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Flashcards in Muscle_BTED Deck (47):
1

What is the function of the muscle?

1) Allow you to stand upright (oppose gravity)
2) Allow movement
3) Allow digestion, control waste removal
4) Affect blood flow
5) Help to maintain normal body temperature

2

What does the muscle cell contain?

Myofibre - elongated and highly differentiated cell

3

What is a muscle fibre consisted of?

Bundle of myofibres

4

What is a fascicles?

Bundle of muscle fibres

5

What is a muscle?

Bundle of fascicle

6

What do myofibres contain?

Cytoplasmic filaments - actin and myosin

7

What ar the organelles in a muscle?

- Cytoplasm = Sarcoplasm
- Smooth ER = Sarcoplasmic Reticulum
- Cell membrane (plasmalemma) = sarcolemma

8

Name the three different types of muscle

1) Skeletal Muscle
2) Cardiac Muscle
3) Smooth Muscle

9

What is the most common and characteristic type of muscle?

Skeletal muscle

10

What is the skeletal muscle used for?

Movement of skeleton (hard tissue)
Movement of organ (soft tissue)

11

What are the properties of skeletal muscle?

1) Voluntary
2) Striated (striped)

12

Why is the skeletal muscle striated?

Arrangement of contractile proteins

13

What does the Cardiac muscle do?

Forms muscle in heart (myocardium)

14

What are the properties of cardiac muscle?

1) Involuntary
2) Striated
3) Rich blood supply

15

Where is the smooth muscle found?

In walls of blood vessels, and in internal organs (e.g. stomach, bladder, intestines)

16

What are the properties of smooth muscle?

1) Involuntary
2) No striations
3) Fusiform small cells
4) Central single nucleus

17

What is the physiology of skeletal muscle?

- Each myofibril receives neural input from one motor neuron at the neuromuscular junction
- Simultaneous contraction of all muscle fibres in a unit

18

What is found in the histology of skeletal muscle?

Consists of long, cylindrical, multinucleated myofibrils (muscle fibres/cells)
Striation
Peripheral nuclei

19

How long and how thick are the muscle fibres in the skeletal muscle?

Up to 100 micrometer in diameter
Several cm in length

20

What are myofibrils?

Orderly arrangement of contractile myofilaments actin + myosin

21

What does the myofibril structure look like?

- Highly regular banding pattern
- Myofibrils pack the full cell volume, pushing organelles to periphery

22

What does Myosin do?

Forms thick filaments attached to M - line

23

What does Actin do?

Forms thin filament attached to Z - line

24

What do the myofibril structure striations contain?

Striations are alternating
- A bands (Anisotropic - refers to behaviour of polarised light)
- I bands (Isotropic)
- Z bands (Bisect I bands)

25

What do Z bands do?

Divide each myofibril into numerous contractile units - sarcomeres - arranged end to end

26

What is Actin?

Gobular

27

What is Myosin?

2 heads, hinged tail

28

What happens during muscle contraction?

1) Myosin binds to actin
2) Ca2+ binding - pushes tropomyosin out of binding site
3) Myosin uses ATP as energy source to move head and release actin for another cycle
4) Resting muscle - myosin cannot bind (tropomyosin covers binding site)

29

What does the conducting system of skeletal muscle allow?

Permits synchronous contraction of all sarcomeres

30

What does the conducting system of skeletal muscle contain?

1) T tubule system
2) Sarcoplasmic Reticulum
3) Terminal Cisternae

31

What is the T tubule system?

Extension of Sarcolemma

32

What is the Sarcoplasmic reticulum?

Membranous network surrounding each myofibril

33

What is the Terminal cisternae?

Flattened SR beside T tubules - forms a triad

34

What happens in the Conducting system of skeletal muscle?

1) When a nerve stimulates a myofibre, signal is transmitted by T tubules, causing release of Ca2+ into sarcoplasm from SR
2) The Ca2+ ions activate the sliding filament mechanism - muscle contraction

35

Where are the Ca2+ ions specifically concentrated in the conducting system?

Ca2+ ions - concentrated within the sarcoplasmic reticulum

36

What do myocytes look like?

Long, cylindrical cells (1 nucleus)

37

How are the cells arranged in cardiac muscle?

Cells are in branching alignment

38

Where do the ends connect to in cardiac muscle?

Ends connect to adjacent cells at intercalated discs

39

Where are the nuclei located in the cardiac myocytes?

Centrally located

40

What do the intercalated discs do?

Allow intercommunicating network of cells - contract in synchrony to pump blood

41

What is the basic organisation of the cardiac myocytes?

Same basic organisation as skeletal muscle - myofibrils, myofilaments and cross - striations

42

What is located at intercalated discs?

Desmosomes and Gap Junctions

43

What do the Desmosomes do in intercalated discs?

Provide mechanical stability

44

What do the Gap Junctions in the Intercalated discs do?

Allow transmission of chemical/electrical signals between cells

45

What is the smooth muscle for?

Specialised for continuous contractions of relatively low force

46

What happens during a smooth muscle contraction?

1) No longitudinal organisation of proteins
2) Bundles criss-cross the cell, insert into anchoring points (focal densities) in cytoplasm, cel membrane

47

What are the difference in activity between the three muscles?

Skeletal: Strong, quick discontinuous voluntary contraction
Cardiac: Strong, quick continuous involuntary contraction
Smooth: Weak, slow involuntary contraction