8 Muscle Tissue Flashcards
What are the properties of muscle tissue?
Excitability, contractility, extensibility, elasticity
Functions of muscle tissue?
Movement, posture maintenance, temperature regulation, storage and movement of materials (Ca), support abominable organs, joint stabilization
What are the three types of muscle tissue?
Cardiac muscle, smooth muscle, skeletal msucle
What are intercalated discs?
Connection points between individual muscle cells in heart muscle.
How many nuclei in cardiac muscle tissue
One
Does cardiac muscle tissue have striations?
Yes
What is the shape of cardiac muscle?
Y-shaped
What is the shape of smooth muscle?
Fusiform
Is smooth muscle striated?
No
How many nuclei does a smooth muscle cell have?
One
What is the shape of skeletal muscle cells (myofibers)?
Cylindrical
How many nuclei do muscle fibers have?
Many
What are the layers of connective tissues wrapping a muscle?
The deepest is the endomysium which surrounds each muscle fiber (ie each muscle cell), next is the perimysium which surrounds a group of muscle fibers called fascicles, then the epimysium which surrounds groups of fascicles (ie the whole muscle), then deep fascia which covers the epimysium. All four are continuous with attaching tendon.
What is the epimysium made out of?
Dense irregular CT
What is the perimysium made of?
Dense irregular connective tissue
What is the endomysium made of?
Areolar and reticular fibers, loose connective tissue.
What is the sarcolemma?
The cell membrane that surround each muscle fiber/cell deep to the endomysium
What is sarcoplasm?
The cytoplasm of a muscle cell, surrounding the many myofibrils in each muscle cell.
What are t-tubules?
Invaginations of sarcolemma that allow nerve impulses to penetrate the deepest portions of the muscle cell and allow all muscle fibers to fire in response to nerve impulse.
What is the other name for t-tubules?
Transverse tubules.
What is the sarcoplasmic reticulum?
Modified smooth endoplasmic reticulum that wraps around each myofibril and stores calcium. Contains terminal cisternae.
What are myofibrils?
Bundles of myofilaments contained within a single muscle cell. Each muscle cell contains many myofibrils and each myofibril contains many myofilaments.
What proteins make up myofilaments?
Troponin, tropomyosin, actin, myosin
What proteins make up the thick filament of myofilaments and which make up the thin?
Troponin, tropomyosin, and actin make up the thin filament. Myosin makes up the thick filament.
What are sarcomeres?
Functional and contractile unit of skeletal muscle fiber. Defined from z disk to z disk.
What is a z disk?
Remember picture in your head.
Describe sliding filament theory.
Nerve impulse travels down a neuron. Impulse travels down t-tubules, striking terminal cisternae and causing a release of calcium ions. Those ions bind to the active cites of troponin, causing a change of conformation in troponin-tropomyosin complex that exposes binding cites on actin fibers. Heads of myosin fibers bind to actin active sites and curl down, contracting the muscle.
What is rigor mortis?
When ATP runs out in muscle fibers after death and myosin heads can no longer retract from actin fibers, resulting in uncontrolled muscle contraction. After 15-24 hours, myofilaments break down, allowing movement once again.
What is tetanus?
A disease caused by clostridium tetani which causes uncontrollable muscle contraction. Aka lockjaw.
What is botulism?
Caused by the bacterium clostridium botulinum, causes muscle paralysis. Toxin approved for use by the FDA in 2002.
When do muscle contractions begin in development?
Week seven
When do divisions of muscle cells cease?
Age nine.
