Flashcards in Histology Deck (57):
1
What are the three main features of skeletal muscle?
Striated
Unbranched
Multinucleate
2
What is a syncytium? Give an example?
A multinucleate cell that forms from fusion of many uninucleate cells
Skeletal muscle cell
3
How long and wide are skeletal muscle cells/fibres?
10-100 micrometre diameter
1,000-200,000 micrometre long
4
Where are the nuclei located in skeletal muscle cells?
At the peripheries
5
What is the sarcolemma?
Muscle cell membrane
6
What are muscle fibres grouped into?
Fascicles
7
What is the name for the connective tissue surrounding the following:
1. Single muscle fibre
2. Single fascicle
3. Whole muscle
1. Endomysium
2. Perimysium
3. Epimysium
8
What is a myofibril?
Sarcomeres end to end
9
How can you tell that the myofibrils are held in registry with one another?
Z-discs all aligned
10
What does a motor unit consist of?
One motor neurone
All muscle fibres it innervates
11
True or false; More muscles fibres in a motor unit = More precise movement control?
False
The fewer muscle fibres a motor neurone supplies in a unit, the more precise a movement will be
12
True or false; The muscle fibres supplied by a motor neurone are scattered throughout the muscle?
True (They are all the same fibre type but do not have to be bundled together)
13
How do the three types of skeletal muscle fibres appear on succinate dehydrogenase stain?
Type i - Blue
Type iia - Pale blue
Type iib - White
14
Rank the types of skeletal muscle fibres in terms of contractile speed
Type iib
Type iia
Type i
15
Rank the types of skeletal muscle fibres in terms of resistance to fatigue and explain why
Type i
Type iia
Type iib
16
What type of muscle fibre is dependent on oxidative metabolism?
Type i
17
What type of muscle fibre is dependent on anaerobic metabolism?
Type iib
18
What type of muscle fibre is most uncommon?
Type iia
19
What type of muscle fibres are the following terms describing;
1. Red
2. White
3. Produce least force
4. Produce most force
5. Intermediate
1. Type i
2. Type iib
3. Type i
4. Type iib
5. Type iia
20
What is this describing?
A semi-rigid substance that is very permeable. It is avascular and its cells are nourished vis diffusion through the ECM
Cartilage
21
What is this describing?
A rigid substance that is non-permeable. It receives nourishment from blood vessels
Bone
22
Where are chondrocytes found? Specifically?
Cartilage
In ECM - LAcuna
23
What is the name for immature chondrocytes?
Chondroblasts
24
What is the function of chondrocytes?
Secrete and maintain ECM
25
What is the most abundant component of hyaline cartilage?
ECM
26
What is the most abundant component of the ECM in cartilage? What % does it make up?
Water
75%
27
What makes up the rest of the ECM in cartilage? What % does it make up?
25% total
60% of which is Type ii Collagen:
- Forms 3D mesh
40% of which is proteoglycan aggregates:
- Made of GAGs
- Bound to core protein
- Often linked to hyaluronon
28
How does Type ii Collagen differ from Type i?
Finer (15-45nm vs 75nm)
Type i found in connective tissue
29
What are the three types of cartilage?
Hyaline
Elastic
Fibrocartilage
30
How do each type of cartilage appear?
Hyaline - Blue/White + Translucent
Elastic - Yellow
Fibrocartilage - White
31
What is the most common form of cartilage?
Hyaline
32
What is fibrocartilage?
Tendon-Hyaline hybrid
Bands of dense type i Collagen:
- Interweaved with chondocytes
- Surrounded by little ECM
33
Which of the following is not a place where hyaline cartilage is found:
- Articular surfaces
- Tracheal rings
- Costal cartilage
- Pinnae
- Epiphyseal growth plate
Pinnae (Outer ear - Elastic cartilage)
34
Where does haemopoiesis occur in utero?
Liver and spleen
(Begins in bone marrow)
35
What are the components of bone?
Mineral - Calcium hydroxyapatite (65%)
Collagen - Type i (23%)
Water (10%)
Non-collagen proteins (2%)
36
What type of bone makes up the outer shell and the diaphysis?
Cortical
37
What type of bone is present at the epiphyses?
Cancellous/Trabecular
38
What is the difference between the two bone types?
Cortical is dense; Cancellous is a fine mess
- Marrow cavities are next to cancellous bone
39
What do Haversian canals convey?
Blood vessels and nerves
40
What structures link Haversian canals to each other and the periosteum?
Volkmann's canals
41
What is the functional unit of bone called? What is it surrounded by?
Osteon
Cement line
42
What bone cells are located on the surface and are pools of reserve osteoblasts?
Osteoprogenitor cells
43
What is the function of osteoblasts?
Form bone
44
Where are osteoblasts located and what cellular features do they possess?
On surface of developing bone
Features:
- Plentiful RER
- Prominent mitochondria
45
Where are osteocytes found?
Trapped in bone matrix
46
What do osteoclasts look like?
Large (40 micrometres)
Multinucleated
47
What is the function of osteoclasts and where are they found?
Bone reabsorption
On bone surface
48
What makes up the Basic Multicellular Unit?
Osteoclasts + Osteoblasts
49
How does bone remodelling occur?
1. Osteoclasts congregate
2. Osteoclasts 'drill' into bone
3. Blood vessels grow into tunnel - Bring osteoblasts
4. Osteoblasts line tunnel -> Lay down new bone
5. Continues until tunnel is filled in right up to vessels -> Haversian canal
50
Where do osteoclasts derive from?
Macrophage lineage
Several fuse into giant cell
51
What is the chemical formula of calcium hydroxyapatite?
Ca10(PO4)6(OH)2
52
What do osteoblasts secrete and what is it made up of?
Osteoid:
- Collagen
- Glycosaminoglycans (GAGs)
- Proteoglycans
- Other
53
How is the bone ECM formed?
Osteoid mineralises over time
54
What effect can younger osteons have on older osteons?
Can partially obliterate them
55
What is woven bone?
New bone laid done haphazardly:
- During development
- After fracture
56
What is woven bone remodelled into and how?
Lamellar bone:
- Osteoclasts break it down
- Osteoblasts reform it
57