Muscle Tissue Flashcards
Skeletal muscle tissue
Description: Long, cylindrical, striations
Function: Voluntary movement, locomotion
Location: skeletal muscles, attached to bones or occasionally to skin
Cardiac Muscle tissue
Description: branching, striated, intercalated disks
Function: as it contracts, it propels blood into the circulation, involuntary
Location: in the walls of the heart
Smooth Muscle Tissue
Description: spindle shaped cells with central nuclei, no striations, cells arranged closely to form sheets
Function: propels substances or objects along internal passageways: involuntary control
Location: mostly in the walls of hallow organs
Physical characteristics of a muscle
- Excitability: receive and respond to a stimulus
- Contractility: the ability to shorten forcefully when stimulated
- Extensibility: the ability to be stretched or extended
- Elasticity: the ability to recoil after being stretched
Muscle functions
- Producing movement
- Maintaining posture and body position
- Stabilizing joints
- Generating heat
Types of muscle
Skeletal, cardiac, smooth
The connective tissue sheaths
Epimysium, perimysium and endomysium
Insertion and origin
When a muscle contracts, the movable bone, the INSERTION, moves towards the immovable bone, the ORIGIN
Sarcoplasm
Cytoplasm of a muscle fiber
Contains glycosomes and myoglobin
Sarcolemma
A muscle fibres plasma membrane
Glycosomes
Granules of stored glycogen: provide glucose during muscle cell activity
Myoglobin
Red coloured protein: stores oxygen to use during muscle cell activity
Myofibrils
Densely packed fibers that are involved in muscle contraction.
Each muscle fiber contains thousands of rodlike myofibrils
Myofilaments
Composes myofibrils that are organized into sarcomeres
A Bands and I Bands
Perfectly aligned with each other
Gives the cell it’s striated appearance
A band: darker in colour
I band: lighter in colour (bisected by a dark line called the Z DISK)
H zone
The midsection of the A band. Lighter in colour than the A band
Bisected vertically by a dark line called M LINE
Epimysium
A tissue that surrounds the whole muscle
Perimysium
A tissue that surrounds fascicles
Endomysium
A tissue that surrounds each fiber
How do calcium ions have a part in muscle contraction?
They signal the myofibrils to contract
Myosin and actin
Contractile proteins that make up the thick and thin filaments
Tropomyosin
Protein that spirals around each thin filament to help stabilize it
It helps to control the myosin-actin interaction involved in contraction
Epimysium
A tissue that surrounds the whole muscle
Perimysium
A tissue that surrounds fascicles
Endomysium
A tissue that surrounds each fiber
How do calcium ions have a part in muscle contraction?
They signal the myofibrils to contract
Myosin and actin
Contractile proteins that make up the thick and thin filaments
Tropomyosin
Protein that spirals around each thin filament to help stabilize it
It helps to control the myosin-actin interaction involved in contraction
Sarcoplasmic Reticulum
Smooth endoplasmic reticulum that wraps each myofibril
Role: to regulate intracellular levels of ionic calcium
Sarcoplasmic Reticulum
Smooth endoplasmic reticulum that wraps each myofibril
Role: to regulate intracellular levels of ionic calcium
T Tubules
The muscles Sarcolemma sticks into the cell interior forming a t tubule.
It comes into contact with the sarcoplasmic reticulum
Neuromuscular junction
Where action potentials occur
The synapse between a somatic motor neurone and a skeletal muscle fiber
Synapse
A region of communication between two neutrons
They separate cells from cells from direct physical contact
Events of the Neuromuscular Junction
- Action potential arrives at motor neurons axon terminal
2. Voltage-gated Ca+ channels open and Ca+ enters the axon terminal
