6 Myology Flashcards
What’s a general description of muscle tissue, what 3 types of mm tissue are there and what are their general functions?
- specialized cells that use ATP in the generation of force
- 3 types: skeletal, smooth, cardiac
- functions include: body movement, substance movement, control of substance movement, thermogenesis
What are common characteristics of all mm tissue types?
- electrical excitability
- contractility
- extensibility
- esasticity
What’s the hierarchy of skeletal mm organization? i.e. its structures from macro to micro
Muscle
♦
Fascicle
♦
Muscle Fibre (Muscle Cell - [multinucleat)
♦
Myofibril (organelles within mm fibre that help contribute to contractility) (made up of segments called sarcomeres)
♦
Sarcomere
♦
Actin & Myosin protein fibres
What scale of measurement would be used to measure diameter of mm fascicles? (e.g. meter, cm, mm…)
mm
What are mm fascicles made up of?
mm fibres
This is the cell (plasma) membrane of the mm cell:
sarcolemma
What scale of measurement would be used to measure diameter of mm fascicles? (e.g. meter, cm, mm…)
micrometers (millionth) x 100
Tiny invaginations tunnel in from the sarcolemma towards the centre of the mm fibre (allow AP to travel deeper into mm). These are called:
transverse tubules
The cytoplasm of mm fibres (lots of glycogen) is called:
sarcoplasm
A protein that binds oxygen that has diffused into the mm fibre and delivers it to the mitochondria:
myoglobin
Can you increase number of mm cells or myofibrils in the body?
- mm cells: can’t increase number
- myofibriles: can incrase with exercise
What’s a general description of myofibrils?
- specialized contractile organelles of the mm cell
- they extend the length of the mm fibre
- they are held in place by cytoskeletal proteins
- sarcoplasmic reticiulum: fluid filled tubes and sacs running along and surrounding each myofibril – they store and release calcium into the cell (when it’s needed)
- contain a number of sarcomeres arranged in series (end to end)
pp108-9
What’s a general description of the sarcomere?
- the funcitonal unit of a myobiril (of contraction)
- contain 2 contractile proteins: actin and myosin (these show as striations)
- actin: makes up the thin filaments
- myosin: makes up the thick filaments (these pull actin closer together, resulting in contraction)
- thick and thin filaments overlap and their interaction is what generates force/contraction
- their overlap also creases light and dark stripes which gives skeletal mm its striated appearance
The nerve cell that stimulates muscles to contract is called a:
motor neuron
Each motor neuron axon terminal forms a junction called the ___ junction with the ___ of a number of different muscle cells
neuromuscular; sarcolemma
The motor neuron’s axon terminal and the sarcolemma never actually touch – there is a gap between them called the __ __
Synaptic cleft
When the signal arrives at the end of the motor neurons axons, It releases and neurotransmitter called ___ which crosses the ___ ___, stimulates the ___ and the muscle continues the signal
acetylcholine (ACh); synaptic cleft; sarcolemma
Is skeletal muscle activated by chemical potential, electrical potential, or both?
Always chemical; always ACh
The functional unit of a myofibril (of contraction) is the:
sarcomere
The Sarcomere contains two contractile proteins called:
actin and myosin
There are thin and thick filaments in the sarcomere. What are each called?
thin filaments: actin (remember Tiina’s “actinee”)
thick filaments: myosin
A nere cell that stimulates muscles to contract is called a:
motor neuron
The sliding filament mechanism:
- once the signal reaches the mm fibres, it crosses the ___ ___
- the signal is then continued by the mm fibres and spreads out across the ___
- it then travels down the ___ ___ and stimulates the ___ ___ to release calcium
…
- synaptic cleft
- sarcolemma
- transverse tubules; sarcoplasmic reticulum
The sliding filament mechanism:
…
when the signal reaches the sarcomere:
- the calcium allows the ___ (of the thick filament) to connect with the ___ (of the thin filament)
- the ___ pulls (‘slides’) the ___/thin filaments together
- it disengages and starts the cycle again
- this ‘ratcheting’ of the filaments uses ___
- with repitition, it shortens the ___, the myofibril, the muscle fibre, the muscle
…
- myosin; actin
- myosin; actin
- ATP
- sarcomere
