Thursday - Downing - muscle tissue Flashcards
What helps individual cells in muscle tissue function as a whole?
Connective tissue.
Striated muscles. which is involuntary?
skeletal, cardiac. Cardiac is involuntary
Where is actin in a myofibril?
In the I-band and the A-band
Where is myosin in a myofibril
A-band, H-band, M-line
Sarcoplasm
cytoplasm of a muscle cell. Between myofibrils.
Sarcolemma
plasma membrane of a muscle cell, nucleii are directly underneath. Forms the T-tubules.
sarcoplasmic reticulum
smooth ER of a muscle cell.
Releases calcium during contracture.
General features of skeletal muscle
Striated, voluntary, well developed sarcoplasmic reticulum, multinucleated with nucleii at periphery.
Be able to describe and explain the predictable filament pattern that you would observe in cross sections through the I-band, H-band, and the A-band
I-band - just actin filaments, small dots arranged hexagonally
H-band - Just thick (H, think heavy and thick) filaments (myosin). Larger dots
A-band - the teams all there. actin and myosin filaments together.
What bands contract when a skeletal muscle cell contracts?
I-band, H-band.
Where is the M band? What is interconnected there and what interconnects it?
At the center of the H-band, which is in the center of the A-band. It contains myomesin and interconnects the thick myosin filaments to maintain their specific lattice arrangement.
What is a Z disk and what connects there?
Region where attachment of ends of actin
Where does the transverse tubule (T-tubule) of the sarcoplasmic reticulum intersect myofibrils?
The A-I junction (z band in lower vertebrates)
What releases calcium during muscle contracture?
Sarcoplasmic reticulum
What is a “triad” made of?
T-tubule + two lateral cisternae of sarcoplasmic reticulum
This is helically wound along grooves of the actin helix and prevents myosin binding.
Tropomyosin
This binds calcium and releases tropomyosin from actin
Troponin complex
Alpha-actinin
Component of the Z-disk. Holds actin filaments in register by binding them in parallel array.
Titin
One of the largest molecules we know about. Helps position myosin filaments. extends from each half of a myosin filament to the Z-disk.
Nebulin
Long, non elastic protein that helps anchor actin to z-disk. two molecules wrap around each filament.
Disease characterized by weakness and easy fatigue of muscles, autoimmune response to the ACh receptor. What is it and what type of drug helps?
Myasthenia gravis.
ACh esterase inhibitors are both diagnostic and therapeutic. (AChE allows for the recycling of Ach)
Alpha motor neuron
Causes a whole muscle to contract
Golgi tendon organ
Spindle-shaped bodies comprised of collagen, sensory fibers that are between collagen fibers and are sensitive to stretching forces on tendons.
General features of cardiac muscle
Striated, involuntary, t-tubule system, smaller SR than in skeletal muscle. Have intercalated disks (dark bands that frequently appear step-like). Single, centrally located nucleus.
Which type of muscle has LOTs of mitochondia
cardiac muscle
Where are the t-tubules located in cardiac muscle?
z-lines. They are wider than those in skeletal muscle.
Purkinje fibers
modified cardiac muscle cells. They are the conduction system of the heart.
General features of smooth muscle
No striations, no t-tubules, involuntary. They produce extracellular products like collagen, elastin, and growth factors.
Doctor word for tapered ends (like seen in smooth muscle cells)
Fusiform.
What type of cell’s nucleus “corkscrews” as the cell contracts?
smooth muscle.
Neuromuscular spindle
Wrap around the bodies of muscles and detect whether or not the muscle is contracted (proprioception)
Golgi tendon organ
Spindle shaped bodies comprised of collagen and enclosed by a thin capsule. Afferent (sensory) fibers penetrate between the collagen fibers. They are sensitive to stretching forces on tendons.
Motor end plates
The ends of efferent fibers. they end mid-region on intrafusal fibers.
