Histology Flashcards
What are the 3 principle types of muscle
skeletal
cardiac
smooth
Describe the major features of skeletal muscle
Striated
Unbranched - long fibres
Multinucleated - syncytium
What is the name for the cell membrane in muscle cells
sarcolemma
A muscle tends to only contain one fascicle - true or false
False
Usually contains several
What are fascicle made up of
A number of individual muscle cells
These are made up of many myofibrils which can be divided into sarcomeres (made of actin and myosin)
What causes the striated appearance of skeletal muscles
repeating pattern of actin and myosin in the sarcomere
As myosin is thicker the pattern shows up as a series of dark and light bands
What does a motor unit consist of
One motor neuron and all of the muscle fibres that it innervates
What is a neuromuscular junction
The synapse between the motor neurone and the muscle
The neurone travels down from the brain and spinal cord and terminates near the muscle
The more muscle fibres in a motor unit, the finer the control - true or false
False
fewer fibres = finer movement
How are the cells in cartilage nourished
Diffusion through the extracellular matrix
It is permeable and avascular
How are cells in bone nourished
Must be nourished by the vessels that pervade the tissue
They have blood supply as they aren’t permeable
What is the extracellular space that chondrocytes live in
a lacuna
Chondrocytes are active cells, what do they secrete
They secrete the compounds to form the extracellular matrix
Also help to maintain it
What makes up the ECM in cartilage
Mostly water
Type 2 collagen - forms a meshwork
Proteoglycans
What is the most common type of cartilage
Hyaline
Found at end of bones e.g. costal regions
Also in trachea
Where do you find elastic cartilage
The ear
It has a lot of elastic fibres that make it flexible
What is fibrocartilage
Hybrid between tendon and hyaline cartilage
Appears in connections between tendons and bone
what are the functions of bone
Support Levers for movement Protection of internal organs - hard tissue Calcium store Haemopoiesis - blood cell production
What are the 2 types of bone
Cortical
Cancellous/ trabecular
Where is cortical bone found
Forms the dense outer layer of the bone sheath
Where is cancellous or trabecular bone found
Occupies the end of bone - epiphyses
Its the fine meshwork
What is the main difference between the 2 types of bone
Trabecular bone has spaces adjacent to it
Cortical does not - it is compact
Trabecular bone tends to lack haversian canals
What are the living cells in bone called
osteocytes
Is bone a living or dead tissue
Living
Therefore requires a blood supply
what is found in the haversian canals
Blood vessels that supply the bone
What type of bone is sometimes called ‘spongy’
trabecular
What are osteoprogenitor cells
located on bone surfaces
pool of reserve osteoblasts
If there is a break they will proliferate and form new bone
What are osteoblasts
Bone forming cells
Found on the surface of developing bone
Have lots of mitochondria and RER
What are osteocytes
Living bone cells that are trapped within the matrix
What are osteoclasts
Large multinucleated cells found on the surface of bone
Break down bone - responsible for bone resorption
How do osteoblasts form bone
Secrete collagen, GAG and other proteins (including enzymes) into the extracellular matrix
Over time this becomes mineralised by attracting calcium
Eventually the mature bone will be formed
What is the main mineral component of bone
calcium phosphate crystals
Where are osteoclasts derived from
The macrophage lineage of cells
What is woven bone
A weaker formation of bone
Collagen is laid down in an unorganised way
First thing that forms in healing -e.g. after break
In time it is broken down and replaced by lamellar bone
