Lecture 4: Structure & Function Of Cardiac, Smooth, And Skeletal Muscles Flashcards

1
Q

What are the several types of muscle? How do they differ?

A
  • Skeletal, Cardiac, Smooth.
  • They differ in structure, function, and location.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What is the function and characteristics of the skeletal muscle?

A
  • For bone movement & maintaining posture.

~ Some muscles in the core/limbs are constantly active.

  • Striated appearance (horizontal fibres), multinucleated.

~ Horizontal fibres –> formed by the fusion of many individual cells.

  • Voluntary.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

State the characteristics of cardiac muscles.

A
  • Found only in the heart.
  • Striated appearance, intercalated discs.
  • Involuntary.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What are intercalated discs?

A

Gap junctions that link the cells together and define their borders (appear as dense vertical lines).

~ Not fully fused, don’t share cytoplasm.

They are the major portal for cardiac cell-to-cell communication, which is required for coordinated muscle contraction and maintenance of circulation.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What is the difference between skeletal and cardiac muscle cells?

A

Cardiac muscle cells don’t fuse together.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What is the function and the characteristics of smooth muscle cells?

A
  • Walls of blood vessels & the lining of hollow organs.

~ Controls the volume of the container that it is lining (function varies depending on the organ).

  • Not striated, single central nucleus.

~ Has a different way of contracting. Cells don’t connect to one another, spindle shaped.

  • Involuntary.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

How and why are the nuclei positioned differently in skeletal/cardiac muscle cells compared to smooth muscle cells?

A

Nuclei tends to be squished towards the edge of the cell for skeletal/cardiac muscles, because the cell is packed with contractile machinery.

Smooth muscle cells have a different way of contracting.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What is a myocyte?

A

A muscle cell.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

State what is connective tissue crucial for.

A

It is important to hold the muscle together and distribute the force.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What is a tendon?

A

Attachment between muscle and bone matrix.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What is a fascicle?

A

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

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What is sarcolemma?

A

The cell membrane of a myocyte.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What is a muscle fibre (cell)?

A

Bundles of interconnected protein filaments of striated muscles.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

State the differences between epimysium, perimysium, and endomysium.

A
  • Epimysium – connective tissue surrounding entre muscle.
  • Perimysium – connective tissue around muscle fascicles.
  • Endomysium – connective tissue around muscle cells/fibres.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What does the prefix sarco- mean?

A

Regarding muscles.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What are the characteristics of the muscle fibre?

A
  • Comprises of myofibrils.
  • Mitochondria for energy.
  • Surrounded by sarcolemma.
  • Degree of overlap determines contractile state of the muscle.

~ More overlap -> shorter, contraction.
~ Less overlap –> longer, relaxation.

17
Q

What is a myofibril?

A

Elongated contractile threads found in striated muscle cells.

  • Made up of myofilaments (actin & myosin).
  • Actin forms the thin filament (I band, doesn’t contain overlap).
  • Myosin forms the thick filament (A band, contains overlap).
  • Contractile unit is the sarcomere (Z line to Z line).
18
Q

What are myofilaments?

A

Contractile proteins (actin & myosin).

19
Q

What is the I & A band, Z disc, H zone, and M line?

A
  • Z disc – where all the connective proteins of thin filaments lie. Attachment site for thin filaments.
  • I (isotopic) bands – light bands that contain only the thin filaments (actin) and are located between the two thick filaments.
  • A (anisotropic) bands – contains the entire length of a single thick filament. The anisotropic band contains both thick and thin filaments.
  • H zone – the zone of the thick filaments that has no actin.
  • M line – attachement site for thick filaments, centre of A band and sarcomere.