HAP II Lecture Exam 2: practice quizzes

What is the smallest structural and functional unit of muscle contraction?

sarcomere

What is the final step that triggers or allows the actin and myosin to bind and subsequently engage in a power stroke?

binding of intracellular calcium ions to troponin

A fascicle in skeletal muscle represents what level of structural organization?

tissue

The presence of ____ is required to detach the myosin head from the active site on the actin filament to either prepare for the next power stroke or to begin allowing relaxation to occur.

ATP

The _________is the intracellular organelle in skeletal muscle cells that stores calcium ions used in the molecular physiology of contraction.

sarcoplasmic reticulum

The muscle cell displays the same all-or-none phenomenon as a neuron in terms of its generation of an action potential and subsequent generation of a contractile force.

True

The connective tissue wrapping around an entire skeletal muscle

Epimysium

The very fine connective tissue wrapping around an individual muscle cell

Endomysium

Another name for a muscle cell

Myocyte

The name for the muscle cell's cell membrane

Sarcolemma

Which neurotransmitter is used to ultimately stimulate a muscle fiber to contract?

acetylcholine

Invaginations of the muscle cell membrane, leading to tunnels throughout the cell, and designed to carry action potentials on that membrane close to all areas inside the cell, are called:

T tubules

The protein making the thin filament is _____, whereas the protein making the thick filament is _______.

actin, myosin

When acetylcholine binds to the receptors on the muscle cell, these receptors open gates on their ion channels (ligand-gated ion channels) and allow what ion to enter the cell?

sodium

Surrounding a myofibril in a muscle cell, a T tubule flanked by two terminal cisternae of the SR is called a______

triad

The response of a muscle fiber to a single stimulus is called a ______

twitch

Muscle contraction with active shortening of muscle fibers, bringing the load toward the origin

Isotonic contraction

Muscle contraction with muscle fibers resisting lengthening of the sarcomeres due to the load pulling against them, often due to the force of gravity

isometric contraction

Increased frequency of nervous stimuli leading to stronger muscle contraction

Temporal summation

Recruitment of more motor units in the muscle leading to stronger muscle contraction

Spatial summation

All of the following are functions of skeletal muscle EXCEPT:

Producing heat

Storing vitamin D

Maintenance of posture

Protecting visceral organs

Storing vitamin D

An immediate but limited store of phosphate groups for regenerating ATP for energy during muscle contraction is accomplished by which of the following molecules?

Creatine

The (very brief, mere milliseconds) period of a twitch during which all of the events of excitation-contraction coupling, up until the start of the actual contraction, occur is called the______

latent period

If insufficient oxygen is available to meet a muscle's current metabolic demand, then pyruvate is reduced to which compound to allow glycolysis to keep going? In other words, pyruvate serves as the final electron acceptor at the end of glycolysis in the cytoplasm instead of oxygen at the end of aerobic respiration with the electron transport chain in the mitochondrion, and it forms a certain molecule. What is that molecule?

Lactate/lactic acid

When a muscle switches into anaerobic respiration for an extended period and then begins to rest, it is said that it must recover with an amount of oxygen equal to what would have been needed had oxygen supply kept up all along, and to re-oxidize lactate to pyruvate in the process. This amount is sometimes termed the muscle's "oxygen debt".

true

The length-tension relationship of a skeletal muscle dictates that, generally speaking, unlike smooth muscle, the maximum contractile force of the muscle will be generated when the initial sarcomere length is:

At or slightly above resting length

When temporal summation occurs and stimuli are frequent enough to cause sustained contraction of the muscle, but still with repolarization of the membrane under normal physiologic conditions, the muscle is said to be displaying:

Tetany

Slow fibers, or dark muscle fibers, contain more myoglobin but are easily fatigued.

False

With proper nutrition, a prolonged recovery from a surgery with bedrest will never lead to muscle atrophy.

False

A muscle controlling fine movements would be expected to have______(more/fewer)_______(larger/smaller) motor units, whereas a muscle controlling gross movements, such as standing/weight-bearing, would be expected to have ________ (more/fewer) _______(larger/smaller) motor units.

more, smaller, fewer, larger

The autonomic nervous system is set up with a series of how many (mostly) peripheral neurons in any give sequence to project to a target organ? (To be clear, we are not including central oversight here.)

two

The ________ division of the ANS is said to generally control "fight or flight" (or "fright") activities, while the _________ division is said to control "rest and digest" activities.

sympathetic; parasympathetic

Preganglionic sympathetic fibers synapse on their respective postganglionic neurons (only excepting the adrenal medulla) in ganglia located where?

In a chain of ganglia located anterolateral to the thoracic and upper lumbar vertebral bodies on both sides

Postganglionic parasympathetic fibers release acetylcholine intended to bind to _________ receptors on the target organs.

muscarinic

Alpha-1 receptors found in smooth muscle in the walls of arteries have an inhibitory effect when bound by their neurotransmitter. t or f

false

Adrenal medullary cells are modified:

Postganglionic sympathetic fibers

Both sympathetic tone and the modestly prolonged effects of the sympathetic nervous system after a sudden fight-or-flight response can be explained physiologically how?

NE takes longer to be metabolized and excreted than the simple breakdown of ACh

Which of the following areas of the brain exhibits some level of central control over the ANS?

The hypothalamus

All preganglionic fibers throughout the ANS release which neurotransmitter?

ACh

An increase in rate and depth of respiration would represent a sympathetic response.

True

When the thin filament is actually actively pulled toward the M line by the thick filament, we call it a(n):

power stroke

which of the following typically has three or four small glands

parathyroid

which pancreatic hormone has the exact opposite effect of insulin

glucagon

All preganglionic neurons release which neurotransmitter?

ACh Acetylcholine

The endocrine system operates largely on which type of feedback system to maintain hormone ranges?

Negative feedback (loop)

The hypothalamus releases hormones that control the pituitary called what, and sends them through what?

Releasing; hypophyseal portal system

the part of ATP cycling that powers the contraction on the myosin head is actually accomplished by the discharge of

ADP + P (cause behind rigor mortis)

the response of the appropriate gland to an increase in blood glucose levels would be which type of response

humoral

postganglionic neurons in the parasympathetic division originate where

almost right on the target organ

what is the general receptor type for parasympathetic targets

muscarinic

a major target of calcitonin is:

osteoblasts

from what intracellular structure are calcium ions released, and to what do they bind?

SR; troponin

the upper level of preganglionic neurons in the parasympathetic division travel through what/where?

motor cranial nerves

T or F muscarinic receptors can be involved somewhat in slowing heart rate

true

Alpha-1 receptors are known to cause what specific effect

vasoconstriction

the preganglionic neuron in the sequence of ANS neurons synapses, for the sympathetic division, where?

thoracic chain ganglia

There is CNS oversight of much ANS activity in the hypothalamus t or f

true

even when not in fight or flight, the SNS is said to exhibit more of an underlying tone, in terms of neurotransmitters, why?

because NE (and E), its ultimate signalers are metabolized more slowly

T or F target organ of sympathetic stimulation can have alpha receptors

true

the sarcomere runs between two of what letter discs

Z discs

what is the neurotransmitter that triggers depolarization at the motor end plate, and what ion then moves where?

ACh; sodium in

endocrine glands are typically made up of which shape of epithelial cells

cuboidal epithelium

thyroid hormones acts on basically every cell in the body, at least in terms of the Na/K pump synthesis. Which can be a clinical consequence of hypothyroidism

goiter

if levels of PTH are elevated, what is the most likely consequence regarding levels of ionized calcium in the blood

hypercalcemia (elevated levels)