Histology Lecture 7 - Muscle Flashcards
What are the four types of muscle tissue?
Skeletal striated, visceral striated, cardiac, smooth
What is visceral striated muscle?
Does not act on joints (like in tongue, upper esophagus)
Where are muscle cells derived from?
Myoblasts from mesenchyme
Are skeletal muscle cells multinucleate? Why?
Yes, they fused as embryonic myoblasts (syncitium)
What is a triad?
Two cisterns + t tubule
What provides for proprioceptive information regarding muscle tendons?
Golgi tendon organs
What is the defect in muscular dystrophy?
Dystrophin protein connects the actin filaments to the sarcolemma leading to destruction of the cell
What muscle type has intercalated discs?
Cardiac
What muscle types have gap junctions?
Cardiac and smooth
Where are the cell nuclei located in skeletal, cardiac, and smooth muscle cells?
Periphery, central, central
What do intercalated discs consist of?
Macula adherens/fascia adherens
In what muscle type are diads found?
Cardiac
What cells do BNP and ANP come from?
Cardiac endocrine cells
What muscle cells appear as empty spaces histologically? Why?
Purkinje fibers - cuz they have glycogen.
Is smooth muscle striated?
No
In what muscle type are orthogonal layers found? For what function?
Smooth muscle for peristalsis
Which muscle type exhibits elliptical and corkscrew nuclei?
Smooth muscle
In what muscle cell types are dense bodies found?
Smooth muscle (equivalent of intercalated discs)
Where are bouton en passant found? What do they do?
Smooth muscle - they release neurotransmitter
What is caveolae and where are they found?
Smooth muscles’ version of t-tubules
What is myogenic stimulation?
Mechanical stimulation using mechanosensitive ion channels in smooth muscle
What type of muscle does oxytocin work on?
Smooth
Which skeletal muscle-associated CT is continuous with tendons?
Epimysium (outermost CT layer)
Are fibroblasts present in skeletal muscle?
Yes, they can be in the perimysium (CT surrounding fiber bundles)
What type of collagen makes up the endomysium?
Type III collagen
What is a diagnostic feature of cardiac muscle in cross section? (vs. skeletal)
Cardiac muscle will have irregular shapes like figure eights and U shapes
What type of collagen makes up the perimysium, epimysium, and endomesium (in non-cardiac striated muscle)?
Type I, Type I, Type III (reticular fibers)
Does the I Band contain thick filaments?
No, only thin filaments.
What happens to the H zone during contraction?
It shrinks.
What fibers are in the A band?
Thick and thin
Are white fibers fast or slow twitch?
Fast
Does golgi tendon organ activation result in muscle contraction or relaxation?
Relaxation
Does muscle spindle activation result in muscle contraction or relaxation?
Contraction
What is the mode of inheritance for Duchenne Muscular Dystrophy? What is the defect?
X-linked, dystrophin defect
What are the steps of nerve regeneration?
- Nerve injury
- Degradation of axon distal to injury
- Persistence of Schwann cell basal lamina
- Schwann cells form cellular cords
- Axon sprouts grow into basal lamina
- Remyelination (if applicable)
Do A bands shorten during muscle contraction?
No
What type of muscle has an external lamina?
All of them
Is the external lamina of smooth muscle continuous?
No
Does smooth muscle have troponin-tropomyosin complexes?
Nope
Are nerve cell bodies (perikarya) found in peripheral nerves?
Nooope. The nerve cell bodies will be in the DRG or in the CNS.
Which cells assosiated with the nervous system have an external lamina?
Schwann cells
