BIOL 2401 Unit 4

events that occur at a neuromuscular junction in order

1st -nerve signal arrives at synaptic knob 2nd -calcium enters and binds synaptic vesicle 3rd- ACh is released via exocytosis into the synaptic cleft 4th-ACh binds receptors on the motor end plate

Sacromere crossbridge cycling

A. Ca2+ binds troponin; myosin-binding sites uncovered B. cross-bridge formation C. power stroke D. release of myosin head by ATP E. reset of myosin head

Match the structures of a smooth muscle fiber with their functions. A. intermediate filaments B. dense body C. dense plaque

A. cytoskeleton network B. anchoring point between intermediate filaments and the sarcoplasm C. anchoring point between intermediate filaments and the sarcolemma

Identify the metabolic components pictured in the diagram.

A. glycolysis B. decarboxylation of pyruvate to Acetyl CoA C. citric acid cycle D.electron transport chain

components of a smooth muscle cell

A. intermediate filaments B. caveolae C. varicosity D. dense plaque

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

A; H

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

T-tubules

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

T-tubules

When calcium ions bind to troponin, which of the following then occurs?

The myosin-binding sites on actin are exposed.

True or false: Smooth muscle cells lack transverse tubules.

True

The discs that anchor the sarcomere on either end in skeletal muscle that are absent from smooth muscle cells are called _______________

Z discs

ACh is an acronym for _______________

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

To start a muscle contraction, a nerve impulse causes ______ release at a neuromuscular junction.

acetylcholine

Contraction of a muscle fiber requires that the myosin heads in the thick filament bind to active sites on ______ molecules within the thin filaments

actin

Cardiac muscle cells use _____________ respiration almost exclusively.

aerobic

Smooth muscle is found where in the respiratory system?

around the bronchioles

Contractile proteins in smooth muscle are arranged ______.

between dense bodies and dense plaques

Cardiac muscle cells are ______ and contain ______ nuclei.

branched; 1-2

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

calcium

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

calcium voltage-gated

During contraction of smooth muscle, ______ binds to calcium and activates myosin light chain kinase.

calmodulin

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

calmodulin

The sarcolemma of smooth muscle cells has small invaginations called ______.

caveolae

As a result of muscle fiber contraction, thick filaments in neighboring sarcomeres move ______.

closer together

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

debt

In smooth muscle cells, thin filaments are attached to ______.

dense bodies

In smooth muscle, thin filaments are attached to ______ by elements of the cytoskeleton.

dense bodies

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

elasticity

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

excitability

Smooth muscle cells are ______ in shape.

fusiform

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

heat production

Smooth muscle is found

in the walls of hollow internal structures such as blood vessels, airways, stomach, intestines, gallbladder, and bladder

Which structure anchors adjacent cardiac muscle cells together?

intercalated disc

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

Cardiac muscle cells contain a large number of ______ to generate the ATP required for their unceasing work.

mitochondria

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

motor end plate

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

myosin heads

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

phosphagen

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

sacrolemma

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

sacromeres

Thick and thin filaments maintain their ______, whether the muscle is relaxed or contracted.

same length

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

sarcoplasmic

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

skeletal

Movement of the body, heat production, protection, and support are functions of ______ muscle.

skeletal

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

slide; sacromere or myofibril

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

sliding

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 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

1. a nerve signal arrives at this structure 2. ACh is released into this space matches 3. ACh binds to receptors on this surface matches

synaptic knob synaptic cleft motor end plate

As a result of ACh stimulation, calcium ions are released from the ______ of the sarcoplasmic reticulum.

terminal cisternae

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

terminal cisternae

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

When a muscle fiber is in a relaxed state, the ______ molecules cover the G-actin active sites, preventing interaction between thick filaments and thin filaments.

tropomyosin

Calcium ions bind to what protein in a thin myofilament?

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 or False

true

Within a synaptic knob, synaptic ______ contain the neurotransmitter ACh

vesicles