Nervous System Flashcards
Central Nervous System (CNS)
- Brain and spinal cord
- Command center
- Concious and subconsious
Integration
Peripheral Nervous System (PNS)
- all nerves NOT in brain/spinal cord
- connects everything
- 31 spinal nerves
- 12 cranial nerves
Sensory division (afferent)
- Sends impulses from the senses to the CNS
sensory input
Motor division (efferent)
- sends impulses from the CNS to muscles & glands
response
Sympathetic division
- Used in emergency situations (flight/fight/freeze)
Parasympathetic division
- Reduces sympathetic responses
- Resting fxns digestion and urination
Autonomic nervous System (ANS)
- Involuntary muscle control
Somatic nervous System (SNS)
- Voluntary muscle control
- Reflexes skeletal motion
Dendrites
- bring impulses towards the cell body
Axon
- Sends impulses away from the cell body
- End in axon terminal
- Which release neurotransmitters to pass the impulse to the next neuron
Myelin sheath
- Axons are wrapped in myelin (waxy insulation)
- Myelin is formed by Schwann cells wrapping around the axon
- Helps impulses move faster
Nodes of ranvier
- gaps between myelin
Cell body (soma)
- houses the organelles and recieves the impulse from dendrites
Unipolar neurons
- 1 process of cell body
Bipolar neurons
- 2 processes of cell body
Multipolar neurons
- many processes
most common
Where do afferent neurons carry impulses towards?
CNS
Where do efferent neurons carry impulses away from?
CNS
What connects efferent and afferent neurons?
Interneurons
What do neuroglial cells do?
- the glue, support, and protection for neurons to do their jobs
Astrocyte
- support and anchor neurons to surrounding capillaries
- facilitate exchange
Microglia
- provides immune response to neurons in CNS
What do phagocytes do?
- eat dead cells and invaders
Ependymal cells
- secrete and circulate cerebral spinal fluid (CSF)
Oligodendrocytes
- provide the myelin insulation for neurons in the CNS
Satellite cells
- support and anchor neurons in the PNS
Schwann cells
- provide myelin insulation to neurons in the PNS
Which neuroglia cells are found in the CNS?
Astrocyte, microglia, ependymal, oligodendrocytes
Which neuroglia cells are found in the PNS?
Satellite cells, Schwann cells
As the impulse arrives…
sodium (on outside) rushes into the neuron and change the charge of the neuron
action potential
At rest…
inside of neuron=negatively charged enviorment outside=positively charged
resting potential
When the impulse reaches the synapse (end of nerve)
stimulates neurotransmitters and are released from the axon terminals. Causes channel to open to the next neuron continuing the impulse
Synaptic cleft
space between synapses
action potential
reverse of charge
Step 1 to an impulse
Impulse arrives and threshold is met
Step 2 to an impulse
Voltage gated Na+ channels are opened and Na+ enters the cells
Step 3 to an impulse
Voltage gated K+ channels are opened and K+ levels the cell, Na+ channels begin to rest
Step 4 to an impulse
Voltage gated K+ channels are still open, Na+ channels are in resting state
Step 5 to an impulse
Na+ K+ pump restores voltage to resting state
All or nothing response
A nerve impulse is an all or nothing response. Either the threshold is met and the impulse continued, or it is never started
Resting is…
polarized
Action potential is….
depolarization and repolarization
Step 1 to a synaptic transmission
Action potential (impulse) arrives at the pre synaptic terminal
Step 2 to a synaptic transmission
Ca+ channels open on pre synaptic terminal
Step 3 to a synaptic transmission
Synaptic vessles release neurotransmitters
Step 4 to a synaptic transmission
Neurotransmitters released into synapse bind to receptors on the next dendrite
Step 5 to a synaptic transmission
Na+ channels open on the dendrite to relay impulse
What are the 2 things that happen to left over neurotransmitters?
- reuptake protein
- enzymes can break them down
What are the order of the meninges layers? (surface to deep)
Dura mater, subdural space, arachnoid, sub arachnoid space, pia mater
Where is CSF found?
- between the arachnoid layer and the pia mater
What does CSF do?
- protects the brain by preventing it from contacting the skull
- maintains the blood brain barrier, which controls homeostasis for the brain and prevents infection
Where does CSF produce?
In the 4 ventricles: 2 lateral, 3rd and 4th (lateral and 3rd ventricles connected by interventricular foramen
Where is CSF secreated?
- in choroid plexuses of ventricles, then circulated before being reabsorbed by arachnoid granulations
Dura mater
- thick, tough layer with a subdural space
Arachnoid membrane
- thin, cobweb - like layer
subarachnoid space
Pia mater
- thin layer containing lots of blood vessles
Where does the spinal cord extend from?
From the medulla oblongata to the lumbar vertebrae
Where does it relay impulses between?
cranial nerves
PNS and brain
Cross section
“butterfly” of grey matter surrounded by white matter
Afferent nerves
dorsal horns -> ventral horns -> efferent nerves
*sometimes interneurons between A and E
What does the reflex arc involve?
1.) receptor
2.) sensory neurons
3.) integration
4.) motor neurons
5.) effector
Reflexes are…
pre programmed responses
Endoneurium
surrounds each neuron
Perineurium
surrounds a group of neurons (fascicle)
Epineurium
surrounds a whole nerve
