Kaitlyn Skidmore Qua’Shaya Hammon Camille Torres

THE FUNCTIONS OF THE MUSCULAR SYSTEM The Muscular System: Provides Structure Provides Structure Aids in Movement Aids in Movement Production of Heat Production of Heat Stability of Joints Stability of Joints

SKELETAL MUSCLE STRUCTURE

MUSCLE FIBER STRUCTURE

Neuromuscular junction- Connection between the motor neuron and the muscle fiber Motor End Plate- Motor End Plate- The flattened end of a motor neuron that transmits neural impulses to a muscle Neurotransmitter- Cytoplasm at the distal ends of these motor neuron axons; rich in mitochondria and contains many tiny vesicles that stores chemicals. Muscle Contraction- A complex interaction of organelles and molecules in which myosin binds to actin and exerts pulling action.

ACTIN AND MYOSIN Actin: A protein involved in cell movement: a protein present in all cells and in muscle tissue where it plays a role in contraction. Myosin: A muscle protein: a protein in muscles that helps them contract when connected with the protein actin.

SLIDING FILAMENT THEORY The process of contraction begins with: The stimulation of a motor neuron, which releases acetylcholine, causing the chemical, calcium (Ca++) to be released. This calcium molecule will shift a troponin, making a site available for the myosin heads to connect to the actin molecule creating the contraction. Once the myosin filament attaches to the actin, ATP releases the bond between the two, then a chemical, acetylcholinesterase, is released to digest the acetylcholine, so that it may be recycled and used once again for contraction.

Muscle Fatigue: a muscle exercised strenuously for a prolonged period may lose its ability to contract.Muscle Fatigue: a muscle exercised strenuously for a prolonged period may lose its ability to contract. Cramps: is a painful condition in which a muscle undergoes a sustained involuntary contraction.Cramps: is a painful condition in which a muscle undergoes a sustained involuntary contraction.

SKELETAL MUSCLE CONTRACTION TYPES Sustained ContractionsSustained Contractions Even when a muscle is at rest, a certain amount of sustained contraction is occurring in its fibers. This is called muscle tone.Even when a muscle is at rest, a certain amount of sustained contraction is occurring in its fibers. This is called muscle tone. Isometric contractionIsometric contraction The muscle becomes taut, but the attachment(s) do not move; tensing a muscleThe muscle becomes taut, but the attachment(s) do not move; tensing a muscle Isotonic contractionsIsotonic contractions The muscle shortens and its attachment(s) move(s).The muscle shortens and its attachment(s) move(s).

SMOOTH MUSCLE CONTRACTION 1.A protein, calmodulin binds to calcium ions (no troponin) and activates the contraction mechanism. 2.Most calcium diffuses in to smooth muscle cells from the extracellular fluid (reduced SR). 3.Norepinephrine and acetylcholine are smooth muscle neurotransmitters. 4.Contraction is slow and sustained. 1.A protein, calmodulin binds to calcium ions (no troponin) and activates the contraction mechanism. 2.Most calcium diffuses in to smooth muscle cells from the extracellular fluid (reduced SR). 3.Norepinephrine and acetylcholine are smooth muscle neurotransmitters. 4.Contraction is slow and sustained.

Prime Mover (agonist) = the primary muscle responsible for a movement. The biceps brachii in flexing the arm at the elbowThe biceps brachii in flexing the arm at the elbow Antagonist(s) = the muscle(s) in opposition to the action of the prime mover. The antagonist relaxes (or stretches) during the prime movement. The triceps brachii is the antagonist of the biceps brachii when we flex the arm at the elbow.The triceps brachii is the antagonist of the biceps brachii when we flex the arm at the elbow. Synergist(s) = muscles that assist the prime mover. The brachialis helps the biceps brachii during elbow flexion.The brachialis helps the biceps brachii during elbow flexion. Origin = the attachment site of the muscle’s tendon to a more stationary bone. It has very less movement and normally a muscle contracts towards it. Some muscles have more than one origin, for example, biceps brachii.Some muscles have more than one origin, for example, biceps brachii. Insertion = the attachment site of the muscle’s tendon to a more movable bone is known as the muscle’s insertion. It has the greatest motion when the muscle contracts and it tends to be more distal. radius/ulnaradius/ulna

Insertion is the attachment site of the muscle’s tendon to a more movable bone is known as the muscle’s insertion. It has the greatest motion when the muscle contracts and it tends to be more distal. Origin is the attachment site of the muscle’s tendon to a more stationary bone. It has very less movement and normally a muscle contracts towards it. Some muscles have more than one origin, for example, biceps brachii. ORIGIN AND INSERTION

An antagonist muscle is one that works in opposition to the movement initiated by an agonist muscle. The antagonist muscle in a muscle set brings a limb or other anatomical part back to its initial position of rest. A synergist muscle is a muscle which works in concert with another muscle to generate movement. These muscles can work with the agonists or prime movers which surround a joint, or the antagonistic muscles, which move in the opposite direction. ANTAGONIST AND SYNERGIST

Muscular dystrophy is a group of inherited disorders that involve muscle weakness and loss of muscle tissue, which get worse over time. Muscular dystrophy is a group of inherited disorders that involve muscle weakness and loss of muscle tissue, which get worse over time. MUSCULAR DYSTROPHY

CAUSES AND SYMPTOMS Muscular dystrophies, or MD, are a group of inherited conditions, which means they are passed down through families. They may occur in childhood or adulthood. Symptoms include: Intellectual disability (only present in some types of the condition) Intellectual disability (only present in some types of the condition) Muscle weakness that slowly gets worse Muscle weakness that slowly gets worse Delayed development of muscle motor skills Delayed development of muscle motor skills Difficulty using one or more muscle groups Difficulty using one or more muscle groups Drooling Drooling Eyelid drooping (ptosis) Eyelid drooping (ptosis) Frequent falls Frequent falls Loss of strength in a muscle or group of muscles as an adult Loss of strength in a muscle or group of muscles as an adult Loss in muscle size Loss in muscle size Problems walking (delayed walking) Problems walking (delayed walking)

TEST/TREATMENTS The doctor's exam may show: Abnormally curved spine (scoliosis) Joint contractures (clubfoot, clawhand, or others) Low muscle tone (hypotonia) And And Heart testing - electrocardiography (ECG) Nerve testing - electromyography (EMG) Blood testing - including CPK level Genetic testing for some forms of muscular dystrophy There are no known cures for the various muscular dystrophies. The goal of treatment is to control symptoms

Summation- Occurs in the neuromuscular junction; it is the additive effect of several electrical impulses. Recruitment- contraction of one motor unit and all muscle fibers at the same time Sustained contraction- also called a tetanic contraction, occurs when there is an accumulation of acetylcholine in the neuromuscular junction. -It occurs rapidly, giving no time for the muscle to relax between stimuli -Remains constant in a steady state; maximal muscle contraction Muscle Tone- continuous and partial contraction of muscles -recruitment and summation combined

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