Reflex Control of the circulation Flashcards
What happens in the pressor response? [3 marks]
- Increased sympathetic nerve activity
- Decreased vagus nerve activity
- Increased cardiac output
- Increased total peripheral resistance
- Increased blood pressure
What happens in the depressor response? [5 marks]
- Decreased sympathetic nerve activity
- Increased vagus nerve activity
- Decreased cardiac output
- Decreased total peripheral resistance
- Decreased blood pressure
What are the excitatory inputs? [2 marks]
- Arterial chemoreceptors
- Muscle metaboreceptors
What are the inhibitory inputs? [2 marks]
- Arterial baroreceptors
- Cardiac pulmonary receptors
What do arterial baroreceptors measure and how? [2 marks]
- Blood pressure in carotid and coronary arteries
- Via arterial wall stretch
What is the formula for blood pressure? [3 marks]
BP = CO x TPR
Why would cardiac output be the same as blood flow? [1 mark]
Same units (volume/time)
What do baroreceptors respond to? [1 mark]
Changes in pressure
What does an increase in BP cause the baroreflex to do? [1 mark]
Depressor effect
What is the formula for cardiac output? [3 mark]
CO = HR x SV
What things are secreted in a decrease of BP? [3 marks]
- Adrenaline
- ADH
- Angiotensin II
What do veno-atrial mechanoreceptors do? [1 marks]
Detect increased cardiac filling pressure on the right atrium
What does the Bainbridge effect cause? [3 marks]
- Increase diuresis via the increase of ADH, ANP and RAAS
- Turns off sympathetic activity to kidneys
- Increase glomerular filtration
What are ventricular mechanoreceptors stimulated by? [2 marks]
- Over-distension of the ventricles
- Weak depressor effect from that
What are nociceptive sympathetic afferents stimulated by? [2 marks]
- Build up of metabolites
- Ischaemia
What causes referred pain? [1 mark]
Some of the neurones from the arm and jaw join the same bundle of neurones as the nociceptive afferent
What are arterial chemoreceptors stimulated by? [3 marks]
- hypoxia
- hypercapnia
- elevated levels of H+ and K+
Where are the arterial chemoreceptors found? [2 marks]
- Aortic and carotid bodies
- Via the vagus and glossopharyngeal nerve
When are muscle metaboreceptors fired? [1 marks]
At elevated levels of metabolites
What happens at isometric exercise [3 marks]
- Higher blood pressure to maintain perfusion.
- Local dilation in tensed muscles.
- Metabolic hyperaemia
Process on how baroreceptors causes an effect
Stretch from baroreceptors → NTS sends info → CVLM sends inhibitory info → RVLM is inhibited → inhibition of sympathetic effects
What do vagal parasympathetic impulses do? [1 mark]
Depressor effect on the heart
What does the inspiratory centre do? [2 marks]
- Temporarily switches off nucleus ambiguus
- Causes sinus tachycardia
How can emotional fainting occur? [3 marks]
- Limbic system stimulates nucleus ambiguus
- Increased activity of vagal nerve
- Depressor effect on the AV and SA nodes
