Ch .12 (vascular) pt. 5

Characteristics of Venules?

1) form when capillaires unite

2) porous

Characteristics of Veins?

1) little smooth muscle/elastin

2) capacitance vessels: blood reservoirs

3) 1-way valve to heart

What is the blood pressure of veins?

15 mmHg (quite low)

what mechanisms aid in venous return to heart?

1) muscular pump

2) respiratory pump

3) smooth muscle sympathetic innvervation

characteristics of capillaries

1) smallest blood vessels

2) permeate every tissue except cornea

3) this is where gas/nutrient exchange occur via diffusion

What is the intracellular cleft? Where are these abundant in & rare in?

parts of capillaries that assist with gas/nutrient exchange

-there are diff sized gaps/clefts throughout human body

(common in LIVER but rare in BRAIN)

Do capillaries have smooth muscle?

NO

What are metarterioles & pre capillary sphincters?

capillaries don’t have smooth muscle SO…

these structures next to capillaries have smooth muscle & CAN relax/constrict→determine volume of blood capillaries receive

metarterioles connect arterioles & venules

What happens to velocity of blood when it reaches capillaries? Why?

velocity decreases a LOT bc capillaries have highest cross-sectional area

What does a capillary deliver to a muscle cell? And Vice Versa?

Capillary→O2 & Glucose to muscles

Muscle cell→CO2 to capillaries

What are baroreceptors? Where are they located?

touch/pressure receptors that regulate BP short-term by sending signals to the Medulla

1) Carotid Sinus

2) Aortic Arch

What do baroreceptors do when MAP(mean arterial pressure) increases?

MAP increases→Baroreceptor firing increases→Medulla will decrease sympathetic signals & increase parasympathetic signals(decrease heart rate)

How does Carotid Stenting work?

Stent in Carotid artery stretches baroreceptors→increases baroreceptor firing→body thinks BP is high→decrease sympathetic signals & increase parasympathetic(vagal) signals→Brachycardia=heart rate decreases & hypotension

What are the 4 Starling Forces(bulk flow)?

1) Pc→capillary hydrostatic pressure(OUT)

2) πc→osmotic force due to plasma protein concentration(IN)
3) PIF→interstitial hydrostatic pressure(IN)

4) πIF→osmotic force due to interstitial fluid protein concentration (OUT)

There is net ______at the arterial end of a capillary. Why?

filtration BC there is greater Pc(pressure) pushing outwards & less πc(osmotic force) going in

There is net ______at the venous end of a capillary. Why?

absorption BC there is less Pc(pressure) going out & more πc(osmotic force) going into capillary

Why is Pc(capillary hydrostatic pressure) lesser at the venous end than arterial end?

Pressure drops after the artery at the arterioles & continues to drop

What is Edema?

condition where there is an imbalance of starling forces→abnormal accumulation of fluid in interstitial spaces

-kids w/ edema have poor nutrition→less protein so plasma proteins can’t suck in water into capillaries→bloated state bc too much water in interstitial fluid

Causes of Edema?

1) Protein defiency

2) heart failure

3) liver disease