Chapter 16 Vascular Physiology Flashcards
What surround veins and drain interstitial fluid?
lymphatic ducts
What drain into thoracic duct?
lower extremities and left thorax
What drain into right lymphatic duct?
head, neck, right thorax
What is the presentation of SVC Superior Venous Cava Syndrome?
swollen head and neck
unilateral ankle swelling?
DVT until ruled otherwise
bilateral ankle swelling?
right-sided heart failure
What lab value goes up with clots in body?
D-dimer
What radiographic test done for DVT?
Doppler ultrasound
What is Virchow’s triad?
cause of clotting: hypercoagulability, stasis, endothelial injury
Tx for DVT?
heparin
1 Cause venous clots?
stasis
1 cause arterial clots?
endothelial injury
Tx arterial clots
aspirin
Homan’s sign
calf pain upon dorsiflexion
How do veins constrict before arteries?
vessel constriction via norepinephrine (main neurotransmitter of ANS); NE has more affinity for alpha 1 receptors; veins have more alpha 1 receptors
When body loses volume, which is first to constrict, veins or arteries?
veins! always first before arteries
Poor perfusion of skin signs
- poor capillary refill
- cool extremities
- mottled appearance (lentigo reticularis)
Which vessels have greatest surface area and greatest diffusion?
capillaries
Explain Fick’s equation
In capillaries there is hydrostatic pressure pushing out of vessel and oncotic pressure pulling water and proteins into the capillary while the interstitium surrounding the capillary has hydrostatic pressure pushing fluids into capillaries and oncotic pressure pulling fluids out of the capillaries. There is usually a balance, but if the balance is interrupted (i.e. low albumin in the blood), the oncotic pressure inside will be less than the oncotic pressure in intersitium and proteins and fluid will be pulled more into the interstitium ; that is edema.
Which second messengers work in the veins?
veins, alpha 1 receptors, 2nd messenger IP3/DAG, causing constriction
Which second messengers work in the arteries?
beta 2, cAMP, causing dilation
plasma proteins usually don’t leak out of vessels, why not?
heparan sulfate provides a negative charge in the BM that repel negatively charged plasma proteins
What is transudate?
transudate is effusion that is mostly water; due to CHF, renal failure or hypothyroidism
What is exudate?
exudate is effusion that is mostly protein ( greater than 0.5 protein or LDH greater than 0.6 ) caused by purulent, granulomatous, caseous infections; always pathological
The epithelium of aorta is lined by which cells?
stratified squamous
What is the blood supply of the aorta?
vaso vasorum
Monckeberg’s Arteriosclerosis cause
As we get older, vaso vasorum undergoes atherosclerosis, calcifies and dies. The aorta does not have much blood supply and cannot maintain its stratified squamous epithelium. Calcifcations can be seen in the walls of the aorta (not the lumen); physiological response to aging. Loss of epithelial layers will expose underlying smooth muscle to RBC and cause aneurysms and dissections.
causes of aneurysms early in life
syphilis, takayasu, collagen dis., basement membrane dis.
aortic aneurysm Type A
ascending aorta dissection usually from collagen dis. like Marfan’s
aortic aneurysm Type B
descending usually caused by HTN ; usually no surgery, can be controlled with BB, lower BP
Which organs have resistance in series (have to filtrate)
Liver, Kidney, spleen, lung, placenta
If you take out one of the organs that have parallel (with heart), what will happen to blood pressure?
BP will go up (that’s why have to control BP after eclampsia when the placenta is removed)
when does the heart receive blood from coronary arteries?
in diastole
What happens to coronary artery flow if the heart rate is high?
time in diastole is very short and not enough blood can get to the heart; could result in MI
What is the difference between oxygen in artery and its vein
A-V O2 difference
Which organ always has lowest A-V O2 difference?
kidney
Which one has the greatest A-V O2 difference after eating?
GI system
Which organ has the greatest A-V O2 difference after exercise?
skeletal muscle
What does it mean if AV O2 difference increases?
less O2 on venous side, tissue more metabolically active or there was less blood flow into the tissue, forcing it to extract more
What does it mean if AVO2 difference decreases?
more O2 on venous side, tissue less metabolically active; or more blood flow into the tissue
What does it mean if AVO2 difference very low?
blood never reached tissue (shunting)
normal AVO2 difference?
25-40%
example of iatrogenic AV shunt?
guide-wire pokes through vein to artery; dialysis fistula; Blalock-Taussig shunt (descending aorta to pulmonary artery)
example of congenital AVM shunt?
PDA; AVM; Osler-Weber-Rendu (multiple AVMs); Von-Hippel-Lindau multiple AVM in abdomen and brain
example of traumatic AV Shunt
stab wound
If you cut a vessels radius in half, what happens to resistance?
It goes up r to the 4 times
If you increase length of vessel, what happens to flow?
decreases
What does our body regulate first, resistance or pressure?
resistance
If you want to increase flow in the brain, what should you do?
increase PCO2, decrease PO2
If you want to increase flow in the lungs, what shouldyou do?
increase pO2
If you want to increase flow in the kidneys, what shouldyou do?
increase PGE2, increase dopamine, increase ANP (secubitril)
What does adenosine do?
opens up coronary arteries
What happens to your brain vessels in high altitudes?
pO2 decreases, cerebral vessels dilate, ICP rises
mechanism of migraines
vasoconstriction causes localized hypoxia; aura then rapid severe vasodilation causing increased contractility of hear, nausea and vomiting due to ICP increase; increased flow to eyes causing photosensitivity; increased flow to ears causing noise sensitivity
tx migraine
O2, sleep, sumatriptan (acute); propranolol (preventive)
definition of chronic migraine
more than 14 days in one month