Week 4: Nerve System (Human Bioscience A

Which of the following is NOT a difference between graded potentials and action potentials?

• None of the above

• Spatial and temporal summation is used to increase the amplitude of both graded potentials and action potentials

• Graded potentials occur along dendrites, whereas action potentials occur along axons

• Greater stimulus intensity results in larger graded potentials, but not larger action potentials

• Graded potentials can result from the opening of chemically gated channels; action potentials require the opening of voltage-gated channels

The axon is connected to the soma (body) of a neuron at the:

• synaptic terminal

• myelin sheath

• synapse

• dendrites

• axon hillock

For this question or incomplete statement, ONE or MORE of the suggested answers given is correct.

Answer:

A) if only W, X and Y are correct

B) if only W and Y are correct

C) if only X and Z are correct

D) if only Z is correct

E) if all are correct

The resting membrane potential:

W. is determined by the permeability of the cell membrane to K+

X. is negative because the membrane is selectively permeable to K+

Y. is due to leak channels in the cellular membrane.

Z. is maintained by the presence of active Na+/K+ ATPase pumps in the cellular membrane

• a. A

• b. B

• c. C

• d.D

• e. E

The ________ division of the autonomic nervous system is said to function during "rest and digest".

• sympathetic

• visceral

• parasympathetic

• thoracolumbar

• somatic

For this question or incomplete statement, ONE or MORE of the suggested answers given is correct.

Answer:

A) if only W, X and Y are correct

B) if only W and Y are correct

C) if only X and Z are correct

D) if only Z is correct

E) if all are correct

An excitatory post-synaptic potential (EPSP):

W. is a sub threshold depolarisation of the cell membrane

X. occurs as a result of positively charged ions flowing into the neuron

Y. results if a synaptic event moves the membrane potential closer to threshold

Z. always results in the generation of an action potential in the neuron

• B

• A

• E

• D

• C

For this question or incomplete statement, ONE or MORE of the suggested answers given is correct.

Answer:

A) if only W, X and Y are correct

B) if only W and Y are correct

C) if only X and Z are correct

D) if only Z is correct

E) if all are correct

At the synapse:

W. action potentials cause release of neurotransmitter from the synaptic terminal

X. activity results in the compulsory generation of an action potential in the post-synaptic cell

Y. released neurotransmitter passively diffuses across the synaptic cleft

Z. there is a physical connection between the pre and post -synaptic cells

• D

• C

• A

• E

• B

For this question or incomplete statement, ONE or MORE of the suggested answers given is correct.

Answer:

A) if only W, X and Y are correct

B) if only W and Y are correct

C) if only X and Z are correct

D) if only Z is correct

E) if all are correct

A threshold stimulus:

W. occurs at the peak of an action potential

X. is necessary to maintain the resting membrane potential

Y. results in hyperpolarisation of an axon

Z. is the depolarisation necessary to cause an action potential

• C

• A

• E

• B

• D

The sodium-potassium ATPase pump:

• does not require energy

• moves sodium and potassium opposite to the direction of their chemical gradients

• transports sodium ions into the cell during depolarisation

• is only active immediately after each action potential

• transports potassium ions out of the cell during repolarisation

The somatic motor division of the peripheral nervous system innervates:

• heart muscle cells

• glandular cells

• skeletal muscle cells

• all of the answers are correct

• smooth muscle cells

For this question or incomplete statement, ONE or MORE of the suggested answers given is correct.

Answer:

A) if only W, X and Y are correct

B) if only W and Y are correct

C) if only X and Z are correct

D) if only Z is correct

E) if all are correct

The following ion is found in higher concentrations outside of a nerve cell:

W. potassium

X. glucose

Y. haemoglobin

Z. sodium

• E

• C

• A

• D

• B