muscular system Flashcards
What percentage of total body weight does skeletal muscle constitute?
40-50%
What type of muscle is primarily attached to bones and is voluntary?
Skeletal muscle
Which type of muscle is striated and only found in the heart?
Cardiac muscle
What is the primary function of cardiac muscle?
Develops pressure for arterial blood flow
What type of muscle is non-striated and involuntary?
Smooth/visceral muscle
Where is smooth muscle primarily grouped?
In walls of hollow organs
What are the five main functions of muscle tissue?
- Production of body movements
- Stabilization of body positions - posture
- Regulation of organ volume
- Movement of substances internally
- Production of heat
List the properties of muscle tissue.
- Excitable
- Contractile
- Extensible
- Elastic
What surrounds the entire muscle?
Epimysium
What is the connective tissue that surrounds fiber bundles called?
Perimysium
What surrounds each individual muscle fiber?
Endomysium
What are the two types of muscle attachments?
- Direct
- Indirect
What is the origin in muscle attachment?
Immovable bone
What is the insertion in muscle attachment?
Movable bone
What provides the stimulus for muscle contraction?
Nerves
What is the primary metabolic need of muscle tissue?
Oxygen and energy from macromolecules
Describe the structure of skeletal muscle fibers.
Really large cells, usually long (up to 30cm) and cylindrical (10-100um)
What are the main components found in sarcoplasm?
- Glycosomes
- Myoglobin
- Mitochondria
- Myofibrils
- Sarcoplasmic reticulum
- T-tubules
What are the dark and light bands in myofibrils called?
- A bands - dark
- I bands - light
What is the H Zone in myofibrils?
Light band in the center of the A band
What structure connects thick filaments in the sarcomere?
M line
What are the Z discs made of?
Alpha actinin
What is the role of titin in skeletal muscle?
Elastic filaments connecting myosin in the sarcomere
Which myofilament is primarily made of actin?
Thin filaments
What is the function of the sarcoplasmic reticulum?
Stores calcium ions and releases them during contraction
What are T tubules?
Invaginations of the sarcolemma at the A-I band junction
How do T tubules assist during muscle contraction?
They allow action potentials to quickly reach all sarcomeres in a muscle fiber
What happens during muscle contraction at the molecular level?
Myosin heads bind to actin sites and pull actin molecules toward H-zone
True or False: Indirect muscle attachments are much less common than direct attachments.
False
