CNS and Hormonal Control of the heart

Question 1

sympathetic system

Answer 1

part of the autonomic nervous system that speeds up heart rate

Question 2

parasympathetic system

Answer 2

part of the autonomic nervous system that decreases heart rate

Question 3

medulla oblongata

Answer 3

most important part of the brain as it regulates processes that keep us alive such as breathing and heart rate

Question 4

how does the heart know to speed up

Answer 4

the autonomic nervous system (ANS) determines the rate at which the SAN sends out impulses

Question 5

sympathetic nervous system

Answer 5

• increases HR by releasing adrenaline
• adrenaline increases strength of ventricular contraction which increases stroke volume
• noradrenaline aids the spread of electrical impulse throughout the heart increasing HR
• increased metabolic activity= increased co2 concentration, lactic acid, decreasing pH of blood
• these changes are picked up by chemoreceptors and inform the sympathetic centre to increase HR to flush out the waste products
• results in increased cardiac output

Question 6

parasympathetic nervous system

Answer 6

releases acetylcholine which slows the spread of impulses throughout the heart
- this results in a lower heart rate

Question 7

sympathetic nerves

Answer 7

‘fight or flight’

Question 8

parasympathetic nerves

Answer 8

‘rest and digest’

Question 9

neural control mechanism

Answer 9

involves the sympathetic nervous system which stimulates the heart to beat faster and the parasympathetic system which returns the heart to its resting level

Question 10

what does the CNS consist of

Answer 10

brain and spinal cord

Question 11

what does the peripheral nervous system consist of

Answer 11

nerve cells that transmit info to and from the CNS

Question 12

receptors

Answer 12

receive and convert signals to areas of the body to initiate a response

Question 13

chemoreceptors

Answer 13

-increase in co2-increase in heart rate
- during exercise, they detect an increase in carbon dioxide, the role of blood carbon dioxide is important in controlling heart rate. increased concentration of carbon dioxide in the blood will have the effect of stimulating the sympathetic nervous system, meaning the heart will beat faster

Question 14

baroreceptors

Answer 14

-increase in blood pressure-decrease in heart rate
- respond to the stretching of the arterial wall
- establish a set point for blood pressure, an increase above or below this signals will be sent to the medulla in the brain
-increase in arterial pressure=increase in stretch of baroreceptor sensors= decrease in heart rate
-decrease in arterial pressure=decrease in stretch=increase in heart rate

Question 15

proprioceptors

Answer 15

• increase in muscle movement- increase in heart rate
  -sensory nerve endings located in muscles, tendons, joints provide info about movement and body position
• start of exercise, detect increase in muscle movement, these receptors then send an impulse to the medulla, which then sends an impulse through the sympathetic nervous system to the SAN to increase heart rate
• when the parasympathetic system stimulates the SAN, heart rate decreases

Question 16

hormonal control mechanism

Answer 16

• release of adrenaline
• adrenaline = stress hormone, released by sympathetic nerves and cardiac nerve during exercise
• stimulates the SAN= increase in both speed and force of contraction, increasing cardiac output
• results in more blood being pumped to the working muscles so they can receive more oxygen for the energy they need