Lecture 9 part one (SECOND MIDTERM) Flashcards
What kind of tissue surrounds the muscle? What is it called?
Connective tissue; Epimysium
What makes up a muscle?
Fascicles or muscle bundles
What kind of tissue surrounds the muscle bundle? What is it called?
Connective tissue; Perimysium
What makes up the muscle bundle?
Muscle fibers/cells (myocytes)
What kind of tissue surrounds the muscle cells? What is it called?
Connective tissue; Endomysium
What makes up muscle fibers/cells?
Muscle fibrils (myofibrils)
What makes up the muscle fibrils?
Sarcomeres
What makes up a sarcomere?
Muscle filaments
What makes up a muscle filament?
Proteins
What is the smallest functional unit of the muscle fiber?
sarcomere
The complex of a transverse tubule and two adjacent terminal cisternae is known as a…
triad
Name the muscle layers from superficial to deep.
Epimysium Perimysium Fascicle Endomysium Muscle Fiber Myofibril
The repeating unit of a skeletal muscle fiber is the…
sarcomere
At rest, what blocks actin from attachment to myosin?
troponin
The area in the center of the A band that contains no thin filaments is the..
H band
Unlike smooth and cardiac muscle, striated muscle has multiple…
nuclei
2 proteins involved in skeletal (striated) muscle:
Which is thick and which is thin?
actin (thin) and myosin (thick)
What makes skeletal muscle appear striated?
myofibrils
What indicates the ends of the sarcomere?
Z lines
What is the “middle” of the sarcomere called?
M line
What do the actin attach to?
Z lines
What is the portion that is JUST thin filaments?
I band
What is the dark region where thin filaments are located between thick filaments?
Zone of overlap
What is the plasma membrane of a muscle fiber called?
sarcolemma
What does the sarcolemma surround?
sarcoplasm
Each myofibril is surrounded by a network of tubes and sacs. What do the tubes and sacs do and together what are they called?
- They transmit the continuation of the nerve impulse to the muscle cell
- Sarcoplasmic reticulum
What runs at right angles and connects to the sarcoplasmic reticulum?
transverse tubules (T tubules)
Depolarization (and action potential) from neuron at neuromuscular junction carries on through what?
the T-tubules
What “stores” calcium? and where?
Sarcoplasmic reticulum
terminal cisternae
Many muscle fibers may be innervated by one motor neuron. This complex is called the…
motor unit
Junction between neuron and muscle fiber is the…
neuromuscular junction
Actual contact, or the spot of communication, is at the…
motor endplate
What floods into the end of neuron at a neuromuscular junction, triggering the release of a neurotransmitter? What is the neurotransmitter?
Calcium
Acetylcholine
Sarcoplasmic reticulum releases calcium into what?
myofibril
When a myosin head rocks back toward the M-line, it attaches to the actin filament and forms what?
a cross-bridge
Troponin is laced around the actin in a spiral-like manner by a structural protein called what?
tropomyosin
When calcium floods in, the calcium binds to what?
Troponin
What does calcium do to the troponin-tropomyosin complex?
it changes the shape enough to move it out of the way and allow the cross-bridge to form and the myosin heads to rock backward
What is rigor mortis?
When one dies, no ATP is available, and movement is not possible
ATP is not required to…
but it IS required to…
rock the cross bridges
detach and reset them
What covers the active sites on the G-actin and prevents actin-myosin interaction?
tropomyosin
Thin filaments sliding toward the center of each sarcomere alongside the thick filaments is called…
the sliding filament theory
Cells of cardiac muscle tissue…
cardiocytes
Compared to skeletal muscle, what does cardiac muscle LACK?
the sarcoplasmic reticulum lacks terminal cisternae; there is NO triad!
Skeletal muscle has long, multinucleated cells (fibers). How are cardiac cells?
Uninucleate and branching
Intercalated discs are…
Function?
- Sarcolemmas of adjacent discs that are interdigitating and connected by gap junctions
- Signal can travel directly from cell to cell, essentially causing the muscle to act like a single cell (coordinated)
Prepotential, or pacemaker potential, is described as…
specialized cardiac muscle cells (more like nerves) that contain very little myofibrils are called the Conducting System or Nodal System
Nodes included in Conducting System:
Sinoatrial node
Atrioventricular node
Conducting cells
Even if there is no neuronal signal, what will sodium do to the heart? Because of what?
It will cause the membrane potential to reach threshold on its own.
Because of the “leaky” cells of the nodes
Unlike striated muscle, the calcium binds to what? What does it activate?
binds to Calmodulin
activates Myosin Light Chain Kinase
What is plasticity? What muscle has this trait?
The ability to function over a wide range of lengths
Smooth muscle
Kinase allows what?
cross bridges to form, thus initiating contraction
