Microcirculation Flashcards
nutrient and waste exchange occurs because of/by
diffusion–through/btwn capillary ENDOTHELIAL cells
diffusion based on
pressure within/out
proteins in vascular system generally
remain within system and contribute to oncotic pressure
arterial capillary hydrostatic pressure tends to
promote FILTRATION across capillary wall
oncotic pressure tends to promote
filtration from arterial side and
reabsorption by venous side
interstitial fluid osmotic pressure is generally lower
than oncotic pressure
lymphatic capillaries are formed by
single layer of endothelial cells with fenestrated basement membrane for movement of interstitial fluid and large particles
stationed along the lymphatic vessels
lymph nodes
immune system cells in lymphnodes
sample lymph gathered from tissues
pathophysiology of lymph system
- lymph edema–damage to normal lymph channels
- lymphatic cancer spread–can spread locally (i.e melanoma) or globally
- lymphadenitis
- lymphoma
knowing lymph drainage in relation to cancer will
instruct where to look for tumors around known tumor site–surgeons may remove surrounding lymph nodes when removing cancer
most common cause of lymph edema worldwide
Filariasis–worm that infiltrates lymphnodes causing inflammation–>obstruction
alarming for lymph cancer
large, very firm, NONTENDER nodes
press deeply on swollen extremity with finger–stays depressed
pitting edema
blood flow to capilaries relates to
precapillary sphincter status (contracted vs. relaxed)
greatly controls capillary function
autonomic NS – Alpha 1 adrenergic receptors
Ex. of vasoactive substances and hormonal control
- epinephrine–may inject with lido to decrease blood flow
- histamine–>bradykinins
- serotonin–vascular spasm
- prostaglandins–vasoconstriction or vasodilation
- nitric oxide–vasodilator
- substance made by endothelial cells for purpose of vasodialtion
nitric oxide
decreased O2 to capillaries
dilates capillary beds–except in lungs
lung capilaries _____ with decrease in O2
constrict–imp. increases blood flow to healthy or unobstructed (mucos/fluid buildup) lung spots–trouble with COPD pt’s (leads to RIGHT VENTRICULAR hypertrophy) (hypoxic pulmonary vasoconstriction)
the maintenance of constant blood flow to an organ despite changing arterial pressure
AUTOREGULATION of organ blood flow
autoregulation of organ blood flow may be due to_____________ or _____________
- Myogenic hypothesis–smooth muscle contraction when stretched
- metabolic hypothesis–vasodilation upon buildup of metabolic byproducts i.e. CO2, H+, lactate
decrease in flow will lead to vasodilation
cerebral blood flow normal
50-150 mmHg – related to autoregulation or organ systems
capillary dilation when
low pH, high CO2, histamine–except in lungs (opposite)
