Histology Flashcards
Where in a muscle fibre is the nucleus located?
Nuclei are at the periphery of the fibre
under the cell membrane (sarcolemma)
Describe the difference between the three types of connective tissue found in muscle
Epimysium - surrounds the muscle as a whole
Perimysium - around a single fascicle
Endomysium. - around a single muscle fibre
Describe the main differences between cartilage and bone
CARTILAGE: Semi-rigid and Deformable Permeable Avascular Cells nourished by diffusion through the extracellular matrix.
BONE:
Rigid
Not Permeable
Cells within the bone must be nourished by blood vessels that pervade the tissue.
What cells make up cartilage?
chondrocytes
chondroblasts when immature
Where can chondrocytes specifically be found?
space in the extracellular matrix = LACUNA
What do chondrocytes do to the extracellular matrix around them?
secrete and maintain the extracellular matrix around them
What components are found in the extracellular matrix of hyaline cartilage
75% water
25% organic material.
- 60% Type II collagen
- 40% proteoglycan
Describe the main differences between Hyaline, Elastic and Fibrocartilage
Hyaline cartilage = blue-white in colour and translucent
Elastic cartilage = Light yellow in colour.
- The elastic fibres makes flexible
Fibrocartilage = white
- Hybrid between tendon and hyaline cartilage
- bands of densely packed Type 1 Collagen and rows of chondrocytes surrounded by little cartilagenous ECM
Give examples of where hyaline cartilage is commonly found
Articular surfaces Tracheal rings Costal cartilage Epiphyseal growth plates Precursor in fetus to many bones
What are the main functions of bone?
Support Levers for effective movement. Protection of internal organs (e.g. cranium, ribs) Calcium store Haemopoiesis
Describe the basic make up of bone
65% bioapatite (a form of calcium phosphate)
23% collagen
10% water
2% non-collagen proteins
What two types of bone can be recognised in a longitudinal section through a long bone?
Outer shell of dense cortical bone makes up the shaft (diaphysis)
Cancellous or trabecular bone occupies the ends of the bone (the epiphyses)
What are the names given to the two types of canal carrying blood vessels in bone?
Haversian canal = supplies vessels that give vascular supply to osteocytes
Volkmanns canal = carries vessels transversely which branch into Haversian canals
What is the main difference between cortical and trabecular bone?
presence of spaces (marrow cavities) adjacent to trabecular bone
Why does trabecular bone generally lack Haversian canals?
the struts are thin
=> the osteocytes can survive from contact with the blood vessels in marrow spaces
What are the main types of bone cells?
Osteoprogenitor cells Osteoblasts Osteocytes Osteoclasts .
What is the function of Osteoprogenitor cells and where are they found?
- located on bone surfaces
- function as a pool of reserve osteoblasts
What is the main function of Osteoblasts?
- bone forming cells
- found on the surface of developing bone
What type of bone cell is an Osteocyte?
bone cell trapped within the bone matrix
Describe the appearance, location and function of osteoclasts
- large multinucleated cells
- found on the surface of bone
- responsible for bone resorption
What do osteoblasts secrete?
collagen
glycosaminoglycans (GAGs)
proteoglycans
and organic components of the matrix
This is collectively termed OSTEOID
What happens to osteoid secreted by osteoblasts over a period of time?
It becomes mineralized over time in the extracellular space
What is woven bone?
During development/following a break
Bone has collagen fibres are laid down in a haphazard fashion rather than in one direction
