Cellular level of muscles Continued
Card Set Information
Cellular level of muscles Continued
Cellular level muscles
The Sarcoplasmic Reticulum is a:
series of tubes formed by membranes around each myofibril. Is similar to smooth endoplasmic reticulum.
The action of the Sarcoplasmic Reticulum is to:
Store the calcium ions in relaxed muscle.
What are the dilated ends of a section of the sarcoplasmic reticulum called:
Describe what a Transverse Tubule looks like:
Tunnel like infoldings of the sarcolemma that extend inward at right angles to the myofilaments
Each sarcomere has ______ and are filled with _____________ _______
two T Tubules, extracellular fluid.
transverse tubule + 2 terminal cisterns on either side of it.
_______ are the basic functional units of striated muscle fibers.
Sarcomeres are divided into _____ and _____
bands and zones
The Z-discs mark the divisions between _________
Darker areas in the sarcomere is called the
The lighter area in the sarcomere is called the
The Transverse tubules are located at the junction between ____ and ____ bands
A and I
The ____ band has only thin filaments in relaxed muscle
The __ zone within the A band have overlapping filaments.
Other parts of the __ band have overlapping filaments
__ line is formed by proteins that connect adjacent thick filaments
Z discs are places where:
thick filaments are anchored
During Contraction, thin filaments slide:
inward toward the H zone
Explain why Muscles shorten?
filaments overlap but do not change in length
Myosin molecules have a head and tail region what is the head also referred to as?
In a relaxed muscle the heads become activated by energy from _____
Actin molecules have myosin binding sites that are covered in a relaxed muscle by a regulatory molecule called?
Another regulatory molecule called _____ is present in the thin filaments
Signals from nerves result in:
changes in the membrane of muscle that travels into the transverse tubule system to release of calcium ions from the sarcoplasmic reticulum
The _____ ____ combine with tropin , causing it to change shape
The shape change moves the _______ and the _______ away from the myosin binding sites.
troponin and the tropomyosin
The activated myosin heads bind to the myosin-binding sites on _____
When the nerve stops stimulating the muscle, muscle action potentials _____
During _______, calcium stops being released from the sarcoplasmic reticulum and is pumped back into
Explain Rigor Mortis (rigidity of death)
Calcium leaks out and the cross bridges attach, No ATP produced so cross bridges cant detach
When does Rigor Mortis begin
3-4 hours after death, peaks at about 12 hours
When does Rigor Mortis end:
Diminishes over the next 48-60 hours as tissues begin to disintegrate.
Maximum force is exerted when maximum number of ______ ______ make contact
At ______ ______, fewer cross bridges can bind
At ______ _______, thick filaments crumple
Maximum force is exerted at ________ ________
Neurons that stimulate muscles to contract are _____ ______
A motor neuron and all the skeletal muscle fibers it stimulates=
a motor unit
All the fibers of a ____ _____ contract and relax together
________ is the minimum voltage necessary to produce contraction.
Amount of force generated on muscles depends on 4 factors which are:
length of muscle fibers before they contract, Number of muscle fibers contracting, The structure of muscle (arrangement of fascicles) and the Frequency of stimulation
The number of muscle fibers contracting depends n the number of _____ ______ and the ____ of an individual____ _____
motor unit, size, motor unit
The process of increasing the number of active motor units
Twitch Contraction is a:
briefd contraction of all the fibers in a motor unit in response to a single action potential in the motor neuron
First Part of Twitch contraction = latent period where:
calcium is released and slack taken up in the system
Second Part of Twitch contraction= contraction phase:
muscle tension increases
Third Part of Twitch contraction= ________ phase in which calcium ions are taken back up and muscle tension decreases.
Wave (temporal summation) is caused by?
a stimuli that arrives after the refractory period but before the relaxation period is over
In the ________ period a muscle that has contracted temporarily loses its ability to contract.
What is Tetanus
no relation between stimuli
What the cause of Muscle Fibers?
few muscle fibers are contracted involuntarily at a given time.
What is the cause of Cramps?
Painful, spasmodic contractions triggered by the spinal cord
Cramps are initiating by:
irritating factors such as extreme cold, heavy exercise, lack of blood flow, electrolyte depletion, dehydration, or low blood glucose.
All fibers of a single motor are of the:
Nearly all muscles have a mixture of _____ twitch and _____ twitch motor units in them but the proportions differ according to each muscles function.
slow and fast
Slow-twitch fibers are:
smaller have abundant mitochondria, capillaries, myoglobin , Are RED, low glycogen content, aerobic respiration, resistant to fatigue,
: Soleus and postural muscles of spinal column
Fast- Twitch fibers are:
Larger, fewer mitochondria, capillaries and low myoglobin content, and WHITE, high glycogen content, anaerobic,poor resistant to fatigue
: Gastrocnemius, biceps brachii
Slow twitch muscles are used in:
Fast-Twitch are used int:
Rapid intense movements of short duration