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Histology > 1.05 - Muscle > Flashcards

1.05 - Muscle Flashcards

1
Q

What are the three types of muscle?

A

Skeletal
Smooth
Cardiac

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2
Q

Group the three types of muscles based on voluntary/involuntary action

A 
Involuntary:
- Cardiac
- Smooth
Voluntary:
- Skeletal
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3
Q

Group the three muscle types based on presence or absence of striations

A 
Striated:
- Skeletal
- Cardiac
Non-striated:
- Smooth
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4
Q

What is the sarcolemma?

A

The Plasma Membrane of skeletal muscle

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5
Q

What is the Sarcoplasm?

A

The cytoplasm of skeletal muscle

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6
Q

What is the sarcoplasmic reticulum?

A

Endoplasmic reticulum of skeletal musce

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7
Q

What is the skeletal muscle belly surrounded by?

A

Epimysium

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8
Q

What are fascicles and what are they surrounded by?

A

A fascicle is a bundle of skeletal muscle fibres and is surrounded by perimysium, a type of connective tissue.

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9
Q

What are muscle fibres and what are they surrounded by?

A

Muscle fibres are the individual muscle cells and are surrounded by endomysium
Each muscle fibre is contractile.
Contains myofibrils which are made up of contractile filaments

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10
Q

What are some distinctive features of skeletal muscle cells?

A

Extremely elongated
Multinucleated (peripherally located nuclei)
Basic 5 sided structure

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11
Q

What are the two types of Skeletal Muscle?

A

Type 1: Slow Contraction

Type 2: Fast Contraction

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12
Q

Describe Type 1 Skeletal Muscle

A 
Slow contraction
Aerobic, using oxidative phosphorylation
Contain many mitochondria
Cell contain large amount of myoglobin (O2 storage)
 - Red in colour
Many capillaries
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13
Q

Describe Type 2 Skeletal Muscle

A

Fast contraction
Anaerobic, using glycolysis
Therefore rich in glycogen
White in colour

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14
Q

Describe the Myofibrils

A

Muscle fibres contain myofibrils
They are elongated cylindrical structures made up of contractile proteins
Cross striations of striated muscle is due to the ordered arrangement of these proteins

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15
Q

List and describe the bands in the myofibrils

A

I Band: Light. Made up of thin actin filaments
A Band: Dark. Made up of thick myosin filaments
Z Band = Black. Z-Band to Z-Band outlines the sarcomere, anchor points of the actin filaments, and represents the contractile unit.

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16
Q

Describe the Innervation of Skeletal Muscle

A

Voluntary Muscles

  • Motor innervation
  • Sensory innervation: maintain posture, coordinates voluntary movement
  • Sympathetic innervation: regulate blood flow via effect on vascular smooth muscle
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17
Q

What is a motor unit?

A

The combination of a motor neuron and the muscle fibres it supplies.
The nerve and all supplied muscle fibres fire as a unit

18
Q

Describe the transmission of signals to Skeletal Muscle

A

Neuron action potential causes release of acetylcholine at the neuromuscular junction. ACh binds to receptor and results in an action potential at the motor end plate –> spread of depolarisation throughout the sarcolemma

19
Q

Describe the structure of Skeletal muscle as it relates to function

A

T - Tubules - extensions of the sarcolemma allow depolarisation to enter the cell.
Sarcoplasmic reticulum - modified endoplasmic reticulum releases Ca2+ ions –> this activates contraction of myofibrils

20
Q

Describe a pathological condition associated with Skeletal Muscle

A

Duchenne’s Muscular Dystrophy
X-linked recessive
Abnormalities in the gene encoding dystrophin protein. it normally concentrates at the plasma membrane over Z bands where it links to cytoplasmic actin

21
Q

Describe Smooth Muscle

A 
Not striated
Involuntary
Autonomic and Hormonal control
Visceral structures
Enables continual contractions of low force
22
Q

Describe Smooth Muscle Cells

A

Spindle shaped
Have a single central oval nucleus
Cells form irregular branching fascicle, which are the functional contractile units
Do not have myofibrils as in skeletal muscle and therefore no striations
But have filaments made of myosin and actin

23
Q

Instead of Z-Bands what do smooth muscle cells have?

A 
Dense Bodies (focal densities): which act as anchor points in the cytoplasm
Attachment junctions: Act as anchor points on the cell membrane
24
Q

Describe the contraction of Smooth Muscle Cells

A

During contraction, due to the crisscross arrangement of contractile proteins, the cell shortens and becomes ‘plump’

25
Q

What are the two types of Smooth Muscle?

A

Single Unit

Multi-unit

26
Q

Describe Single Unit Type Smooth Muscle

A

Smooth muscles cells have extensive communications via gap junctions with adjacent cells so that the cells contract as a single unit
Found in the GIT and uterus

27
Q

Describe Multiunit Type Smooth Muscle

A

Each smooth muscle cell acts independently from its neighbour. Thus type of muscle behaves like multiple independent cells or groups of cells. Capable of finer control.
Found in the ciliary muscle of the eye, piloerector muscles of the skin

28
Q

What is the classification system for Smooth Muscle and what are the subtypes?

A

By activity pattern:
Phasic
Tonic

29
Q

Describe Phasic Smooth Muscle

A

Smooth muscle exhibiting rhythmic or intermittent activity.
Often single unit type
GIT or Urogenital

30
Q

Describe Tonic Smooth Muscle

A

Continuously active, maintaining a level of “tone”
Often multiunit type
Blood vessels

31
Q

Describe a pathological condition that affects smooth muscle

A

Familial Visceral Myopathy
Common cause of chronic primary intestinal pseudo-obstruction
Segmental dilation of the digestive tract and urinary bladder
Degenerating muscle cells
Smooth muscle fibrosis

32
Q

Describe the basic features of Cardiac Muscle

A

Cardiac myocytes have features similar to both skeletal and smooth muscle.
Striated
Involuntary
Strong and continual contractions

33
Q

Describe the structure of cardiac myocytes

A

Elongated cells
Central nuclei
Branching fibres with intercalated discs
Contractile proteins arranged similarly to skeletal muscle.
Cross striations
Contractile units: sarcomeres made of myosin and actin but also contain troponin and tropomyosin
T-Tubules and Sarcoplasmic reticulum similar to that of skeletal muscle

34
Q

What are intercalated discs?

A

Specialised junctions
Permit rapid spread of contractile stimuli due to areas of low electrical resistance –> fibres contract almost simultaneously
Coincide with Z lines

35
Q

What are the three types of membrane contact that Intercalated discs are made up of?

A 
Fascia Adherens (site of actin insertion)
Desmosomes (anchorage for intermediate filaments)
Gap junctions (pores with low electrical resistance, enabling ion and molecule transfer between the cells --> coordinated contraction)
36
Q

Describe a pathological condition that affects cardiac muscle

A 
Cardiomyopathies
Myocardial dysfunction due to disease of myocardial muscle.
 - Dilated cardiomyopathy
 - Hyperthrophic cardiomyopathy
 - Restrictive cardiomyopathy
37
Q

Compare the location of the three muscle types

A

Skeletal: skeleton, tongue, eye
Smooth: Vessels, Organs
Cardiac: Heart

38
Q

Compare the presence of striations in the three muscle types

A

Skeletal: Yes
Smooth: No
Cardiac: Yes

39
Q

Compare the features of the nucleus in the three muscle types

A

Skeletal: Multiple and peripheral
Smooth: Single and central
Cardiac: Single and central

40
Q

Compare the Cell-To-Cell communication in the three muscle types

A

Skeletal: None
Smooth: Gap Junctions
Cardiac: Intercalated Discs

41
Q

Compare the Innervation of the three muscle types

A

Skeletal: Voluntary
Smooth: Involuntary
Cardiac: Involuntary

Histology (9 decks)

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