Short term control of blood pressure

Question 1

Why is it important to regulate mean arterial pressure

Answer 1

MAP is the driving force pushing blood through the circulation

Question 2

What is a possible out come if mean arterial pressure is reduced

Answer 2

A reduced mean arterial pressure reduced cardiac output therefore less oxygen is reaching the brain = fainting

Question 3

What is the possible outcomes is the mean arterial pressure is increased over time

Answer 3

Hypertension

Continual damage to the capillary vessels can result in cardiac disease or a stroke

Question 4

What kind of receptors are baro receptors

Answer 4

Stretch receptors

Question 5

What is the function of baroreceptors

Answer 5

Monitor arterial pressure

Question 6

What is the affect of an increase in pressure on the baroreceptors firing rate

Answer 6

Increase mean arterial pressure increases the contractility therefore increasing the stretch, which stimulates the baroreceptors firing rate

Question 7

Around what pressure range is the mean arterial pressure proportion to the baroreceptor firing rate

Answer 7

In between 40 -120mmHg

Question 8

Where is the two baroreceptors located

Answer 8

wall of aortic arch

carotid sinus

Question 9

What nerve is the sensory stretch response singled through by the baroreceptors

Answer 9

aortic arch - Vagus nerve

Carotid sinus - Glossopharyngeal nerve

Question 10

What is the name of the integrating system that the baroreceptors fire there signal to

Answer 10

medullary cardiovascular centres

Question 11

What is the potential actions of the medullary cardiovascular centres

Answer 11

Send a signal either through the sympathetic NS or the parasympathetic, carrying cardiac output or/and total pulmonary resistance to maintain mean arterial pressure

Question 12

How does the parasympathetic nervous system respond to a increased mean arterial pressure sensed by the baroreceptors

Answer 12

Parasympathetic fibres release ACH which acts on muscarinic receptors, this hyperpolorises pacemaker cells and decrease the heart rate
therefore decreasing mean arterial pressure

Question 13

What is the different pathways of the sympathetic nervous system responding to decreased mean arterial pressure detected by the baroreceptors

Answer 13

• Release noradrenaline on B1 receptors , depolarising pacemaker cells, creating a shorter cardia interval, increasing heart rate
• Release adrenaline hormone into the blood from adrenal medulla
• Causes an increase in calcium levels, whci increases contractility, increasing stroke volume, therefore increasing cardiac output
• Innervates BV

all of theses lead to a increased regaled mean arterial pressure

Question 14

What is the effect of sympathetic intervention on the BV lead to increased mean arterial pressure

Answer 14

SNS release noradrenaline of alpha 1 receptors, causing venoconstriction (capacitance vessels) with squeezes the blood back to the heart, increases EDV, SV, and Cardiac output, therefore increasing mean arterial pressure

Question 15

What are further receptors that influence into the medullary of the cardiovascular centres

Answer 15

Cardiopulmonary baroreceptors
Central chemoreceptors
Chemoreceptors in muscle 
Joint receptors
Higher centres

Question 16

Where can cardiopulmoary baroreceptors be found

Answer 16

In Low pressure systems i.e. the lungs the heart

Question 17

What stimulates the central chemoreceptors to increase blood pressure

Answer 17

Respiratory drive (low oxygen, high CO2)

Question 18

What stimulates the chemoreceptors in the muscle to increase blood pressure

Answer 18

Increase exercising Increasing the metabolite concentration in the blood

Question 19

What stimulates the joint receptors to increase blood pressure

Answer 19

Increased movement of the joints

Question 20

What receptors produces a feed forward response

Answer 20

Higher centres

Question 21

Where are signals from the higher centres sent to

Answer 21

The hypothalamus

Question 22

What is the most common time to use the arterial baroreceptors

Answer 22

Changes in posture

Question 23

What does a change in posture from standing up affect your baroreceptors firing rate

Answer 23

Standing up you are under the affects of gravity, this increases the hydrostatic pressure in the limbs pulling the blood towards your feet, therefore preventing venous return and lowering the EDV
decreasing the preload /SV/CO/ MAP
And baroreceptors firing rate is decreased

Question 24

What is the is the immediate response to a decreased baroreceptor firing rate to prevent fainting due to decreased cardiac output

Answer 24

Decreased baroreceptors cause a reflex response to increase cardiac out put

Question 25

What is the two pathways of the reflex response

Answer 25

Decrease of vagal tone

Increase in sympathetic tone

Question 26

What is the effect of increasing the sympathetic tone in the reflex response to increase cardiac output

Answer 26

Increases Heart rate
Increases contractility of the heart
Causes venoconstriction, increasing venous return
Causes arteriolar constriction - preventing blood leaving the arteries therefore increases TPR

Question 27

What is the affect of decreasing the vagal tone, that results in increased HR and CO

Answer 27

Reducing the activity of the parasympathetic nerves traveling in the vagus nerve which innervate the SA node, preventing the SA node from maintaining heart beat so the heart rate increases

Question 28

What is the valsalva manoeuvre

Answer 28

forced expiration against a closed glottis

Question 29

What is the result of the valsalva manoeuvre on the body

Answer 29

Increase in pressure in the abdomen, increases the thoracic pressure

Question 30

What triggers the baroreceptors to reduce MAP in valsalva manoeuvre

Answer 30

Increase in thoracic pressure

Question 31

How does baroreceptors decrease MAP in valsalva manoeuvre

Answer 31

Causes a decrease in Venous return - EDV - Stroke volume - Cardiac output - reduced Mean arterial pressure

Question 32

What happens when the MAP is reduced in valsalva manoeuvre

Answer 32

reflex kicks in eg adrenaline

Question 33

Why is Blood pressure increases above before retuning to normal after baroreceptor reflex

Answer 33

As the reflex even though stopped, has a long lasting effect therefore originally increases then decreases to normal range