circulation of blood

Question 1

what is the definition of perfusion pressure?

Answer 1

Perfusion pressure—the pressure gradient needed to maintain blood flow through a local tissue

Question 2

a direct relationship exists wit arterial blood volume and arteriole blood pressure. as volume increases, what happens to pressure?

Answer 2

More volume in blood vessels, more blood pressure
Similarly if you decrease

Cardiac Output and Peripheral Resistance work to increase blood volume which will increase blood pressure

Question 3

What is Cardiac Output?

Answer 3

CO: Volume of blood pumped out of the heart per unit of time (ml/min or L/min)

Anything that changes SV or HR will change CO, arterial blood volume, and blood pressure in the same direction

CO IS 5000 ML/PER MIN or 5L
Skeletal muscles and Gastro Intestinal system take greatest percentage of CO

Question 4

What is Stroke Volume?

Answer 4

Stroke volume = volume pumped per heartbeat

Stroke – contraction

Question 5

How is cardiac output calculated?

Answer 5

CO = SV x HR

Question 6

What was starlings law?

Answer 6

More stretch on muscle = stronger contraction

***The harder your heart contracts the more volume of blood will leave the heart

–> Contraction strength also altered by:
CHEMICAL FACTORS
e.g. norepinephrine, epinephrine, with stress or exercise

Question 7

What is Ventricular volume?

Answer 7

Ventricular volume is the blood in the ventricles after diastole – filling

**When we increase the volume that is in the ventricles after filling phase/diastole, it will have effect on contraction

Question 8

When more volume of blood is returning to the heart, does it stretch more and is the contraction harder?

Answer 8

-YES The more volume that returns to the heart, the more stretch, the harder the contraction

Question 9

What is end diastolic volume and end systolic volume?

Answer 9

End Diastolic Volume- Volume that is the ventricles at the end of diastole. (after it is fully done filling)

End Systolic Volume– The amount of blood left in the ventricles after a contraction

Question 10

What is ejection fraction?

Answer 10

Ejection Fraction – ratio of stroke volume (SV) to end-diastolic volume (EDV)
An ejection fraction is the volumetric fraction of fluid ejected from a chamber with each contraction.
Fraction of blood that is ejected, because when our ventricles fill with blood and contract it is not pushing out all the blood it is pushing out a percentage of what is in there.

Question 11

How do you calculate the total amount of blood that was pumped out?

Answer 11

Divide SV by EDV that tells you what the total amount of blood is that was pumped out

Question 12

What is the function of baroreceptors and where are they located?

Answer 12

Baroreceptors- receptors detect difference in blood pressure that is running through main arteries
located: carotid sinus and in the aortic arch

Question 13

How does the carotid and aortic baroreceptors feed info to the brain stem to calm tf down?

How does it do the same but to SPEED UP?

Answer 13

Carotid and Aortic
Baroreceptors- receptors detect difference in blood pressure that is running through main arteries
Feed info to brain stem
Brain tells SA node to release ACH to calm tf down
Brain stem then increases parasympathetic output

Need to know that when brain stem detects increase in pressure it will send a signal to the SA node found in the RV of heart.

Carotid rec and aortic rec will detect decrease in pressure
Send response to control center (medulla)
Affects: stimulating the SA node to increase HR will also send response to arterioles (small arteries) causing them to vasoconstrict to increase pressure
The increase pressure in the veins will pump more blood back to the heart

Question 14

What is peripheral Resistance

What factors influence peripheral resistance?

Answer 14

PR: resistance to blood flow imposed by the force of friction between blood and the walls of its vessels

Factors that influence peripheral resistance:
Blood viscosity –thicker blood has more pr
Diameter of arterioles – larger they are the less pr

Question 15

at rest where is most of the blood in the body?

Answer 15

At rest most blood supply is in the veins and venules

Question 16

When/where does blood slow down in our vessels?

Answer 16

Velocity – speed
Blood will slow down in speed once we get to the branches (nutrience exchange) because of the WIDER AREA (think of river going into a large bay.)
There is a wider over all cross sectional area

Question 17

If there is a reduction in O2 or increase in CO2 or reduction in pH, what receptors will pick up the change?

Answer 17

If there is a reduction in the amount of O2 and increase in CO2 or if there is a reduction in pH these chemoreceptors will pick u the change in concentration.
Located in the medulla and located in the same place and c and a baroreceptors

Medulla will send out response to the heart in order for it to carry out a response

Question 18

What determines the amount of blood returned to the heart?

Answer 18

Four major influences

1. Stress-relaxation effect—occurs when a change in blood pressure causes a change in vessel diameter (because of elasticity) that accommodates the new pressure and thereby keeps blood flowing (works only within certain limits)
   - Veins can adapt to increased pressure
2. Gravity—the pull of gravity on venous blood while sitting or standing tends to cause a decrease in venous return (orthostatic effect)
   - Gravity acts DOWN so it makes it harder for venous blood to return to the heart
3. Venous pumps
4. Total blood volume

Question 19

What is happening when you feel your PULSE?

Answer 19

Pulse Waves
Left Ventricle – the handle of the spoon is the aorta
Lots of force of blood through the ventricle to the aorta
When the semilunar valve stretches it creates energy in aortic valves so that when the ventricle is relaxed,
stored energy is released and keeps blood moving and shuts the semilunar valves
This stored energy is what you feel when you feel your pulse

Question 20

Inspiration ___ thorax pressure and ___ blood into the central veins

Expiration ___ thorax pressure and ___ venous blood into the heart

Answer 20

Inspiration decreases thorax pressure - pulls blood into the central veins

Expiration increases thorax pressure - pushes venous blood into heart

Question 21

describe the skeletal pump

Answer 21

Skeletal PUMP

• When muscles are relaxed, blood has a difficult time moving upward.
• When muscles contract it will milk the blood in your veins upward towards your heart

Question 22

What increases and decreases blood volume?

Answer 22

Changes in total blood volume change the amount of blood returned to the heart

ADH increases blood volume
Aldosterone increases blood volume
ANH decreases blood volume

Amount of fluid in tissues also affects blood volume