Cardiovascular System Lecture 6

Question 1

What are Hemodynamics?

Answer 1

factors that affect blood flow

Question 2

What is Blood Pressure (BP)

Answer 2

force per unit area exerted by blood on the blood vessel wall (mmHg)

= Hydrostatic Pressure

Question 3

How to find ∆P?

Answer 3

∆P = P1 - P2

P1 = Upstream Pressure
P2 = Downstream Pressure

Question 4

What is Blood Resistance (R)?
What is the Formula to find it?

Answer 4

friction as blood moves through the blood vessel

Question 5

What is Blood Flow (F)?
What is the Formula to find it?

Answer 5

blood volume moved per unit time (mL/min)

Question 6

Poiseuille’s Equation:

Answer 6

Question 7

What Values have the greatest difference in calculating blood flow?
What values have the least?

Answer 7

Radius has a larger effect than viscosity
or length since to 4th power.

Viscosity and length less variable over
short amounts of time.

Question 8

What is Vasoconstriction?

What is Vasodilation?

Answer 8

Vasoconstriction – decreased radius.

Vasodilation – increase radius.

Question 9

What is it called when the radius of a blood vessel decreases?

What is it called when the radius of a blood vessel increases?

Answer 9

Vasoconstriction – decreased radius.

Vasodilation – increase radius.

Question 10

Cardiac Output Equation - Q?

Answer 10

Q = HR x SV

Question 11

What 2 Variables affect the distribution of Q in Blood Vessels?

Answer 11

1. Total Peripheral Resistance (TPR)
   - Sum of all resistance in systemic circulation
2. Mean Arterial Pressure (MAP)
   - pressure driving blood into tissues averaged over the entire cardiac cycle

Question 12

What is Mean Arterial Pressure determined by?

What would MAP be if 120/80?

Answer 12

MAP determined by:

Systolic pressure (SBP)
– maximum arterial pressure.

Diastolic pressure (DBP)
– minimum arterial pressure.

MAP = DBP + (1/3 * (SBP – DBP)).
Example:

MAP = 80 + (1/3 * (120 – 80)) = 93 mmHg

Question 13

Factors in Arteries that?

Answer 13

Blood Pressure
* MAP – little change

Cross-Sectional Area
Large vessels – minimal branching – minimal cross-sectional area – minimal resistance

Velocity of Blood Flow
* High; ideal for getting blood flow where needed.

Question 14

How many Types of Arteries are there?
What are they?

Answer 14

Elastic Arteries & Muscular Arteries

Both have Smooth Muscles and Elastic

Question 15

What are Elastic Arteries?

Answer 15

Elastic arteries, such as the aorta, are responsible for conducting blood away from the heart and have a high content of elastic fibers in their walls, allowing them to expand and recoil to maintain consistent blood flow.
* Heart to medium sized arteries.
* Form a “pressure reservoir”

Question 16

What are Muscular Arteries?
(aka distribution arteries)

Answer 16

Muscular arteries distribute blood to specific organs and tissues, featuring a thicker layer of smooth muscle in their walls that helps regulate blood pressure and flow to these areas.
* Medium-sized or smaller arteries.

Question 17

How is MAP regulated in the Short Term?

Answer 17

In Seconds by altering cardiac output (Q) from the heart and/or TPR in blood vessels

• Alter Q via HR - Sa Node Firing, AV Node Delay
• Alter Q via SV - preload, contractility, afterload
• Alter TPR via vasoconstriction, vasodilation

Question 18

How is MAP regulated in the Long Term?

Answer 18

In minutes or days by altering blood volume using kidneys:
* Alter BV - will see more detail with urinary system

Question 19

What are Arterial baroreceptors?

Answer 19

Pressure sensors; key receptors in certain arteries
monitoring MAP (changes in blood pressure) and transmit this information to the brain to regulate cardiovascular functions

Question 20

Where are Arterial baroreceptors found?

Answer 20

Carotid sinus – monitor MAP to brain.

Aortic arch - monitor MAP to systemic circulation

Question 21

Function of the Vasomotor Center

Answer 21

Sympathetic
Effector responses in blood vessel vasoconstriction and vasodilation leading to responses in TPR

Question 22

The function of the CV Center in Medulla Oblongata:

Answer 22

Cardioacceleratory Center - sympathetic
Cardioinhibitory Center - parasympathetic
Effector responses in HR and SV leading to responses in Q