BIOL 207 Midterm 2 Review

Questions from Poll Everywhere

The most important channel for creating the resting membrane potential is

K+ leak channel

The most important channel for action potentials is the

Voltage gated Na+ channel

The period from -50mv to +30mv is the __ phase.

Depolarization

The influx of Cl- to the dendrites would cause a(n)

Inhibitory oostsynaptic potential

The action potentials are initiated at the

Axon hillock

SNARE proteins are stimulated by

Ca2+ influx

What are thick filaments made out of

myosin

T/F I bands are dark and A bands are light

false

Where is calcium stored in muscle?

Sarcoplasmic reticulum

What is the "cork" that lets Ca2+ come out of SR?

DHP receptor

What is the protein that pumps Ca2+ back into the SR?

SERCA protein

Which muscle fiber type is not present in humans?

2B

What happens when ATP binds to myosin during cross bridge?

Detachment

What is the neurotransmitter that activates skeletal muscle?

Acetylcholine

What contributes the most to the resting membrane potential (RMP)?

Potassium leak channels

What does the sodium-potassium ATPase pump move each cycle?

3 Na+ out and 2 K+ in

A typical resting membrane potential is closest to:

-70 mV

What usually brings a neuron to threshold before an action potential?

A graded potential

Action potentials usually begin when which channels open at threshold?

Voltage-gated sodium channels

The threshold for opening voltage-gated sodium channels is about:

-50 mV

During depolarization of an action potential, which ion moves into the cell?

Na+

The peak of the action potential is about:

+30 mV

Which event causes repolarization?

K+ leaving the cell through voltage-gated potassium channels

Hyperpolarization occurs because:

K+ channels stay open a little too long

What best describes the absolute refractory period?

No new action potential can be started

What best describes the relative refractory period?

An action potential is possible but requires a stronger stimulus

How does an action potential travel in an unmyelinated axon?

By contiguous conduction

How does an action potential travel in a myelinated axon?

By saltatory conduction

What are Nodes of Ranvier?

Gaps in myelin with voltage-gated channels

Multiple sclerosis primarily damages:

Myelin

When an action potential reaches the axon terminal, what opens first to trigger neurotransmitter release?

Voltage-gated Ca2+ channels

What do SNARE proteins mainly do?

Help vesicles fuse and release neurotransmitter

An EPSP is most likely caused by:

Positive ions entering the postsynaptic cell

An IPSP is most likely caused by:

Cl- entering or K+ leaving the cell

Which receptor type is associated with acetylcholine?

Nicotinic and muscarinic receptors

Which receptor family is associated with norepinephrine and epinephrine?

Alpha and beta adrenergic receptors

Which brain region is most associated with smooth, coordinated voluntary movement?

Cerebellum

Which brain region helps control cardiovascular and respiratory centers?

Medulla

Most sympathetic postganglionic neurons release:

Norepinephrine

Most parasympathetic postganglionic neurons release:

Acetylcholine

What does the adrenal medulla mainly do in the sympathetic system?

Releases epinephrine into the blood

The thick filament in skeletal muscle is primarily:

Myosin

The thin filament in skeletal muscle contains:

Actin, troponin, and tropomyosin

What is the role of tropomyosin?

Covers actin and blocks cross-bridge formation

What is the role of troponin?

Binds calcium and helps move tropomyosin

The dark band of a sarcomere is the:

A band

The light band of a sarcomere is the:

I band

Z lines are best described as:

The ends of each sarcomere

What neurotransmitter is released at the neuromuscular junction?

Acetylcholine

After ACh binds at the neuromuscular junction, what opens to start the muscle action potential?

Voltage-gated Na+ channels

What carries the muscle action potential deep into the muscle fiber?

T tubules

The DHP receptor in skeletal muscle acts mainly as a:

Voltage sensor

Which receptor is the calcium release channel of the sarcoplasmic reticulum?

Ryanodine receptor

What pumps calcium back into the sarcoplasmic reticulum after contraction?

SERCA

What two things are required for the cross-bridge cycle to continue?

ATP and Ca2+

What is motor unit recruitment?

Activating more motor units to increase force

Which type of contraction shortens the muscle?

Concentric

Which type of contraction lengthens the muscle while under tension?

Eccentric

Which type of contraction produces force without changing muscle length?

Isometric

According to the force-velocity relationship, contraction is fastest when:

There is little or no resistance

According to the length-tension relationship, muscle force is greatest when:

Sarcomeres have optimal overlap

Which muscle fiber type is slow oxidative and fatigue resistant?

Type I

Which muscle fibers are generally faster and more variable in metabolism?

Type II fibers

Rods are best adapted for:

Low-light vision

Cones are best adapted for:

Color vision and bright light

Photoreceptors in the retina are unusual because they:

Face backward relative to incoming light

The visual pigment is made from retinene bound to:

Opsin

Light causes retinene to change from:

Cis to trans

Which receptor type fires continuously while a stimulus is present?

Tonic receptor

Which receptor type responds mainly to changes in stimulus intensity?

Phasic receptor

The Nernst equation is mainly used to calculate:

The equilibrium potential for an ion

Which two main factors are most important in the Nernst equation?

Ion concentration difference and ion charge

Most of the resting membrane potential is caused by:

Potassium leaking out of the cell

The sodium-potassium pump contributes to resting membrane potential by:

Moving 3 Na+ out and 2 K+ in

Why does potassium have a bigger effect on resting membrane potential than sodium?

There are many more potassium leak channels than sodium leak channels

At rest, a voltage-gated sodium channel is usually:

Closed but capable of opening

The inactivated state of a voltage-gated sodium channel occurs:

After depolarization, when the channel cannot reopen right away

Voltage-gated potassium channels mainly open:

Near the peak of the action potential

Why does hyperpolarization happen after an action potential?

Potassium channels stay open a bit longer than needed

The phrase “all-or-none” means that an action potential:

Has a constant size once threshold is reached

Nondecremental conduction means an action potential:

Does not fade as it travels

Acetylcholinesterase is important because it:

Breaks down acetylcholine in the synapse

Temporal summation occurs when:

One presynaptic neuron fires repeatedly in rapid succession

Spatial summation occurs when:

Multiple presynaptic neurons stimulate the postsynaptic cell at the same time

An inhibitory input can “cancel” an excitatory input by:

Hyperpolarizing the postsynaptic cell

Tetanus, botulism, and some venoms are important because they affect:

SNARE proteins and neurotransmitter release

Which group includes major glial cell types discussed in class?

Astrocytes, oligodendrocytes, microglia, and ependymal cells

The medulla is especially important for controlling:

Cardiovascular and respiratory functions

The cerebellum mainly helps:

Smooth and coordinate voluntary movement

CTE stands for:

Chronic traumatic encephalopathy

An ischemic stroke happens when:

Blood flow to part of the brain is blocked

Brain edema refers to:

Excess fluid and pressure in the brain

In the autonomic nervous system, all preganglionic neurons release:

Acetylcholine

Most sympathetic postganglionic neurons release:

Norepinephrine

Parasympathetic postganglionic neurons usually release:

Acetylcholine

Parasympathetic outflow is best described as:

Craniosacral

Sympathetic outflow is best described as:

Thoracolumbar

Sweat glands are an important autonomic exception because they:

Receive sympathetic input that uses acetylcholine

Most blood vessels are unusual because they:

Usually lack dual innervation and are mainly sympathetically controlled

Salivary glands are different because:

Both sympathetic and parasympathetic input can stimulate secretion