Cardiac muscle and smooth muscle is involuntary or voluntary
involuntary
What does Involuntary and voluntary mean?
Involuntary is something you are not aware of and voluntary is something you are.
Where are involuntary muscles mostly found?
In walls of organs, used primarily to push substances through tubes.
Which muscle attaches to bone directly or indirectly and preform specific functions?
Skeletal
What are the functions of skeletal muscle?
produce skeletal movement, maintain posture and body position, support soft tissues, regulate the entering and exiting of materials, and maintain body temperature.
Skeletal muscle fiber arise from embryonic cells called
Myoblasts
Why does skeletal muscle fibers have more than one nucleus during development?
Because during development groups of embryonic cells fuse together to form a single muscle fiber
Brevis means
short
Orbicularis means
circle
rectus means
muscle fiber orientation and direction
Flexure carpi radialis means
Lateral forearm muscle that bends the wrist
What three concentric layers of connective tissue is wraps each muscle fiber?
Epiysium, perimysium, and endomysium
What are Tendons or Aponeuroses?
They are at the ends of muscles and attach the muscle to other structures.
Connective tissue surrounding skeletal muscle are collectively called..
Deep Fascia
Communication between a neuron and a muscle fiber occur across the..
Neuromuscular junction or Myoneural junction
What three components do skeletal muscle cells have?
Sarcolemma, sarcoplasm, and sarcoplasmic reticulum
_________ is large multinucleated cell
Skeletal muscle cell
Invaginations, or deep indentations, of the sarcolemma into the sarcoplasm of the skeletal muscle cell are called
Transverse ( T ) Tubules
The transverse tubules carry the electrical impulse that stimulates contraction into the sarcoplasm, which contain numerous amounts of..
microfibrils.
Protein filaments insides a myofibril are organized into repeating functional units called
Sarcomeres
Myofilaments form
Myofibrils
Myofibrils consist of
thin and thick filaments
Myofibril is..
the structure with in the muscle fibers that shorten to cause skeletal muscle fiber contraction.
What is the sliding filament theory of muscle contraction..
explains how a muscle fiber exerts tension (a pull) and shortens.
The four-step contraction process includes
actives sites from thin filaments and cross bridges of thick filaments.
Sliding involves a cycle of ...
"Attach, Pivot, Detach, and Return" for the myosin bridges.
At rest the necessary interactions are prevent by which two associated proteins on thin filaments?
Tropomyosin and Troponin
Contraction is a ________ Process?
Active
Elongation is a _______ process
Passive
Elongation can occur where?
either through elastic forces or through the movement of other, opposing muscles
Amount of tension is _______ to the degree of ________
proportional, overlap between thick and thin filaments
Neural control of muscles involves
a link between release of chemicals by the neurons and electrical activity in the sarcolemma leading to the initiation of contraction.
Each muscle fiber is controlled by what?
a neuron at a neuromuscular junction
Each neuromuscular junction includes what?
Synaptic terminal, synaptic vesicles, and synaptic cleft.
What is Acetylcholine (Ach)?
its release leads to the stimulation of the motor end plate and the generation of electrical impulses the spread across the sarcolemma.
What are Acetylcholinesterase (AchE)?
They break down Ach and limits the duration of the stimulation.
Summarize Muscle Contraction.
Ach Release from synaptic vesicles> binding of Ach to the motor plate> generation of an electrical impulse in the sarcolemma> conduction of the impulse along T tubule> release of calcium ions by the SR> exposure of active sites on the thin filaments> Cross bridge information and contraction.
What happens to the bands during contraction?
the I band begins to disappear, the A band remains constant, the H bands gets smaller, and the Z line moves closer together
what indicates how precisely controlled muscle movements are?
Motor units
What is a Muscle Twitch?
A single momentary muscle contraction and it is a response to a single stimulus.
What is the All or None principle?
Means that a muscle fiber either contracts completely or does not contract at all.
What muscle fiber type twitches fast?
A large muscle fiber
What are motor units doing to a muscle at rest?
Motor units are randomly stimulated so that a constant tension is maintained in the attached tendon.
This resting tension in a skeletal muscle is called?
Muscle tone.
What does Resting Muscle tone do?
It stabilizes bone and joints
Excessive repeated stimulation to produce near-maximal tension in skeletal muscle can lead to what?
Hypertrophy of the stimulated muscles
Inadequate stimulation to maintain resting muscle tone causes muscles to become flaccid and under go what?
Atrophy
What are the three types of skeletal fiber?
Fast Fibers, slow fibers and intermediate fibers
Where are fast fibers and slow fibers not found?
In the eye and hands.
What are Fast Fibers?
They are large in Diameter, they contain densely packed myofibrils, large glycogen reserves and relatively few mitochondria.
What do Fast Fibers produce?
They produce rapid and powerful contractions of relatively brief durations.
What are Slow Fibers?
They are about half the diameter of fast fibers, and they take three times as long to contract after stimulation.
Slow Fibers are specialized to do what?
They are specialized to enable muscles to continue contraction for extended periods.
What are intermediate fibers?
They are similar to fast and slow fibers, although they have greater resistance to fatigue.
Fibers with one motor unit are of the same type. True or false?
True
The powerful muscle fiber arrangement is..
Pennate
A muscle can be classified according to the arrangement of fibers and fascicles which include?
Parallel Muscle, convergent muscle, pennate muscle, or circular muscle.
Which muscle is are the fascicles are parallel to the long axis of the muscle? Ex. Biceps
Parallel Muscle
What is a convergent muscle? and where can it be found?
It is muscles fibers based over a broad area but all fibers come together at a common attachment site. It can be found in pectoralis group.
What is a Pennate Muscle?
They are one or more tendons that run through the body of the masucle, and the fascicles from a oblique angle to the tendon.
When Pennate muscle contracts its generates more tension than what other Skeletal Muscle Fiber of the same size?
Parallel muscle.
There are three types of Pennate Muscle which are?
Unipennate, Bipennate, and mutipennate.
What Skeletal muscle fiber are concentrically arranged around an opening?
Circular Muscle
Each may be identified by what?
Origin, insertion, and primary action.
What four classification of Skeletal Muscle Fibers?
Prime mover, Agonist, Synergist, or Antagonist
Names of muscles often hint what about muscles?
Location, orientation, and funcation
A ______ is rigid structure that moves on a fixed point called the ________?
