Blood Vessels

Arteries

-       Carry blood away from the heart (oxygen-rich)

-       Thick strong walls to withstand high pressure from the heart

-       Tunica Media – thick  allows for stretch and recoil

-       Tunica Intima – thick  allows for stretch and heartbeat

Veins

-       Carry blood towards the heart (oxygen-poor)

-       Thinner walls since they carry blood under lower pressure

-       Tunica Media – thinner

-       Tunica Intima - thin  forms valves

3 types of arteries

Elastic arteries:

-       Conducting

-       Recoil to maintain blood pressure

Muscular arteries:

-       Distributing

-       Control blood flow

-       Supply groups of organs, organs and parts of organs

Arterioles:

-       Important in regulating blood flow into capillaries and controlling blood pressure

Which type of blood vessels is referred to as capacitance vessels and why?

Venous System: Veins because they store large volumes of blood.

Which type of blood vessels is referred to as resistant vessels and why?

Arterioles because they provide the primary resistance to blood flow.

Capillary Bed

a network of capillaries (connect the arterioles with the venules) in tissues

 

Precapillary Sphincters

smooth muscle at the entrance of capillaries branching off arterioles. They control blood flow into capillary beds.

-       When precapillary sphincters are open - exchange

-       When precapillary sphincters are closed - NO exchange

Shunt

A pathway that redirects blood flow depending on the body’s needs.

Filtration

fluid moves from blood across the capillary wall into interstitial fluid

Reabsorption

fluid moves from interstitial fluid across the capillary wall into blood

Starling Forces: Favor Filtration

• HPc

• OPif

Starling Forces: Favor Reabsoprtion

• OPc

• HPif

Edema

swelling caused by excess fluid trapped in the body’s tissues

4 Factors of Starling Forces that Affect Edema

-       Increase OPif – increases filtration pressure causing swelling of tissues with acute inflammation

- Decreased OPc - decreases reabsorption causing low plasma proteins which could lead to liver failure

- Increased HPc - on arteriolar end can cause hypertension

- Decreased OPc - decreases reabsorption causing kidney disease

Baroreceptor

Sense how much blood vessels are being stretched by the pressure of blood in them. This happens in medulla oblongata

Baroreceptors correcting

(a) decreased blood pressure - baroreceptors fire less frequently to increase sympathetic activity and raise heart rate.

 (b) increased blood pressure - baroreceptors fire more frequently to increase sympathetic activity to decrease heart rate and lower blood.

Explain why ACE inhibitors are used in the management of hypertension.

 

• Renin catalyzes ANG I

• ACE converts ANG I to ANG II and then binds to ANG ii receptors

• Stimulates the release of aldosterone in the kidneys

• Stimulates the reabsorption of Na+ and water

• This increases blood volume and blood pressure leading to hypertesion

• ACE inhibitors would prevent ANG I to convert to ANG II to inhibit the realase of aldosterone which would increase blood pressure

Obligatory water reabsorption

NaCL reabsorption in blood followed by water reabsorption

Facultative water reabsorption

water reabsorption in the kidneys that onlt happens when needed, controlled by ADH

Skeletal Pump

contraction of skeletal muscles pump blood toward the heart and valves prevent backflow

Respiratory Pump

pressure changes created during breathing move blood toward the heart

MAP (Mean Arterial Pressure)

pulse pressure /3 + diastolic pressure

• Do the before vs after lifestyle changes and if after lifestyle changes the MAP decreases then it worked

Vasodilation - diameter of a blood vessel is doubled

• Radius increase

• 4th power of the of the radius is indirectly correlated to the blood flow

• Blood flow decreases

Vasoconstriction - diameter of a blood vessel is halved

• Radius decrease

• 4th power of the radius is indirectly correlated to the blood flow

• The blood flow will decrease

How baroreceptors correct increase blood pressure:

• Increase firing to stimulate the cardioinhibitory center to increase parasympathetic output to the heart to decrease heart rate

• Increase firing to inhibit the cardioacceleratory center to inhibit sympathetic outflow to the heart to decrease heart rate

• Increase firing to inhibit the vasomotor center and sympathetic output to blood vessels to decrease BP and heart rate

How baroreceptors correct increase blood pressure:

• Decrease firing to inhibit the cardioinhibitory center to decrease parasympathetic output to the heart to increased heart rate

• Decrease firing to stimulate the cardioacceleratory center to activate sympathetic outflow to the heart to increase heart rate

• Decrease firing to stimulate the vasomotor center and sympathetic output to blood vessels to increase BP and heart rate