A&P Chapter 10: Muscle Tissue
Place the 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
The sodium-potassium exchange pump moves _____ sodium ions out of the cell for every _____ potassium ions it brings in
3:2
According to the sliding filament theory, the length of the ____ band remains constant, but the _____ zone disappears
A/H
Energy to dive the myosin movement in the sliding filament process is provided in the form of _____
ATP
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
To stop motor end plate stimulation, usually acetylcholine is quickly broken down and removed from the receptor by _____
Acetylcholinesterase
Contraction of a muscle fiber requires that the myosin heads in the thick filament bind to active sites on the _____ molecules within the thin filaments
Actin
Which of the following proteins are found in a thin filament?
Actin
For longer contractions, muscle cells obtain ATP by which process?
Aerobic respiration
A tendon that forms a thin, flattened sheet is called a/an _____
Aponeurosis
The cyclic events of "attach, pivot, detach, return" continues as long as ____ ions remain bound to troponin
Calcium
The sarcoplasmic reticulum stores _____ ions needed to initiate muscle contraction
Calcium
When an actin potential travels down the t-tubules to the terminal cistern of the SR, what ion is released into the sarcoplasm?
Calcium
The wall of the heart is compose of _____ muscle
Cardiac
The sarcolemma of smooth muscle cells has a small invaginations called _____
Caveolae
The long tails of the myosin molecules in the thick filaments points toward the _____ of the filament
Center
The ACh receptors on the motor end plate are _____ ion channels
Chemically-gated
The enzyme acetylcholinesterase resides in the synaptic
Cleft
When smooth muscle is stretch, it responds by _____
Contracting then relaxing
After exposure of the active sites on acting myosin heads attach to the actin and form ____
Cross bridges
In smooth muscle cells, thin filaments are attached to ____
Dense bodies
Myosin head attachment and pivoting do not require energy, but ATP is needed for the myosin head cross bridge to _____ from actin and re-cock
Detach
Acetylcholine moves across the synaptic cleft by _____
Diffusion
A sarcomere is defined as the distance for on Z _____ to the next
Disc
Muscle tissue demonstrates the property of ____ when it is done contracting and returns to its resting length
Elasticity
In a thin filament, individual G-actin molecules are strung together to form ____
F-actin
The majority of skeletal muscle fibers in the body are _____ fibers
Fast glycolytic
Which of the three skeletal muscle fiber types has the largest diameter and provides both power and speed?
Fast glycolytic
In a concentric isotonic contraction, the tension produced is _____ than the resistance
Greater
In a relaxed muscle fiber there are no thin filaments overlapping the thick filaments in the ____ zone
H
In a sarcomere, the _____ zone (or band) is the light, central region of the A band
H
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
When viewed under a light microscope, the light bands, called _____ contain only _____ filaments
I; thin
The calcium needed to activate smooth muscle contraction originates in the _____ around the cell
Interstitial fluid
Smooth muscle contraction is under ______ control
Involuntary
If you strain to push on a wall that does not move, you muscles are in what type of contraction
Isometric
The two types of muscle contractions are: a.) _____ contraction (when muscle contractions but does not change length) b.) _____ contraction (when muscle contract and does change length)
Isometric; isotonic
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 allows muscle to maintain muscle contraction without the use of additional ATP
Latch bridge
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
The _____ line is a thin, transverse, protein meshwork structure in the center of the H zone of a sarcomere
M
Skeletal muscle contraction is controlled by _____ neurons
Motor
Upon release from the synaptic knob, acetylcholine attached to receptors on the _____
Motor end plate
During development, many groups of _____ fuse to form single skeletal muscle fibers
Myoblasts
The sarcoplasm of skeletal muscle fiber contains hundreds to thousands of long, cylindrical structures called _____ that extended the length of the cell
Myofibrils
Termination of the nerve impulse at the NMJ results in the passive sliding of _____ back to their original state
Myofilaments
Thick myofilaments are composed of bundles of what protein?
Myosin
An internal membrane complex in skeletal muscle cells that is similar to the smooth. endoplasmic reticulum of other cells is called the sarcoplasmic _____
Reticulum
Within a myofibril, each _____ shortens as the muscle fiber contracts
Sarcomere
At the end of the contraction, when the stimulation from the nerve impulse ceases, calcium ions are pumped back into the _____
Sarcoplasmic reticulum
During development of skeletal muscle cells, some myoblastes do not fuse and instead become _____ cells
Satellite
The length-tension relationship of _____ muscle cells is limited by the Z-discs which are lacking in _____ muscle cells
Skeletal; smooth
Smooth muscle contraction is _____, resistant to _____, and usually sustained for an extended period of time
Slow; fatigue
Although smooth muscle cells have both thick and thin filaments, they're not precisely aligned, so no visible ____ are present
Striations
A "step-wise" increase in the force of contraction of a single muscle fiber motor unit due to repeated stimulation is called _____
Summation
A narrow space separating the synaptic knob and the motor end plate
Synaptic cleft
A nerve impulse travels through a axon to its _____
Synaptic knob
The motor end plate has folds 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
An action potential travels down the sarcolemma, throughout the t-tubules, to the _____
Terminal cisternae
As a result of ACh stimulation, calcium ions are released from the _____ of the sarcoplasmic reticulum
Terminal cisternae
When calcium ions bind to troponin, which of the following then occurs?
The myosin binding sites on actin are exposed
The striated appearance in skeletal muscle cells is due to size and density difference between _____ and _____ filaments
Thick; thin
In a sarcomere, Z discs serve as anchors for _____
Thin filaments
Single unit muscle cells contract ____
Together
Spread of muscle impulses along the sarcolemma, then down the _____, causes calcium ions to leak out of the SR into the sarcoplasm of the muscle fiber
Transverse tubules
The two regulatory proteins associated with thin myofilaments are:
Tropomyosin and troponin
Calcium ions bind to what protein in a thin myofilament?
Troponin
Upon release from the terminal cisternae, some ions bind to _____ causing it to change shape
Troponin
Smooth muscle cells retains its mitotic ability
True
T/F: In the absence of calcium, troponin attaches to tropomyosin to hold it in place on the surface of the F actin strand
True
A single contraction and relaxation of a muscle fiber is referred to as a muscle
Twitch
Each myosin protein molecule in a thick filament consists of _____ strands
Two
Thick filaments are about _____ the diameter of thin filaments
Two times
Autonomic motor neurons that control smooth muscle contraction have bulbous swellings called _____ that contain synaptic vesicles
Varicosities
In which activities are muscles in an isometric contraction?
-Sitting up very straight -Holding a yoga pose -Pushing on a locked door
The skeletal muscles arrange in layers along the walls of the abdominal cavity and the floor of the pelvic cavity perform what function?
-Support -Protection -Contraction
A neuromuscular junction contains a(n) _____
-Synaptic knob -Motor end plate -Synaptic cleft
Which of the following proteins are found within a sarcomere?
-Actin -Connectin
Which are characteristics of oxidative fibers?
-Good for endurance -Use of aerobic respiration -Red -High concentration of myoglobin
Smooth muscle is found in which of the following locations
-In the wall of the uterus -Around blood vessels -In the wall of the small intestine
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 and thin filaments allows for contraction even when stretched
Which are characteristics of glycolytic fibers?
-Low concentration of myoglobin -White