Histology 1 - MSK histology Flashcards Preview

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Flashcards in Histology 1 - MSK histology Deck (70)
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1
Q

What are the 3 principle types of muscle?

A

Skeletal/ voluntary
Cardiac
Smooth

2
Q

Are skeletal muscle cells striated or unstriated?

A

Striated

3
Q

What are the names of the bundles of muscle fibres?

A

Fasicles

4
Q

What is the name of the connective tissue that surrounds the entire muscle?

A

Epimysium

5
Q

What is the name of the connective tissue around a single fasicle?

A

Perimysium

6
Q

What is the name of the connective tissue around a single muscle fibre?

A

Endomysium

7
Q

What causes the striated appearance of skeletal muscle?

A

The organisation of the contractile units (sarcomere) - the sarcomeres in the myofibrils with their alternating dark and light bands, are held in registry with one another across the fibre (Z-diskss in the sarcomere of one myofibril will be aligned with Z-disks of the sarcomeres in the surrounding myofibrils) - nothing is physically running across the fibre

8
Q

What are the units of contraction within muscle fibres?

A

Sacromeres (thousands of these in a single muscle cell) - smallest contractile elements in striated muscle cell

9
Q

What is the name of the structure formed when thousands of sarcomeres are packed end to end in a muscle cell?

A

myofibril

10
Q

What is a sarcomere in terms of actin and myosin?

A

One Z disc to another Z disc

11
Q

What is a motor unit?

A

One motor neurone and all the muscle fibres that it innervates (anywhere from a few to more than a hundred fibres)

12
Q

Does fewer muscle fibres in a motor unit cause more fine or less fine control of movement?

A

More fine

13
Q

The axon of the motor neurone branches as it nears its termination and each branch ends in a special type of synapse called?

A

The neuromuscular junction

14
Q

Are the fibres in a motor unit bunched together?

A

No, they are scattered in the muscle

15
Q

Are the fibres in a motor unit of the same fibre type?

A

Yes

16
Q

What are the names of the 3 types of skeletal muscle fibres?

A

Type I
Type IIa
Type IIb

17
Q

Describe type I skeletal muscle fibres?

A

Relatively slowly contracting fibres that depend on oxidative metabolism
They have abundant mitochondria, are resistant to fatigue and produce relatively less force

18
Q

Is cartilage or bone permeable?

A

Cartilage is permeable, bone is not permeable

19
Q

Is cartilage or bone avascular?

A
Cartilage = avascular
Bone = cells within the bone must be nourished by blood vessels that pervade the tissue
20
Q

How is cartilage nourished?

A

Diffusion through the extracellular matrix

21
Q

Name for the cells founds in cartilage?

Name for these cells when they are immature?

A

Chondrocytes

Chondroblasts

22
Q

Where do chondrocytes live?

A

Within a space in the extracellular matrix termed a lucana

23
Q

What do chondrocytes do?

A

Active cells which not only secrete, but also maintain the extracellular matrix around them

24
Q

What are the 3 common types of cartilage?

A

Hyaline cartilage
Elastic cartilage
Fibrocartilage

25
Q

What type of cartilage is grossly, blue-white in in colour and translucent - most common form?

A

Hyaline cartilage

26
Q

What type of cartilage is mainly light yellow in colour?

What does it have added that makes it quite flexible?

A

Elastic cartilage

Elastic fibres

27
Q

What type of cartilage forms hybrid between tendon and hyaline cartilage - grossly appears white?

A

Fibrocartilage

28
Q

What is the structure of fibrocartilage?

A

Bands of densely packed type I collagen interleaved with rows of chondrocytes surrounded by small amounts of cartilaginous ECM

29
Q

Purpose of bone?

A
Support
Levers for effective movement
Protection of internal organs
Calcium store
Haemopoiesis (blood cell production)
30
Q

How much calcium is stored int the bone?

A

More than 95% of the total calcium in the body is found in bone and there is constant exchange of calcium between bone and the blood

31
Q

Where does the Haemopoiesis occur?

A

In utero blood is produced in the liver and spleen
It begins in the bone marrow well before birth and by birth bone marrow is the site of haemopoiesis
By early 20s typically only in the axial and limb girdle skeleton is involved in blood production

32
Q

Are skeletal muscle fibres branches or unbranched?

A

Unbranched

33
Q

Are skeletal muscle fibres multinucleated?
What do they form?
What does this mean?

A

yes
Form a synctium
A single cell or cytoplasmic mass containing several nuclei, formed by fusion of cells or by division of nuclei

34
Q

Approximate diameter and length of a skeletal muscle fibre?

A

Approx. 10-100 micro m in diameter

approx 1,000 - 200,000 micro metres in length

35
Q

Where are the nuclei located in a skeletal muscle fibre?

A

At the periphery of the fibre, just under the cell membrane

36
Q

What is the name of the cell membrane in skeletal muscle cells?

A

Sarcolemma

37
Q

Apart from skeletal muscle, what other type of muscle is striated?

A

Cardiac muscle

38
Q

What is another name for type I skeletal muscle fibres (aerobic)?

A

Red fibres

39
Q

Describe type IIA skeletal muscle fibres (Intermediate)?

A

Intermediate between the other two

Relatively fast contracting but also reasonably resistant to fatigue (relatively uncommon)

40
Q

Describe type IIB skeletal muscle fibres?

A

Fast contracting fibres that depend on anaerobic metabolism 0 they have few mitochondria, fatigue relatively easy and produce relatively greater force

41
Q

Other name for type IIB skeletal muscle fibres (anaerobic)?

A

White fibres

42
Q

What stain is used to identify the different types of skeletal muscle fibres?

A

Succinate dehydrogenase stain

43
Q

Appearance of the different type of muscle fibres using succinate dehydrogenase stain?

A
Type 1 (aerobic) = Dark
Type IIa (intermediate) = intermediate between dark and light
Type IIb = Light
44
Q

What is the composition of the ECM in hyaline cartilage (the most common form of cartilage)?

A

75% water

25% organic material (60% type II collagen, 40% proteoglycan aggregates)

45
Q

What is the common form of collagen found in most connective tissue?

A

Type I collagen

46
Q

How does type II collagen differ from type I collagen?

A

It is finer and instead of aggregating into linear bundles, it forms a 3D meshwork

47
Q

What are proteoglycan aggregates made up of?

A

GAGs (Most common keratin sulphate and chondroitin sulphate) bound to a core protein and often linked to hyaluronan

48
Q

5 places where hyaline cartilage is found?

A
Articular surfaces
Tracheal rings
Costal cartilage
Epiphyseal growth plates
Precurosor in fetus to many bones
49
Q

What is the composition of bone?

A
65% = mineral (calcium hydroyapatite crystals)
23% = collagen
10% = water
2% = non-collagen proteins
50
Q

What type of bone can be recognised with the naked eye in a longitudinal section through a long bone?

A

An outer shell of dense cortical/ compact bone (forms the main part of the shaft/ diaphysis)
Cancellous/ trabecular bone (occupies the ends of the bone/ epiphyses)

51
Q

What are the main differences between compact/ cortical bone and cancellous/ trabecular bone?

A

Presence of spaces (marrow cavities) adjacent to trabecular bone - bone cells and matrix are similar
Lacks haversian canals (osteocytes can survive from contact with the marrow spaces)

52
Q

What type of bone are lamellar?

A

Both (made up of layers)

53
Q

What are the living cells in bone called?

A

Osteocytes

54
Q

What are lacunae?

A

A cavity/ unfilled space

55
Q

What do Haversion canals do?

A

Carry blood vessels in the long axis of the bone

56
Q

What do Volkmann’s canals do?

A

Carry blood vessels in the horizontal axis of bone

57
Q

What are osteons?

A

The functional unit of cortical bone (basic structural unit)

58
Q

What are canaliculi?

A

Microscopic canals between the lacunae of ossified bone - radiating processes of osteocytes project into these

59
Q

What are cement lines?

A

Line that are often visible surrounding the often - only found in osteons that have formed during remodelling (not formed in original development)

60
Q

What are the 4 cells of bone?

A

Osteoprogenitor cells
Osteoblasts
Osteocytes
Osteoclasts

61
Q

What are osteoprogenitor cells?

A

Cells found on bone surfaces, for example under the periosteum, that serve as a pool of reserve osteoblasts

62
Q

What are osteoblasts?

A

Bone forming cells found on the surface of developing bone - they have plentiful RER and prominent mitochondria

63
Q

What are osteocytes?

A

A bone cell trapped within the bone matrix

64
Q

What are osteoclasts?

A

Large multinucleated cells

Found on the surface of bone and are responsible for bone resorption

65
Q

What happens during bone remodelling?

A

A number of osteoclasts will congregate and begin to drill into the bone forming a tunnel
A blood vessel will grow into the tunnel brining with it osteoclasts which line the tunnel and begin laying down new lamellar bone
This process continues until only the space of a Haversian canal remains

66
Q

What do osteoblasts secrete?

A
Collagen
Glycosaminoglycans (GAGs)
Proteoglycans
Other organic components of the matrix 
This is collectively termed osteoid
This becomes mineralised over time in the extracellular space
67
Q

What are osteoclasts believed to be derived from?

A

The macrophage lineage of cells - several of these will fuse and form a single giant cells

68
Q

What is the name of the type of bone that is laid down following a break/ during development?

A

Woven bone

69
Q

How does woven bone differ in appearance to normal bone?

A

Rather than the collagen fibres orientated all in one direction (at least within a single lamella - the angle of deposition changes with each lamellae), the collagen fibres are laid down in a haphazard fasion

70
Q

How is woven bone remodelled into lamellar bone?

A

By being broken down by osteoclasts and reformed by new osteoblasts