Chapter 10 Flashcards
Describe the anatomical and functional divisions of the nervous system
CNS consists of brain and spinal cord
PNS consists of peripheral nerves connecting CNS to other parts of body
ANS controls involuntary effectors
Somatic nervous system controls consciously controlled movements
What forms the anatomical divisions of nervous system
CNS
PNS
What forms the functional divisions of the nervous system
Somatic nervous system
ANS
List the basic functions of the nervous system
Sensory receptors at end of peripheral Neurons provide nervous systems sensory functions
Sensory receptors relay info in response to environmental changes
Information converted to nerve impulses
Impulses processed so motor functions can act appropriately
Effectors (o/s nervous system) are response structures
Effectors include: contractile muscle/glands that secrete and perform other reactive functions
SNS controls conscious motor functions & skeletal muscles
ANS controls involuntary effectors: heart, smooth muscle in BVs and certain glands
Maintains homeostasis
List the important structural components of a neuron
Neurons have rounded cell body (soma) with extensions. Dendrites and axons
Neurons have 1 axon which arises from atonal hillock on cell body
Some Neurons have short or no axons
In others, axon makes up entire neuron length
Neurons are larger than other cells in nervous system because they are highly specialised In conduction Of impulses
Similar in structure but vary in size
Dendrites have multiple branches and Are tapered/short and have diffusely branched extensions
Define the neuron
Structural and functional units of nervous system
What do the multiple branches of dendrites make up
Main receptive surfaces
Describe synapses and synaptic transmission
Happens in 1 direction and carried by biochemicals (neurotransmitters)
When impulse reaches synaptic knob synaptic vesicle releases neurotransmitter
Diffuses across cleft to react with certain receptors on post synaptic neuron membrane either exciting or inhibiting a post synaptic cell
This depends on the combined effect of excitatory and inhibitory inputs from presynaptic Neurons
What do chemical synapses allow
Release and reception of chemical neurotransmitters
What is a chemical synapse more common than.
What is it made up of
Electrical synapses
Axon terminal
Neurotransmitter receptor region
What does axon terminal contain and what is this made up of
Synaptic vesicles
Small membrane bounded sacs holding thousands of neurotransmitter molecules
Where is the neurotransmitter receptor region located
Post synaptic Neurons membrane
On cell body or dendrite
What is the synaptic cleft
Fluid filled space separating presynaptic/postsynaptic membranes
What size is the cleft
1 millionth of 1 inch wide
What dissipates in each synaptic cleft
Electrical current from presynaptic membrane
Due to dissipation of electrical current what happens
And what happens instead
Chemical synapses prevent nerve impulses being directly transmitted between Neurons
Instead they’re transmitted through chemical events based on release, diffusion and receptor building of neurotransmitter molecules
Neurons have what type of communication between them
Unidirectional
List the major types of neurotransmitters
Acetylcholine
AAs (GABA and glutamic)
Monoamines (dopamine, histamine, norepinephrine, serotonin)
Neuropeptides (endorphins, enkephalins, substance P, gases nitric oxide)
Define action potential
Basis for nerve impulse
Based on cell membrane reaching threshold potential
Is a brief reversal of membrane potential with a change in voltage of 100Mv
Explain classifications of nerve fibres
Classified by
Diameter
Degree of myelination
Speed of conduction
Group A: serve joints, skeletal muscle, skin. Are somatic sensory and motor fibres.
Largest diameter of all fibre types and thick myelin sheaths.
Conduct impulses <300mph
Group B: intermediate diameter
Light myelination
Impulses conducted <20mph
Group C: non myelinated
Smallest diameter
Can’t create saltatory conduction
Conduct impulses <2mph
What Neurons can be replaced and what are the ones that can’t be replaced known as
Olfactory epithelium Of nose and regions of hippocampus in brain (memory)
Amitotic losing ability to divide
What do Neurons require and why
O2 and glucose due to high metabolic rate
What happens without o2
Neurons don’t last more than a few mins
Where does biosynthesis occur in the neuron
Cell body (soma)
