Body Systems: Musculatory System (Muscle Anatomy) Flashcards
Antagonistic muscles:
-flexor= muscles that bend a limb.
-extensors= muscles that straighten a limb.
-antagonists= muscles that cause movement in opposite.
-ex: contraction of hamstring flexes at knee, but contraction of quadriceps causes leg to extend.
Terms: tendons:
Tendons: link muscle to bone
Terms: ligament:
Ligament: link bone to bone.
Types of muscle: cardiac muscle:
•only in the heart.
•one nucleus.
•tubular, striated, branched.
•involuntarily control.
•controlled by autonomic nervous system (automatic- don’t need to think about it!)
Types of muscle: smooth muscle:
•lines blood vessels, tubes and organs.
•ex. Esophagus, stomach.
•non-striated.
•one nucleus.
•involuntary contractions.
•controlled by autonomic nervous system (automatic- don’t need to think about it!)
Types of muscles: skeletal muscle:
•all over body.
•aids in locomotion.
•tubular and striated.
•many nuclei.
•very long.
•contraction is voluntary.
•central nervous system.
•supports the body.
Components of skeletal muscles:
•muscles are made up of bundles of muscle fibres, which are made up of myofibrils.
•the fibres are enclosed within a membrane called the sarcolemma.
•within the muscle fibres are tiny myofilaments bundled together.
•myofilaments: thread of contractile proteins found within the muscle.
Two kinds of myofilaments can be seen:
- Thin myofilaments composed of actin.
- Thick myofilaments composed of myosin.
-they overlap to produce a striated, or striped, appearance.
What is the sarcomere?
Basic, repeating unit of a muscle cell.
Sarcomere (Z line):
-the length of the muscle fibre that anchor the actin fibres.
-Z line to Z line = 1 sarcomere.
Sarcomere (A band):
-full length of the thick myosin filaments including the part that is overlapped with actin filaments (aka dark band).
Sarcomere (I band): (i)
-thin actin- filaments (aka light band).
Sarcomere (H zone):
-in the middle of A-band where only think filaments are found.
Sarcomere (M line):
-Center of the H zone where thick filaments are bound in the centre.
Sarcomere (cross bridges):
-spaces where thick and thin overlap and attach to each other.
-myosin heads attach onto actin filaments.
Muscle fibre:
-Description: Single muscle cell.
-function: is responsible for muscle contractions.
Myoglobin:
-Description: Oxygen-binding pigment (similar to hemoglobin) in a skeletal muscle fibre.
-function: stores oxygen for use during muscle contractions.
Sarcolemma:
-description: membrane of a muscle fibre.
-funnction: surrounds the muscle fibre and regulates the entry and exit of materials.
Sacroplasm:
-definition: cytoplasm of a muscle fibre.
-function: is the site of metabolic processes for normal cell activities; contains myoglobin and glycogen (which stores energy for muscle contractions).
Sarcoplasmic reticulum:
-definition: smooth endoplasmic reticulum in a muscle fibre.
-function: stores calcium ions needed for muscle contractions.
Myofibrils:
-definition: organized bundles of myofilaments; cylindrical structures as long as the muscle fibre itself.
-function: contain myofilaments that are responsible for muscle contractions.
Thick filament:
-definition: Fine myofilament composed of bundles of protein called myosin (about 11nm (nanometers) in diameter).
-function: binds to actin and causes muscle contractions.
Thin filament:
-definition: Fine myofilament composed of strands of protein called actin (about 5nm (nanometers) in diameter.
-function: binds to myosin and causes muscle contractions.
