The Muscular System: CHP 6 Flashcards
List the 5 functions of the muscular system.
- Body movement
- Regulate organ volume
- Heat Production
- Stabilize body positions
- Move substances in the body
How much of the body mass do muscles make up?
40-50%
What are the three types of muscle tissue?
Skeletal, cardiac, smooth
Which types of muscle are striated?
Skeletal and cardiac
What is skeletal muscle responsible for?
Body movements (voluntary/involuntary)
What is cardiac muscle responsible for?
Generation of force to pump blood
What is a unique ability of the cardiac muscle?
The ability to contract without oversight from the nervous system (autorhythmic)
What is smooth muscle responsible for?
Moving substances in the body and regulating organ volume.
Where is smooth muscle found?
Hollow body organ walls (stomach, uterus), attached to skin/hair follicles
Describe the structure of smooth muscle.
Smaller cell size
Single nucleus
Spindle shaped
No T-tubules
Irregular filament arrangement
Which muscle tissues are completely involuntary?
Cardiac and smooth
How does cardiac muscle communicate?
Through gap junctions in intercalated discs
What are intercalated discs?
The junction of two adjoining cardiac cells
What do cardiac cells look like?
Branched
What are pacemaker cells?
Heart muscle cells
How many twitch contractions does cardiac muscle have per minute?
70-80 per min
What are desmosomes?
Connections that mechanically bind cells like velcro
What are hemidesmosomes?
Connections that mechanically bind cells to the basement membrane
What is a sarcomere?
A building block of muscle fibers
What is thin filament made of?
Actin protein
What is thick filament made of?
Myosin protein
What is a z disc?
The boundary of a sarcomere unit
Explain the relationship between perimysium, endomysium, and epimysium.
All are a connective tissue. The epimysium surrounds the muscle, the perimysium surrounds a bundle of muscle fibers, the endomysium surrounds each muscle fiber.
What are fascicles?
Bundles of muscle cells/fibers wrapped in connective tissue.
True or False: Skeletal muscle is multinucleated.
True
What is the plasma membrane of skeletal muscle tissue called?
Sarcolemma
What does the sarcolemma form?
T-tubules (transverse)
What is the endoplasmic reticulum of skeletal muscle called?
Sarcoplasmic reticulum
What does the sarcoplasmic reticulum do?
Serves a calcium reservoir, located near the T-tubules
What are myofilaments?
Threadlike proteins that allow muscle fibers to shorten
Explain the function of a joint.
A joint is 2 bones, working together for movement. One bone is stationary and the other is moveable.
What is the origin of the muscle?
The end of the muscle attached to the stationary bone
What is the insertion of the muscle?
The end of the muscle attached to the moveable bone
What is the belly of the muscle?
The part of the muscle between origin and insertion tendons (middle)
How do muscles work?
In antagonistic pairs, opposing
What does the agonist do?
Starts the desired action or movement
What does the synergist do?
Reduces unnecessary movements to help agonist function efficiently
What do the fixators do?
Stabilize the bones to allow the agonist to move other bones more efficiently
What causes muscle fatigue?
Insufficient ATP
Depleted creatine or glycogen
Inadequate delivery of oxygen to muscle
Lactic acid buildup
Describe the first 3 steps of Excitation/Contraction Coupling.
- Nerve impulses arrive @ axon terminal of motor neuron & trigger ACh release.
- ACh diffuses synaptic cleft, binds to receptors, & triggers muscle action potential (AP).
- Acetylcholinesterase destroys ACh so another muscle action potential does not arise unless ACh is released from motor neuron.
Describe steps 4-6 of Excitation/Contraction Coupling.
- Muscle AP traveling along transverse tubule opens Ca+ release channels in SR membrane, allowing calcium ions to flood sarcoplasm.
- Ca2+ binds to troponin on the thin filaments, exposing binding sites for myosin.
- Contraction: power strokes use ATP, myosin heads bind to actin, swivel, and release. Thin filaments are pulled toward the center or sarcomere.
Describe steps 7-9 of Excitation/Contraction Coupling.
- Ca2+ release channels close and Ca2+ active transport pumps use ATP to restore low levels of Ca2+ in sarcoplasm.
- Troponin and tropomyosin slide back into position.
- Muscle relaxes.
The oxygen binding protein in skeletal muscle is…
Myoglobin
