Week 6 Flashcards
Two Parts of the Nervous System
- Central Nervous System (CNS)
- Peripheral Nervous System (PNS)
Central Nervous System (CNS)
- Brain & Spinal Cord
- Dorsal Cavity
- Cannot regenerate
Peripheral Nervous System (PNS)
- everything BUT brain & spinal cord
- contains ganglion
Ganglion
groups of cell bodies
Function of the Nervous System
Communication in the body
3 Parts to Communication in the NS
- Recieve Signal
- Respond to Signal
- Integration
Receiving a Signal
- through sensation AKA stimulus
Three Parts of Sensation
- Chemical (smell/taste)
- Physical (touch)
- Mechanical (hearing/touch)
Two types of Responses
- Involuntary
- Voluntary
Autonomic NS
- Involuntary response
- not in control
ex. breathing & digestion
Somatic NS
- voluntary response
- in control
ex. moving the skeletal muscles
Perception
making sense of the signal going to your brain
Integration
deciding how to react to stimuli
White Matter
myelin axons
Grey Matter
cell bodies
Two types of Cell in Nervous Tissue
- Neurons
- Glial Cells
Neruons
carry the signal
Glial Cells
support the neurons
Convergence
- a lot of connections between neurons
- multiple pathways to do one thing
Parts of the Neuron
- Soma
- Dendrite
- Axon
- Nodes of Ranvier
- Axon Terminal
- Synapse
Soma
cell body/grey matter
Dendrite
receives signal from other neurons
Axon
carries signal to the axon terminal
Node of Ranvier
space between myelin on the axon
Axon Terminal
end of the axon
Synapse
space between neurons
Types of Neurons
- Unipolar
- Multipolar
Unipolar Neuron
- one process leaves the cell
Where are unipolar neurons found?
In the Peripheral Nervous System
Multipolar Neuron
lots of processes leave the cell
Where are multipolar neurons found?
Found in the Central Nervous System
Types of Glial Cells in CNS
- Astrocyte
- microglia
- oligodendrocyte
- ependymal cell
Astrocyte
- supports the neurons/holds them in place
- Maintain the blood brain barrier (BBB)
Blood Brain Barrier (BBB)
keeps stuff out of the brain
Microglia
defense
Oligodendrocyte
makes myelin in the CNS
Ependymal Cell
makes cerebral spinal fluid (CSF)
Cerebral Spinal Fluid
cushions brain/keeps it safe
Types of Glial Cells in PNS
- Satellite Cells
- Schwann Cells
Satellite Cells
Supports neurons
Schwann Cells
-makes myelin in the PNS
-helps with nerve regeneration
Myelin
speeds up the signal of a neuron
How do neurons communicate?
Carrying an electric charge (Action Potential)
Action Potential (AP)
- electric charges carried to communicate between neurons
- ALL or NOTHING
How does the brain differentiate between stimulus?
-frequency of AP is what defines signal in the brain
- different amounts of AP mean different things in the brain
Channel Protein
-helps cells cross the membrane
-not always open
- requires something to help open them up
ex. Sodium-Potassium Pump
Sodium-Potassium Pump (Na+/K+)
- pumps 3 sodium out of the cell and 2 potassium in the cell
Acetylcholine
neurotransmitter that makes muscles move
Types of Channel Proteins
- Ligand-gated channel
- Mechanically-gated channel
- Voltage-gated channel
Ligand- Gated Channel
-lock and key
- channel opens with specific key
- found in the synapse
- NT is the key to open the channel
Mechanically-gated channel
uses sense of touch/pressure to open the channel
Voltage Gated Channel
- needs a specific voltage to open
- -55mV
Parts of the Action Potential
- Threshold
- Resting Potential
- Depolarization
- Repolarization
- Hyperpolarization
How does an Action Potential Work?
- Starts at Resting Potential (-70mV)
- Stimulus is applied
- if it crosses -55mV, an AP is sent
- Sodium Channels OPEN
-Na rushing IN cell
- Cell gets POSITIVE (depolarization) - Na Channels CLOSE; K Channels OPEN (@ +30mV)
-K rushes OUT of cell
-cell become NEGATIVE (repolarization) - K Channels CLOSE slowly
- gets TOO NEGATIVE (hyperpolarization) - Na/K pump initiates
-brings cell back to RESTING - Arrives at resting potential (-70mV)
Continuous Conduction
-NO myelin on axon
- signal moves SLOW
Saltatory Conduction
- HAS myelin on axon
- signal jumps along the myelin & goes fast
How Connections are made in the Synapse
- AP gets to axon terminal
- Calcium channels OPEN
- Calcium rushes IN cell
- Calcium stimulate NT to be released INTO SYNAPSE
- NT bind to ligand-gated receptor on the dendrite on next neuron
- Ligand gate OPENS
-Na rushes IN cell - Action Potential occurs!!