluid outward through the capillaries
pressures that push fluid out, _______ filtration.
promote
What substance is the main factor for colloid osmotic pressure?
Albumin
What does Starling’s law of capillaries state?
Reduced interstitial fluid formation will decrease..
filtration
Changes to venous resistance affects filtration more than
arteriolar resistance
Edema is
excessive amount of fluid in the interstitial compartment
what are the four main causes of edema?
-increased capillary hydrostatic pressure
-loss of plasma protein
-obstruction of lymphatic circulation
-increased capillary permeability
Fluid balance is kept by what four things?
-thirst mechanism
-antidiuretic hormone
-aldosterone
-atrial natriuretic peptide
what type of fluid balance control has osmoreceptors in the hypothalamus?
thirst mechanism
how does aldosterone keep fluid balance?
it determines the resorption of sodium ions and water
Which mechanism of fluid balance promotes resorption of water into blood from kidney tubules?
antidiuretic
Which type of fluid balance regulates fluid, sodium, and potassium levels?
atrial natriuretic peptide