Cardiovascular regulation

Question 1

What is cardiovascular regulation?

Answer 1

A set of measures in order to keep proper blood circulation aka arterial blood pressure regulation.

Question 2

What are the 3 main cardiovascular regulatory mechanisms?

Answer 2

Local, nervous and humoral.

Question 3

What are the subcategories of local cardiovascular regulation?

Answer 3

Metabolic, myogenic, and endothelial.

Question 4

How is the blood flow to each tissue regulated?

Answer 4

At the minimal level needed to keep the tissue well alive (no nutritional deficiencies) but to save the workload of the heart at the same time.

Question 5

What are the two types of local regulation?

Answer 5

Acute (blood flow changes in seconds to minutes) and long term (blood flow changes in days to months).

Question 6

Name measures of acute local regulation:

Answer 6

Vasoconstriction and dilation.

Question 7

Name measures of long term local regulation:

Answer 7

Changes in the size or number of blood vessels.

Question 8

What is metabolic local regulation?

Answer 8

That each tissue controls its own blood flow according to its own metabolic needs. In other words, flow is closely related to the metabolic rate of tissues. For example, O2 deficiency causes vasodilation which increases blood flow and allows the tissue to receive more O2.

Question 9

What is myogenic regulation?

Answer 9

The theory that when arterial blood pressure is high and stretches the vessels, the vascular smooth muscle intrinsically constrict reducing blood flow and VICE VERSA
= When arterial blood pressure is low and does not constrict the vessels, the muscles relax and allow increased blood flow.

Question 10

What is the purpose of myogenic local regulation?

Answer 10

To protect capillaries from too high pressures.

Question 11

What is endothelial regulation?

Answer 11

The theory that incresed velocity blood flow in arterioles causes releases of NO (nitric oxide) which has an inhibitory effect causing vasodilation and eventially leading to decreased velocity of blood flow.

Question 12

What is the main nervous control of CV function?

Answer 12

ANS.

Question 13

What is the main nervous regulator of circulation?

Answer 13

SNS.

Question 14

What type of control does the NS provide for circulation an CV?

Answer 14

More generic, such as redistribution of blood flow, regulation of HR and contractility and rapid control of blood pressure.

Question 15

What are the 3 ways in which SNS increases arterial blood pressure?

Answer 15

Constrict arterioles
COnstrict veins
Increase HR and contractility

Question 16

How does SNS control vasomotor tone (vessel diametre)?

Answer 16

By stimulating receptors inside the vessels’ walls by norepinephrine.

Question 17

Where are cardioregulatory and vasomotor centres located?

Answer 17

In medulla oblongata.

Question 18

Explain the excitatory effect of SNS for blood pressure:

Answer 18

Noradrenaline and adrenaline bind to alpha adrenergic receptor which causes vasoconstriction.

Question 19

Explain the inhibitory effect of SNS for blood pressure:

Answer 19

In skeletal muscle blood vessels, adrenaline binds to beta adrenergic receptors which causes vasodilation.

Question 20

What is the importance for PNS for blood pressure?

Answer 20

It only decreases heart rate!

Question 21

What is humoral regulation of blood pressure?

Answer 21

Substances secreted or absorbed into the body fluids either cause vasoconstriction or vasodilation and thus regulate the blood pressure.

Question 22

Which (humoral) substances cause vasodilation?

Answer 22

Bradykin, histamin, and prostaglandins, and K+ and Mg2+ ions, acetate, citrate, and CO2.

Question 23

What is bradykin?

Answer 23

A powerful arteriolar dilator, which increases the permeability of the capillaries.

Question 24

What is histamine?

Answer 24

An arterial dilator, which increases the permeability of the capillaries. It is releases from damaged or inflammed tissue as well as during allergies.

Question 25

What are prostaglandins?

Answer 25

Vasodilators, which are contained by all the body tissues.

Question 26

Which humoral substances cause vasoconstriction?

Answer 26

Norepinephrine/epinephrine, angiotensin II, vasopressin (ADH), and endothelin A and Ca2+ ions.

Question 27

What is vasopressin?

Answer 27

Anti-diuretic hormone, very potent vasoconstrictor, which is secreted by posterior pituitary. It also increases the renal H2O reabsorbtion.

Question 28

What is endothelin A?

Answer 28

A vasoconstrictor that is released from damaged vessels.

Question 29

What is the effect of H+ ions in blood pressure?

Answer 29

Increase causes vasodilation and decrease causes vasoconstriction.

Question 30

Explain short term arterial pressure regulation:

Answer 30

ANS regulates arterial blood pressure fast through baroreceptors, chemoreceptors, and CNS ischemic response. The effect cannot last for long.

Question 31

Explain medium term arterial pressure regulation:

Answer 31

If the AP is not “good enough” after short-term mechanisms, endocrine mechanisms kick on. Their effect can last for hours.

Question 32

Explain long term arterial pressure regulation:

Answer 32

RAAS (renal-angiotensin-aldosterone system) can last even for months.

Question 33

Which organ is responsible for the long term blood pressure control and how?

Answer 33

The kidneys, as by regulating the volume of blood (and extracellular fluid) volume, they control arterial pressure.

Question 34

What is the result of increased arterial pressure?

Answer 34

An increased renal output of H2O (pressure diuresis) and Na (pressure natriuresis) to keep AP constant.

Question 35

What is baroreflex?

Answer 35

The baroreceptors in carotid sinuses and aortic arch detect high physical pressure and send a signal to cardio-regulatory centre in the medulla oblongata, which then decreases pressure by vasodilation and decreasing HR. So it activates PNS ans deactivates SNS:

Question 36

What is chemoreflex?

Answer 36

The chemoreceptors in carotid body and aortic body detect low O2 and high CO2 and H+ levels and send a signal to the cardio-regulatory centre in the medulla oblongata, which increases pressure via SNS (vasoconstriction, HR) and increases the rate of respiration.

Question 37

What is Cushing reflex?

Answer 37

CNS ischemic reflex = accumulation of CO2 in the chemoreceptors of vasomotor centre triggers a very strong sympathetic response of vasoconstriction and HR acceleration rapidly. EMERGENCY SYSTEM WHICH ACTIVATES WHEN CO2 LEVELS CLOSE TO LETHAL.

Question 38

What is Bainbridge reflex?

Answer 38

Atrial reflex = stretch receptors in the right atrial wall react by increasing HR when preload or AP increases. OPPOSITE EFFECT TO BAROREFLEX.

Question 39

What is RAAS?

Answer 39

Renin-angiotensin-aldosterone system.
The liver produces constantly angiotensinogen. The kidneys release renin in response to decreased pressure or low NA+ levels.

When renin and angiotensinogen meet, renin acts as an enzyme cutting most of the peptides of from angiotensinogen and convert it to angiotensin I. Angiotensin I gets activated by ACE (angiotensin convertase enzyme in endothelium) in (lung) capillaries and becomes angiotensin II.

Angiotensin II increases sympathetic activity, increases reabsorption of NA+ and Cl-, while excreting K+, causes the pituitary gland to produce ADH (which increases water reabsorption, increases arteriolar vasoconstriction and stimulates adrenal glands to release aldosterone. Aldosterone also increases of Na+ and water reabsorption.

Question 40

What is ANP?

Answer 40

The atrial natriuretic peptide is a substance released when atrial wall detects increased stretching (ie. HIGH AP/increased VOLEMIA). It blocks the release of renin and thus leads to more excretion NA+ and water lowering blood pressure.