Impulses Flashcards
What are the 10 events in a reflex.
Stimulus -> Receptor -> Sensory neurone -> Synapse -> Relay neurone -> Synapse -> Motor neurone -> Neuromuscular junction -> Effector -> Response
What is the receptor when the stimulus is ‘external or internal temperature’?
Thermo-receptor
What is the receptor when the stimulus is the ‘level of water in the blood’?
Osmoreceptor
What is the receptor when the stimulus is ‘bright light’?
Cone cell
What is the receptor when the stimulus is ‘dim light’?
Rod cell
What is the receptor when the stimulus is ‘blood pressure’?
Bara receptor
What is the receptor when the stimulus is ‘carbon dioxide in the blood’?
Chemoreceptor
What is the reflex arc process for an increase in heart rate?
- There’s a normal concentration of CO2 in the blood.
- Chemoreceptors detect a rise in CO2 levels in the blood (through repairing muscles).
- Sensory neurone to the coordinator (which is the medulla).
- Motor neurone to the effector.
- This causes an increase in heart rate and stroke volume.
- This leads to a normal concentration of CO2 in the blood again.
What is the reflex arc process for a decrease in heart rate?
- Normal concentration of CO2 in the blood.
- Chemoreceptors in the aortic arch detect fall in CO2 levels in blood.
- This leads to impulses in the sensory neurones.
- This leads to coordinator in the medulla.
- This impulses in motor neurone.
- Leading to a decrease in heart rate and stroke volume.
- This ends in a normal concentration of CO2 in blood
What are reflexes needed for?
To protect from danger and maintain pressure.
Why are reflexes fast?
Because of the minimum number of synapses and neurones.
What do motor neurones do?
Transmit electrical impulses from the CNS to the effector.
What is a synapse?
The physical gap between two neurones.
What is noradrenaline?
Noradrenaline is a chemical which is secreted onto the SAN when the heart rate needs to increase.
Define resting potential.
The potential across the plasma membrane of a cell that is not conducting an impulse.
How do you calculate cardiac output?
Stroke volume x heart rate.
What does the sympathetic nervous system do?
- increases HR and SV
- releases noradrenaline onto the SAN
What does the parasympathetic nervous system do?
- decreases HR and SV
- decreases blood pressure
- releases acetylcholine onto the SAN
What transport process is used by the sodium potassium pump?
Active transport
Why is it important for the pupil to enlarge in dim light?
Because this allows rod cells to gain sufficient light energy to produce a greater generator potential.
Why is it important for the pupil to become smaller in bright light?
To prevent damage to the retina due to too much light energy.
Which three neurones are present in a reflex action?
Sensory, relay, motor.
Why does the synapse only work in one direction?
- calcium ion channels are only found in the pre-synaptic nerve.
- receptors for neurotransmitters are only found in the post-synaptic nerve.
- vesicles containing neurotransmitters are only found in the pre-synaptic nerve.
