Flashcards in Histology Deck (57):
What are the three main features of skeletal muscle?
What is a syncytium? Give an example?
A multinucleate cell that forms from fusion of many uninucleate cells
Skeletal muscle cell
How long and wide are skeletal muscle cells/fibres?
10-100 micrometre diameter
1,000-200,000 micrometre long
Where are the nuclei located in skeletal muscle cells?
At the peripheries
What is the sarcolemma?
Muscle cell membrane
What are muscle fibres grouped into?
What is the name for the connective tissue surrounding the following:
1. Single muscle fibre
2. Single fascicle
3. Whole muscle
What is a myofibril?
Sarcomeres end to end
How can you tell that the myofibrils are held in registry with one another?
Z-discs all aligned
What does a motor unit consist of?
One motor neurone
All muscle fibres it innervates
True or false; More muscles fibres in a motor unit = More precise movement control?
The fewer muscle fibres a motor neurone supplies in a unit, the more precise a movement will be
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)
How do the three types of skeletal muscle fibres appear on succinate dehydrogenase stain?
Type i - Blue
Type iia - Pale blue
Type iib - White
Rank the types of skeletal muscle fibres in terms of contractile speed
Rank the types of skeletal muscle fibres in terms of resistance to fatigue and explain why
What type of muscle fibre is dependent on oxidative metabolism?
What type of muscle fibre is dependent on anaerobic metabolism?
What type of muscle fibre is most uncommon?
What type of muscle fibres are the following terms describing;
3. Produce least force
4. Produce most force
1. Type i
2. Type iib
3. Type i
4. Type iib
5. Type iia
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
What is this describing?
A rigid substance that is non-permeable. It receives nourishment from blood vessels
Where are chondrocytes found? Specifically?
In ECM - LAcuna
What is the name for immature chondrocytes?
What is the function of chondrocytes?
Secrete and maintain ECM
What is the most abundant component of hyaline cartilage?
What is the most abundant component of the ECM in cartilage? What % does it make up?
What makes up the rest of the ECM in cartilage? What % does it make up?
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
How does Type ii Collagen differ from Type i?
Finer (15-45nm vs 75nm)
Type i found in connective tissue
What are the three types of cartilage?
How do each type of cartilage appear?
Hyaline - Blue/White + Translucent
Elastic - Yellow
Fibrocartilage - White
What is the most common form of cartilage?
What is fibrocartilage?
Bands of dense type i Collagen:
- Interweaved with chondocytes
- Surrounded by little ECM
Which of the following is not a place where hyaline cartilage is found:
- Articular surfaces
- Tracheal rings
- Costal cartilage
- Epiphyseal growth plate
Pinnae (Outer ear - Elastic cartilage)
Where does haemopoiesis occur in utero?
Liver and spleen
(Begins in bone marrow)
What are the components of bone?
Mineral - Calcium hydroxyapatite (65%)
Collagen - Type i (23%)
Non-collagen proteins (2%)
What type of bone makes up the outer shell and the diaphysis?
What type of bone is present at the epiphyses?
What is the difference between the two bone types?
Cortical is dense; Cancellous is a fine mess
- Marrow cavities are next to cancellous bone
What do Haversian canals convey?
Blood vessels and nerves
What structures link Haversian canals to each other and the periosteum?
What is the functional unit of bone called? What is it surrounded by?
What bone cells are located on the surface and are pools of reserve osteoblasts?
What is the function of osteoblasts?
Where are osteoblasts located and what cellular features do they possess?
On surface of developing bone
- Plentiful RER
- Prominent mitochondria
Where are osteocytes found?
Trapped in bone matrix
What do osteoclasts look like?
Large (40 micrometres)
What is the function of osteoclasts and where are they found?
On bone surface
What makes up the Basic Multicellular Unit?
Osteoclasts + Osteoblasts
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
Where do osteoclasts derive from?
Several fuse into giant cell
What is the chemical formula of calcium hydroxyapatite?
What do osteoblasts secrete and what is it made up of?
- Glycosaminoglycans (GAGs)
How is the bone ECM formed?
Osteoid mineralises over time
What effect can younger osteons have on older osteons?
Can partially obliterate them
What is woven bone?
New bone laid done haphazardly:
- During development
- After fracture
What is woven bone remodelled into and how?
- Osteoclasts break it down
- Osteoblasts reform it