CH4 Nervous System Flashcards
Neurons Parts
Who produces myelin sheath in CNS and PNS?
Synapse composed of what parts?
Soma (cell body): Where nucleus is found with endoplasmic reticulum and ribosomes
Dendrites: The branches that receive info in the soma
Axon Hillock: lower part of the some which gets the AP ready to be sent
Axon: long part where AP travels
Myelin Sheath: Fatty membrane that encloses parts of the axon
Nodes of Ranvier: Segments in b/w myelinated sections
Nerve Terminals / Synaptic bouton (nob): release of neurotransmitter and signal to the next neuron
Myelin in CNS: Olygodendocytes
Synapse: Nerve terminal - Synaptic Cleft - Postsynaptic neuron
Myelin in PNS: Schwann Cells
Cell types?
- Astrocytes
- Ependymal Cells
- Microglia
- Oligodendrocytes and Schawn cells
Astrocytes: Nourish neurons and form the blood-brain barrier which controls the transmission of solutes from the bloodstream into nervous tissue
Ependymal Cells: line the ventricles of the brain and produce cerebrospinal fluid (serves as a shock absorber)
Microglia: Phagocytic cells, break down wastes and pathogens in the CNS
Oligodendrocytes: Myelin in CNS
Schawn Cell: Myelin in PSN
Resting membrane potential of Cell?
what about
Potassium?
Sodium?
and its concentrations?
Resting = -70 mV (it’s closer to Ks resiting since there are more K leaking channels)
K = -90mV
Concentration: there is more K inside the cell, therefore, K has channels leaking it out of the cell
Na = +60mV
Concentration: there is more Na outside the cell, therefore, Na has channels getting it inside the cell
Na/K ATPase
what does it do
Pumps Na out of the cell
and K back into the cell
powered by ATP
Depolarization vs Hyperpolarization
which one is guided by excitatory or inhibitory input?
AP threshold?
Depolarization: Raising the membrane potential (Vm) from its resting potential. Happens from excitatory input
Hyperpolarization: Lowering the membrane potential (Vm) from its resting potential. Happens from inhibitory input
cell is depolarized and cause AP when it passes Vm= -55 mV (Threshold)
States of Sodium Channels
Closed: before cell reaches threshold
Open: from -55 mV (threshold) to +35mV
Inactive: from +35mV to the resting potential
Action Potential Graph
Synapse: How do neurotransmitter transmission get triggered
- AP depolarized never terminal, which causes Ca+2 channels to open.
- Ca+2 comes into the cell causing vesicles carrying neurotransmitter to fuse with the membrane and release the neurotransmitter
3 Types of getting rid of excess neurotransmitter in synapse?
- Enzymes break them down
- Reuptake carriers take them back to the presynaptic neuron
- Diffuse out of the synaptic cleft. i.e Nitric oxide (NO)
Absolute vs Relative refractory period
Relative: AP can still be fired but stimuli have to be stronger than normal.
White matter vs Grey Matter
White: axons encased in myelin sheaths lies deeper in the brain
Grey: unmyelinated cell bodies and dendrites
Monosynaptic Reflex?
Polysynaptic?
give examples
a sensory (afferent) neuron synapsis directly with a motor (efferent) neuron
i.e Knee jerk reflex
Polysynaptic: same but can also fire another motor neuron through interneurons
Nerves vs Tracks
where is the cell body in each?
Nerves: Collection of neurons in the PNS and contain multiple types of info (sensory and motor). Contain cell bodies in ganglia
Tracks: Collection of neurons in CNS, contain only 1 type of info and have cell bodies in nuclei
Spinal Chord
In what part are sensory and motor neurons found?
Sensory: afferent goes into the dorsal side of the spine
Motor: efferent exists the spinal cord on the ventral side
Autonomic Nervous System
preganglionic neuron
postganglionic neuron
what hormone does each release
Preganglionic releases Acetylcholine (ACH) in both para and sympathetic NS
Postganglionic:
Sympathetic: Norepinephrine
Parasympathetic: Acetylcholine
