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RUSVM Histology > Muscle Tissue > Flashcards

Muscle Tissue Flashcards

1
Q

4 basic tissue types of the body

A
  1. Epithelium
  2. Connective Tissue
  3. Muscle Tissue
  4. Nervous Tissue
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2
Q

Muscle cells (myocytes/myofibers) are specialized cells capable of contraction to produce movement for…

A

locomotion
propulsion
pressure regulation

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3
Q

Muscle cells originate from the

A

mesoderm

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4
Q

Sarcoplasm

A

cytoplasm of muscle cells

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5
Q

sarcolemma

A

plasma membrane of a muscle cell

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6
Q

Sarcoplasmic Reticulum

A

Smooth ER of muscle cell. Regulates Ca++ flow.

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7
Q

Classifications of muscle tissue

A 
Cross striated (skeletal and cardiac)
Smooth
Myoepithelial cells (basket cells)
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8
Q

Size of skeletal muscle fiber

A

10 - 110um diameter

4mm - 50cm in length

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9
Q

Size of cardiac muscle cell

A

15um diameter

100um length

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10
Q

Size of smooth muscle cell

A

6 - 8um diameter
20 - 40um length
up to 1mm long in uterus

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11
Q

Strongest muscles in the body

A

tongue (skeletal)
masseter (skeletal)
heart (cardiac)

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12
Q

Muscle type that contracts fast and voluntarily

A

skeletal

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13
Q

Steps in skeletal muscle development

A
  1. Mesenchymal myoblasts align and fuse together, forming multinucleated tubes (myotubes)
  2. Myotubes differentiate, forming functional myofilaments, and nuclei are displaced against the plasma membrane.
  3. Some cells (satellite) do not differentiate and remain as mesenchymal cells. Role in muscle repair.
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14
Q

CT layer that surrounds the muscle

A

epimysium

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15
Q

CT that surrounds each fascicle

A

perimysium

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16
Q

Reticular fiber between muscle fibers (myocytes)

A

endomysium

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17
Q

Levels of organization of skeletal muscle

A

Muscle > fascicle > muscle fiber > myofibrils > myofilaments

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18
Q

Dark vs light bands on muscle fiber

A 
Dark = myosin
Light = actin
19
Q

Contractile elements of skeletal muscle

A

myofibrils - composed of repeating sections of myofilaments (myosin and actin, seen only in EM)

20
Q

Peripheral nuclei, AKA

A

hypolemmal nuclei

21
Q

What kind of protein is tropomyosin?

A

Regulatory. (regulates binding site on actin)

22
Q

A bands contain

A

Actin and myosin filaments overlapping (dark)

23
Q

I bands contain

A

actin only (light)

24
Q

H zone/M line contains

A

myosin only

25
Q

Z line

A

Bisects each I band. Where actin filaments are anchored. Length from one Z line to another denotes a sarcomere.

26
Q

What holds actin and myosin in position in the skeletal myofibril?

A

Desmin, tropomyosin, troponin

27
Q

Which myofilament moves during skeletal muscle contraction?

A

Actin slides across myosin toward the M line. I band and H band get shorter, but A band stays the same length (length of myosin filaments).

28
Q

Steps in skeletal muscle contraction

A
  1. Ca++ binds to troponin, causing a conformational change in tropomyosin and exposing the binding site on actin
  2. ATP > ADP on myosin heads allows formation of cross bridge.
  3. Release of ADP causes myosin head action and slides actin toward the M line, shortening the sarcomere and causing muscle contraction
29
Q

T Tubules

A

Invaginations of the sarcolemma that allow membrance depolarization to quickly penetrate to the interior of the cell and induce calcium release from SR

30
Q

Type 1 muscle fibers

A 
"red" 
slow contraction/slow fatigue
oxidative metabolism
lots of mitochondria
high fat/low glycogen
myoglobin
31
Q

Type 2 muscle fibers

A 
"white"
fast contracting/fast fatiguing
anaerobic/glycolytic metabolism
fewer mitochondria
low fat, high glycogen
32
Q

Characteristics of Cardiac muscle cells

A 
"cardiomyocytes"
single cell with central nucleus
striated and branching
intercalated discs (gap junctions and desmosomes)
many mitochondria
sarcoplasmic reticulum
33
Q

Intercalated discs

A

Hold cardiomyocytes together. Transversely with desmosomes for structural support. Longitudinally with gap junctions for communication. Allows muscle fibers with work as syncytium, and AP to proliferate across membranes of cells.

34
Q

Purkinje cells

A

Cardiac muscle cells involved in impulse conduction. Bundles make up purkinje fibers. Cells are bigger and paler than contractile cardiac muscle cells, with sparse myofibrils at the periphery.

35
Q

Characteristics of smooth muscle cells

A 
spindle shaped
basal lamina and reticular fibers surround
involuntary
single, central nucleus
no striations
dense bodies instead of Z discs
myofilaments are not ordered
no T tubules 
poorly developed SR
36
Q

Single unit smooth muscle

A

sparse innervtion, but cells communicate via gap junctions, which allows them to act as a syncytium. In visceral organs.

37
Q

Multi unit smooth muscle

A

each fiber is independently innervated, contract separately, no gap junctions. In iris of eye.

38
Q

Functions of smooth muscle

A
  1. Peristalsis (GI tract)
  2. Vascular dynamics (alter blood flow, BP)
  3. Propulsion (urinary bladder, uterus)
  4. Secretion (minor role)
39
Q

Tunica mucosa

A

mucous membrane

40
Q

Tunica muscularis

A

innermost circular layer

outer longitudinal layer

41
Q

Appearance of smooth muscle upon contraction

A

Oblique arrangement of myosin, actin and intermediate filaments (allow shortening of the cell bu up to 80%), corkscrew shaped nucleus

42
Q

Myoepithelial cells

A 
"Basket cells"
Contractile, non muscle cells. 
Surround glandular cells
Contain actin and myosin
Role in muscle repair
Similar to smooth muscle
43
Q

Satellite cells (skeletal muscle)

A

Don’t differentiate
Positioned between basal lamina and sarcolemma
Retain mitotic potential
Some muscle repair, allow limited regeneration

44
Q

Regeneration ability of muscle types

A

Cardiac: NO
Smooth: limited regeneration from mesenchymal cells
Skeletal: Limited via satellite cells

*repair is always completed by scar tissue formation (fibroblasts)

RUSVM Histology (6 decks)

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