Muscle Histology Flashcards
A muscle _______is a cell, while muscle ________ and muscle ________ are structures within the cell.
Fiber
Fibril
Filament
What are the histology names for muscle fibers, fibrils, and filaments?
Myofiber
Myofibril
Myofilament
Muscle forms the flesh of the body, and over __% of body weight
40%
Muscle is specialized for ________.
Contraction
Muscles transform _____ into mechanical _______.
ATP
Energy
What are the 4 functions of skeletal muscle?
Create movement
Stabilize joints
Maintain posture
Create heat
In embryo, ________ elongate and fuse together
myoblasts
Nuclei in muscle cells are pushed to the side by many ________ proteins.
Contractile proteins
Postnatally, muscles increase in ________, not _______.
Size
Number
What is the plasma membrane of muscle cell?
Sarcolemma
What is the cytoplasm of a muscle cell?
Sarcoplasm
What two things of note are in sarcoplasm?
Glycogen
Myoglobin
What is myoglobin?
A red pigment that binds O2 until its needed
What CT surrounds a myofiber?
Endomysium
What CT surrounds a fascicle of fibers?
Perimysyium
What CT surrounds the whole muscle?
Epimysium
How is tendon formed?
All three of these CTs meet at the ends of muscles to form the tendon
What does a tendon do? What shape is it?
Connects muscle to bone, is round in shape
What is aponeurosis?
A sheet of CT (dense regular) connecting a muscle to the part it moves
What is an example of aponeurosis?
Found on the skull and in the abdomen
What color are the markings on skeletal muscle?
Skeletal muscle has alternating dark and light bands
This are not surface markings, involve total fiber thickness
What is a myofibril?
Inside the cell, are long, rod-like contractile elements, most of cell volume
What are myofibrils made of?
Myofilaments
What two components make myofibrils?
Actin: A thinner filament of protein
Myosin: A thicker filament of protein
What is the A band?
The dark overlap of actin and myosin
What is the I band?
The light band, only actin is present
In 3-D, 6 ______ surround 1 ______.
Actin
Myosin
What is the functional unit of skeletal muscle?
The sarcomere
What is the smallest contractile unit of the muscle?
The sarcomere
What are the Z lines?
They define the sarcomere; are a disc that anchors the myofilaments
What is the H zone?
In the middle of the sarcomere, only visible in relaxed muscle
What is the M line?
Fine stabilizing threads that interconnect the myosin filaments
Which muscle zone can only be seen when the muscle is at rest?
The H zone
What is the sarcoplasmic reticulum?
Interconnecting tubules that surround each myofibril, like the sleeve of a sweater
In the sarcoplasmic reticulum, which way do most tubules run?
Longitudinally
What is the terminal cisternae? Where is it found?
Perpendicular channels formed at the A-I band junction
What is a T tubule?
A tube that travels through the muscle fiber and out the other side
This elongated tubule is called the T (transverse) tubule, and contains ECF
Where is the T tubule located?
At the A-I band junction
The T tubule is an __________ of sarcolemma into the cell interior.
Invagination
How does the T tubule assist with signal transmission?
This tremendously increases the muscle fiber’s surface area
When the sarcolemma is depolarized, the signal goes along the surface and down into the interior through the T tubule- and is very efficient
The T Tubules encircle each _______, and pass from one myofibril to the next
myofibril
What fluid do T tubules contain?
ECF
What is the triad?
Each T tubule is between 2 terminal cisternae
The signal to contract will go down the T tubule and release stored ______ out into the sarcoplasm
Ca++
