Nervous + Muscular system Flashcards
what is actin?
a thin filament protein involved in muscle contraction
what is myosin?
a thick filament protein involved in muscle contraction
what is an A band?
the dark band in a sarcomere representing where myosin filaments are present
what is an I band?
the light band in a sarcomere representing where actin filaments are present
describe aerobic exercise
physical activity that uses oxygen to produce energy, promoting cardiovascular health and endurance
define contractility
the ability of muscle tissue to shorten and generate force
define elasticity
the ability of a muscle tissue to return to its original length after being stretched
define endomysium
sheath of connective tissue that surrounds each muscle fiber
define epimysium
a sheath of connective tissue that surrounds the entire muscle
define perimysium
a sheath of connective tissue that surrounds a fascicle
define Golgi tendon organ (GTO)
a sensory receptor located in tendons that detects changes in muscle tension
stops contraction/mm relaxation
define irritability/responsivity
the ability of muscle tissue to respond to stimuli, typically from the nervous system
define an isometric contraction
no movement occurs
ex: holding a plank position
define an isotonic contraction
movement occurs
concentric vs eccentric
ex: lifting a box or squatting
explain the 5 golden rules of skeletal muscle activity
- With a few exceptions, all muscles cross at least 1 joint
- The bulk of a muscle mass lies proximal to the joint it crosses
- All skeletal muscles have an origin and insertion
- During contraction, the insertion moves toward the origin
- All skeletal muscles can only pull, never push
tendons vs ligaments
Tendons: connect muscle to bone
Ligaments: connect bone to bone
define muscle spindle
Skeletal muscle (intrafusal fibers)
- Measures: muscle stretch and length
- Reflex: resist stretch
what are the 4 muscle movers and what do they do?
- Agonist: prime mover
- Antagonist: opposes prime mover
- Synergists: assists prime mover, reduces undesirable movements
- Fixators: specialized synergist, stabilizes to allow the prime mover to move the insertion point
describe cardiac muscle type
- branching chains, uninucleate, striations, intercalated discs
- involuntary, slow contraction
- controls pacemaker (SA node) and nervous system
describe skeletal muscle type
- single, long and cylindrical, multinucleate, striations
- voluntary contraction, speed varies
- controls the nervous system
describe smooth muscle type
- single, fusiform, uninucleate, no striations
- involuntary contraction, speed varies
- controls nervous system, hormones, chemicals, and stretch
what are the 4 skeletal muscle functions?
- Produce movement
- Maintain body posture and position
- Stabilize joints
- Produce heat
describe the 4 skeletal muscle fiber properties
- irritability/responsivity
- Contractility
- Extensibility
- Elasticity
describe the key components of a neuromuscular junction
The neuromuscular junction is where a motor neuron communicates with a muscle fiber. It includes the axon terminal of the neuron, the synaptic cleft, and the motor end plate (specialized region of the sarcolemma) on the muscle fiber.
What is a motor unit and why is it considered the functional unit of skeletal muscle?
The neuromuscular junction is where a motor neuron communicates with a muscle fiber. It includes the axon terminal of the neuron, the synaptic cleft, and the motor end plate (specialized region of the sarcolemma) on the muscle fiber.
Briefly summarize the sliding filament theory.
The sliding filament theory explains that muscle contraction occurs when the protein filaments actin and myosin slide past each other. This overlapping shortens the sarcomere, the basic unit of muscle contraction, leading to overall muscle shortening.
What is the primary cause of Amyotrophic Lateral Sclerosis (ALS) and how does it affect muscle function?
ALS is caused by the degeneration of motor neurons, the nerve cells responsible for transmitting signals from the brain and spinal cord to muscles. This disrupts nerve impulses to muscles, leading to progressive muscle weakness and paralysis.
State the typical prognosis for an individual diagnosed with ALS and explain why.
The typical prognosis for ALS is a life expectancy of 3-5 years. This is primarily because the muscles involved in breathing eventually become affected, leading to respiratory failure and suffocation.
Explain how Myasthenia Gravis leads to muscle weakness.
Myasthenia Gravis results in muscle weakness because the communication between nerves and muscles is disrupted. This occurs due to a shortage of acetylcholine receptors or antibodies attacking these receptors at the neuromuscular junction, preventing effective muscle stimulation.
What are the two main causes of the disruption at the neuromuscular junction in Myasthenia Gravis?
The two main causes of disruption at the neuromuscular junction in Myasthenia Gravis are:
1) a shortage of acetylcholine (ACh) receptors on the muscle fiber membrane and
2) the presence of antibodies that attack and block existing ACh receptors.
