Nervous System Flashcards
neuronal
cellular communication
fast, direct, targets specific cells/tissues (nerves)
hormonal
cellular communication
- seen in the endocrine system
- slow
- widespread
- affects multiple cells/tissues throughout body
paracrine system
cellular communication
local hormones released by cells into IF to act on a nearby cell
neuron structure
soma, dendrites, and axons
neuron function
transmit electrical signals from one cell to another
soma
cell body
dendrites
extension –> receives signals signal
axon
sends signal out
* axon hillock
* myelin sheath
* nodes of ranvier
axon hillock
axon
connection to cell body
myelin sheath
axon
fatty acid insulation (speed up AP by stopping ion exchange)
cells that make myelin
axon
- oligodendrocytes in CNS
- schwann cells in PNS
white matter
axons with myelin
gray matter
axons without myelin
Resting membrane potential
- 70 mV
- Establish by Na+/K+ pump
- 3 Na+ out, 2 K+ in makes inside of cell have negative charge relative to outside
- Maintained by Na+/K+ ATPases via hydrolysis of ATP
- K+ leaky channels also maintain RMP
Depolarization
- Stimulus cause threshold potential to be -55 mV
- Voltage-gated Na channels open, Na+ diffuses into cell
- Inside develops a positive charge
- K+ channels close
Transition point
- Depolarization to repolarization
- Na+ reaches peak and channels close
Repolarization
- Na+ channels close
- Voltage gated K+ channels open, K+ diffuses out
- Inside of cell becomes negative once again
- Absolute refractory period
Hyperpolarization
- Inside of cell becomes more negative than resting potential due to K+ flow
- Relative refractory period
Absolute refractory period
no stimulus can cause AP
* Due to inactivation of Na+ channels
Relative refractory period
requires strong stimulus for AP
Synapse
- AP reaches end of presynaptic axon voltage gated Ca++ channels open and enters neuron
- Ca++ cause synaptic vesicles to fuse/exocytosis from neuron with NT inside
- NT binds to ligand gated ion channels on post synaptic neuron graded potentials
- Graded potentials summate at axon hillock and AP fires once it passes threshold
EPSP (excitatory postsynaptic potential)
depolarized membrane and cause Na+ ions to flow into cell
IPSP (inhibitory postsynaptic potential)
hyperpolarized membrane and causes K+ to flow OUT and Cl- in
Electrical synapse
in cardiac/smooth muscle cells
* Gap junctions allow electrical signal to go through much faster than chemical synapse
Chemical synapse
NT released into synaptic cleft diffuses to receptors on next cell
* Second messenger system: G protein connected to receptor activated when NT binds, can open channels, activate proteins or cause gene transcription
* can only happen in 1D, slowest part
sensory/afferent
carries signals from receptors to brain via interneurons
interneurons
carries signal from neuron to neuron
motor/efferent
carries signals from brain to muscle/glands
glia cells
- non-neuronal cells in nervous system
- support and surround neurons
microglial cells
macrophages that protect CNS
macroglial cells
- astrocytes: from blood brain barrier, recycle NT, provide blood to CNS
- satellite cells: astrocytes of PNS
- schwann cells: myelin sheath in PNS
- oligodendrocytes: myelin sheath in CNS
- ependymal cells: produce CSF in CNS
amino acid NT
- glutamate: excitatory
- GABA and glycine: inhibitory
amino acid derived NT
- Epi/NE: excitatory @ postsynaptic neuron
- dopamine: excitatory in brain (reward-motivated)
- serotonin: inhibitory in brain (mood, sleep) and increases contraction in GI
gas NT
NO –> vasodilation
other NT
ACh
* excitatory @ presynatpic neurons
* excitatory @ muscles
* post-synaptic NT in PNS
CNS
brain + spinal cord
higher brain
cerebrum, cerebral cortex
* conscious activties like memories and thoughts
lower brain
medulla, hypothalamus, thalamus, cerebellum
* subconscious activies like breathing, BP, emotions, reactions to pains
meninges
protect CNS and have 3 layers
* DAP: dura mater, arachnoid mater, pia mater
frontal lobe
high function processes
* decision making, problem solving, attention, and concentration
temporal lobe
speech and hearing
occipital lobe
vision
parietal lobe
spatial perception (PAT) and sensation
cerebellum
mini brain underneath occipital lobe, import for coordination of movement
brainstem
midbrain, pons, medulla oblongata
midbrain
relays sensory information
pons
relays messages between forebrain and medulla
medulla oblongata
HR, breathing rate, BP, toxic sensing
limibic system
emotions, memory, learning, and motivation
* thalamus, hypothalamus, hippocampus, amygdala
thalamus
relays sensory and motor information
hypothalamus
regulates hormone secretion in body
hippocampus
responsible for memory consolidation
amydala
emotional reactions happen here to scents
PNS
- everything else (all nerves branching off CNS)
- CNS
- ANS
- recieves input from sensory (afferent) neurons
somatic nervous system (SNS)
voluntary sensor and motor functions, responds to environment
* controls skeletal muscle, use ACh
autonomic nervous sytem
involuntary controls smooth muscle, cardiac muscle
* sympathetic and parasympathetic ANS
sympathetic ANS
- “fight or flight”, increases HR, increases blood flow to skeletal msucles, decreases blood flow to digestive system
- Epi/NE
- releases sugar into blood for energy
- increase HR for oxygen delivery
- vasodilation of skeletal blood vessels
- vasoconstriction of GI system
- dilation of bronchi and bronchioles to allow O2 to lungs
- dilates pupils to increase information to the brain
parasympathetic ANS
- “rest and digest”, opposite of sympathetic
- ACh
- SLUDGE (salivation, lacrimation, urination, defamation, GI, excretion)
- relaxes muscles
- decrease HR
- maintains homeostasis
