Neuro 1 Flashcards
Central nervous system is made up of the
brain and spinal cord
peripheral nervous system is made of
cranial nerves and spinal nerves
general nervous system function
Stimuli -> sensory receptors -> afferent signals ->
CNS (integration and processing) -> efferent signals
-> response (muscle contract, gland secretion, etc.)
Nervous system development
Thickening of ectoderm -> neural plate -> fold into neural tube
neural tube = CNS, edge cells or neural crest = PNS
CNS development
neural tube = CNS
parts grow at different rates
prosencephalon (forebrain) grows most rapidly and surrounds other parts of the tube
(grows so rapidly it folds in on itself creating the gyri and sulci)
Neuroepithelial cell pathways
-> multipotential stem cell, splits into
Glial progenitor and neuronal progenitor
NP -> neuroblast -> neuron
GP -> (splits into 3) ependymal , astrocyte, and oligodendrocyte
Neuron overview
5 parts
Functional cell of the nervous system
• Highly specialized and post-mitotic (does not divide)
• Cell body or soma
• ATP production
• Protein synthesis
• Dentrites
• Receive incoming signals
• Axon
• Conduct outgoing signals
• Axon Terminal
• Releases chemical neurotransmitters which bind to adjacent receptors
•Synapse
•site of interaction
3 types of neurons
sensory, motor, interneurons
Sensory neuron overview
• Detect environmental stimuli
• Cell bodies outside CNS
• Relay information to the central nervous system
(axons on both sides, cell body in the middle, not a lot of dendrites)
Motor neuron overview
• Relay information from the central nervous system to the effector organs
• Muscles
• Glands
• Cell bodies inside CNS
long axon, body at top, normal looking
Interneuron overview
- communication between neurons
- Just in the CNS
(cell body in the middle, little to no axon, most dendrites and terminals)
Gray matter=
mostly cell bodies and dendrites
(40% of brain)
White matter =
mostly axons
(60% of brain)
Resting membrane potential
-70 mV
• Concentration of ions creates a charge differential across the membrane
• More negative inside the cell
• More positive outside the cell
• Maintained by a pump that brings K+ into the cell and Na+ outside the cell
Inhibitory ion channels
K+ voltage gated pump and Cl- ligand gated pump
Excitatory ion channels
Na+ voltage gated pump and Na+ Ca+ ligand gated pump
voltage gated ion channels
triggered by +/- charge across membrane
(Na+ and Ka+ pumps)
ligand gated ion channels
triggered by ligands bonding to receptors, changes charge of membrane
(Na+ Ca+ and Cl- pumps)
Action potential is caused by
depolarization and hyperpolarization
depolarization
• Resting membrane potential becomes less negative
• Positive ions flow into the cell or
• Negative ions flow out of the cell
(+30 mV)
hyperpolarization
• RMP becomes more negative
• Positive ions out
• Negative ions in
Action potential electrical communication pathway
signal from dendrites (+mV) -> Na+ channels open (+mV)
-> Na+ channels close and K+ channels open (- mV)
-> K+ channels close (+mV a little to balance)
What happens at the synapse (pathway from pictures)
membrane bound vesicles holding neurotransmitters->
release vesicles into place between synapse and dendrite
-> neurotransmitters attach and open channel on dendrite
-> signal relayed with polarization
Excitatory neurotransmitters
Acetylcholine
Glutamate
Inhibitory neurotransmitters
GABA
Glycine
2 types of glia
macroglia and microglia
PROTECT AND CLEAN
Macroglia 3 types
Astrocytes
oligodendrocytes
ependymal cells
Microglia
Derived from precursors in yolk sac
• Important for phagocytosis of necrotic neural tissue
(eats debris or calls in backup for toxic agent)
Astrocytes overview
1st bestie
Star-shaped with many processes (neuron w/o axon)
• Functions
• Structural support
• Take up excess K+, transmitters
• Foot processes = part of blood brain barrier (gatekeep)
• Store glycogen (main source of energy for neurons)
• Produce glutamate
Oligodendrocytes
2nd besties, like schwann cells for CNS
• Small round condensed nuclei with clear halo
• Grey and white matter
• Function: insulation of CNS neuron axons
• Insulation = myelin
• One oligodendrocyte can insulate 50 axons
mostly in white matter
Schwann Cells
Similar to oligodendrocytes, but in the peripheral nervous system
• One Schwann cell insulates just one axon
• Important in peripheral nerve regeneration after injury (does not happen in the CNS)
Ependymal cells/choroid plexus
• Ependymal cells line the ventricles and central canal
• Specialized ependymal cells and blood vessels form choroid plexus
• Makes cerebrospinal fluid
forms barrier between fluid and neurons
Patellar reflex example
stimuli in the patella - shoots electrical signal through sensory neuron to dorsal horn of spinal cord
send signal to ventral horn of spinal cord which sends a message through a motor neuron to move
