Flashcards in Chapter 7 - Control Of Movement And Balance Deck (36):
What does the control of our movements and balance involve?
It involves both the central nervous system (CNS) and the peripheral nervous system (PNS).
What is the motor association area of the cerebral cortex?
It is a large area towards the front of the cerebral cortex where our behavior is planned.
How do our intention to voluntarily contract muscles begin in the motor association area of the cerebral cortex?
The neurons in this area make up a program for the sequence and intensity of the muscle contractions required to perform the planned activity.
What occurs at the primary motor cortex?
It is located just behind the motor association area and it is where the program is sent. From here, nerve impulses are sent to lower centers in the brain and to the spinal cord, eventually resulting in contractions of the muscles.
Describe the structure of the Primary Motor Area.
It is one of the folds of the cerebrum. It is like a band that wraps over that part of the cerebrum.
Why is the band (primary motor area) like a map of the body?
This band is like a map of the body because the neurons that control the contraction of muscles in different parts of the body are located in different places along the band.
How did scientists determine the muscles controlled by each part of the primary motor area?
By touching electrodes on different parts of the cortex. Muscles controlled by neurons in the stimulated part contracted.
How are the muscles that are adjacent in the body controlled?
By neurons that are adjacent in the primary motor area.
Parts of the body that have more muscles =
Controlled by more neurons.
How big is the hand control area of the cortex?
It is about the same size as that for the whole of the leg and foot.
What is a homunculus?
It is a diagram if the body that shows the relative size of parts of the cortex devoted to control of different muscles.
Explain what occurs in the Upper motor neurons.
They carry the nerve impulses away from the motor area of the cerebral cortex. These neurons connect the brain to the appropriate level in the spinal cord.
What happens once the neurons connect the brain to the appropriate level in the spinal cord?
At that point the messages are passed to lower motor neurons that carry the impulses to the muscles.
Last line Before The Rile of the Cerebellum
Where does the cerebellum receive nerve impulses and information from?
From the cerebrum through the upper motor neurons. It also receives info from the eyes, ears and stretch receptors in the muscles and joints.
How does one's muscles respond in a smooth and coordinated way?
The cerebellum assesses the conscious desire to move along with the info about the position of the body and the state of the muscles. All of the input is then integrated so that the person's muscles can respond in a smooth and coordinated way.
What does the cerebellum smooths contraction of the muscles do?
It maintains muscle gone and posture, and coordinates movements of the joints involved in complex actions such as walking, throwing and jumping.
How does the cerebellum help in the learning of motor skills?
When there is a difference between a person's intentions and actual performance, messages are sent to the cerebellum that relays them to the cerebral cortex. The info from the cerebellum is used to correct he performance of the muscles.
Why are movements in babies and toddlers jerky and uncoordinated?
Because their development of pathways of neurons in the cerebellum is undeveloped. (This also applies to people who have suffered damage to the cerebellum).
What does our sense of balance (Equilibrium) require?
It requires constant contraction and relaxation of muscles.
Where does the cerebellum receive input from?
• Cerebrum - info about conscious awareness of the position of the body.
• Semicircular Canals - located in the inner ear, info about movements of the head.
• Saccule and Utricle - 2 chambers in the inner ear, info about the position of the head ( therefore, body)
• Eyes - observe the body's position in space
• Pressure receptors - in skin ( esp. feet) info about relative amounts of pressure on parts of the body.
• stretch receptors - in muscles and joints, reports body movements and joint positions
What is a Reflex?
It is a rapid, automatic response to a change in the extern or internal environment.
What are the 4 important proprieties of Reflexes?
• a STIMULUS is requires to trigger off a reflex - it is it spontaneous
• a reflex is INVOLUNTARY - it occurs without any conscious thought.
• a reflex response is RAPID - only a small number of neurons are involved
• a reflex is STEREOTYPED - it occurs in the same way each time it happens
Are all messages that come from
nerve impulses in the spinal cord sent to the brain?
Not necessarily, the impulse may be passed to motor neurons at the same level in the cord, or may travel a few segments up or down the cord before traveling out through a motor neuron.
What is a spinal reflex?
It is a reflex which is carried out by the spinal cord alone.
What is a reflex arc?
It is the pathway a nerve impulse follows in traveling from a receptor to an effector. Or in the case of a spinal reflex, a spinal reflex arc.
A spinal reflex does not involve the brain, therefore it is?
It is involuntary, even though contraction of skeletal muscles may occur. Impulses may be sent to the brain after the response had been initiated so that we become aware of what is happening.
What basic components does a reflex arc have?
• Sensory Neuron
• Motor Neuron
What is a Receptor?
It is either the ending of a sensory neuron or a specialized cell associated with the end of a sensory neuron. It reacts to a change in the internal or external environment by initiation a nerve impulse in the sensory neuron.
What is the function of a Sensory Neuron?
It carries impulses from the receptor to the CNS.
How would a synapse serve a reflex arc?
The nerve impulses may be passed directly to a motor neuron or there may be one or more interneurons, which direct the impulse to the correct motor neuron.
What is the function of a motor neuron?
It carried the nerve impulse to an effector.
What is the function of an effector?
Effectors are muse cells or secretory cells. It receives the nerve impulse and carries out the appropriate response.
How would a response occur?
The response would occur in a fraction of a second and while it was occurring, impulses would travel up the spinal cord to the brain.
What innate reflexes are determined genetically?
More complex motor patterns appear during baby's development.