5 - MZH - Homeostasis 7 - Neuronal Communication Flashcards
What does the nervous system do?
- What type of response does it provide?
- Give 4 examples
Provides rapid responses to changes in both the internal and external environment
What does a general nervous pathway look like?
What does each stage do?
Define Stimulus, Receptor and Effector
Stimulus = Detectable change in the external or internal environment of an organism
Receptor = A cell, or protein on a CSM that detects specific stimuli
Effector = A muscle or gland which carries a body’s response to a stimulus
What are sensory receptors?
What are transducers?
Sensory receptor = Specialised cells that respond to stimuli. Most sensory receptors are known as transducers - they convert one form of energy into another.
In this case the transducers are converting energy to electrical impulses/ action potentials.
Give 4 examples of:
Stimulus - Sensory receptor - Energy change involved (what brings abou this every transfer change?)
Transducers bring about this transfer of energy
What are Pacinian Corpuscles?
Structure + Function?
Pacinian corpuscles = (type of mechanoreceptor) which detects changes in pressure on the skin and joints.
NOTE: NOT constant pressure.
Structure:
- Each pacinian corpuscle consists of a single nerve fibre of a dendrite of a sensory neurone wrapped around by layers of a membrane called lamellae.
- Layers of connective tissue are seperated by a jelly/ viscous gel like material.
Function:
- Pressure applied to skin deforms the lamaellae which pushes up against the dendrite triggering a generator potential.
- Stretch in membrane opens voltage gated Na+ ion channels. Inflow of Na+ ions raises membrane potential - depolarises it.
- The more intense the stimuli the larger the generator potential.
4.
Resting potential = ?
Resting potential = -70mV
Structure of a neurone:
Feature: Large cell body
Decription?
Contains the nucleus and many of the cell organelles
Structure of a neurone:
Feature: Dendrons
Decription?
Short extensions of the cell body which transmit impulses towards the cell body.
Structure of a neurone:
Feature: Dendrites
Decription?
- Each dendron has smaller extensions called dendrites
- Dendrites are stimulated by other neurones
Structure of a neurone:
Feature: Axon
Decription?
- It’s a single entension of the cell body
- Can be up to 1m long
- Always transmits nerve impulses away from cell body
- Ends in series of synaptic knobs
Structure of a neurone:
Feature: Myelin
Decription?
- In mammals many axons are surrounded by a sheath of fatty material = Myelin sheath
- Myelin enables the neurones to conduct action potentials rapidly
Structure of a neurone:
Feature: Schwann cell
Decription?
Specialised cells which produce myelin
Structure of a neurone:
Feature: Node of Ranvier
Decription?
- Small gaps between the myelin sheath where bare membrane is exposed.
- Nerve impulses travel along in a series of jumps from one node to the next - Advantage of myelination.
- This jumping is called Salutatory conduction
Name the different types of neurones (3)
What do they do?
Sensory neurone = Carries action potential from a sensory receptor → CNS
Motor neurones = Carries action potentials from the CNS → effector e.g. muscle or gland
Relay neurones = Connects the sensory and motor neurones together