Heart Control Flashcards

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1
Q

Cardiac output

A

Volume of blood pumped by one ventricle of the heart in one minute (dm3min-1)

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2
Q

Cardiac output depends upon

A

1) heart rate (bpm)

2) stroke volume

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3
Q

Cardiac output

A

Heart rate x stroke volume

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4
Q

Increasing cardiac outputs

A

Strong heart muscles with a higher stroke volume

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5
Q

Pulse

A
  • wave of pressure that pass along the arteries
  • causes them to expand & recoil rhythmically
  • not always same as heart rate, if heartbeat becomes irregular
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6
Q

Myogenic contractions

A

When cardiac muscles are provided with O2, nutrients and mineral salts, they contract spontaneously (without nervous or hormonal stimulation)

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7
Q

Sinoatrial node

A

Small patch of tissue which has its own inherent rhythm of contraction

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8
Q

Cardiac impulses

A

Electrical impulses generated by the SA

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9
Q

Chemoreceptors

A
  • sensory receptors that detect changes in the concentration of chemicals in the blood (pH)
  • found in the carotid and aortic sinuses and arteries
  • act as transducers, transferring chemical energy into electrical energy; can be conducted as an action potential along a neurone
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10
Q

Stretch receptors

A
  • detect movement of the limbs
  • located in the muscles
  • transduce kinetic energy to electrical energy
  • informs brain that more O2 may soon be needed
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11
Q

Baroreceptors

A
  • a type of stretch receptor
  • detect changes in blood pressure that affect stretch of artery walls
  • found in the walls of the carotid sinus
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12
Q

Medulla oblongata

A

Contains the cardiorespiratory (cardiovascular) centre

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13
Q

Autonomic nervous system

A

• responsible for controlling involuntary motor activities
• two divisions
i) sympathetic
ii) parasympathetic

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14
Q

Sympathetic system

A
  • excitatory
  • accelerans nerve
  • most active at times of stress
  • uses noradrenaline
  • increases heart rate
  • dilates pupils
  • increases ventilation rate
  • reduces digestive activity
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15
Q

Parasympathetic system

A
  • inhibitory
  • vagus nerve
  • most active during sleep or relaxation
  • uses acetylcholine
  • opposite effects
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16
Q

The process of cardiac control

A

1) sensory receptors (chemo, stretch) detect changes in internal/external environment
2) sensory neurones conduct electron impulses along the neuronal system to the medulla oblongata
3) medulla oblongata uses cell signalling through the autonomic nervous system to communicate with the sinoatrial node
4) the sinoatrial node effector changes the frequency of the initiation of the waves of excitation

17
Q

Venous return

A
  • the volume of blood returning the heart
  • causes variation in cardiac output
  • high levels causes Bainbridge reflex and the Frank-Starling effect
  • enables the heart to adjust strength and rate of contractions according to volume of blood passing through
18
Q

Bainbridge reflux

A

stretching of the walls of the right atrium, causing the heart to beat faster

19
Q

Frank-Starling effect

A
  • stretching of the walls of the left ventricle, causing ventricles to contract more strongly
  • gives a greater stroke volume