human phys exam 2

Which of the neurons in this picture is efferent?

middle

The speed of the action potential in myelinated neurons can be 100 m/s. Roughly estimate the time it takes the signal to travel from the spine to the fingertips of an adult person

10 ms

How do signals spread through electrical synapses?

By diffusion of ions through gap junctions

What, if anything, is shown incorrectly?

Calcium-induced translocation of vesicles toward the active zone (step 5)

What is the mechanism of neurotransmitter reuptake?

 

By secondary active transport

Enter the missing words: Nicotine _______ acetylcholine receptors, which are ________

Enter the missing words: Nicotine activates acetylcholine receptors, which are ionotropic .

Based on this figure from a slide, by what factor does myelin increase the conduction velocity compared to unmyelinated axons of the same diameter?

Between 6 and 6

What is the main characteristic of the membrane that makes the action potential possible?

High density of voltage-gated sodium or calcium channels

Acetylcholine carries a positive charge. How would you expect it to be loaded into vesicles?

By a H+-coupled antiporter

What happens to the action potential once the depolarization wave has reached the terminal of a chemical synapse?

Depolarization is terminated by outward currents

Inhibitory synapses produce action potentials through the activation of potassium channels T/F

F

Curare is a competitive antagonist of acetylcholine receptors. How can inhibition of acetylcholinesterase alleviate curare poisoning?

By increasing the concentration of acetylcholine, so it would displace curare

Match channel type to its typical function in neurons

• Ligand-gated ion channels

• Voltage-gated potassium channels

• Voltage-gated sodium channels

• Voltage-gated calcium channels

-Generation of graded potential

-Termination of action potential

-Generation of action potential

-Release of neurotransmitter

Ligand-gated ion channels : Generation of graded potential

Voltage-gated potassium channels : Termination of action potential

Voltage-gated sodium channels : Generation of action potential

Voltage-gated calcium channels : Release of neurotransmitter

What is VERY wrong with this picture?

Neurotransmitter vesicles don’t come out into the cleft

Dendrites can provide either presynaptic or postsynaptic terminals T/F

F

Which of the following characteristics apply to neurotransmitters (put N), and which to hormones (put H)?

Fast action

Acts locally

Long-lasting effects

Travels to distant targets

Fast action N

Acts locally N

Long-lasting effects H

Travels to distant targets H

What is the main mechanism of stimulation of glucose uptake in response to insulin?

Translocation of glucose transporters to the membrane

What can we say about the localization of insulin and of glucose transporters within their storage vesicles?

Insulin is in the lumen and transporters are in the membrane

The following events play a role in insulin release. Arrange them according to their place in the sequence leading to insulin release, from 1 (the initial event) to 6 (the final event)

Glucose elevation in blood

Calcium elevation

Membrane depolarization

ATP elevation

Vesicle exocytosis

Potassium elevation

Glucose elevation in blood 1

Calcium elevation 5

Membrane depolarization 4

ATP elevation 2

Vesicle exocytosis 6

Potassium elevation 3

A characteristic common to both types of diabetes is

Blood glucose increase

Which process will be directly affected by depolarization of thyroid cells?

The absorption of iodide by thyroid cells

Sympathetic neurons are efferent T/F

T

Find the error in the following statement:

“Acetylcholine is the neurotransmitter in: (1) motor neurons; (2) preganglionic neurons; (3) postganglionic sympathetic neurons”

Not in postganglionic sympathetic neurons

Efferent neurons that are not autonomic are…

Somatic

How would iodide absorption by the thyroid gland be affected if the Na+-K+ pump was inhibited? Choose the best answer.

Iodide absorption will decrease because of the accumulation of sodium

Signaling at a synaptic terminal can be classified as

Paracrine signaling

How are hydrophobic hormones carried through the blood?

Complexed with proteins

Insert "yes" or "no".

Both epinephrine and norepinephrine mediate fight-or-flight responses

Both epinephrine and norepinephrine are released from the adrenal medulla

Both epinephrine and norepinephrine are released from sympathetic neurons

The adrenal medulla is stimulated by acetylcholine

Both epinephrine and norepinephrine mediate fight-or-flight responses yes

Both epinephrine and norepinephrine are released from the adrenal medulla yes

Both epinephrine and norepinephrine are released from sympathetic neurons no

The adrenal medulla is stimulated by acetylcholine yes

Glycogen synthesis is a parasympathetic response T/F

T

Passive force in a skeletal muscle contributes to resistance in both stretching and compression T/F

F

What property of a muscle is most critical for the generation of small, precise movements?

Small motor units

The graph shows the load-velocity relationship in a muscle. Match the regions A, B, C to contraction type

A - eccentric, B - isometric, C - concentric

In the skeletal muscle, depolarization directly activates _________ , but most of the calcium required to activate _______ flows into the cytosol through ________ from the _______.

In the skeletal muscle, depolarization directly activates DHPR , but most of the calcium required to activate myosin flows into the cytosol through RyR from the sarcoplasmic reticulum

Inhibition of the calcium pump prolongs the twitch T/F

T

What mechanical characteristics apply to rigor mortis?

Tension, no power

Sarcolemma surrounds...

Muscle fiber

Match cause (left column) to effect (right column)

ATP hydrolysis —-Release of the products of ATP hydrolysis

Elevation of calcium ——-Development of stress in myosin

Binding of myosin to actin——- Binding of myosin to actin

ATP binding to myosin ——-Dissociation of myosin from actin

ATP hydrolysis : Development of stress in myosin

Elevation of calcium : Binding of myosin to actin

Binding of myosin to actin : Release of the products of ATP hydrolysis

ATP binding to myosin : Dissociation of myosin from actin

What could the numbers in the second column stand for?

The relative rate of ATP generation

Which distance shortens during contraction?

a-b

Which number indicates the protein responsible for bringing the largest amount of calcium into the muscle fiber?

3

Contraction of tonic muscles may be independent of...

Action potential

The rate of ATP hydrolysis in smooth muscle contractions is low. Which relationship does most directly account for this fact?

Power = Velocity * Force

In which phase of energy generation (1, 2, or 3) is the ATP synthase most important? The graph shows ATP consumption during continuous physical activity.

3

Which number indicates the place from where calcium comes from?

5

Which phase of a running race would be most affected by creatine kinase activity?

0 - 5 seconds

The units of kcal∙min-1 represent

Power

This picture shows various stages of muscle activation. Which is which?

1 → Action potential in neuron

2 → Action potential in muscle

3 → Ca concentration in muscle

4 → Force

In calcium-induced calcium release, the second wave of calcium comes from

sarcoplasmic reticulum

The channels responsible for the second influx of calcium into the cytosol of cardiac contractile cells are:

Ryanodine receptors

The picture shows four time traces corresponding to different heart locations: SA node, AV node, atrial muscle and ventricular muscle. Which one corresponds to the ventricular muscle?

4

Match ion to the role its influx plays in cardiac pacemaker cells

Brings membrane potential to a threshold

Na+

Match ion to the role its influx plays in cardiac pacemaker cells

Stimulate rapid depolarization

Ca2+

Match ion to the role its influx plays in cardiac pacemaker cells

Terminate depolarization

K+

Does the Frank-Starling law apply to skeletal muscles? Choose the best answer.

No, because the length-tension curve for skeletal muscles passes through a maximum

The broken line shows the normal AV nodal potential. Additional stimulation of acetylcholine muscarinic receptors shifts the curve. The new curve is … (enter 1 or 2)

2

Estimate the cardiac output (in liters/min) for an untrained individual at 100 beats/minute. SV, stroke volume.

between 10 and 14 (13)

Which formula correctly expresses the relationship between the cardiac output (O), the end-diastolic volume of the ventricle (V), the ejection fraction (E) and the heartbeat rate (R)?

O = VER

The volume of the ventricle is the smallest

At the end of systole

The vertical axis shows the force developed in the heart muscle and the horizontal axis shows the concentration... of what? (Hint: The concentrations are in the physiological range)

Intracellular Ca2+

Which statement is correct?

Depolarization does not directly affect the atrioventricular valves

A chemical that reduces the activity of F channels would be expected to

Reduce the heart rate

What is the common requirement for heart, skeletal and smooth muscle activation?

Calcium increase

Beta blockers are antagonists of β-adrenergic receptors. What would be their effect on the heart?

Decrease the heart rate

The following questions refer to the Wiggers diagram in the slide 9-5.

Tension in the ventricle increases but its volume remains constant in region

2

The following questions refer to the Wiggers diagram in the slide 9-5.

Aortic valve is open, tension in the ventricle continues to increase in region

3

The following questions refer to the Wiggers diagram in the slide 9-5.

Refilling of the ventricle begins in region

6

The following questions refer to the Wiggers diagram in the slide 9-5.

Both valves are closed, the ventricle is relaxing in region

5

What is the direct effect of an increased afterload?

The duration of ventricular ejection is decreased

Where are these cells located?

In the eye

A signal is interpreted as pain because

It arrives at a special part of the brain

What is the main target of local anesthetics?

Voltage-gated sodium channels

Hyperpolarization of nociceptors would likely cause

Analgesia

Pain is transmitted by efferent neurons T/F

F

The mechanism of frequency coding of nerve impulses has to do with

Relative refractory period

All of the following might in principle be considered for pain treatment except the one that just doesn’t make sense. Which one is that?

Blockers of potassium channels

What is the purpose of the round window?

To enable vibrations of the perilymph

What physical characteristic corresponds to sound pitch?

Frequency of sound wave

Hearing is mediated by

Mechanoreceptors

Resonant audio frequency is the frequency at which …

The amplitude of vibration is the largest

Age-related farsightedness (presbyopia) results from

insufficient refraction in the lens

Focusing an image of a closely positioned object on the retina is accomplished by _______________________

Choose between:

1 - increasing, decreasing

2 - curvature, refractive index

3 - cornea, eye lens, retina

1 → increasing

2→ curvature

3→ eye lens

Focusing an image of a closely positioned object on the retina is accomplished by increasing the curvature of the eye lens

What is common between amyloidosis (Unit 2) and cataract (Unit 10)?

Loss of protein solubility

The refractive index of the eye lens is higher than that of the cornea; nevertheless, cornea’s contribution to light refraction is greater than that of the lens. The main reason for that is:

Cornea faces air on one side

Blue violets and red asters may look about equally bright in daylight. How would their appearance change late in the evening?

They violets will be better visible

Are we farsighted or nearsighted when trying to see underwater?

Farsighted (sharp image is formed too far)

Tension in the ventricle increases but its volume remains constant

2

Aortic valve is open, tension in the ventricle continues to increase

3

Refilling of the ventricle begins

6

Both valves are closed, the ventricle is relaxing

5

Pressure in the atrium CONTINUES to be higher than in the ventricle

7

Ventricle activation begins

2

The atriventricular valve has just closed

2

The antioventricular valve has just opened

1

End-diastolic volume is achieved

2