2.2. Control of HR (CCC) Flashcards
What is the CCC?
Regulates HR and force of contraction
Where is the CCC found in the body?
Medulla oblongata
What does it mean by the CCC being controlled by the autonomic nervous system?
System that is involuntary and acts unconsciously
What do sympathetic nerves do?
Increase HR via accelerator nerve
What do parasympathetic nerves do?
Decrease HR via vagus nerve
How does the CCC regulate HR?
CCC initiates the sympathetic or parasympathetic nervous system to stimulate the SA node causing either increase or decrease in HR
What are the 3 main factors that affect the CCC?
- Neural control
- Hormonal control
- Intrinsic control
Neural control
- Proprioceptors
- Chemoreceptors
- Baroreceptors
Hormonal control
Adrenaline
Intrinsic control
- Temperature
- VR
Proprioreceptors
In muscles, tendons + joints to inform the CCC that movement activity has increased
Chemoreceptors
- Detect chemical changes in muscles, aorta and carotid arteries.
- They inform the CCC that lactic acid and Co2 levels have increased and O2 and pH levels have decreased
Baroreceptors
- Detect stretch within vessel walls and inform the CCC that blood pressure has increased
- When pressure increases, they attempt to decrease HR but are overridden by chemo and proprioreceptors
What hormone is released into the bloodstream before and during exercise and what area of the heart does it affect?
- Adrenaline is released from adrenal glands
- Adrenaline stimulates the SA node to increase both HR and strength of contraction which leads to increased SV.
Intrinsic =
internal factors
Factors affecting intrinsic control of HR during exercise
- Temp increases = faster nerve impulses = increased HR
- VR increases= SV increases (Starling’s law) = stronger contraction of heart
Factors affecting intrinsic control of HR after exercise
- Temp decreases = HR falls
- VR decreases = SV decreases
Venous return meaning
Blood returning to the right atrium
Starling’s law
Increase in VR = increase in SV = increase in Q
