Exam 1 Flashcards
What is the order of activity that a voltage-gated Na+ channel goes through during an actionable potential: starting at the resting potential, then when membrane Vm is sufficiently depolarized, and finally during the refractory period?
Channel is closed, channel opens, channel is inactivated
A single motor neuron and the myofibrils on which it synapses is called a:
Motor unit
What neurotransmitter is NOT derived from an amino acid?
Acetylcholine (ACh)
_______ aid in regeneration of cut axons in the PNS; whereas glial scars formed from _________ will block axon regeneration in the CNS
Schwann cells; astrocytes
The primary excitatory neurotransmitter in the nervous system is?
Glutamate
Sensory neurons are an example of ________ and motor neurons are an example of ________?
Afferents; efferents
An increase in sarcoplasmic Ca++ causes muscular contraction by?
Binding to tropic, which shifts the position of tropomyosin on actin
If a neurotransmitter causes an increase in cAMP in the post synaptic cell, then the receptions are probably:
G-protein coupled receptors
The primary inhibitory neurotransmitter in the nervous system is:
GABA
Rigor Mortis is caused by?
The slow leakage of Ca++ from the sarcoplasmic reticulum
The knee-jerk reflex is usually suppressed in normal subjects because?
Descending input from the cerebral cortex inhibits the synapse in the spinal cord
Stimulus intensity is encoded by neurons as the ______?
Rate of firing of action potentials
Which of the following is NOT a difference between neuropeptides and small classical neurotransmitters (NTs)?
Neuropeptides are not co-localized in neurons with classical NTs
______________ allow for saltatory conduction
Myelin and nodes of Ranvier
Voltage-gated _______ channels are responsible for the DEpolarization of neurons; whereas ____ channels cause REpolarization of neurons.
Na+ ; K+
The _______ stimulates the fusion of synaptic vesicles that results in exocytosis of neurotransmitters into the synapse.
Ca2+ -protein complex
The mongoose is resistant to the venom of a cobra because
The venom does not bind to the evolved acetylcholine receptors of the mongoose
Gap junctions are an integral part of?
An electrical synapse
Astrocytes in the CNS provide energy for neurons by converting glucose into _______
Lactate
Positive and negative inputs are summated in the ___________ of the neuron
Dendrites
The plasma membrane is a barrier to what types of molecules?
Large
Polar molecules
EX: proteins, nucleic acids
What falls under Carrier-Mediated transport?
Facilitated diffusion
Active transport
In simple diffusion how does the solute move on the concentration gradient?
Moves down the concentration gradient
Rate of diffusion:
Increases with? (3)
Decreases with? (1)
Increases with: Temperature Concentration gradient Decreases with: Distance
Things that CAN diffuse across a cell membrane
Nonpolar molecules (lipids, steroids, etc.) Small gas molecules Ions through protein channels (if they're open)
How does water move in Osmosis?
Low solute concentration to high solute concentration
How strongly a concentrated solution pulls water by osmosis
Osmotic pressure
Equal osmotic concentration on each side
Isotonic
Less concentrated solution: lower osmotic pressure
Hypotonic
More concentrated solution: higher osmotic pressure
Hypertonic
Osmotic concentration of a solution is determined by number of _________
Particles of a compound
Osmotic concentration is measured in _______
Osmolality
Body tries to maintain constant osmotic concentration of ____ Osm for both intracellular and Extracellular fluids
0.3
If _____ is too high, then animal will try to dilute blood with water
NaCl
Carrier-Mediated Transport are mediated by?
Carrier proteins
Facilitated Diffusion
Moves how?
Down its concentration gradient
Facilitated Diffusion
How does it get it’s energy?
Does not require ATP; uses potential energy of concentration gradient
Primary Active Transport
How does it move?
Up the concentration gradient
Primary Active Transport
How does it get energy?
ATPase breaks down ATP to release energy
Coupled Active Transport
How does it move?
Molecule 1 moves down concentration gradient
Molecule 2 moves up concentration gradient
Coupled Active Transport
How does it use energy?
Uses energy to establish steep concentration gradient for molecule 1
What is the saturable transport of simple diffusion?
Non-saturable transport
What is the saturable transport of Carrier Mediated Transport?
Saturated transport
Facilitated diffusion can be _______ by increasing or decreasing the number of transporters
Regulated
__ Na+ out, __ K+ in for every 1 ATP molecule
3 ; 2
Vm
Vinside - Voutside
________ charges on inside of cell
________ charges on outside of cell
Negative ; positive
Concentration of ions inside and outside reaches equilibrium (stays constant)
Equilibrium potential
Voutside always equals
0 mV
Chemical driving force
Depends on?
Concentration gradient across membrane
Electrical driving force
Depends on?
Electrical potential
K+ has chemical driving force ___ of cell, but electrical driving force ____ cell
Out ; into
Na+ ions have both chemical driving force and electrical driving force ___ the cell
Into
Vm is dependent on?
Most permeable ion
The most permeable ion is?
K+
Because K+ has the highest permeability, it has the _______ flux and so contributes the ____ to the overall membrane potential
Highest flux
Contributes the most
Parts of the CNS
Brain
Spinal cord
Cluster of neuron cell bodies in brain (gray matter)
Nucleus
Bundle of axons connecting regions of the brain & spinal cord (white matter)
Tract
Cluster of neuron cell bodies in the peripheral body
Ganglion
Bundle of axons surrounded by glial cells in periphery
Nerve
Somatic motor neurons go towards?
Skeletal muscles
Autonomic motor neurons go towards?
Smooth muscle
Cardiac muscle
Glands
What do glial cells do?
Provide electrical insulation, nutrition, and growth factors to neurons
What do Schwann cells do?
Insulate peripheral axons
What do oligodendrocytes do?
Insulate brain & spinal neurons
What CANT regenerate?
Central nerves
What do astrocytes do?
Provide nutrition to brain & spinal neurons.
Take up glucose from blood, convert to lactate, released for neurons.
Remove excess K+ and neurotransmitters from intracellular space
Depolarization becomes more ______
Positive
Excitation
Hyperpolarization becomes more ____
Negative
Inhibition
What does tetrodoxin do? (Puffer fish)
Blocks voltage-gated Na+ channels
Differences between Electrical synapse delay and Chemical synapse delay?
Electrical synapse: no delay
Chemical synapse: 1-5 ms delay
Differences between electrical synapse transmission and chemical synapse transmission?
Electrical synapse: bidirectional transmission
Chemical synapse: unidirectional transmission
Influx of Na+ raises Vm
Excitatory post synaptic potential (epsp)
Influx of Cl- lowers Vm
Inhibitory postsynaptic potential (ipsp)
If multiple epsp’s combine to raise Vm above threshold for action potential, then neuron will?
Fire an action potential
If ipsp’s combine with epsp’s, then lower Vm due to ipsp will cancel out epsp’s and action potentials will be?
Inhibited
What is the primary neurotransmitter in the neuromuscular junction?
Acetylcholine
What is the effect of glutamate and GABA on ligand-gated receptors?
Glutamate is the primary excitatory neurotransmitter
GABA is the primary inhibitory neurotransmitter
What does the synthetic pathway for the catecholamines look like?
Tyrosine ——-> DOPA ——–> Dopamine
What’s the difference between ligand-gated ion channel receptors VS G-protein coupled receptors
Ligand-gated : neurotransmitter binds to CHANNEL protein, causing it to open and allow ions to move into the cell
G-Protein coupled receptors : neurotransmitter binds to RECEPTOR protein, which activates a complex of G-proteins
Skeletal muscle
Muscles attached to bones by tendons
Smooth muscle
Muscles in circular layers around blood vessels. Air passages, etc
Internal storage of Ca++ ions
Sarcoplasmic reticulum
Motor neuron innervates one group of muscle fibers
Motor unit
What does acetylcholine do in Neuromuscular junction?
Binds to nicotinic receptors
What does bungarotoxin do? (Snake venom)
Binds tightly to ACh receptor
What does curare do? (Plant toxin)
Binds weakly to ACh receptor