Chapter 3 Flashcards
Tetanus
- block inhibitory responses by preventing the pre-sympathetic relapse of GABA
Symptoms: uncontrolled muscles spasms, lockjaw, progresses to breaking muscles, death
Parkinson’s disease
- deficiency of dopamine in the basal nuclei
Symptoms: muscular rigidity, involuntary tremors
What is the treatment for PD
Leva-Dopa
—> precursor of dopamine
Effect of Cocaine on the synapse
- generates long-term modular adaptions
- cocaine leads to increased dopamine activity
- the number or dopamine receptors is reduced in response to glut, so the user must increase the dosage to satisfy the post synaptic cells
Presynaptic facilation
- release of neurotransmitters in enhanced
Presynaptic inhibition
- amount of neurotransmitters released is reduced
Neuropeptides
- larger
- synthesized in the ER or golgi complex
- slow prolonged response
- lower concentrations
Neurotransmitters
- small, rapid acting
- synthesized in the synaptic vesicles in the cytoplasm
- mainly amino acids
- typically trigger the opening of specific ion channels the bring about change in the post synaptic neuron’s (EPSP or IPSP)
Inhibitory synapse
IPSP
- moves the synaptic neuron farther from threshold
- leakage of k; hyoerpolarization
- cl efflux
Excitatory Synapse
EPSP
- both ions are increased at the same time
- neurons is easier to bring to threshold
- excite the next neuron
MS
- demyelination’s disease
Symptoms: fatigue, wheelchair bound, loos of vision, muscle weakness
Cause: herpes 4 and 6, environmental
Oligodendrocytes
- myelin forming cells in the CNS
- not not have regenerative ability
Schwann cells
- form myelin in the PNS
- form regeneration tube
- provide neurotrophic factors
Satellite cells
- form casual around the body
- in PNS
Astrocytes
- secrete paracrine signals
- form tight junctions (BBB)
- provide neurotrophic nature
Microglia
- brains immune cells
- scavengers
Epidymal cells
- in CNS
- secrete cerebralspinal fluid
- act as stem cells
Where are epidymal cells located
Hippocampus
Modes of Ranvier
- where the axon is bare and exposed to the ECF
- can produce action potential ( has a high concentration of voltage gated na channels)
Myelin
-80% lipids, 20% proteins
- insulator to prevent current leakage
Variable of speed of conduction
- myelinated or unmyelinated
- diameter of the finer (larger = faster)
Saltatory conduction
- myelinated neurons
- jumps
- faster communication
- energy efficient
- travels longer distances
Contiguous conduction
- unmyelinated fibres
- action potential spreads whole length of the neuron
Voltage gated channels
- open and close in response to membrane potential
Leak channels
- open all the time
- unregulated leakage of ions
Na - k concentration
2-3
Na
Extracellular: 150
Intracellular: 15
Relative permubility: 1
K
Extracellular: 5
Intracellular: 150
Relative permubility: 50-75
A
Extracellular: 0
Intracellular: 65
Relative permubiality: 0
Membrane potential
- difference charge between the ICF and ECF
- exhibited by all membranes
Depolarization
- increased permubility of na (na influx)
-“ climbing” - upward
Repolarization
- increased k permubility
- falling
- downward movement
Hypolarization
Dip
- leakage of k into the cell
Relative refractory period
- na gates close; k gates open
- last part of repolarization and hyperpolarization
Absolute refractory period
- depolarization and repolarization
Action potential
- long distance signaling
- spends the entire length of the neuron
- rapid
- positive feedback
Mechanically gated channels
- stretching or other mechanical deformation
Ex. Touch
Chemically gated channels
- change conformation in response to the binding of specific chemical messengers in a membrane receptor
Ex. Neurotransmitters
Thermally gated channels
- local changes in temp
Types of gated channels
- voltage
- chemically
- mechanically, temperature
Gated channels
- prevent ion passage through channels
- change in three dimensional shape of the protein to open/close
Graded potential
- short distance signaling
- variable strength
