05a: Muscle Tissue Histology Flashcards
Contractile cells/tissues can be divided into which subcategories?
- Single cell units
2. Multicellular tissues
Give examples of contractile cells that work as single-cell units.
- Myoepithelium
- Myofibroblasts
- Pericytes
Which muscle tissue type(s) is/are striated?
Skeletal and Cardiac
What are the types of skeletal muscle tissue?
- Type I
- Type IIa
- Type IIb
Type I skeletal muscle, aka (X), has (more/less) mitochondria than the other types.
X = red
More
Smooth muscle is (unitary/multiunit).
Can be either
Which muscle tissue type(s) is/are innervated by the autonomic NS?
Cardiac and smooth
T/F: Skeletal muscle is multinucleated.
True
T/F: Skeletal muscle fiber diameter can be as small as the diameter of RBC.
True (10 micrometers)
The PM of muscle fiber is called:
Sarcolemma
The cytoplasm of muscle fiber is called:
Sarcoplasm
The specialized (X) ER of the muscle fiber is called (Y) and functions primarily to:
X = smooth Y = sarcoplasmic reticulum
Sequester Ca
Smallest functional unit of contraction.
Sarcomere
Series of sarcomeres constitute (X). And a group of (X) constitutes (Y).
X = Myofibril Y = Muscle fiber
Going from one Z-band to the middle of the sarcomere, list all bands you’d encounter in order
- Z band
- I band
- A band
- H band
- M band
What’s nebulin?
Linear protein that controls actin filament length (template for precise filament assembly)
Titin is a(n) (X) that attaches to (Y). What is/are its function(s).
X = protien Y = Z-line and myosin
Functions to:
- Confer elasticity
- Keep myosin centered
Desmin is a(n) (X) that functions to (Y).
X = intermediate filament (for muscle) Y = keep sarcomeres in vertical array
Which filament(s) shorten during muscle contraction?
No shortening! Sliding mechanism
During contraction, the sarcomere shortens by (X)%.
X = 25
Max range of contraction is related to (X). Max strength is related to (Y).
X = muscle length Y = muscle diameter
Skeletal muscle: T-tubules arranged in what fashion?
Precisely arranged at A-I interface of myofibrils
Skeletal muscle: Terminal cisterns of (X) are associated with (Y). These components form a (diad/triad).
X = sarcoplasmic reticulum Y = T-tubules
Triad
Skeletal muscle: where, specifically, is Ca stored?
Terminal cisterns of sarcoplasmic reticulum
T/F: Skeletal muscle membrane depolarization can be detected from outside/periphery of the fiber.
False - depolarization reaches fiber interior
Skeletal muscle: (X) depolarization leads to (Y) depolarization and which subsequent event?
X = membrane Y = t-tubule (triad)
Opening of Ca channels in terminal cistern
Which muscle type capable of repeated contraction without fatigue?
Type I (red)
(Slow/fast)-twitch, glycolytic muscle appears (red/white/intermediate) and is (quick/resistant) to fatigue.
Fast; white; quick
Intermediate skeletal muscle type is (slow/fast)-twitch.
Fast
PAS stain is a stain for:
Glycogen
Which skeletal muscle type would be most PAS positive? Which color would they appear in the slide?
White (fast-twitch, glycolytic); appear most pink of the fibers in the slide
Which LM technique can be used to visualize mitochondria levels in skeletal muscle?
Cytochrome oxidase (via enzyme cytochemistry)
In skeletal muscle slide using cytochrome oxidase, to portray (X) levels, how does the appearance of red/white muscle types differ?
X = mitochondria
Red: smallest, darkest fibers
White: largest, lightest fibers
Which skeletal muscle type used for posture?
Slow-twitch, oxidative (red/type I)
Which skeletal muscle type used for sprinting?
Fast-twitch, glycolytic (white/type IIb)
T/F: All body muscles have mixture of skeletal muscle fiber subtypes.
True
T/F: The skeletal muscle fiber subtype cannot be altered once the muscle has developed.
False - subtype based on neuron that innervates fiber. So these innervations, and the subtype, can change
Describe basic steps in skeletal muscle formation.
- Myoblast matures
- Myoblasts fuse (form syncytium, then myotube)
- New myoblasts fuse at ends/sides and fiber grows in diameter
- Satellite cells attach peripherally and fiber is innervated
What are satellite cells?
Muscle (multi-potent) stem cells
Upon activation, what’s the function of satellite cells?
Can re-enter the cell cycle to proliferate and differentiate into myoblasts
Sarcopenia is:
Age-related involuntary loss of skeletal muscle
Loss of muscle mass in older people parallels gain of:
fat mass
Cachexia is:
Muscle-wasting stage of disease; body breaks down skeletal muscle for glucose (to keep brain function)
Which diseases can eventually lead to Cachexia?
Cancer, AIDS, chronic forms of kidney disease, heart failure
Where, wrt the heart, is cardiac muscle found?
In heart walls and septum
What are the cardiac muscle equivalent of skeletal muscle satellite cells?
There is none
Describe some key artifacts in the cardiac muscle histology slide.
- Intercalated disc
- Sarcoplasmic cone
- Less clear banding pattern (due to high mitochondria levels)
Primary function of intercalated discs.
Hold cells together
Intercalated disc is a complex of:
3 Intercellular junctions (fascia adherens, gap junction, desmosome)
The fascia adherens in (X) muscle is critical for connecting (Y) of cells.
X = cardiac Y = myofibrils' actin
Which structure(s) are responsible for the spread of depolarization in cardiac muscle?
Gap junctions (part of intercalated disc)
Which intercellular junction, part of (X) in cardiac muscle, acts like zonular adherens?
X = intercalated disc
Fascia adherens
The intermediate filament, (X), is important in which cardiac muscle structure(s)?
X = desmin
In desmosome of intercalated disc
Cardiac muscle: T-tubules arranged in what fashion?
Located at Z-lines
Cardiac muscle: location/storage of Ca.
Ca bound to external lamina in T-tubule
External lamina (is/isn’t) charged.
Is; negatively-charged
What differs about the connection of the sarcoplasmic reticulum and the T-tubules between cardiac and skeletal muscle?
Cardiac: not as extensive of sarcoplasmic reticulum network, so association with T-tubule forms DIAD, not triad
What’s ANP in (X) muscle?
X = cardiac
Atrial Naturietic Peptide; a powerful vasodilator
ANP released in response to (X) and acts on (Y).
X = stretch of atrial walls Y = kidneys (reduce body fluid/BP)
Purkinje and Bundle fibers have an increase in which characteristic(s) of cardiac muscle?
- Size of cardiac cells
- Number of gap junctions
- Glycogen content
Purkinje and Bundle fibers have an decrease in which characteristic(s) of cardiac muscle?
Number of myofibrils
Smallest smooth muscle fibers found in (X). Largest found in (Y).
X = vessels (metarterioles) Y = uterus
Shape of smooth muscle cell.
Fusiform
T/F: Skeletal and Smooth muscle are capable of mitotic division.
False - only smooth muscle; skeletal muscle incapable once syncytium formed
(X) muscle is capable of (synthesizing/secreting) fibers and nonfribrillar ECM.
X = smooth
Both synthesizes and secretes
(X) muscle behaves more like viscous mass (plasticity).
X = smooth
Compare the contraction rate/energy use of smooth muscle and skeletal muscle.
Smooth muscle contraction takes 10x longer, can be prolonged, and requires less energy
(X) are electron-dense structures in smooth muscle tissue, to which actin is attached.
X = dense plaques and bodies
T/F: Gap junctions found in all smooth muscle types.
False - in unitary type smooth muscle
Cytoplasm of smooth muscle dominated by:
Cytoplasmic filaments (primarily actin)
Nucleus of smooth muscle cells is slightly (heterochromatic/euchromatic/nonexistent).
Euchromatic