Control of heart rate
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?- Created by: vezting
- Created on: 27-04-16 10:17
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- control of heartrate
- heart rate
- 1: heart is myogenic
- 2: heart contains pace-maker the sino- atrial node
- 3: this initiates waves of excitation over the atria walls through the atriventricular node, down the purkyne fibres to ventircles, causing them to contract
- 4: the heart is supplied with nerves from the medulla oblongata in the brain
- 5: these nerves connect with the SAN and they affect the frequency of the contractions
- response of the heart
- action potential sent down accelerator nerve increases heart rate
- action potenital sent down the vegus nerve decreases the heart rate
- the frequency of excitation waves are controlled by the cardiovascular center in the medulla oblongata
- the heart also responds to Adrenalin in the blood
- factors affecting heart rate
- stretch receptors in limbs send impulses to cardiovascular centre
- causes cardiovascular centre to increase frequency of action potential down accelerator nerve
- CO2 from increases respiration reduces blood pH level and is detected by chemo receptors
- chemo receptors send impulses to cardiovascular centre and they increase frequency of action potential down the accelerator nerve
- blood pressure is monitored by stretch receptors in the walls of carotid sinus
- they send signals to cardiovascular centre and increase frequency of impulse along accelerator nerve
- stress and shock are detected by the hypothalamus and adrenaline is secreted from adrenyl medulla
- binds to cell surface membrane and activates adenyl cyclase t convert ATP to cAMP
- fight or flight response-
- hypothalamus also releases CRF into blood which stimulates release of ACTH into blood to stimulate secretion of other hormones from adrenyl cortex
- adrenaline binds to receptors in mucles
- fight or flight response-
- binds to cell surface membrane and activates adenyl cyclase t convert ATP to cAMP
- stretch receptors in limbs send impulses to cardiovascular centre
- heart rate
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