Biology unit 1 signals Flashcards
What is the nervous system made of?
peripheral nervous system and the central nervous system.
What is the central nervous system made of?
Brain and spinal cord.
What are neurones?
Neurones are cells that carry electrical signals, or nerve impulses ,from one part of the body to the other.
What does dendrites do in a nerve cell?
Dendrites recieve chemical signals from the axon terminal of other neurons.
What does the node of ranvier do?
The node of ranvier allows the electrical impulse to pick up speed.
What is the axon made of ?
Mylelin sheath and schwann cell. Mylin sheath is electriciyt insulating layer and the schwann cell produces the mylin sheath.
What does a schwann cell do in a nerve cell?
Produces the mylin sheath.
What does node of ranveer do?
Allows the electrical signal to pick up.
What are features of non-myelinated nerve cell?
They have a small diameter, no mylin sheath, grey, slow impulse, no rodes of ranveer and transmits aches, soreness and temperature changes.
What are features of myelinated nerve cells?
Large diameter, mylin sheath,white,fast impulses, nodes of ranvier, and sharp pain.
What are the three neurones and what do they do?
Sensory neuron-they carry a signal from the receptors to the cns. Motor neuron-carry signal from cns to effector. Relay neuron-found in the cns.
What makes the voltage changes when a signal passes through a membrane?
The gates which open and close.
How can sodium and potassium ions move through the membrane?
Some gates open all the time so these ions can move through diffusion and some gates which can be open and closed. And there are pumps which make them move.
What is depolarisation and what happens?
An electrical charge within a neuron from a negative charge to a positive charge and it occurs when the voltage goes from -70mv which is the resting potential to 30mv. This happens because more sodium comes in as the sodium gates open and so makes it more positive and potassium stays the same does not go in or out as potassium gates stay close.
What do sodium and potassium channels depend on?
They depend on diffusion.
What does it mean if the gate is voltage gated?
The gate will open when the voltage becomes a certain value.
What happens step by step in the action potential when a signal moves across a membrane?
A stimulus comes and opens the sodium channels. This causes the sodium to diffuse in and so potential difference starts to rise from -70mv. When and if the volateg reaches -50mv threshold occures this causes the voltage gated sodium channels to open and so lots of sodium ions starts to move in and so the voltage rises rapidly from 30 mv and potassium gates open and also come into the cell. Then the sodium gates close and potassium gates open then sodium ions move out and potassium ions move out and this causes the voltage to decrease to -90mv. Then the sodium and potassium pump does its job and returns the potential difference back to resting potential–70mv it does this as sodium ions move out and potassium ions move in.
What is repolarisation?
When potassium ions and sodium ions move out and potential difference is -90mv.
What is hyperpolarisation?
When potential difference returns to resting potential and sodium is moved out and potassium moves in and so potential difference is -70mv.
Why does action potential travel faste r in myelinated neurones?
Because myelinated has a mylin sheah which is an insulator and stops sodium ions moving in which prevents depolarisation and so signal travels from gap to gap instead which causes saltatory conduction which means leaping.
What is an ECG?
ECG measures the action potential of the heart.
What do electrodes do for patients?
They are placed on the body which detect electrical impulses. A machine amplifies, records and displays them.
What is the ECG Graph and what does each point represent?
The p point is when the atria contract, QRS is when the ventricles contract (ventricular systole) and T wave is the repolarisation of the ventricles as they relax and recover (Diastole).
What does the pacemaker do?
Produces an electrical impulse which causes the heart muscles to contract.
What are synapses?
Synapses are connections between neurones.
What is the process of when action potential occures across synapses?
Action potential occures. Then calcium ions are then produced and comes flowing in. The calcium ions allow proteins to be produced in the vesicles. The proteins dock with proteins in the membrane as the vesicles have diffused to the membrane. The vesicles then produce neurotransmitters. Neurotransmitters then are released into the cleft and then bind to the receptors on the other side when the gate opens. Then the neurotransmitters stay for a while and then are removed or recycled by enzymes in the cleft.
What are symptoms of parksinsons disease?
Muscle tremors(shakes), stiff muscles, slow movement, poor balance, walking problems, difficulty with speech and breathing and depression. Cause of parkinson disease is when the neurones that produce dopamine die which then reduces dopamine levels and causes parkinsons disease.
How to treat parkinsons?
Increase dopamine levels by taking L-dopa medications. L-dopa are molecules that produce dopamine so dopamine can be absorbed into the bloodstream and so flow to the brain.
What are symptomps of clinical
Symptomps of clinical depression are prolonged feeling of sadness, anxiety, loss of interest and insomnia.
What is the cause of depression?
Lack of serotonin
What does the neurotransmitter serotonin do?
It leads to feeling of reward and pleasure.
How can drugs intefer with normal synapse function?
It can affect the synthesis and storage of a neurotransmitter. Affect the release of the neurotransmitter, affect the function of the receptors on the post synaptic neuron, may prevent the reuptake of neurotransmitters in the pre synaptic membrane and may inhibit enzymes that break down the neurotransmitters in the synaptic cleft.
