5 - Control of heart rate Flashcards
What is the Peripheral Nervous System (PNS) made up of?
The neurones that connect the CNS to the rest of the body
What are the two different systems the PNS is made up of?
- The Somatic Nervous System
- The Autonomic Nervous System
What does the Somatic Nervous system control?
Conscious activities
What does the Autonomic Nervous System control?
Unconscious activities
What are the two different systems the Autonomic Nervous System is made up of?
- The Sympathetic Nervous System
- The parasympathetic Nervous System
What does the Parasympathetic Nervous System do?
It is the ‘rest and digest’ system that calms the body down
What does the Sympathetic Nervous System do?
It is the ‘fight or flight’ system that gets the body ready for action
What is myogenic contraction?
When muscle cells are able to contract and relax without receiving signals from nerves
What is the SAN (Sino-atrial node)
A group of cells in the wall of the right atrium that set the rhythm of the heartbeat by sending out regular waves of electrical energy to the atrial wall
What is the AVN (Atrioventricular node)
A group of cells in the heart wall that is responsible for passing waves of electrical activity from the SAN on to the bundle of His
What is the bundle of His?
A group of muscle fibres in the heart, responsible for conducting waves of electrical activity from the AVN to the Purkyne fibres
What is Purkyne fibres?
Fine muscle fibres in the heart that carry waves of electrical activity into the muscular walls of the right and left ventricles
What is the medulla?
A part of the brain that controls heart rate
Which receptors detect internal stimuli in order to alter heart rate?
- Pressure Receptors
- Chemical receptors
Name the pressure receptor found in the heart. Where Is it specifically found and what are they stimulated by?
- Baroreceptors
- Found in the aorta and carotid arteries
- Stimulated by high and low blood pressure
Name the chemical receptor found in the heart. In which parts of the heart is it found and what is its function?
- Chemoreceptor
- Found in the aorta, carotid arteries and the medulla
- They measure the oxygen levels in the blood and also carbon dioxide and PH (which are indicators of oxygen level)
How is the heart rate controlled in response to. high blood pressure?
- Baroreceptors detect high blood pressure
- They send impulses along sensory neurones to the medulla
- Which then send impulses along parasympathetic neurones
- These secrete acetylcholine, which binds receptors to the SAN
- This causes the heart rate to slow down in order to reduce blood pressure
How is the heart rate controlled in response to low blood pressure?
- Baroreceptors detect low blood pressure
- They sens impulses along the sensory neurone to the medulla
- Which sends impulses along sympathetic neurones
- These secrete noradrenaline which binds to receptors on the SAN
- This causes the heart rate to speed up in order to increase blood pressure
How is the heart rate controlled in response to high blood Oxygen levels? (Low Carbon dioxide or high blood PH levels)
- Chemoreceptors detect chemical changes in the blood
- They send impulses along sensory neurones to the medulla
- These send impulses along parasympathetic neurones
- These secrete acetylcholine which binds to receptors on the SAN
- This causes the heart rate to decrease in order to return oxygen (or other levels) back to normal
How is the heart rate controlled in response to low blood Oxygen levels? (High Carbon dioxide or low blood PH levels)
- Chemoreceptors detect chemical changes in the blood
- They send impulses along sensory neurones to the medulla
- These send impulses along sympathetic neurones
- These secrete noradrenaline which binds to receptors on the SAN
- This causes the heart rate to increase in order to return oxygen (or other levels) back to normal
