- Striated and tubular, many nuclei, voluntary contractions, Attached to the skeleton.
- The purpose is to:
- - Support the body
- - Bone movement
- - Maintain body temp (ATP and shivering)
- - Protect internal organs and stabilize joints
non-striated, one nucleus, involuntary contractions.
Found in walls of internal organs
Striated, tubular, branched, one nucleus, involuntary contractions.
Found in walls of the heart
Contractions cause the muscle to shorten and pull into each other, then stretch when relaxed.
- Flexor: Contract to bend a joint, extensor relaxes.
- Extensor: COntract to straighten a joint, flexor relaxes.
- 1) Muscle: Lies along a bone, attached with a tendon.
- 2) Muscle fibre bundle: A layer of connective tissue wrapped around a bundle of muscle fibres. Blood vessels and nerves run between them.
- 3)Muscle fibres: A long singular muscle cells bound by a sarcolemma membrane. Contains myoglobin, sarcoplasm, sarcoplasm reticulum, and myofibrils.
- 4)Myofibril: An organized bundle of myofilaments that are responsible for muscle contractions. A single unit is called a sarcomere.
- 5) Myofilaments: thin filament and thick filament. Each contains its own specific protein structure that is responsible for muscle contractions. Actin and Myosin.
Oxygen binding pigment that stores oxygen for cellular respiration during muscle contraction.
Stores calcium Ions needed for muscle contractions.
Myosin filament contraction
- Flex -> Pull -> Rebind -> Set
- 1. Myosin head attaches to actin through chemical binding.
- 2. Myosin head flexes backwards and inwards to pull the actin in the direction of the flex.
- 3. Molecule of ATP provides energy to release the myosin head and reposition it again for the next flex.
- 4. Myosin attaches further along the filament and continues to slides actin past the myosin
Calcium binds to a protein called troponin that is found on the actin. It causes the tropomyosin to reposition itself away from the active sites so the myosin heads can bind to the actin.
Without calcium, myosin is unable to reach the actin because of a long filament composed of tropomyosin blocking the active sites.
Calcium is stored in the: Sarcoplasmic reticulum
Process of calcium
- 1: Muscle fibre is stimulated by the nervous system to contract
- 2: Calcium is released from sarcoplasmic reticulum and diffused into the myofibrils
- 3: Nerve impulse signals muscle fibres to stop contraction
- 4: Calcium returns to the sarcoplasmic reticulum through active transport
Creatine Phosphate breakdown
- High energy compound that builds up when a muscle is relaxing.
- The fastest way to make ATP
- Regenerates: Creatine Phosphate + ADP -> Creatine and ADP
Aerobic Cellular respiration
- Provides most of the muscles ATP
- glucose + oxygen + ADP -> Carbon dioxide + water + ATP
- ^ Creates heat
Myoglobin is an oxygen-carrying muscle that temporarily stores oxygen and makes it available for the mitochondrial when cellular respiration begins.
- Provides ATP without consuming Oxygen.
- glucose + ADP -> lactate(lactic acid) + ATP
The buildup of lactate in the muscle fibres causes enzymes to stop functioning well.
- Oxygen goes toward breaking down the lactic acid in the muscle fibres instead of aerobic respiration.
Painful muscle spasms triggered by strenuous exercise, cold, dehydration, electrolyte imbalance, or low blood glucose.
Prolonged contractions of skeletal muscle fibres caused by toxins produced by Clostridium tetani, through deep wounds or rust.
Muscles are controlled by electrical impulses from the nervous system. Each muscle has a different voltage point. Once the threshold of minimum voltage is reached, the muscle will contract.
- Muscle twitches are short, fast, muscle contraction.
- 1) Latent period: the period of time between stimulation and initiation of contraction
- 2) Contraction period: when the muscle shortens ( calcium being dumped)
- 3) Relaxation period: When the muscle returns to its original length.
Burns through ATP fast.
Rapid generation of power. Produces the energy anaerobically but fatigues quickly. Rich in glycogen but has fewer mitochondria and blood vessels.
Light pink colour.
Efficient with ATP usage
Contracts slowly. Built towards endurance and tire only when fuel is gone. Lots of myoglobin, mitochondrial, and blood vessels.
Dark in colour
Series of events during muscle contraction
nervous stimulation -> calcium is released from Sarcoplasmic Reticulum -> calcium binds to troponin -> tropomyosin repositions, exposing active sites on actin -> fibre contracts -> nervous system stimulation stops -> calcium goes back to the SR using active transport -> tropomyosin re-covers active site -> bond between actin and myosin is severed -> myofiliments slide back to relax