HW Qs

stages of cross-bridge cycling in order

1. calcium binds troponin; myosin-binding site uncovered 2. cross-bridge formation 3. power stroke 4. release of myosin head by ATP 5. reset of myosin head

events that occur at a neuromuscular junction in order

1. nerve signals arrives at synaptic knob 2. calcium enters & binds synaptic vesicle 3. ACh is released via exocytosis into the synaptic cleft 4. ACh binds receptors on the motor end plate

When a muscle fiber contracts, which parts of the sarcomere maintain a constant length throughout contraction?

A band

According to the sliding filament theory, the length of the ______ band remains constant, but the ______ zone disappears.

A;H

Glycolysis and aerobic respiration are used to generate ______ in muscle fibers.

ATP

In a sarcomere, the ______ zone (or band) is the light, central region of the A band.

H

Match the structure with its description Structure: (Z-disc, H-Zone, I-Band, M-line)

H zone = lighter region in the middle of an A band M line = appears as a dark protein disc in center of H zone Z disc = Made of dark proteins that create zig zag line I band = light band containing thin filaments only

When viewed under a light microscope, the light bands, called ______ bands, contain only ______ filaments.

I; thin

Match each protein with its function. MLCK calmodulin MLCP

MLCK - phosphorylates myosin calmodulin - binds calcium MLCP - dephosphorylates myosin

molecules in the neuromuscular junction

Moves into the axonal terminal - calcium ions Moves into the sarcoplasm - sodium ions Moves across the synaptic gap - acetylcholine Moves out of the sarcoplasm - potassium ions

sarcolemma function

Regulates entry and exit of materials

sarcoplasm function

Site of metabolic processes for normal muscle fiber activities

An action potential is carried along the sarcolemma, then down ___________ tubules to the terminal cisternae of the sarcoplasmic reticulum.

T (transverse)

Deep invaginations of sarcolemma are called ______.

T-tubules

Once started, a muscle impulse will travel along the sarcolemma and into the muscle fiber via the ______.

T-tubules

After being generated, the muscle impulse continues to spread throughout the muscle fiber as long as ______ keeps the motor end plate receptors open.

acetylcholine

The arrival of a nerve impulse at the synaptic knob of a motor neuron causes synaptic vesicles to release _____________ into the synaptic cleft.

acetylcholine

The motor end plate has large numbers of ______ receptors.

acetylcholine

In a neuromuscular junction, the enzyme ____________ breaks down acetylcholine.

acetylcholinesterase

To stop motor end plate stimulation, usually acetylcholine is quickly broken down and removed from the receptor by ______.

acetylcholinesterase

Each myosin head in a thick filament can bind to the protein in a thin filament called...

actin

Slow and intermediate fibers require oxygen to produce ATP, so the metabolic reactions within these fibers are termed ______.

aerobic

Ten minutes into a marathon, your body is relying on __________ cellular respiration for ATP.

aerobic

Smooth muscle cells generally generate ATP through which mechanism?

aerobic respiration

The ATP needed to fuel a 100m sprint would be supplied primarily from ______.

anaerobic respiration

Smooth muscle is found where in the respiratory system?

around the bronchioles

After breaking your arm, you have a cast on it for three months. When the cast is removed, your arm looks much smaller than it did before. The process called ______ caused this to happen.

atrophy

Contractile proteins in smooth muscle are arranged ______

between dense bodies & dense plaques

The cyclic events of "attach, pivot, detach, return" continue as long as ____________ ions remain bound to the troponin.

calcium

When an action potential travels down T-tubules to the terminal cisternae of the SR, what ion is released into the sarcoplasm?

calcium

When a nerve signal arrives at a synaptic knob, what type of channels open in the membrane?

calcium voltage-gated

The mechanism of contraction in smooth muscle involves a calcium-binding protein called ______.

calmodulin

The type of tetany in which a muscle cell is stimulated so frequently that it is not allowed to relax at all between stimuli is called ____________ tetany.

complete

A (An) _______ contraction of the arm muscles allows you to lift a book from the table, whereas a (an) ______ contraction of the arm muscles allows you to lower the book back down to the table.

concentric; eccentric

The amount of additional oxygen that must be inhaled in order to restore pre-exercise levels is called oxygen __________

debt

The amount of additional oxygen that must be inhaled in order to restore pre-exercise levels is called oxygen ____________

debt

In an isometric contraction, the muscle ______ body movement.

doesn't produce

Muscle tissue demonstrates the property of _____ when it is done contracting and returns to its resting length

elasticity

muscle cell connective tissue layer that surrounds it

endomysium

The motor neuron axon travels through the epimysium and perimysium and enters the ______, where it delivers a nerve impulse to an individual ______.

endomysium; muscle fiber

muscle connective tissue layer that surrounds it

epimysium

Muscle cells are said to have what characteristic because they can respond to stimulation from the nervous system?

excitability

True or false: A muscle fiber that is partially shortened can produce a contraction stronger than the contraction it can produce when at its resting length.

false

In a transverse section of a muscle, you can see that each skeletal muscle is actually composed of many __________, which are bundles of muscle fibers.

fascicles

A piano player uses her hands for brief quick movements. Which muscle fiber type would you therefore predict to be predominant in these muscles?

fast glycolytic

If used repeatedly for endurance events, ______ fibers can develop the appearance and functional capabilities of ______ fibers.

fast; intermediate

In a normally functioning muscle, the inability to contract and produce tension is called muscle __________

fatigue

Overall, as aging progresses, muscle strength and endurance are impaired, and the individual has a tendency to ___________ quickly.

fatigue

Smooth muscle cells are ______ in shape

fusiform

With endurance training, it is possible for fast ______ fibers to take on characteristics of fast ______ fibers.

glycolytic; oxidative

Slow muscle fibers are about ______ the diameter of fast muscle fibers.

half

The act of shivering is an example of skeletal muscle performing what function?

heat production

If a muscle cell is stimulated to contract, allowed to partially relax, then stimulated again, its force of contraction the second time will be ______.

higher

The diameter of a muscle fiber will predict ______

how much power it will produce

You make a New Year's resolution to work out more and by March notice your muscles are getting bigger. This is a result of muscle ______.

hypertrophy

Multiunit smooth muscle cells are stimulated ______.

individually

When a nerve impulse reaches the end of an axon of a neuromuscular junction, calcium flows ______ the synaptic knob.

into

Smooth muscle contraction is under ______ control.

involuntary

If you strain to push on a wall that does not move, your muscles are in what type of contraction?

isometric

Big muscles like the "quads," which are used for power, have ______ motor units.

large

Smooth muscle cells have a ______ mechanism that allows them to contract with more power and use less ATP than a skeletal muscle cell.

latch bridge

The mechanism that allows smooth muscle to maintain muscle contraction without the use of additional ATP is the ____________ mechanism.

latchbridge

each stage of a muscle twitch with the amount of tension generated.

latent period - no tension contraction period - tension increases relaxation period - tension decreases

In order to predict how much tension a muscle can produce when contracting, it is important to consider the ______ relationship of thick and thin filaments.

length-tension

Eccentric contractions actively ______ a muscle.

lengthen

muscle fiber function

metabolic activities; contraction

Because muscle cells require a huge amount of ATP in order to contract, they have a large number of which organelle?

mitochondria

Slow fibers have a relatively large number of ______. This permits slow muscle fibers to produce a greater amount of ______ than fast muscle fibers while contractions are underway.

mitochondria; ATP

Athletes have more defined muscles than non-athletes even while at rest because they have ______ motor units contracting all the time.

more

The vascular supply to slow muscle fibers is ______ than the network of capillaries around fast muscle fibers.

more extensive

Neurons that stimulate muscle contraction are called ______ neurons.

motor

Upon release from the synaptic knob, acetylcholine attaches to receptors on the ______

motor end plate

Upon release from the synaptic knob, acetylcholine attaches to receptors on the ______.

motor end plate

A motor unit is composed of a single ______ and all of the muscle fibers it controls

motor neuron

After the age of 30, the number of ______ in existing muscle fibers decreases.

myofibrils

Hypertrophy results from an increase in the number of ____ in a muscle cell.

myofibrils

As a result of exercise, each muscle fiber develops more myofibrils, and each myofibril contains a larger number of ______.

myofilaments

Muscle fibers contain cylindrical structures called myofibrils, which are composed of ______

myofilaments

Termination of the nerve impulse at an NMJ results in the passive sliding of ______ back to their original state.

myofilaments

Muscle cells store oxygen bound to a _____________ molecule

myoglobin

Muscle fibers that rely on aerobic respiration for ATP synthesis contain a high concentration of _____________ , which gives them a reddish appearance.

myoglobin

Smooth muscle cells have a unique protein called ______ light-chain kinase.

myosin

After the cross bridges are formed, ATP is required to detach the ______ and complete the sequence of cyclic events.

myosin heads

Where a motor neuron axon terminal and a muscle cell meet is called a ___________ junction.

neuromuscular

While observing skeletal muscle tissue under the microscope you note that it appears striated. You tell your lab partner this is because ______.

of the arrangement of myofilaments in each sarcomere

Slow fibers or type 1 fibers are also called ___________ fibers because they contain the pigment myoglobin.

oxidative

After you stop running, you notice that you keep breathing heavily for some time. This is because your body is in ______.

oxygen debt

fascicle connective tissue layer that surrounds it

perimysium

The immediate supply of ATP for use in muscle contraction is generated by the ______ system.

phosphagen

ATP is generated when the enzyme creatine kinase transfers Pi from creatine ____________ to ADP.

phosphate

As you hold a barbell and begin to flex your arm in a curl, your biceps brachii slowly lifts the weight by using more and more motor units. This phenomenon, which increases the strength of the contraction, is referred to as ___________

recruitment

As you struggle to twist open a jar, more motor units are called into action until you finally generate enough force to open it. This is an example of ______.

recruitment

After stimulation of ACh receptors, a muscle impulse spreads quickly along the ____________ and into the muscle fiber along T-tubules.

sarcolemma

Within a myofibril, each ______ shortens as the muscle fiber contracts

sarcomere

Match the structure of a myofibril with its description sacromere A band H zone I band

sarcomere - functional contractile unit of skeletal muscle A band - dark band containing both actin myosin H zone - contains thick filaments only I band - light band containing thin filaments only

A contracting skeletal muscle fiber typically shortens as all of its ______ shorten in length

sarcomeres

Within a myofibril, Z discs separate the functional contractile units known as...

sarcomeres

At the end of muscle contraction, calcium ions are moved back into the ________________ reticulum by ATP-driven ion pumps.

sarcoplasmic

Concentric isotonic contractions actively ______ a muscle.

shorten

Attached to the skeleton and surrounding the openings of the urinary and gastrointestinal traces are locations of ______ muscle.

skeletal

Maintenance of posture and production of heat are functions of ______ muscle.

skeletal

Somatic motor neurons innervate ______ muscle.

skeletal

The length-tension relationship of ____________ muscle cells is limited by the Z discs that are lacking in _______________ muscle cells.

skeletal; smooth

According to the sliding filament theory, when a muscle contracts, thick and thin filaments ________ past each other, and the _______________ shortens.

slide; sarcomere

The ___________ filament theory explains how muscle fibers shorten during contraction.

sliding

An individual has better proficiency in performing repeated contractions under aerobic conditions if he or she has a greater percentage of ______ fibers in specific muscles.

slow

Over longer distances, runners who have higher proportions of ______ muscle fibers in their leg muscles are able to outperform runners who have a greater number of ______ muscle fibers in their leg muscles.

slow; fast

Smooth muscle contraction is _____________ , resistant to _____________ , and usually sustained for an extended period of time.

slow; fatigue

Type I muscle fibers contract more ______ than type IIa and IIb muscle fibers.

slowly

The attachment of ACh to the receptor on the motor end plate causes the receptor to open, allowing ____________ ions to enter the muscle fiber.

sodium

The muscle that surrounds the opening to your esophagus and opens reflexively to allow you to swallow food is what type of muscle?

sphincter

sacroplasmic reticulum function

stores calcium ions needed for muscle contraction

A "step-wise" increase in the force of contraction of a single muscle fiber or single motor unit due to repeated stimulation is called __________

summation

The narrow space separating the synaptic knob and the motor end plate is called the ______.

synaptic cleft

The motor end plate has folds and indentations to increase the membrane surface area adjacent to the ______.

synaptic knob

______ distribute the muscle impulse throughout the inside of the muscle fiber.

t-tubules

A thick cordlike structure that attaches a muscle to a bone is called a(n) ______.

tendon

T-tubules are located adjacent to ______, which are reservoirs storing the calcium ions required for muscle contraction

terminal cisternae

Slow-twitch and fast-twitch muscle fibers differ primarily in ______.

their ATPase which splits ATP

The H band (or H zone) is more lightly shaded because only _________ filaments are present.

thick

Single unit muscle cells contract ______.

together

As you sit there reading this your muscles, even your relaxed ones are not completely relaxed and soft. This is because they have some background tension called resting muscle ______.

tone

t-tubule function

transports the action potential from the sarcolemma throughout the entire muscle fiber

The deep invaginations of the sarcolemma that extend into the sarcoplasm of skeletal muscle fibers as a network of narrow membranous tubules are called ______.

transverse tubules

As the troponin changes shape (due to binding calcium), it moves the ______ molecule to which it is attached, thus exposing the active sites on the G-actin molecules.

tropomyosin

If the sarcoplasm of a muscle cell is flooded with calcium ions, to which protein will they bind?

troponin

Smooth muscle thin filaments do not contain ______ as in skeletal muscle.

troponin

Upon release from the terminal cisternae, some calcium ions bind to ______ causing it to change shape.

troponin

Smooth muscle cells retains their mitotic ability.

true

True or false: Most muscles contain a combination of all three muscle types, slow oxidative, fast oxidative, and fast glycolytic.

true

True or false: Most muscles contain a combination of all three muscle types, slow oxidative, fast oxidative, and fast glycolytic. True false question.

true

True or false: Playing the piano with your fingers uses very small motor units.

true

True or false: Skeletal muscle is usually attached to the skeleton, but it is also found at the openings between the digestive tract and the external environment and the urinary tract and the opening to the external environment.

true

A single contraction and relaxation of a muscle fiber is referred to as a muscle ________

twitch

Skeletal muscle fibers are classified into three types based on what two characteristics?

type of contraction and ATP supply

Within a synaptic knob, synaptic ____________, contain the neurotransmitter ACh.

vesicles

Within a synaptic knob, synaptic _____________ contain the neurotransmitter ACh.

vesicles

You have hooked a frog calf muscle up to a myogram that records muscle tension. You notice that when you stimulate the muscle to contract, then stimulate it again before it can fully relax, the amount of tension generated in the second contraction is greater than the first contraction. This phenomenon is called ______.

wave summation

Which can cause muscle fatigue?

-build up of intracellular P1 - insufficient Ca2+ - Na+ or K+ imbalances

Which are characteristics of oxidative fibers?

-red -good for endurance - high concentration of myoglobin - use aerobic respiration

Match the muscle fiber component with its function. Myofibrils Thick filament Thin filament Actin Tropomyosin

- Myofibrils: Contain myofilaments that are responsible for muscle contraction - Thick filament: Bind to thin filaments and cause contraction - Thin filament: Bind to thick filaments and cause contraction - Actin: Binding site for myosin to shorten a sarcomere - Tropomyosin: Covers the active sites on actin when muscle cell is at rest

Match the component of a muscle cell with its description. Myofibrils Thick filament Thin filament Actin Tropomyosin

- Myofibrils: Cylindrical organelles specialized for contraction - Thick filament: Composed of myosin - Thin filament: Composed of actin, troponin, and tropomyosin - Actin: Double-stranded contractile protein - Tropomyosin: Double-stranded regulatory protein

Thin filaments in smooth muscle cells contain which proteins?

- actin - tropomyosin

Smooth muscle is found in which locations?

- in wall of the uterus - around blood vessels - in the wall of the small intestines

Smooth muscle shows a different length-tension relationship than skeletal muscle because ______.

- it lacks Z discs but has dense bodies - the arrangement of the thick & thin filaments allows for contraction even when stretched

Which are characteristics of glycolytic fibers?

- low concentration of myoglobin - white

The skeletal muscles arranged in layers along the walls of the abdominal cavity and the floor of the pelvic cavity perform what function?

- protection - support - contraction

In which activities are muscles in an isometric contraction?

- pushing on a locked door - holding a yoga pose - sitting up very straight