Lecture three - Introduction to Motor Control Flashcards
Need to know the terms:
Dorsal
Ventral
Rostral
Caudal
Anterior
Posterior
What is one argument for why we have a nervous system?
To facilitate movement through our environment.
The tadpol larva to sea squirt adult is one example of when something no longer needs to move through their environment their nervous system is no longer needed.
What is Locked in Syndrome?
Occurs when there is damage to the pons area of the brain stem which leads to complete paralysis, including lung function. Cognitive function remains intact. Normal wake and sleep function.
Some people can move their eyes, which can allow them to communicate.
What is Blindsight?
When there has been damage to the primary visual rendering people unable to consciously see, but they are able to tell when objects move or where they are in space, or even colour (Type I) or ‘feel’ when objects have moved (type II).
What are the three types of muscle in the body?
- Smooth muscle, such as digestive system, arteries, and reproductive organs.
- Striated muscle, such as skeletal muscle.
- Cardiac muscle, which the heart is made of.
How many skeletal muscles are there in the body?
640.
What is a muscle called if it moves a limb toward the body when it contracts?
Flexsor (agonist), e.g. bicep.
What is a muscle called if it moves a limb away from the body when it contracts?
Extensor (antagonist).
What are the two types of muscle contraction?
- Isometric
- Isotonic
What is difference in length and tone of muscle between when performing an isometric or isotonic contraction?
An isometric contraction occurs when the the length of the muscle stays the same but the tone changes. An example would be holding a heavy box (biceps).
An isotonic contraction occurs when the tone of a muscle stays the same despite the length of the muscle changing. This happens when you pick something up or put something down (biceps).
What are the two types of isotonic contractions?
Eccentric - when the tone of the muscle stays the same but the muscle is lengthening. e.g. bicep when putting something down.
Concentric - when the tone of the muscle stays the same, but the muscle is shortening. e.g bicep when picking something up.
How do muscles receive messages from the brain?
Alpha motor neurons.
How many alpha motor neurons innervate a single motor fibre?
Only one.
Where are alpha motor neurons located?
In the spinal cord.
A single alpha motor neuron can innervate many muscle fibres through its branches and terminals. What is the alpha motor neuron and the muscle fibres it innervates called?
A motor unit.
Would alpha motor neurrons that innervate muscles responsible for fine motor movement have connections more muscle fibres than if it were innervating a muscle responsible for gross moto movements?
No. Fine motor movement requires less muscle fibres therefore the alpha motor neuron innervating the fibres would be connected to fewer muscle fibres.
What are muscle fibres?
Muscle fibres are single muscle cells.
what is the structure of a muscle fibre/cell?
Muscle fibres have myofibrils, which run the length of the fibre and are made of thick and thin filaments. Myofibtrils are the contracting part of the cell. They are what give muscle fibres a striated appearance.
The myofibrils are coated in the sarcoplasmic reticulum. This serves the same function as the endoplasmic reticulum in other cells - transports and sorts proteins - also stores calcium.
T-tubules, which are extensions of the membrane that pentrate/invaginate into the muscle fibre. They are surrounded by sarcoplasmic reticulum.
What is the role of t-tubules in muscle fibres?
T-tubules carry the action potential from the neuromascular junction into the cell and the myofibrils.
Where is the nucleus of a muscle fibre/muscle cell located?
It is embedded in the membrane of the cell.
What is the membrane of a muscle cell called?
Sarcolemma.
What is Sliding Filament Theory?
Briefly describe how a muscle contraction occurs once an action potential is generated at the muscle membrane.
Once action potential reaches the neuromascular synapse, after travelling down the axon of an alpha motor neuron, achetylcholine is released into the synapse, which binds to ion-gated channels on the muscle cell/muscle fibre, which causes the influx of sodium. This influx causes an electrical impulse which travels across the muscle membrane, down the hollow t-tubules. The electrical impulse causes the release of calcium from the sarcoplasmic reticulum. Calcium shifts proteins that prevent actin and myocin from touching. Myocin binds to actin and then unbinds and binsd again, this “ratched” action causes sliding of actin and myosin closer together, i.e. the shortening of a sarcomere, which is the unit of actin and myosin, repeating functional units of which make up myofibrils.
What is a contraction caused by a single action potential at the level of the muscle fibre?
A twitch.
