Lecture 30: Blood Pressure

Question 1

What are the 3 factors that are important for regulation of MAP?

Answer 1

1. Cardiac output
2. Total peripheral resistance(TPR)
3. Blood volume

Question 2

What is the purpose of MAP and what happens If it is too high?

Answer 2

MAP maintains the driving force for propelling blood to the tissues. If MAP is too high,, extra work is created for the heart, and it may also cause vascular damage

Question 3

What is the radius of arterioles determined by?

Answer 3

Largely determined by sympathetic stimulation to the arterioles and local metabolic/chemical controls. It is also controlled by hormonal influence

Question 4

What is the Baroreceptor and where is it found and what are they sensitive to?

Answer 4

They are mechanical stretch sensors and are found in the carotid lumen and aortic arch

sensitive to fluctuations in arterial pressure and pulse pressure.

Question 5

What are the short and long term adjustments to altered BP?

Answer 5

Short term- affected by activation autonomic nervous system

Long term- changes to blood volume by modification of salt and water balance

Question 6

How do the Baroreceptor Reflex work and send signals?

Answer 6

-Afferents (to the CNS) and the efferents (from the CNS) pathways. The afferent pathways bring stretch info to the cardiovascular control centre(CCC-integrates) in the brain medulla

-The CCC alters the ratio of sympathetic and parasympathetic activity to the heart and blood vessels

-The heart and blood vessels are the effector organs that respond to control blood pressure

Question 7

What are other reflexes that can influence BP?

Answer 7

1.Atrial volume and hypothalamic osmoreceptors are important for water and salt balance(plasma)

2.Carotid and aortic arch chemoreceptors are sensitive to low oxygen and high [H+] in the blood. Increase respiratory activity to reverse these trends (increased AP burst to CCC)

3.Emotions

4.Exercise centers (discrete) in brain

5.Hypothalamic control over arterioles in the skin to eliminate XS heat

6. Endothelial release of vasoactive substances (NO-Nitric Oxide)
7. Vasoactive neurotransmitters

Question 8

What is prehypertension?

Answer 8

BP between normal and overtly hypertensive-120/80 and 139/89. managed with our medication

Question 9

What could be the cause of Primary Hypertension?

Answer 9

-Salt mismanagement
-Defective plasmalemmal NaK pumps
-inappropriate stimulation of the CCC
-abnormal expression of components of the renin angiotensin axis
-altered regulation of No
-Endogenous digitals like substances
-abnormal vasopressin production

Question 10

in what situation are Baroreceptors ineffective?

Answer 10

They dont help correct BP in chronic hypertension, because they reset themselves to read high BP as the norm. They then effectively maintain BP at a higher level

Question 11

What is orthostatic hypertension?

Answer 11

-Results from transient inadequate sympathetic activity as one stands up after extended periods of watching TV on the couch (head rush)

Question 12

What is Circulatory shock?

Answer 12

BP is so low that inadequate blood flow results in tissues

Question 13

What are the four types of circulatory chock?

Answer 13

-Hypovolemic : caused bye a fall in blood volume
-Cardiogenic :due to a weakened heart
-Vasogenic : From a widespread vasodilation due to a release of vasodilator substances
-Neurogenic -from a widespread vasodilation due to “crashing” decrease of S tone

Question 14

What is the pathway for compensatory events in response to shock?

Answer 14

1.Reducing firing by the baroreceptors
2.Integration of the signal in the CCC
3.CCC modulates increased S and decreased PS output to heart and periphery

Question 15

review slide 17

Question 15

Where does the heart receive most of its blood supply through ?

Answer 15

Through the coronary circulation during the rest phase(diastole)

Question 16

What does vasodilation of the coronaries lead to ? and how much O2 does the heart remove ?

Answer 16

Vasodilation of the coronaries leads to increased delivery of blood.

The heart removes 65% of the O2 available in the blood (higher than other tissues)

Question 17

What is adenosine critical for?

Answer 17

Coronary vessel dilation?

Question 18

What is Coronary Artery Disease (CAD)?

Answer 18

Atherosclerosis and it blocks coronaries leading to ischemia (lack of O2)

Question 19

What are the three mechanisms that schema occurs by?

Answer 19

-Vascular spasm of coronary arteries
-Atherosclerotic plaques plug the coronary lumen
-Thromboembolism

Question 20

What is Spasm?

Answer 20

Reduced O2 leads to release of platelet activating factor (PAF) which causes vascular smooth muscle cell (VSMC) contraction in coronary arteries.

Question 21

What Is heart pain called?

Answer 21

Angina Pectoris

Question 22

What is Thromboembolism?

Answer 22

Obstruction of a blood vessel by a blood clot that has become dislodged from another site in the circulation

When the thrombus breaks free and results in the sudden occlusion of a coronary.

Question 23

Where is Cholesterol synthesized in the body?

Answer 23

Liver

Question 24

How is cholesterol transported around in the body?

Answer 24

Cholesterol is not soluble in the blood and needs to be bound to proteins for transport.

Question 25

What are the protein complexes called that
transfer cholesterol ?

Answer 25

1.HDL-most protein, least cholesterol, moves cholesterol to liver for elimination (GOOD)

2.LDL-less protein, more cholesterol-transported to cells(BAD)

3.VLDL-least protein, most cholesterol (BAD)