Histology - Muscle Flashcards
Name the 4 types of contractile cells
- Muscle
- Myoepithelial cells
- Myofibroblasts
- Pericytes
Name the 3 types of muscle cells
- Skeletal/voluntary
- Cardiac
- Smooth/involuntary
What % of your body weight is made up of skeletal muscle
About 40%
What is muscle tissue formed of
Muscle cells and associated connective tissue
Describe what fibres are, and their size
- They are long cylinders
- 10-100 micrometres in diameter
- 1,000-200,000 micrometres in length
What is the longest muscle in the body
The saratoris muscle (within the thigh)
Within the mesenchyme of the mesoderm, what do cells lose and what do they form
Lose their supporting cell membranes and form multinucleate myotubes
What is a fascicle
These are the bundles that muscles are grouped into; muscle contains several
What is the connective tissue that surrounds the muscle as a whole
Epiymysium
What is the connective tissue that surrounds a single fascicle
Perimysium
What are fascicles made up of and what connective tissue surrounds them
- Muscle fibres
2. Endomysium
What is each muscle fibre made up of
Myofibril which is composed of many sacromeres placed end-to-end
What is the motor unit
The motor neuron and all of the muscle fibres that it innervates
Describe the relationship between muscles fibres in the motor unit
The fewer the number of muscle fibres in a motor unit, the finer the control of movement
What terminates at a neuromuscular junction and was released causing an initation
- Motor axons terminate at a motor end-plate
2. Action potentials arriving, cause the release of acetylcholine, and initiate an action potential in the sacrolemma
What surrounds each myofibril and, roughly, where does this happen
T-tubules; roughly at the A-I junction of each sacromere
What is the sacroplasmic reticulum
A labyrinth of specialised smooth ER within each muscle cell
Where are muscles attached to bone, using a tendon
The myotendinous junction
What information do muscle spindles provide to muscles
The amount of stretch in the muscle and the amount of tension in the muscle
What does cardiac muscle form
- Part of the walls of the heart chambers
2. Origins of the great vessels
How long are the cardiac muscle fibres
50-100 micrometres
Where are satellite cells located
Pressed against the outer surface of the sacrolemma of the muscle cell, under the surrounding basal lamina
What is the function of satellite cells
Following damage they become activated and proliferate to form new muscle fibres
Why is smooth muscle considered ‘smooth’
It contains no visible striations
Name 4 areas smooth muscle can be found
- Gut
- Respiratory tract
- Uterus
- Blood vessels
Describe the rough size of smooth muscle fibres
About 5 micrometres in diameter and 20-500 micrometres in length
What allows smooth muscle cells to contract
They contain many actin and myosin filaments
