Quiz 3

Question 1

Name and define the three kinds of passive and one of the active methods that sustain the resting potential.

Answer 1

Passive:

1. Diffusion- substance moves down concentration gradient, from higher to lower
2. Electrostatic charge – similar repel and opposite attract each other (K+ and Na+ attract to inside negative charge. Cl- and A- attracted to outside positive charge
3. Differential permeability by ionophores or ion channels (target of behave active drugs)

Active:

1: Transporters or ion pumps (sodium potassium pump

Question 2

Name the seven steps in the Action potential

Answer 2

1. At threshold, special gated ion channels sensitive to + charge inside cell, beyond threshold voltage gated ion channels open and free flow of ions across membrane.
2. First Na ions rush in due to diffusion and electrostatic charge,
3. Then with greater depolarization the opening of voltage gated K+ channels

4, K channels open and K+ ions rush out the neuron. RP is neutralized, reversed +40mV;

5. Na channels close mark end of rising phase of action potential
6. K remains open, efflux of K+, repolarization phase. K closes slowly allowing too many K+ to leave resulting in hyperpolarization.
7. Na+ K+ pump restores resting potential.

Question 3

Define the all or none law

Answer 3

Action potential always the same.

As long as stimulus is strong enough to depolarize a cell or its threshold, an action potential will occur.

Question 4

Describe inhibition at synaptic level

Answer 4

Stimulation of dendrites or call body results in opening voltage gated K channels K+ will rush out and the resting potential will increase

Question 5

Describe the receptor and it’s method of action

Answer 5

Receptor: is specialized protein spanning the membrane of the postsynaptic cell and contains a biding site to which a specific neurotransmitter molecule can briefly attach.

When a neurotransmitter with the correct configuration attaches to a receptor the receptor changes it shape, this reconfiguration alter the function of the cell causing certain event to occur such as a shift in its resting potential or change in its biochemistry

Question 6

What chemical is associated with Locus coeruleus, raphe nuclei, ventral tegmental area?

Answer 6

norepinephrine

Question 7

Describe five qualities of glutamate.

Answer 7

1. Major excitatory neurotransmitter
2. From Glutamine
3. Exist throughout body
4. Control learning, motor activity and pain sensitivity
5. Three of its ionotropic recepts called kainate, AMPA and NMDA receptors open to allow and influx of sodium producing EPSPs.

Question 8

Describe the four qualities of GABA.

Answer 8

1. Most widespread inhibitory neurotransmitter 20-30% of neurons in brain. By GAD glutamic acid decarboxylase converting glutamate to GABA. Requires coenzyme Vitamin B6.
2. GABA ionotropic controls Cl- Metabotropic inhibit Ca2
3. GABA inhibits opening of K channel to hyperpolarize the neuron.
4. Act as auto receptor through cAMP

Question 9

What are the major sequence of events allowing communication between neurons across the synapse?

Answer 9

The neuron synthesizes chemicals that serve as neurotransmitters

Action potentials travel down the axon

Released molecules diffuse across the cleft, attach to receptors, and alter the activity of the postsynaptic neuron

The neurotransmitter molecules separate from their receptors

The neurotransmitters are taken back into the presynaptic neuron for recycling or diffuse away

The postsynaptic cell may send reverse messages to slow the release of further neurotransmitters by presynaptic cells

Question 10

draw chart slide 55

Answer 10

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