Topic 5 Nervous system / neurons Flashcards
The 2 main subdivisions of the nervous system ?
Central nervous system (CNS) & Peripheral nervous system (PNS)
The central nervous system consists of?
Brain and spinal cord
The peripheral nervous system consists of ?
All nervous tissue outside of the CNS.
What are the Functions of the NS? (3)
Sensory - detection and input (towards CNC)
Integrative - processing/storing/ analyzing of sensory info;
Decision making
Motor - output (role of PNS)
Types of tissue…
Nervous tissue is designed for what?
Communication
Name the types of cells?
Neurons and neuroglia
Role of the neuroglia (glia cells)?
Support, nourish, protect
Name the 3 parts of the Neurons ( nerve cell)
Dendrite, cell body, axon
Is the input portion of the neuron;
Contains lots of receptor sites for receiving chemical messages from other cells
Dendrite
Part of neuron that is responsible for cell processes;
Contains the neucleus and other organelles
Cell body
Aka soma, perikaryon (holds nucleus DNA/RNA)
A thin cylindrical process off the cell body;
It is the output portion of the neuron
Axon
The end of the axon divides into many fine processes called?
Axon terminals
The swollen ends of the axon terminals?
Synaptic end bulb
Def.
A multilayered lipid and protein covering that speeds up signal conduction
Signal = action potential
Myelin
*myelin insulates to aid the speed of communication
Some axons are myelinated; axons coated in myelin are called?
Myelinated axons
These possess electrical excitability;
Can respond to a stimulus and convert it to an action potential(AP)
Neuron
Def.
Any change in the environment (internal external) that is strong enough to stimulate an Action Potential (AP)
Stimulus
Def.
An electrical signal that travels along the cell membrane of a neuron;
Influenced by myelin, they travel at different speeds
Action potential (AP)
Neurons vary in size and shape;
Structural, they are classified according to the number of processes extending from the cell body - name the 3 types
Multipolar
Biopolar
Unipolar
Neuron structure…
Several dendrites and one axon
* most neutrons in the brain and spinal cord and all motor neurons
Multipolar
Neuron structure…
One main dendrite and one axon
*retina, inner ear, olfactory system
Bipolar
Neuron structure…
Peripheral axon has sensory receptors;
Central axon has a on terminals;
*Sensory neutrons in the PNS are —-
Unipolar
Functionally, neurons are classified according to the direction in which the AP is conducted - name the 3 types
Sensory neurons
Motor neurons
Interneurons
Most are unipolar;
Contain either sensory receptors at the ends or are located just after sensory receptors that are separate cells
Once activated by a stimulus, the AP forms and propagates along the axon and is conveyed into the CNS by these
They travel together in spinal and cranial nerves
Sensory neurons
Aka Afferent neurons
Are multipolar;
The AP propagates way from the CNS to the effectors via these
Motor neurons
Aka Efferent neurons
Def.
The cells and organs (eg. Muscle fibres, glands
Effectors
Most are multipolar
Located primarily in the CNS between the sensory and motor neurons;
They integrate/ process information from sensory neurons -
If motor response is required, the specifics of the response are formulated and relevant motor neurone are activated.
Interneurons
Aka Association neurons
Def.
The site of communication between two neutrons or between a neutron and another type of cell
Synapse
There are 2 types of synapses
Electrical and chemical
Type of synapse…
APs conduct directly between the plasma membranes of adjacent cells through gap junctions
Faster (than chemical)
Allows for synchronization of function
Electrical synapses
Chemical synapses - terms…
The neuron sending the signal
Pre-synaptic neuron
Chemical synapses - terms…
The neutron receiving the signal
Post-synaptic neuron
Chemical synapses - terms…
The space between the communication neurons
Synaptic clef
Chemical synapses - terms…
A chemical released by the pre-synaptic neuron to affect (excite inhibit) the post-synaptic neuron(s) or effector (muscle/glands)
Neurotransmitter (NT)
*NT receptors are specific to the NT released (think lock and key)
Def.
When the AP reaches the end of the pre-synaptic neuron, it causes the release of a neurotransmitter that diffuses across the synaptic clef, binds to the post-synaptic neuron
Chemical synapses
If neurotransmitter is excitatory, continuation of the AP is …
More likely
If neurotransmitter is inhibitory, continuation of the AP is
Less likely
Common Neurotransmitters (4)
Acetylcholine (ACh)
Gamma-aminobutyric acid (GABA)
Dopamine
Serotonin
Neurotransmitter found in the PNS/CNS, excitatory at neuro muscular junction
Acetylcholine
Neurotransmitter found in the CNS, inhibitory
Gamma-aminobutyric acid
* regulate muscle tone, contractions
Neurotransmitter that is excitatory or inhibitory (depending on receptors), emotional responses, addictive behaviours, skeletal tone
Dopamine
* emotional response
Neurotransmitter that is excitatory or inhibitory (depending on receptor), sensory perception , temperature regulation, mood, sleep, appetite
Serotonin
* serotonin stays in the synaptic clef longer
