Semester 2 Final Flashcards
Functions of the muscular system?
provides muscle tone
propels body fluids and food
generates a heartbeat
distributes heat
Sarcolemma
(Cell membrane) membrane covering muscle fibers
Sarcoplasm
(cytoplasm) Material within a muscle fiber
Sarcoplasmic recticulum
(ER) network of channels and tubes throughout the muscle fiber
Synapse
junction between two neurons
Motor unit
Motor neuron and its muscle fibers
Neurotransmitter
chemicals that axons secrete on effectors or other neurons
Motor end plate
specialized region of muscle fiber membrane
Steps of skeletal muscle contraction
Botor Neuron ACh Binds Sodium ions enter T tubules Release calcium Expose myosin bind sites Binds to actin Nerve impulses stop Calcium is actively transported Relax
What is the role of creatine phosphate as an energy source for muscles?
stores excess energy from mitochondria
HIGH ATP = creatine phosphate stores energy
LOW ATP = creatine phosphate transfers stored energy to ADP to make more ATP (P + ADP = ATP)
How do muscles store oxygen?
Due to myoglobin (pigmented protein in muscles)
How and why do muscles become fatigued?
HOW: when a muscle loses its ability to contract
WHY: accumulation of lactic acid in the muscle
lowers pH….. preventing contraction
Myogram
Recording of an electrically-stimulated muscle contraction
Threshold stimulus
Muscle remains unresponsive until the stimulus reaches a certain point
Twitch
Single, short contraction involving a few motor units
Latent Period
Time between application of stimulus and beginning of muscle contraction
Summation
increased force of contraction by a skeletal muscle fiber when a twitch occurs before the previous twitch relaxes
Recruitment
increased number of activated motor units within a muscle at higher intensities of stimulation
Sustained contraction
both summation and recruitment
muscle tone
state of tension that is maintained continuously; achieved by continuous, sustained contraction of motor units within a muscle
Prime mover
muscle that does the majority of the work
antagonist
opposing muscle
synergist
helper muscle; works with the prime mover to produce a movement
Origin
one end of the skeletal muscle is attached to a fixed point on a movable joint
Insertion
one end of a skeletal muscle that is attached to the movable part of the joint
How can relationships between muscles change depending on movement?
when you move muscles in different ways, they have different response
EXAMPLE:
pectoralis major and latissimus dorsi are antagonistic for flexion and extension of the shoulder, but they are synergists for medial rotation of the shoulder
