Muscle Tissue Histology Flashcards
What is muscle cytoplasm referred to as?
Sarcoplasm
What is muscle smooth endoplasmic reticulum referred to as?
Sarcoplasmic reticulum
What is the plasma membrane or plasmalemma referred to as in a muscle cell?
Sarcolemma
What is a muscle cell referred to as?
Muscle fiber or myofiber
What embryonic tissue is muscle derived from?
Mesoderm
What are the three types of muscle tissue?
Skeletal, cardiac, and smooth
What are the four special characteristics of muscle tissue?
- excitability (or irritability)
- contractility
- extensibility
- elasticity
What are the 4 functions of muscle tissue?
- producing movement
- maintaining posture
- stabilizing joints
- generating heat
What are five characteristics of skeletal muscle
Voluntary control, strong quick contractions, striated, large elongated cylindrical syncytial (multinucleated) cells, and peripheral oval nuclei
What is the function of skeletal muscle?
Voluntary movement, locomotion, manipulation of the environment, facial expression, and voluntary control
Where is skeletal muscle located?
In skeletal muscles attached to bones and occasionally skin
Describe cardiac muscle?
Branching, striated, generally uninucleated cells that interdigitate at specialized junctions (intercalated discs)
What is the function of cardiac muscle?
As it contracts it propels blood into circulation, involuntary control
What is a fusiform cell?
These are cells that are wide in the middle but taper towards the ends
Where are smooth muscle nuclei generally located?
In the center of the cell
Describe the contraction strength and duration of smooth muscle?
Weak and slow contractions
What are the three classifications of skeletal muscle in humans?
Type I
Type IIa
Type IIb
What are type I skeletal muscle fibers?
Slow, red oxidative fibers
What are type IIa skeletal muscle fibers?
Fast, intermediate oxidative-glycolytic fibers
What are type IIb skeletal muscle fibers?
Fast, white glycolytic fibers
What do type I skeletal muscle fibers have that creates the dark red color?
Lots of myoglobin (dark red in color)
Where does type I skeletal muscle derive its energy?
Primarily from aerobic oxidative phosphorylation of fatty acids
Describe the contraction duration and speed of type I skeletal muscle?
Slow, continuous contractions over long periods of time
What would one find in abundance in type IIa skeletal muscle? (3)
Many mitochondria, lots of myoglobin and glycogen (intermediate)
How does type IIa skeletal muscle derive its energy?
Utilizes both oxidative metabolism and anaerobic glycolysis to produce energy
Describe the contraction duration and speed of type IIa skeletal muscle?
Rapid contractions and short bursts of activity
What would we find lots of in type IIb skeletal muscle?
Glycogen, this is what gives this type of muscle the pale color
In respect to the other two kinds of skeletal muscle how many mitochondria do type IIb have?
Fewer
How does type IIb skeletal muscle derive its energy?
Primarily via anaerobic glycolysis
Describe the contraction duration and speed of type IIb skeletal muscle?
Rapid contractions, but fatigue quickly
What is the diameter of a myofibril?
2 micrometers
What is the functional unit of the muscle, smallest unit of contraction ?
Sarcomere
What is the width of a sarcomere?
2.5 micrometers
What are the dimensions of a thick (myosin) filament?
1.6 micrometers long and 15 nanometers wide
What are the dimensions of thin (actin) filaments?
1 micrometer in length and 8 nanometers wide
A sarcomere extends from what to what?
Z disc to Z disc
What is the center most line of a sarcomere?
The M line
What section of a sarcomere immediately surrounds an M line?
The H zone
What section of a sarcomere surrounds the H zone of a sarcomere?
The A band
What band in muscle fibers extends between two adjacent sarcomeres?
The I band
As a muscle partially contracts what happens to the different of the sarcomere?
Thick and thin filaments slide past one another. The sarcomere, I band, and H zone are narrower and shorter, Z discs get closer together
When a muscle fully contracts what happens to the different parts of the sarcomere?
The H zone and I band dissapear, and the sarcomere is at its shortest length. The thick and the thin filaments do not change lenght. Z discs again get closer together
The sarcoplasmic reticulum that butts up against the T tubule is called what?
Terminal cisternae
What is a neuromuscular junction?
(Motor end plate) this is a chemical synapse between a motor (efferent) neuron and a skeletal muscle fiber (cell)
What is a motor unit?
Defined as the motor (efferent) neuron and all the muscle fibers (cells) it innervates
What is the function of the troponin complex?
To block the myosin head from interacting with the actin filament, thus preventing contraction
What is the first step of skeletal muscle contraction?
Myosin cross bridge attaches to the actin myofilament
What is the second step of skeletal muscle contraction?
Working stroke- the myosin head pivots and bends as it pulls on the actin filament, sliding it toward the M line
What is the third step of skeletal muscle contraction?
As new ATP attaches to the myosin head, the cross bridge detaches
What is the fourth step of skeletal muscle contraction?
As ATP is split into ADP and P(inorganic), cocking of the myosin head occurs
What are the three connective tissue sheaths associated with skeletal muscle?
Endomysium, perimysium, and epimysium
What layer of connective tissue immediately surrounds the muscle fiber (cell)?
Endomysium
How many T tubules do skeletal muscle sarcomeres have and where?
Two per sarcomere at A-I junction
How many T tubules do cardiac muscle sarcomeres have and where?
One per sarcomere at Z line
Do cardiac muscle fibers have diads or triads associated with the T tubule?
Diads
Do skeletal muscle fibers have diads or triads associated with the T tubule?
Triads
