-
The muscular system
- * Muscles allow body movements
- * Maintain posture
- * Generate heat
- * Three basic types
- o Skeletal
- o Smooth
- o Cardio
-
Skeletal muscle characteristics
- * Are attached to bones
- * Have striation (dark and light bands)
- * Multinucleated
- * Voluntary
- * Stimulated consciously by the nervous system
-
Anatomical appearance of skeletal muscle
- * Muscles are separated by fibrous connective tissue called fascia
- * Fascia forms a tendon
- * Each skeletal muscle is considered an organ
-
Anatomical appearance of skeletal muscle
- * each organ is covered with a membrane called epimysium
- * each muscle is made of many fascicles
- * each fascicles is covered with a membrane called perimysium
-
Anatomical appearance of skeletal muscle
- * Each fascicle is made of many fibers (muscle cells)
- * Each fiber is covered with a membrane called Endomysium
- * Muscle fibers are made of proteins called Myofibrils
-
Anatomical appearance of skeletal muscle
- Sarcomer
- * Sarcomer is the contractible unit of a muscle
- * Striation has 2 parts: the I band (Light) and the A band (dark)
- * I band is made of thin actin filaments
-
Sarcomer
- * A band is made of Thick filaments overlapping with thin filaments
- * H zone consists of only Thick filaments
- * M lines is made of proteins that help hold the thick filaments in place
- * Z lines are made of proteins that attach the thin filaments
- [actin makes up thin filaments]
-
Muscle Fiber
- * Muscle fiber have modified smooth endoplasmic reticulum called sacroplasmic reticulum, which stores calcium
- * Transverse tubules are invaginations of the plasma membrane
-
Muscle Fiber
- * Skeletal muscle cells are voluntary and are stimulated by nerve cells
- * The connection between a nerve cell and a muscle cell is called Neuromuscular junction
-
Neuromuscular junction
- * Small vesicles are found in the axon terminals
- * These vesicles store signaling chemicals known as neurotransmitters
- * The particular NT released on skeletal muscles is called acetylcholine
-
Neuromuscular junction
- * When the nerve cells send an electrical impulse, the neurotransmitters are released onto the membrane of the muscle fiber
- * This causes the muscle fiber to contract
-
Myofibril
- * Myofibrils contain two major contractiles proteins called actin and myosin
- * In addition, two other regulatory proteins called troponin and tropomyosin found on the thin filiments
- * At rest actin has no physical contact with myosin
- * When a muscle contracts myosin binds to actin
- * This binding is known as power stroke
-
What causes muscles to contract?
- * Electrical stimulation is sent from nerve cells
- * The nerve cells release the Neurotransmitter acetylcholine on the muscle cell
- * The muscle cell becomes stimulated
- * This causes the Smooth endoplasmic reticulum to release calcium
- What is the function of calcium? Calcium facilitate the binding of the actin to myosin. ATP=energy
-
Shortening of Sacomere
* Muscle contraction is when the sacromere shortens in length
-
Name two components the sliding filament theory depends on?
- * ATP
- * Calcium�smooth endoplasmic reticulum
-
Force Varies
- * No matter what kind of force is needed
- * When muscles contract, they require energy
- * Where does energy come from?
- * Mitochondria
-
Mitchondria
- * Elongated fluid filled sacs
- * Double membrane
- * Extensive folding of inner membrane
- * Produce energy molecule (ATP)
-
How is energy produced in the mitochondira?
- * Energy production requires two major components:
- * Macromolecules
- o Come from food (carbohydrate, proteins, or fat)
- * Oxygen
- o Comes from the air around us
- * When energy is made carbon dioxide is produced as waste product
-
Why do our muscles get fatigue?
- * Lack of energy molecule
- * Oxygen debt
- * Build-up of carbon dioxide
- * Build-up of lactic acid
|
|
