module 5 - 14.6 controlling heart rate Flashcards
which part of the autonomic nervous system is responsible for heart rate?
medulla oblongata
what is the medulla oblongata?
- located in brain stem
- connects higher levels of the brain to the spinal cord
- cone shaped neuronal mass responsible for involuntary functions
- contains cardiac, respiratory, vomiting and vasomotor centres so deals with autonomic functions
what are the 2 centres in the medulla oblongata responsible for?
- one increases heart rate through SNS using accelerator nerve connected to SAN
- one decreases heart rate through parasympathetic NS using vagus nerve connected to SAN
what are the 2 sets of receptors in blood vessels?
baraoreceptors
chemoreceptors
what are baroreceptors?
- measure blood pressure
- located in aorta, vena cava and carotid arteries
what are chemoreceptors?
- detect blood CO2 concentration by measuring blood pH
0 located in aorta, carotid arteries and mudulla oblongata
what do chemoreceptors do if there is too much CO2 in blood? (opposite for too little)
increased muscle activity → more CO2 produced by tissues from increased respiration → blood pH is lowered → SAN increased heart rate → increased blood flow moves CO2 faster → CO2 level returns to normal
what do baroreceptors do if blood pressure is too high?
- baroreceptors detect change in blood pressure
- nervous impulses sent to medulla oblongata
- medulla oblongata sends nervous impulses along parasympathetic neurones to SAN
- heart responds by decreasing heart rate
- blood pressure is reduced
how do hormones control/influence heart rate?
by affecting SAN directly
what do baroreceptors do if blood pressure is too low?
- baroreceptors detect change in blood pressure
- nervous impulses sent to medulla oblongata
- medulla oblongata sends nervous impulses along sympathetic neurones to SAN
- heart responds by increasing heart rate
- blood pressure is increased
