Week 7 - Movement Flashcards
What are the functions of muscles?
Smooth Muscles - control digestion and other organs
Skeletal or Striated muscles control movement
Cardiac muscles - control the heart
What is a neuromuscular junction?
a synapse between a motor neuron axon and a muscle fibre.
In skeletal muscles, every axon releases…
…acetylcholine at the neuromuscular junction.
Does acetylcholine always excite the muscle to contract?
Yes!
What does a deficite of acetylcholine mean?
that will impair movement.
Every makes ONE movement…
A contraction.
The muscle relaxes when it receives…
NO message.
Moving an arm or leg back and forth requires opposing sets of muscles called…
antagonistic muscles.
Humans (vs. fish) have certain types of muscle fibres bound together. What are they?
Fast-twitch fibres and slow-twitch fibres.
We rely on …… for the least strenuous activities.
slow and intermediate fibres.
Slow twitch fibres do not fatigue rapidly because they are…
Aerobic - they use oxygen during their movements.
Fast-twitch fatigue rapidly because…
they’re Anaerobic - using reactions that do not require oxygen at the time but need oxygen for recovery. Using them builds up an oxygen debt!
What do flexor and extensor muscles do?
Flexor muscles are there to bring a muscle/limb in, extensors are there to pull it back.
What do proprioceptors do?
They are receptors that detect the position or movement of a part of the body.
What do muscle proprioceptors do?
detect the STRETCH and TENSION of a muscle and send messages that enable the spinal cord to adjust its signals. When a muscle is stretched, the spinal cord sends a signal to contract it reflexively.
This STRETCH REFLEX is CAUSED by a stretch, it does not PRODUCE one.
What is a muscle spindle?
a proprioceptor - a receptor parallel to the muscle that responds to a stretch. Whenever the muscle is stretched more than the antagonistic muscle, the muscle spindle sends a message to a motor neuron in the spinal cord, which in turns sends a message back to the muscle, causing a contraction.
When you step on a bump in the road, your knee bends a little, stretching the extensor muscles of that leg. The sensory nerves of the spindles SEND action potentials to the motor neuron in the spinal cord. THEN WHAT?
…then the motor neuron sends action potentials to the extensor muscle. Contracting the extensor muscle straightens the leg, adjusting for the bump on the road.
A tap on the knee is testing what?
stretch reflexes. The tap stretches the extensor muscles and their spindles, resulting in a message that jerks the lower leg upward. A leg that jerks excessively or not at all may indicate a neurological problem.
What are Golgi tendon organs?
they are also proprioceptors, and respond to increases in muscle tension. They are in tendons, acting as a brake against an excessively vigorous contraction.
Vigorous muscle action inhibits further contraction by…
activating the Golgi tendon organs.
What else, other than controling important reflexes, do proprioceptors do?
They send information to the brain.
Why do we perceive smaller objects that weigh the same as larger objects to weigh more?
Proprioceptors, baby. People think that larger means heavier, so the actual weight displaces their proprioceptors less than expected and therefore yields the perception of a lighter object.
What is a reflex?
A consistent, automatic response to stimuli. They are insensitive to reinforceres, punishments and motivations.
Some examples of relfexes.
Stretching, the constriction of the pupil in response to bright light, infant grasping with toes.
What are central pattern generators?
Neural mechanisms IN THE SPINAL CORD of excitation and inhibition that generate rhythmic patterns of motor output.
List some examples of central pattern generators.
Flapping wings, the “wet dog shake”.
What is a motor program?
A fixed sequence of movements.
Can a motor program be gained or lost through evolution?
Yes!
What is an example of a motor program in humans?
Yawning. Smiles, frowns and the raised eyebrow greeting. Hugging is NOT a built in motor program, but it is interesting to note that the average nonromantic hug lasts three seconds for people throughout the world.
Does the primary motor cortex send signals directly to the muscles?
No. Its axons extend to the brainstem and spinal cord, which generate the impulses that control the muscles.
Do some axons go directly from the cerebral cortex to motor neurons?
Yes, presumably giving us greater dexterity.
What is the role of the posterior parietal cortex?
Attention to space around us and planning a movement. The posterior parietal cortex monitors the position of the body relative to the world. It is relatively larger in humans reflecting enhanced role in selecting appropriate actions. It outputs to the PREMOTOR CORTEX.
What is the role of the primary somatosensory cortex?
Main receiving area for touch and other body information.
- responds to shape of object and grasping, lifting or lowering.
- contains a detailed map of the body.
What is the role of the prefrontal cortex?
Active when planning and calculating possible outcomes for a movement.
What is the role of the premotor cortex?
To prepare the body’s muscles for the exact movements it’s about to make. It helps you control your movements.
What is the role of the supplementary motor cortex?
active during preparations for a rapid series of movements; typing, dancing, speaking, playing musical instrument.
What is the role of the cerebral cortex?
Complex actions such as writing - less voluntary movements eg. coughing, laughing, crying are controlled by subcortical areas.
Motor map spans knee, hip, trunk, arm, elbow, wrist, hand, face, lips, jaw tongue etc. Parts with fine control cover more space on the cerebral cortex.
What is the role of the primary motor cortex?
Directly innervates lower motor neurones. It generates neural impulses that control the execution of movement.
