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Although the origin of the      heartbeat comes from within the       heart (the SAN), it is necessary              for th...
1. Nervous System controlling Heart Rate  ‘fight or flight’ responses         ‘relaxing’ responses Sympathetic nerves rele...
The medulla oblongata contains the      cardiovascular centre
1. Nervous System controlling Heart Rate Two nerves link the cardiovascular  centre in the medulla oblongata of brain with...
1. Nervous System controlling Heart RateThe heart rate is therefore determinedby the balance between sympatheticand parasy...
Receptor groups that send inputs to    the cardiovascular centre1. Pressure receptors in heart2. Chemoreceptors in heart (...
ControllingHeart rate
How does the nervous system control heart rate during exercise?1. During exercise oxygen is used up more rapidly, this    ...
How does the nervous system control heart rate during exercise?1. During exercise oxygen is used up more rapidly, this   d...
One heart beat = 0.8s
1. Nervous System controlling Heart RateWhen do you think:c) the Sympathetic NS is most dominant?d) the Parasympathetic NS...
1. Nervous System controlling Heart RateWhen do you think:• the Sympathetic NS is most dominant?  Stress and excitement• t...
2. Hormonal System controlling Heart Rate•   The hormone adrenaline is secreted    from the adrenal glands.•   Adrenalin i...
Control of heart rate
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Control of heart rate

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Publicada em: Saúde e medicina

Control of heart rate

  1. 1. Although the origin of the heartbeat comes from within the heart (the SAN), it is necessary for the heart rate to be modified to meet the different demands of the bodyThis modification is controlled by: 2.Nervous system 3.Hormonal system
  2. 2. 1. Nervous System controlling Heart Rate ‘fight or flight’ responses ‘relaxing’ responses Sympathetic nerves release Parasympathetic nerves release Neurotransmitter molecules Neurotransmitter molecules to INCREASE heart rate to DECREASE heart rate
  3. 3. The medulla oblongata contains the cardiovascular centre
  4. 4. 1. Nervous System controlling Heart Rate Two nerves link the cardiovascular centre in the medulla oblongata of brain with the SA node of the heart1. Accelerator nerve 2. Vagus nerve(sympathetic NS). (parasympathetic NS).When stimulated, When stimulated, releasesreleases neurotransmitter at the SA node toneurotransmitter DECREASE heart rateat the SA node toINCREASE heart rate Numerous sympathetic nerves also link to the walls of the two ventricles where they increase the force of contraction of these chambers
  5. 5. 1. Nervous System controlling Heart RateThe heart rate is therefore determinedby the balance between sympatheticand parasympathetic nerve activityThe cardiovascular centre receivesinput from 4 main receptor groups,these inputs are processed and thesympathetic/ parasympathetic NS isrecruited accordingly.
  6. 6. Receptor groups that send inputs to the cardiovascular centre1. Pressure receptors in heart2. Chemoreceptors in heart (detects CO2 and O2 levels via changes in pH)3. Thermoreceptors in muscles4. Stretch receptors in muscles
  7. 7. ControllingHeart rate
  8. 8. How does the nervous system control heart rate during exercise?1. During exercise oxygen is used up more rapidly, this decrease in O2 concentration and increase in CO2 chemoreceptors concentration is detected by …………………… in the Heart …………. The body responds by dilating veins.2. This causes more blood to be returned to the heart and therefore the heart is stretched more and the pressure in the heart increases. Stretch receptors and3. This is detected by ………………… Heart pressure receptors in the ……………. ……………………4. The cardiovascular centre processes this information and responds by making the heart beat and faster With greater strength
  9. 9. How does the nervous system control heart rate during exercise?1. During exercise oxygen is used up more rapidly, this decrease in O2 concentration and increase in CO2 concentration is detected by …………………… in the …………. The body responds by dilating veins.2. This causes more blood to be returned to the heart and therefore the heart is stretched more and the pressure in the heart increases.3. This is detected by ………………… and …………………… in the …………….4. The ..................................... processes this information and responds by making the heart beat,........... and ....................................
  10. 10. One heart beat = 0.8s
  11. 11. 1. Nervous System controlling Heart RateWhen do you think:c) the Sympathetic NS is most dominant?d) the Parasympathetic NS is most dominant?
  12. 12. 1. Nervous System controlling Heart RateWhen do you think:• the Sympathetic NS is most dominant? Stress and excitement• the Parasympathetic NS is most dominant? Rest and sleep
  13. 13. 2. Hormonal System controlling Heart Rate• The hormone adrenaline is secreted from the adrenal glands.• Adrenalin increases heart rate by• increasing the frequency of impulses released from the SAN,• increasing the force of contractionTherefore CO will…….

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