Vascular tone Flashcards
What is paracrine signalling for local control? [1 mark]
Cell to cell signalling
What is autocrine signalling for local control? [1 mark]
Self cell signalling
What is endocrine signalling for local control? [1 mark]
Cell signalling to a cell further away
What is shear stress? [1 mark]
The stress of blood against the blood vessels.
What do intrinsic controls do in blood flow? [2 marks]
- Regulate local blood flow to organs and tissues
- Regional hyperaemia (increase in blood flow)
What are the intrinsic controls for blood flow? [3 marks]
- Myogenic response
- Paracrine and autoregulation agents e.g. nitric oxide
- Physical factors e.g. temperature
What do extrinsic controls do in blood flow? [2 marks]
- Regulate TPR to control blood pressure
- Selectively alters blood flow to organs according to need
What are the extrinsic controls for blood flow? [3 marks]
- Vasodilator nerves (sympathetic, parasympathetic)
- Vasoconstrictor nerves (sympathetic)
- Hormones e.g. ADH, ANP
What is sympathetic tone? [3 marks]
- Constant sympathetic effect in arteries once a second
- Sends noradrenaline to vessels
- Causes slight vasoconstriction
What happens due to the background production of nitric oxide? [1 mark]
Causes vessels to dilate
Pathway for sympathetic tone [3 marks]
- Axon from spinal cord to IML contains preganglionic sympathetic neurones
- Sympathetic preganglionic fibres reach ganglion with synapses
- Postganglionic fibres go to arterioles (via α1 receptors)
What happens when noradrenaline binds to α1? [1 mark]
Contraction
What happens when noradrenaline binds to α2? [1 mark]
Contraction
What happens when noradrenaline binds to β2? [1 mark]
Relaxation
