Back to AI Flashcard MakerBiology /LGS A-Level OCR Biology - Unit 5 - Neuronal Communication Part 2

LGS A-Level OCR Biology - Unit 5 - Neuronal Communication Part 2

Biology20 CardsCreated about 1 month ago

This deck covers key concepts from Unit 5 of A-Level OCR Biology, focusing on neuronal communication, including the roles of different neurons, the structure of nerve cells, and the processes of depolarization and repolarization.

Chemoreceptors

Chemical binds to a receptor, initiating a signal cascade to control an ion channel
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Key Terms

Term
Definition
Chemoreceptors
Chemical binds to a receptor, initiating a signal cascade to control an ion channel
Photoreceptors
Light alters a membrane protein initiating a signal that controls an ion channel
Motor neurons
Transmit impulses from a sensory/relay neuron to an effector. Have a long axon and short dendrites; Found in CNS
Myelin sheaths
Made of many layers of a plasma membrane produced by Schwann cells. Acts as insulating layer and allows impulses to be conducted much faster
Nodes of Ranvier
Impulses ‘jump’ from one node to another as it travels along the neuron which speeds up the transmission
Axon
Singular elongated nerve fibres that transmit impulses away from the cell body. Cytoplasm surrounded by plasma membrane

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TermDefinition
Chemoreceptors
Chemical binds to a receptor, initiating a signal cascade to control an ion channel
Photoreceptors
Light alters a membrane protein initiating a signal that controls an ion channel
Motor neurons
Transmit impulses from a sensory/relay neuron to an effector. Have a long axon and short dendrites; Found in CNS
Myelin sheaths
Made of many layers of a plasma membrane produced by Schwann cells. Acts as insulating layer and allows impulses to be conducted much faster
Nodes of Ranvier
Impulses ‘jump’ from one node to another as it travels along the neuron which speeds up the transmission
Axon
Singular elongated nerve fibres that transmit impulses away from the cell body. Cytoplasm surrounded by plasma membrane
Relay neurons
Transmit impulses between sensory and motor neurones | Many short axons and dendrons
Cell body
Contains nucleus surrounded by cytoplasm. Contains ER and mitochondria (involved in making neurotransmitters)
Dendrons
Short extensions that come from the cell body, divide into smaller branches (dendrites). Responsible for transmitting electrical impulses towards the cell body
Sensory neuron
Transmit impulses from a sensory receptor cell to a relay/ motor neurone or the brain Dendron carries the impulse to the cell body and the axon carries impulse away from the cell body Found in PNS
Why do motor neurons have long axons
In order to transmit the action potential to the effectors all over the body
Myelination
Prevents ion movement and forces the current to 'jump' along the axon Reduces energy expenditure Stops leakage of charge across membrane and local current is attenuated and insufficient to polarise next node
Why are myelinated neurons found in the PNS
Neurons in the PNS frequently have to transmit over long distances so speed of impulse is critical to efficient function
Action potential
Self regenerating depolarisation that allows excitable cells to carry a signal over a distance -60 to +40
Why does the pre-synaptic knob end in a bulb
To increase SA for release for acetylcholine by exocytosis
Why are Ca^+ channels on the pre-synaptic neuron VG
To prevent acetylcholine being released if theres no action potential
Touch stimulus
Distortion of Pacinian Corpuscles; Causes stretch-mediated Na^+ channels to open; Causes Na^+ to move in and depolarises
Depolarisation
The condition of the membrane that is less highly polarized than the usual resting state so the inside of the cell becomes less -ve with respect to the outside; VG Na - open; VG K - closed
Repolarisation
The condition of the membrane when mechanisms are trying to bring the potential diff. across the cell back being to more - ve on the inside of the cell w/ respect to the outside; VG Na - closed; VG K - open
Hyperpolarisation
The condition of the membrane that is more highly polarized than the usual resting state so the inside of the cell becomes more - ve than usual w/ respect to the outside