Biology - Neuronal Communication

Question	Answer
What are Sensory receptors?	Specialized cells that can detect changes in our surroundings.
What are Pacinian corpuscles?	Pacinian corpuscles is a pressure sensor that detects changes in pressure on the skin.
How do Pacinian corpuscles work?	The oval shaped structure consists of a series of concentric rings of connective tissues wrapped around the end of a nerve cell. When pressure on skin changes the rings deform and push against the nerve ending.
What happens when pressure is constant and why?	They stop responding. The corpuscle is sensitive only to changes in pressure that deforms the rings of connective tissue.
Functions of Motor, Sensory and Relay neurones?	Motor - carry an action potential from the central nervous system to an effector Sensory - carry an action potential from a sensory receptor to the CNS Relay - Connect sensory and motor neurones
Structures of Motor, Sensory and Relay neurones?	Motor - Have their cell body in the CNS, long axon that carrier action potential out to the effector. Sensory - Long dendrites carrying the action potential to the cell body. They have a short axon. Relay - Short axons and short dendrites.
What is the myelin sheath made by?	Schwann cells.
What is the name of the gaps between the myelin sheath?	Nodes of Ranvier.
Advantages of myelination.	1. Can transmit an action potential much more quickly. 2. Can carry action potentials over long distances.
First 3 stages of an action potential.	1. The membrane is in resting state of -60mV on the inside of the cell. More sodium outside and more potassium inside 2. Sodium ion channels open and sodium ions diffuse into the cell. 3. Membrane depolarises (becoming less negative) reaching the threshold of -50mV.
Next 3 stages of an action potential.	1. Voltage-gated sodium ion channels open and more sodium floods in. 2. The cell then becomes positive of +40mV. 3. The sodium ion channels close and potassium channels open
Next 3 stages of an action potential.	1, Potassium ions diffuse out of the cell bringing the potential difference back to negative. (Repolarisation) 2. The potential difference overshoot slightly, making it hyperpolarised. 3. Original resting potential is reached, using a potassium/sodium pump.
What is the refractory period?	A period where another action potential can't be produced right after an action potential has occurred.
What causes a local current to form?	As sodium diffuses into the cell, and moves sideways from high concentration to low concentration. As it becomes depolarised the voltage gated sodium ion channels continuously begin to open.
What is Saltatory Conduction.	As a result of the nerve wrapped in a myelin sheath made by schwann cells, action potential can only occur in the gaps between each myelin sheath: nodes of ranvier. The action potential therefore seems to jump from node to node.
What does the phrase "all or nothing" refer to?	All action potentials will reach +40mv if the stimulus meets the required threshold intensity of -50mV. If not an action potential will not be conducted.
What is the gap between the pre-synaptic neurone and the post-synaptic neurone called?	The synaptic cleft.
What are cholinergic synapses?	Synapse that use acetylcholine as the neurotransmitter.
What can be found in the pre-synaptic neurone? (4)	Mitochondria Large endoplasmic reticulum Large number of vesicles containing acetylcholine Voltage gated calcium channels.
Describe the transmission across a synapse.	The action potential reaches the pre-synaptic neurone. Voltage-gated calcium ion channels open Calcium ions diffuses into the pre-synaptic neurone. Calcium ions make the vesicles containing acetylcholine to move to the plasma membrane. The vesicles release acetylcholine through exocytosis. Acetylcholine diffuse across the synaptic cleft. Acetylcholine bind with the receptors on the sodium ion channels. Sodium ion channels open. Sodium ions diffues across the post-synaptic membrane into the post synaptic neurone., The excitatory post synpatic potential (EPSP) is created. *If the potential created reaches threshold level a new action potential is created.
Role of acetylcholinesterase?	Acetylcholinesterase breaks down acetylcholine in the synaptic cleft through hydrolysis. Leaving Ethanoic acid and choline. Stop transmission of singles and stopping the production of action potentials.
Difference between temporal and spatial summation?	Temporal = Several action potentials in the same pre-synaptic neurone. Spatial = Action potentials arriving from several different pre-synaptic neurones.

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	Created by Micah Asomani over 6 years ago