MSK - Histology - Muscular Tissue Flashcards
Which of these types of muscle is striated?
Cardiac
Smooth
Skeletal
Cardiac,
skeletal
What type of tissue is shown in this micrograph?
What are some of its defining characteristics?
Skeletal muscle;
striations
What type of tissue is shown in this micrograph?
What are some of its defining characteristics?
Cardiac muscle;
striations, intercalated discs
What type of tissue is shown in this micrograph?
What are some of its defining characteristics?
Smooth muscle;
non-striated
When we say some muscle tissue is striated, what does that mean?
The tissue has alternating dark and white lines that are perpendicular to the direction of the muscle fibers
State the proper terminology for the following in relation to a myocyte:
Plasma membrane
Smooth endoplasmic reticulum
Cytoplasm
Sarcolemma;
sarcoplasmic reticulum;
sarcoplasm
What type(s) of muscle is(are) striated?
Skeletal;
cardiac
What type of muscle is striated and involuntary?
What type of muscle is striated and voluntary?
What type of muscle is non-striated and involuntary?
What type of muscle is non-striated and voluntary?
Cardiac;
skeletal;
smooth;
none (does not exist)
Dystrophin connects what filament type to protein complexes of the plasma membrane?
These plasma membrane complexes connect to what extracellular structure?
F-actin;
laminin
What are the two main myofilaments?
Myosin (thick);
actin (thin)
What proteins are associated with myosin?
Titin (anchors thick filaments to Z lines)
What proteins are associated with actin?
Tropomyosin (covers myosin-binding sites);
troponin (binds calcium, moves tropomyosin);
nebulin (stabilizes and aligns actin polymers);
dystrophin (anchors thin filaments to plasma membrane protein complexes)
What protein runs alongside myosin, anchoring it to the Z-lines and running the entire length of a sarcomere?
Titin
What type of protein gives muscle its elasticity?
Titin
What are two unique facts about skeletal muscle nuclei?
Skeletal myocytes are multinucleated;
the nuclei are peripherally located
Skeletal myocytes are basically elongated plasma membranes filled with:
and peripherally lined by:
myofibrils;
many nuclei
In striated muscle, the dark bands are called __ bands.
The light bands are called __ bands.
A
(dArk bands);
I
(lIght bands)
What type of cell has a very limited role in providing regenerative effects in damaged skeletal muscle?
Satellite cells
Many __________ fuse into a single elongated ___________ that runs with other similar cells to make up a muscle fascicle.
Myoblasts;
myofiber (myocyte)
What type of cell junction unites myocytes?
None!
They are held together by layers of connective tissue (endomysium, perimysium, epimysium)
Name 1, 4, 5, 7, 9, 10, and 11.
1 - Z-line
4 - M-line
5 - titin
7 - sarcomere (Z-to-Z)
9 - H-zone
10 - A-band
11 - I-band
What proteins are found in the I band?
Actin,
tropomyosin,
troponin,
nebulin,
z-line proteins,
titin
What proteins are found in the A band?
Myosin, M-line proteins
+ I band proteins
(actin, tropomyosin, troponin, nebulin, titin)
What proteins are found in the H-zone?
Myosin, myomesin (M-line protein), titin
What layer of muscle connective tissue carries most of the vasculature and nervous innervation for the muscle?
Epimysium
Epimysium surrounds bunches of muscle fascicles. It is made of what type of connective tissue?
This is associated with what type of connective tissue fiber in particular?
Dense irregular connective tissue;
type I collagen
In close examination of striated muscle, a thin line can be seen bisecting each I band (lIght band). What is that line?
Z lines
In striated muscle, what dark line bisects each I band?
In striated muscle, what light area bisects each A band?
The Z-line;
the H band
A sarcomere is defined as the space from one __ line to the next.
Z
In striated muscle, which are the A bands and why are they called this?
In striated muscle, which are the I bands and why are they called this?
Dark bands (dArk), they are anisotropic;
light bands (lIght) they are isotropic
How is myocyte contraction linked to surrounding connective tissue?
Dystrophin (intracellular) connects actin to plasma membrane protein complexes;
these complexes connect to laminin in the endomysium basement membrane (extracellular)
Name as many proteins of the sarcomere as you can.
Myosin, titin, myomesin (and C-proteins);
actin, tropomyosin, troponin, nebulin, alpha-actinin
(peripherally associated: dystrophin, desmin)
Which striation bands shorten during muscle contraction?
Which striation band remains the same length during muscle contraction?
The I and H bands;
the A band
What are the two binding sites of a myosin head?
Actin-binding;
ATP-binding
When activated, protein 1 pulls protein 2 off the myosin-binding site on F-actin.
What is protein 1 and what is protein 2?
Troponin;
tropomyosin
What type of myofilament is found in the A band but not in the H band?
Light myofilaments (actin + associated proteins)
What band of the sarcomere is thick filaments only?
What band of the sarcomere is both thick and thin filaments?
What band of the sarcomere is thin filaments only?
H band;
A band (length of thick filaments);
I band
What structure connects two adjacent thick filaments within one sarcomere?
Myomesin (M-line protein)
1st step - myosin bound to actin
What is the 2nd step of the actin-myosin crossbridge cycle?
What is the 3rd step of the actin-myosin crossbridge cycle?
What is the 4th step of the actin-myosin crossbridge cycle?
What is the 5th step of the actin-myosin crossbridge cycle?
ATP binds myosin (myosin releases actin);
ATP hydrolysis (myosin bending);
force generation (contraction, phosphate release);
reattachment (myosin inactive, bound to actin)
What are the triads extending down into each myocyte?
One T-tubule + two sarcoplasmic reticula
(i.e. a long, narrow sarcolemma invagination with two long, narrow smooth endoplasmic reticula on either side)
What protein binds F-actin to Z-lines?
Alpha-actinin
The specific protein found in the M-line of a sarcomere is called:
Myomesin
Identify the muscle spindle apparatus in this cross-section of skeletal muscle.
(Blue circle)
What type of tissue is shown here?
Outline one single cell in this cross-section.
Skeletal muscle
(blue line)
Abnormalities in the dystrophin protein are liked to what two disorders?
Duchenne muscular dystrophy (dystrophin nearly completely absent);
Becker muscular dystrophy (dystrophin partially absent)
What structure is shown in this slide?
A myotendinous junction
(skeletal muscle attaching to tendon)
Duchenne muscular dystrophy is linked to mutations in what protein?
Becker muscular dystrophy is linked to mutations in what protein?
Dystrophin;
dystrophin
What role does desmin play in myocytes?
Does it assist in contraction?
It anchors Z-lines to the sarcolemma;
no (it is structural, maintaining shape)
What protein anchors actin to Z-lines?
What protein anchors myosin to Z-lines?
What protein anchors Z-lines to the sarcolemma?
What protein anchors F-actin to the sarcolemma?
Alpha-actinin;
titin;
desmin;
dystrophin
What protein anchors actin to Z-lines?
Alpha-actinin