Chapter 3 Flashcards
(25 cards)
What are the two types of muscles that work in pairs at joints?
Flexors and extensors
Flexors bend joints, while extensors straighten them.
What is the role of agonist muscles?
Initiate movement
Agonist muscles are responsible for starting the motion.
What do antagonist muscles do?
Counteract agonist muscles
Antagonist muscles help control and refine movement.
What are motor units?
Links between nervous system and muscle function
Motor units consist of alpha motor neurons and multiple muscle fibers.
How does the brain regulate muscle actions?
Through communication with peripheral nerves
This regulation is crucial for coordinated movements.
What happens when motor neurons deteriorate, as seen in ALS?
Movement abilities decline
ALS affects the communication between the brain and muscles.
What is co-contraction in muscle movement?
Opposing muscles contract simultaneously
This stabilizes joints or maintains steady positions.
What functions do head and neck muscles enable?
Eyes movement, chewing, swallowing, speaking, facial expressions
These muscles are controlled similarly to skeletal muscles.
What are reflexes?
Automatic responses to stimuli
Reflexes do not require brain involvement and are processed by spinal cord neurons.
Describe the knee jerk reflex.
Tapping the knee tendon triggers extensor contraction and flexor relaxation
This reflex involves muscle spindles detecting stretch.
What is the flexion withdrawal reflex?
Leg lifts when stepping on a sharp object
The opposite leg extends to maintain balance.
What do motor neurons do?
Send signals from brain to muscles
Some axons are the longest cells in the body, stretching from the spinal cord to the feet.
What are neuromuscular junctions?
Sites where neurons communicate with muscles
These junctions are crucial for muscle contraction.
What function do muscle spindles serve?
Detect changes in muscle length or stretch
They provide feedback to the brain about muscle status.
What are Golgi tendon organs?
Located at muscle-tendon connections
They help regulate movement and force.
What type of movements require conscious planning?
Voluntary and complex movements
These movements involve direct brain input.
What do spinal circuits control?
Rhythmic behaviors like walking and breathing
They are crucial for maintaining these automatic movements.
What are central pattern generators?
Produce rhythmic movement patterns
They are studied for their potential in paralysis recovery.
What is the role of the motor cortex?
Essential for voluntary movement
It sends signals to activate motor neurons for coordinated limb movements.
What do the basal ganglia do?
Facilitate desired movements and suppress unwanted actions
They play a critical role in movement control.
What is Parkinson’s disease caused by?
Loss of dopamine-producing neurons in the substantia nigra
Symptoms include tremors, rigidity, and difficulty moving.
What causes Huntington’s disease?
Loss of inhibitory neurons
This leads to uncontrolled movements.
What is the function of the cerebellum?
Integrates sensory input for smooth, coordinated movements
It is essential for motor learning and balance.
What can damage to the cerebellum cause?
Poor coordination, balance problems, speech difficulties
Long-term alcohol abuse can lead to such damage.
