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Microbiology > Muscle Tissue > Flashcards

Muscle Tissue Flashcards

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1
Q

Relevance of muscle tissue? (3)

A

Muscle tissue is relevent…

  1. general knowledge
  2. physiology
  3. muscle disease and response to injury
  • myopathies
  • inflammation(myositis)
  • myasthenia gravis
  • cardiovascular disease
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2
Q

Muscle tissue: define, cells, origin,

A

Muscles= specialized cells capable of contraction to produce movement.

  • aka myofibers
  • Cells: spindle shaped
  • Origin: from mesoderm (myoblasts)
    • myoblasts fuse to make myotubes
    • myotubes form myofilaments
    • spme cells remain as mesenchymal= Satelite cells
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3
Q

Define: myotubes, myofilaments, satellite cells

A

Origin of muscle

Originates from from mesoderm (myoblasts)

  • myoblasts fuse to make myotubes
  • myotubes form myofilaments
  • some cells remain as mesenchymal= Satelite cells
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4
Q

Define: sarcoplasm, sarcolemma, sarcoplasmic reticulum

A

Sarcoplasm: cytoplasn of muscle cells (w/glycogen and myoglobin)

Sarcolemma: plasma membrane of muscle cell

Sarcoplasmic reticulum: specialized smooth ER (Ca+)

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5
Q

Types of muscle

A

Types of muscle

Striated muscle

  • skeletal muscle
  • cardiac muscle

Smooth muscle

Myoepithelial muscle (basket cells)

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6
Q

Compare Striated Muscle types

A

Striated Muscle: Skeletal and Cardiac

Skeletal:

  • myofibers= multi-nucleated
  • voluntary contraction (sns)

Cardiac:

  • Cardiomyocytes= one-nucleas in single cell (central)
  • involuntary contraction (ans)
  • intercollated discs
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7
Q

Skeletal Muscle

A

Skeletal muscle= type of striated muscle

  • contracts fast and voluntarily
  • 50% of body weight
  • multiple nuclei
  • Structure:
    • whole muscle surrounded by epimysium
    • perimysium divides muscle into smaller fascicles
    • each fascicle is made of many myocytes/myofibers, which are surrounded by endomysium
    • myofibers have bundles of myofibrils
    • myofibrils contain smaller myofilaments (ACTIN/MYOSIN)
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8
Q

Structure of Skeletal Muscle

A

Structure of Skeletal Muscle

  • whole muscle surrounded by epimysium
  • perimysium divides muscle into smaller fascicles
  • each fascicle is made of many myocytes/myofibers, which are surrounded by endomysium
  • myofibers have bundles of myofibrils
  • myofibrils contain smaller myofilaments (actin/myosin)
  • myofilaments are what make muscle contract
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9
Q

Sarcomere: structure and function

A

Skeletal Muscle

Sarcomere= contractile unit of myocyte

*** distance from one I band to the next (A band in between)

  • I band only has actin (lignt)
    • z line is in middle of zone
  • A band is where both overlap (dark)
  • H zone is middle zone where only myosin is
    • M line is middle line
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10
Q

Contraction of skeletal muscle: Legnths

A

Contraction of Skeletal Muscle

Each sarcomete shortens

  • full contraction, Z lines are drawn closer to each other.
  • I band almost dissappears

Myofilament legnth is constant

  • thin filaments slide past thick filaments
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11
Q

Skeletal muscle contraction: molecular

A

Skeletal Muscle Contraction (after AP)

  1. Calcium binds troponin, moving tropomysin so myosin can bind actin.
  2. Atp moves myosin head
  3. contraction
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12
Q

t-tubules

A

Skeletal muscle: t-tubules

= deep invagination in sarcolemma that allows depolarization of membrane to penetrate to sarcoplasmic reticulum causing release of ca+

** terminal cisterna: expanded ends of sarcoplasmic reticulum

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13
Q

Red Muscle vs. White Muscle

A

Skeletal Muscle Fibers

Red Muscle vs. White Muscle

Red Muscle= slow twitch

  • dark color- lots of myoglobin
  • aerobic metablilsm= fatigue resistant
  • high fat, low glycogen content
  • many mitochondria

White Muscle= fast twitch

  • anaerobic metabolism= prone to fatigue
  • low fat, high glycogen content
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14
Q

Cardiac muscle: 5 facts

A

Cardiac muscle

  • striated
  • one nucleus
  • Intercalated disk:
    • gap junctions
    • desmosomes
  • sarcoplasmic reticulum
  • many mitochondria!
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15
Q

Intercalated Discs

A

Intercalated Discs: attach cardiac muscle cells to each other providing stregnth and ability to function s a syncytium.

  • Transverse element=anchor= Desmosome
  • Longitudinal element=communication= gap junctions

NOTE: cardiac muscle is not a true syncytium because the cells work together but are not actually one unit.

(skeletal=true syncytium)

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16
Q

Cardiomyocytes: 2 types

A

Cardiomyocytes: 2 types

Contractile (red)

  • duh…contraction

Conductile (pink)

  • conduct impulses throughout heart
  • less myofibrils (because they are more for communication than contraction)
  • “smoother” cytoplasm
17
Q

ANF/ANP

A

Cardiac muscle: ANF/ANP

Atrial Natriuretic Factor/Peptide= in atrial myocardium

  • atrial muscle cells have atrial granules that have an ENDOCRINE function because of ANF/ANP
18
Q

Smooth Muscle: 5 Facts

A

Smooth Muscle

  • no striations
  • still have actin and myosin (just not organized)=dense bodies
  • desmosomes and gap junctions
  • do NOT have sarcoplasmic reticulum and t-tubes
  • INVOLUNTARY CONTRACTORS
19
Q

Single-unit vs. multi-unit

A

Smooth Muscle: types

Single unit

  • sparse innervation
  • cells communicate via gap junctions
  • in visceral organs (gut, bladder, reproductive syst…)
  • wave like contraction

Multi unit

  • precise contraction
  • individual innervation of each myocyte
  • no gap junctions (cells function individually)
  • iris of eye
20
Q

Smooth Muscle: Function (4)

A

Smooth Muscle: Function

Peristalsis- wave-like contractions (ex. gut)

Vascular dynamics- alters blood flow and pressure

Propulsion- urinary bladder, uterus

Secretion- minor role

21
Q

Identify

A

Smooth muscle

Inner layer is circular layer (cells will be viewed as spindle)

outer layer is longitudinal (only see cross section of spindle cells)

22
Q

Smooth Muscle Contraction

A

Smooth Muscle Contraction

  • dense bodies= equivelent of z disk in skeletal muscle. anchors filaments
  • can contract 80% shorter than normal
  • Ach, NE, EP neurotransmitters!
23
Q

Myoepithelial cells

A

Myoepithelial cells

  • Origin: ectodermal
  • Structure:
    • actin and myosin
    • basket cells (basket shape)
  • Location:
    • salivary glands
    • mamary glands
    • lacrimal glands
  • Function:
    • squeeze glandular cells
24
Q

Satellite cells

A

Skeletal muscle has limited regeneration capacity

Sattelite cells: cells retain mitotic potential and can accomplish some repair

  • Location: between basal lamina and sarcolemma of muscle cells
  • scar tissue is formed by fibroblasts in repair process

NOTE: Cardiac cannot regenerate. Smooth limited regeneration.

25
Q

Identify

A
26
Q

Identify: Purkinje fibers

A

Purkinje fibers: modified cardiac muscle cells

  • 1 or 2 nuclei
  • bigger/paler cells than other cardiac muscle
  • few myofibrils at periphery of cell

Microbiology (32 decks)

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