Control of circulation

Question 1

Key targets for control

Answer 1

Arteriole resistance and blood storage veins, vascular smooth muscle

Question 2

What do pre-capillary vessels have and why?

Answer 2

Sympathetic cholinergic control causing vasodilation, in skeletal muscle, heart, lung, kidney

Question 3

What effect does Endothelium derived relaxing factor have and how?

Answer 3

Released after stimulation by Aah, released from endothelial cells, stimulate cGMP in muscle which causes relaxation

Question 4

What is the simple loop for short term regulation?

Answer 4

Detector, afferent neural pathways, coordinating centre in CNS, efferent neural pathways, effectors

Question 5

What are sensors for the short term control of circulation?

Answer 5

Baroreceptors and chemoreceptors

Question 6

What are the control centres for short term control of circulation?

Answer 6

Mainly medulla but also cortex and hypothalamus

Question 7

What are the effectors for short term control of circulation?

Answer 7

Pacemaker cells in the heart, vascular smooth muscle in arteries and adrenal medulla

Question 8

Where are baroreceptors found?

Answer 8

In carotid sinus and aortic arch

Question 9

What do the negative and positive feedback loops of baroreceptors cause?

Answer 9

negative- decrease BP and bradycardia, positive- increase BP and tachycardia

Question 10

How do baroreceptors work?

Answer 10

Depolarise the baroreceptor nerve ending, increasing the frequency of firing, signal to the medulla

Question 11

What nerve does the carotid sinus baroreceptor use?

Answer 11

Glossopharyngeal

Question 12

What nerve does the aortic arch baroreceptor use?

Answer 12

Vagus

Question 13

What part of the medulla to the baroreceptors project to?

Answer 13

Nucleus tractus solitarii with glutamate

Question 14

Sympathetic activity of baroreceptors results in what?

Answer 14

Increase stroke volume, increase blood pressure, decrease vagal activity to increase cardiac output

Question 15

What is the sympathetic pathway from the medulla?

Answer 15

Cardioaccellatory centre, descending pathway to spinal cord at T1-T4, fibres exit via spinal nerve, enter sympathetic chain (preganglionic and post ganglionic), cardiac nerve, heart, heart rate

Question 16

What is the parasympathetic pathway from the medulla?

Answer 16

Cardioinhibitory centre, vagus nerve, preganglionic synapses with cardiac plexus, post ganglionic, change heart rate

Question 17

What is local control to the medulla?

Answer 17

Metabolites that change tone of vessels in the medulla

Question 18

How can intracranial pressure rise be treated?

Answer 18

Reducing oxygen by increasing ventilation so less oxygen in blood

Question 19

What do buffer nerves do?

Answer 19

Increase arterial pressure and firing, decrease vasoconstriction and cardioinhibition, vasodilation, bradycardia, reduce output and BP

Question 20

Vasalva Manouvre

Answer 20

Forced expiration against closed glottis, increase thoracic pressure and BP, reduces venous return so reduces BP, reduces baroreceptors, tachycardia and vasoconstriction, increase venous return increased CO and increase BP, baroreceptors increase firing giving bradycardia and vasodilation, BP briefly drop giving tacchcardia reflex leading to increase CO and increased BP

Question 21

What does activation of chemoreceptors lead to?

Answer 21

Increase BP

Question 22

What parts of the hypothalamus are involved with para and sympathetic control?

Answer 22

Anteromedial - para, lateroposterior- symp

Question 23

Hypothalamus defence area

Answer 23

Sympathetic dilation of skeletal muscle

Question 24

Hypothalamus thermoregulatory centre

Answer 24

Warm and cold

Question 25

Hypothalamus median pre optic area

Answer 25

Sexual response

Question 26

Anterior cingulate gyrus

Answer 26

Bradycardia hypotension