Feedback Control and the Cardiovascular System

Question 1

What does a negative feedback system require?

Answer 1

Sensor
Control Centre
Effector
A controlled variable

Question 2

What the controlled variable in the cardiovascular system?

Answer 2

Mean Arterial Blood Pressure

Question 3

What are the sensors in the Cardiovascular system?

Answer 3

Baroreceptors

Question 4

What are the effectors of the Cardiovascular system?

Answer 4

Heart

Blood Vessels

Question 5

What is Blood Pressure?

Answer 5

Blood Pressure is the outward hydrostatic pressure exerted by the blood on the blood vessels

Question 6

What is Systemic Systolic Arterial Blood Pressure?

Answer 6

Systemic systolic blood pressure is the pressure exerted by the blood on the walls of the arteries when the heart contracts

Question 7

What is Systemic Diastolic Arterial Blood Pressure?

Answer 7

Diastolic Blood Pressure is the pressure exerted by the blood on the walls of the arteries when the heart relaxes

Question 8

What is Mean Arterial Blood Pressure?

Answer 8

This is the average arterial blood pressure during a single cardiac cycle (Systolic and diastolic )

Question 9

How is the Mean Arterial Blood Pressure calculated?

Answer 9

MAP = (2xDiastolic) + Systolic
———————————
3

This is because the diastolic period is 3 times the length of the systolic period

Question 10

What is normal Arterial Blood Pressure?

Answer 10

< 140 Systolic and < 90 Diastolic

Question 11

What is normal Range of Mean Arterial Blood Pressure?

Answer 11

70 - 105 mm Hg

Question 12

What is the minimum Mean Arterial Blood Pressure required to perfuse the coronary arteries, brain and kidneys?

Answer 12

60 mm Hg

Question 13

Where are the two groups of Baroreceptors located?

Answer 13

Aortic Arch

Carotid Sinus

Question 14

What nerve takes the signal for the carotid sinus Baroreceptors?

Answer 14

The IXth Cranial Nerve

-Glossopharyngeal

Question 15

What nerve takes the signal for the Aortic Baroreceptors?

Answer 15

The Xth Cranial Nerve

- Vagus Nerve

Question 16

What type of receptors are Baroreceptors?

Answer 16

They are Mechanoreceptors that a sensitive to stretch.

Question 17

What increases the firing rate of a Baroreceptor?

Answer 17

Increase in the Mean Arterial Blood Pressure

Question 18

What decreases the firing rate of a Baroreceptor?

Answer 18

Decrease in the Mean Arterial Blood Pressure

Question 19

What is the site of the first synapse for all Cardiovascular Control Centre signals?

Answer 19

Nucleus Tractus Solitarius

Question 20

How does the control centre of the cardiovascular system receive a signal and act on it?

Answer 20

Information sent to the Nucleus Tractus Solitarius (NTS)

NTS relays information to other parts of the brain

Relay to Nucleus Ambiguus (Part of the autonomic Nervous system)

Regulates spinal sympathetic neurones

Question 21

Using Cardiac output how is Mean Arterial Pressure worked out?

Answer 21

MAP = Cardiac Output x Total Peripheral Resistance

Question 22

How is Cardiac Output worked out?

Answer 22

Cardiac Output = Stroke Volume x Heart Rate

Question 23

What is the definition of Total Peripheral Resistance?

Answer 23

Total Peripheral Resistance is the sum of all peripheral vasculature in the systemic circulation

Question 24

What is the Sympathetic nervous system’s affect on the heart?

Answer 24

Accelerates the heart rate (Tachycardia)

Noradrenaline actions on Beta 1 Receptors

Question 25

What is the Parasympathetic nervous system's affect on the heart?

Answer 25

Stimulation of the 10'th cranial nerve slow the heart down (Bradycardia) Acetylcholine acts on Muscarinic receptors

Question 26

What is Tachycardia?

Answer 26

Speeding up the of the heart

Question 27

What is Bradycardia?

Answer 27

Slowing down of the heart

Question 28

What increase the Stroke Volume of the heart?

Answer 28

Stimulation of the Sympathetic nervous system

Question 29

What is the neurotransmitter used for the smooth muscles of the vasculature?

Answer 29

Part of the Sympathetic Nervous System Noradrenaline

Question 30

What occurs if the smooth muscles of the vasculature vasoconstrict?

Answer 30

Increase in TPR Increase in MAP

Question 31

What occurs if the smooth muscles of the vasculature vasodilate?

Answer 31

Decrease in TPR Decrease in MAP

Question 32

What is Vasomotor Tone?

Answer 32

Vascular Smooth Muscle partially constricted at rest

Question 33

What increases the Vasomotor Tone?

Answer 33

Increased Sympathetic Discharge

Question 34

What decreases the Vasomotor Tone?

Answer 34

Decrease Sympathetic Discharge

Question 35

What happens in a decrease in B.P?

Answer 35

Decrease in Baroreceptor Discharge Signal sent to Medulla of Brain Vagal Activity decreased - Increases heart Rate Sympathetic activity increased - Stroke Volume increased Sympathetic increase - Vasoconstriction TPR increases

Question 36

What affect does the Parasympathetic system have on stroke volume?

Answer 36

No effect

Question 37

What happens in a increase in B.P?

Answer 37

Increase in Baroreceptor discharge Signal sent to Medulla Vagal activity increased - Decrease in Heart rate Sympathetic activity decreased - Decrease in Stroke volume Sympathetic decrease - Vasodilation TPR decreases

Question 38

What is the disadvantage of Baroreceptors?

Answer 38

Only respond to acute changes in Blood Pressure Baroreceptors re-set to a high MAP if B.P change lasts