Lecture 3 - Blood Distribution Flashcards
What gets alot of blood?
liver digestive tract and kidneys and skeletal muscles and brain - kidneys get the greatest in respect to mass
Can the amount of blood blow an organ receive be modulated based on demand?
yes via vasoconstriction and vasodilation
What is velocity or flow inversely proportional to?
cross sectional area
Why do capillaries have slowest flow rate?
have greast summed cross sectional area allowing for diffusion of materials
What are the three types of capillaries?
continuous, fenestrated, sinusoidal
What is a continuous capillary?
ther are haps in between adjacent cells and this si just a prore or gap which fluid cna leak throughn and the ion and organis mcolecules come out but not proteins
What are continous cpailalris like in the CNS?
they are sealed by tight junctions and they prevent the diffusion of materials and the astrocyte layers and form the BBB so stuff in plasma cannot get into the brain
What is a fenastrated capillary?
endothelial cells are perforated by many pores and are found in kideny and glomerulus and liver and allows for moevment of plasma proteins via transcytosis - pick up fluid via endocytosis and dump it via exocytosis on other side
What is a sinusoidal?
endothelum not continuous and is where cells need to cross so red bone marrow and spleen need to move rbcs
What do immine cells do to rbs in the spleen?
test them to make sure they are okay but when they are old they can enter the spleen be nabbed by immune cells and be replaced by new ones from red bone marrow
What drives inward fluid movement into the capillary?
colloid gradient is highe rin cpailalry so fluid goes in
What drives outward fluid into capillary?
blood pressure highwr in arteriole side so filtration and lower in venous side so absorption
What are the four causes of edema?
- decreased osmotic gradient due to low plasma protein from malnutirtion or increased interstital osmoalrity (inflammation)
- increased filtration pressure heart failue or incompetent valves or gravity
‘3. increased caoillary permeability from histamine - poor lymph drainage parasute tumors or surigically removed
In preeclampsia what does the liver damage do?
cause low plasma proteins
How does right side heart fasilure cause edema?
fluid back up in the veins cause heart cnat pump all so this causes less absoprtion on venule side of capillaries
How does an incompetent valve cause edema?
left ventrcile if left AV vakve no work cannot make enough pressure to release everything so flkuid backs up into the pulmpnary veins causing less absorption more filrtration
How does histamine cause edema?
mast cells release histamine making the capillaries more leaky
What is the baroreceptor reflex?
-it is used to regulate bp
What is a baroreceptor?
pressure receptor in aorta and cartopid and if there is high pressure there is strecth sensootve nerve whjich trigger a sodium channel and cause an AP which goes to the medulla CV control center which then talks to auotnomic parasympthetic and sympathetic neurons
In the barorecpeot reflex what do sympthetic neurons do?
psoitive chronotropic and ionotropic effect and talk to SA node and ventrciles and artioles and veins
In the baroreceptor reflex what does the parasympatheti neuorns do?
negatuve chronotropic effect by working in SA node
What is the vasalva maneuver?
forced expiration against a closed glottis
What happens to intrathoracic pressure in the esophagus is 0 when you try to exhale against closed glottis?
the pressure increases the pressure in the aorta increases because you also squeeze on the aorta increasing blood pressure
What happens when the baroreceptor reflex in the valsalva manuever senses the high bp?
since the intrathroacic pressure is high and the veins are compressed there is less venous return which is sensed by the baroreceptors and causes tachycardia and increases the peripheral reisistance
What happens when the glottis opens?
IP ois normal and CO resumes but peripheralp reisstance is high so eleveated jump in blood pressure
What does the barorecptor do after the glottis opens and the bp is high due to ihgh peripheral reisiatnce?
causes bradycardia and decreases the epripheral reistsance so it is or the bp is normal again
