Nerves Flashcards
What are the two anatomical classifications can we make of the nervous sytem
- Central Nervous System
- Peripheral Nervous System
What are the two functional classifications we can make of the nervous system?
- Somatic Nervous System
- Autonomic Nervous System
What are the two classifications within the PNS?
- Afferent
- Efferent
What are the two classification of the efferent nervous system?
- Somatic
- Autonomic
What are the two classifications of the autonomic nervous system?
- Sympathetic
- Parasympathetic
What is the function of the PNS?
To recieve information both external and internal
What is the functional unit of the nervous system?
Neuron
What does a neruon do?
Recieves, integrates, and transmits stimuli
What are neruoglia?
Supporting cells
Nonconducting cells closlty associated with neurons
What does the vasculature provide?
Blood Brain Barrier
How many neurons do we have?
Over 10 billion
Is nerve tissue highly vascular or avascular?
Highly vascular
The blood brain barrier limits what enters nerve tissue
What are Nissel Bodies?
Basophilic, granule-like structure
Rough EF
Indicate the amout of synthesis
There is usually a lot of synthesis becasue they’re making neurotransmitters
What does the cell body do? What is it composed of?
Contains the nuclues and organelles
Maintains the cell
What is the axon? What does it do?
Long process esctending from the cell
1 per cell
Transmits impulses away from cell to synapse
What are dendrites? What do they do?
Shorter processes
Numerous
Transmit impulses from periphery toward the body
What is a perikaryon?
The cell body of a neuron
What are axon hillocks?
Organelle-free zone that distinguishes axon from dendrites
What is the branching of the axon limitted to?
Branching restriced to vicinity of its target
What is a good example of the extensive dendritic trees seen on some neruons?
Purkinje Cells
Receives more than 100,000 different signals
What are the 3 categories of neurons based on number of axons and dendrites?
- Multipolar
- Bipolar
- Unipolar (pseudounipolar)
How many axons and dendrites does a multipolar neuron have? What are 3 examples of mulitpolar neruons?
1 axon + 2 or more dendrites
- Motor
- Pyramidal
- Purkinje
How many axons and dendrites do bipolar neurons have? What are two examples of bipolar nuerons?
1 axon and 1 dendrite
- Olfactory
- Special senses??
How many axons and dendrites does a unipolar (pseudounipolar) nueron have? What type of animal typically has pseudounipolar?
1 axon that divides into 2 processes
Vertebrates
What are the 3 types of nuerons bases on function?
- Motor
- Sensory
- Integrative (internuerons)
What type of polarity are motor neruons? What is thier function?
Majority are multipolar
Convey impulses from CNS/ganglia to effector cells
Somatic efferent fibers and visceral efferent fibers belong to what functional neuron group?
Motor neuron
Whare to somatic efferent fibers terminate? Where is its cell body located?
Terminate at the nueromuscular junction of skeletal muscle
Cell body is in ventral horn
Where do visceral efferent neurons located (terminate and cell body location)?
Terminate on internuerons??
Cell body is in the dorsal horn
What do visceral efferent neurons control? (1 with 2 examples)
Smooth Muscle
ex) blood vessels and sweat glands
What kind of polarity do sensory neurons have? What is thier function?
Majority are pseudounipolar (but special senses are bipolar)
Convey impulses from receptors to CNS
Somatic afferent fibers and visceral afferent fibers belong to which functional neuron group?
Sensory Neurons
What is the funciton of somatic afferent fibers? Where is the cell body located?
In the pacinian corpuslcle
Senses vibrations, pressure, pain
Cell body in dorsal root of ganglion
What is a ganglion?
Aggrefation of cell bodies in the PNS
What are nucli?
Aggregation of cell bodies in the CNS
What types of things do visceral afferent fibers sense?
Sense stretching, pain internally
Still dealing with smooth muscle
What polarity do integrative (internerons) have? What is thier funciton?
Majority are Multipolar
Create a network between sensory and motor neurons
Which functional group accounts for 99% of nuerons?
Integrative
How does information flow from the external environment to movement?
Afferent -> Interneruon -> Effernet -> Muscle
What are synapses?
Specialized junctions that facilliate transmission of impulses from one neuron to another
What are the four types of synapses? What are the two parts of each?
- Axodendritic; axon - dendrite
- Axosomatic; axon - cell body
- Axoaxonic; axon - axon
- Dendrodendritic; dendrite - dendrite
What are the two transmission types of synapses?
- Chemical
- Electrical
What type of transmission over synapses do vertebrates have most commonly?
Chemical
What is chemical transmission?
Release of neurotransmitter at presynaptic neuron
What is electrical transmission?
Gap junctions permit movement of ions between cells
Where do we find electrical synapses in humans? (2)
Smooth muscle
Cardiac muscle
What are the 3 major regions in a chemical synapse?
- Presynaptic element
- Synaptic cleft
- Postsynaptic membrane
Talk me through the process of chemical transmission?
AP comes down axon > depolarizes presynaptic element > Ca channels open > further depolarization > release of NT into synaptic cleft > bind to Na channels (ex) > Na influx into post-synaptic membrane > depolarization > transmissionn of signal down axon
What happens at an exititory synapse?
Sodium increases the positive charge in the post-synaptic membrane causing it to depolarize and move the signal forward
What happens at a inhibitory synapse?
Influx of chloride cause the postsynaptic membrane to become even more negative/ hyperpolarized making it more difficult to propagate the signal
How does botulism toxin work?
AcH is not released from the presynaptic neuron > no depolarization > no action potential propogates > no skeletal muscle contraction
How does tetnus toxin work?
AcH is released from the presynaptic neuron, but there are no inhibitory signals > constant depolarization > contant action potential > sustained muscle contaction
What is AcH released by? What is it important in regulating?
AcH is released by cholenergic neurons
Regulate memory, sleeping, and dreaming
Alzeimer’s Disease
What are the 3 ways to get rid of NT in the synaptic cleft?
- Exocytose it back into the presynaptic
- Brake it down (ex. AcHesterase)
- Modifiy it so its no longer funcitonal
What is dopamine released by? What does dopamine regulate?
Dpamine is released by cholenergic neurons
Regulates movement and motivation
What can too much dopamine indicate? Too little?
Too much = schozophrenia
Too little = parkinson’s
How does dopamine function?
Prolong somehting
NaOIs
Inhibits chatocholine NT so its no longer functional > chatocholine functions for longer
What is the function of GABA? What can too low levels of GABA lead to? Does drinking alchol increase or decrease GABA?
GABA is the major inhibitory NT in the brain
Low GABA > tremors, seizures
Drinking alchohol increases GABA which causes reaction times to slow down
What are the two main type of supporing cells of the nervous system?
- Perihperal Neuroglia
- Central Neuroglia