Haemodynamics
- Created by: Labake
- Created on: 28-12-16 18:04
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- Haemo-dynamics
- Dynamic, adjustable networks of blood vessels affected by chemicals
- Affects cardiac output and workload
- Sympathetic input (fight or flight)= higher cardiac output
- Uses Adrenaline hormone and Noradrenaline neuro-transmitter
- Mechanism
- Pre-ganglionic neurones release acetylcholine to synapse
- Activates nicotinic acetylcholine receptors on post-ganglionic neurones
- Post-ganglionic neurones release noradrenaline
- Noradrenaline= increase in BP, heart rate, glyco-genolysis, vasodilation to skeletal muscles and GI relaxation
- Affects a1, a2, B1 and B2 adreno- receptors
- Noradrenaline= increase in BP, heart rate, glyco-genolysis, vasodilation to skeletal muscles and GI relaxation
- Post-ganglionic neurones release noradrenaline
- Activates nicotinic acetylcholine receptors on post-ganglionic neurones
- Pre-ganglionic neurones release acetylcholine to synapse
- Para-sympathetic input= lower cardiac output
- Sympathetic input (fight or flight)= higher cardiac output
- Vessel Structure
- Veins= Endothelium, thin smooth muscle and connective tissue
- Arteries= Endothelium, thick smooth muscle (HIGH PRESSURE) and connective tissue
- Sympathetic= Increase in smooth muscle tone = vaso-constriction
- Greater flow resistance in smaller vessels
- Increased venous pressure and cardiac filling
- Large veins constrict to fill atria faster and oppose the reduced volume
- Increased venous pressure and cardiac filling
- Greater flow resistance in smaller vessels
- Flow auto-regulation
- After a pressure surge- stretch gated receptors increase muscle tone to maintain SAME FLOW by increasing resistance
- Compliance
- Measure of vessel stretching ease due to pressure
- High compliance= veins with thin stretchy walls
- Low compliance = arteries with thick rigid walls
- Measure of vessel stretching ease due to pressure
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