Cardio Vascular Flashcards
Contrast Arteries, veins, capillaries, arterioles and venules.
- Arteries carry blood away from heart (mostly oxygenated)
- Veins carry blood to heart (mostly deoxygenated), low pressure, have valves, movement of blood from skeletal muscle and breathing.
- Capillaries-thin wall, defusion occurs
- Venules- tiny veins
- arterioles- tiny artery
Name the 3 layers in the wall of an artery or vein
- Turnica interna- touches lumen, smooth endothelium tissue
- Turnica media- smooth muscle, thick
- Turnica externa- elastic fibers for stretch and recoil
-The wall of artery is much thicker than vein. The lumen of vein can therefore expand more.
Describe the wall and function of a capillary
- 1 cell layer of endothelial cells (no muscle)
- Defusion, red blood gives oxygen, turning to blue blood to return to heart
Describe the differences in blood velocity in large vs small blood vessels
-velocity is the speed at which blood travels, capillaries have the slowest movement due diffusion
Explain what causes a pulse
-the heart has systole/diastole, this force can be felt in arteries carrying blood away from the heart.
Define blood flow, blood pressure, and resistance
- Blood flow= Pressure/Resistance F=P/R
- Volume passing through a vessel due to pressure
- indirectly related to resistance (more resistance less flow)
- Pressure is the force (higest closest to pump) that drives blood through vessels, highest in aorta, lowest in vena cava
- Resistance is due to blood viscosity, vessel length(cannot alter), and vessel radius
Name some factors that affect resistance
- Blood viscosity -thicker blood more resistance, less flow (dehydration could be a cause)
- Vessel length, (cannot be altered) longer= higher resistance
- vessel radius (can be altered)- **1/Radius to the 4th-== small change in radius there is a huge change in resistance
- Arterioles can get so small that they can actually close causing a LOT of resistance and no flow and therefore are sometimes called the ‘resistance’ blood vessel
Name the vessel that is more important in determining resistance to blood flow
-arterioles
Describe the relationship of blood flow to pressure and resistance
- Flow and pressure are directly related (one goes up, so does other…)
- flow and resistance are indirectly related (one goes up, the other goes down).
Describe the relationship of mean arterial pressure, cardiac output, and total peripheral resistance.
- MAP = CO x TPR
- cardiac output X Total peripheral resistance= means to arterial pressure
- the smallest change in radius there is a huge change in resistance.
List the neural factors that influence arterial pressure and describe how they function
- Vasomotor fibers of the sympathetic efferent, they use vasodilator (decreases resistance and pressure) and vasoconstrictors (bv gets smaller, increases resistance, increases BP)
- The brainstem has a vasomotor center that regulates these sympathetic fibers.
- Baroreceptors (in the vegas nerve) and chemoreceptors (oxygen, carbon dioxide) also provide input to the vasomotor center.
Describe the effects of angiotensin, epinephrine, and ADH on arterial pressure
- Angiotension- a powerful vasoconstrictor (ACE inhibitor)- increases arterial pressure
- Epinephrine- increases cardiac reaction and stroke volume- increases blood pressure
- ADH (vasopressin)- Water reabsorption from kidneys and vasoconstrictions- causes increased blood pressure
Describe the renin-angiotensin-aldosterone interaction
- If not enough blood is going to the kidneys due to low blood pressure, the kidneys release renin.
- This enzyme converts inactive angiotensinogen to angiotensin. (Angiotensin is a strong vasoconstrictor bringing blood pressure back up.)
- angiotensin causes the adrenal cortex to release aldosterone which indirectly raises blood pressure by causing sodium and water reabsorption at the kidney.
Describe how blood volume influences arterial pressure and describe the factors that influence blood volume
-.Increased blood volume leads to increased arterial pressure.
Describe the measurement of blood pressure. What does systolic pressure correspond to? Diastolic pressure?
- 120/80= Systolic pressure/diastolic pressure
- The measurement is on your brachial artery.
- The systolic pressure is representative of the force coming from your heart during systole and the diastolic pressure is representative of the force during diastole.
- due to the elastic nature of arteries, the pressure does not go to zero during diastole, as it does in the ventricle.
- As the tight cuff cuts of blood flow down the brachial artery, you hear no sounds distal to the cuff, as no blood is passing. As you slowly release the cuff pressure, you will reach a point where during systole there is enough force to push blood past the squished artery but during diastole there is not enough force and the blood flow stops again. (the first time blood can get through the artery is your systolic pressure)
- This turbulent blood flow can be heard through the stethoscope and seen as the needle bounces on the sphygmomanometer.
- Finally, you release enough pressure on the cuff that blood can flow unimpeded whether the heart is in diastole or systole and this is your diastolic pressure.
