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Musculoskeletal System

Skeleton

Axial skeleton: Vertical
appendicular skeleton: horizontal
Fibrous joints: allow no movement
cartilaginous joints: allow limited movement
synovial joints: allow considerable movement
hyaline cartilage: articulating bones ends are covered with this
synovial fluid: entire joint is enclosed in a capsule filled with this
uniaxial joints: rotating only one axis (elbow)
biaxial joints: rotating allow in two axis (ankle)
Multiaxial joints: rotating allow in three axes (shoulder)
vertebral column: made of vertebral bones

Skeletal Musculature

Musculoskeletal Macrostructure and Microstructure

epimysium: tissues which covers the body's skeletal muscles
tendon: specialized connective tissues covering all bones
bone periosteum: attached with tendon
Limb muscles: connects proximal and distal
superior and inferior: two attachments of trunk muscles
Muscle fibers: long, cylindrical cells 50 to 100 um in diameter
fascicule: bundles of muscle fibers
perimysium: connective tissues which surrounds muscle fiber
sarcolemma: muscle fiber membrane
motor neuron: nerve cell
neuromuscular junction: where it innervates nerve cell and muscle fiber
motor unit: The whole thing with motor neuron and muscle fiber
sarcoplasm: cytoplasm of muscle fiber
myofibrils: contains apparatus that contracts the muscle cell
myofilament: two types of them: myosin, actin
cross bridge: interacts with actin
sarcomere: smallest contractile unit of skeletal muscle
I, Z, H, A-band: Myofilament cross section
sarcoplasmic reticulum: intricate system of tubules surrounds each myofibril
T-tubules: run perpendicular to the sarcoplasmic reticulum and terminate in the vicinity of the Z-line between two vesicles
action potential: electric nerve pulse

Sliding-Filament Theory of Muscular Contraction

Resting Phase

Excitation-Contraction Coupling Phase

troponin: a protein that is situated at regular intervals along the actin filament and has a high affinity for calcium ions. This causes a shift to occur in another protein molecule.
tropomyosin: runs along the length of the actin filament in the groove of the double helix.

Contraction Phase

Power stroke: comes from hydrolysis (breakdown) of adenosine triphosphate (ATP) to adenosine diphosphate (ADP) and phosphate, a reaction catalyzed by the enzyme myosin adenosine triphosphatase (ATPase)

Recharge Phase

Relaxation Phase

Neuromuscular System

Activation of Muscles

acetylcholine: diffuses across the neuromuscular junction, causing excitation of the sarcolemma.
all-or-none principle: All of the muscle fibers in the motor unit contract and develop force at the same time.
twitch: Each action potential traveling down a motor neuron results in a short period of activation of the muscle fibers within the motor unit.
tetanus: stimuli may be delivered at so high a frequency that the twitches begin to merge and eventually completely fuse. This is the maximal amount of force the motor unit can develop.

Muscle Fiber Types

slow-twitch: Type I, efficient and fatigue resistant and have a high capacity for aerobic energy supply, but they have limited potential for rapid force development.
fast-twitch: Type IIa and Type IIx, inefficient and fatigable and as having low aerobic power, rapid force development.

Motor Unit Recruitment Patterns

Proprioception

Proprioceptors: specialized sensory receptors located within joints, muscles, and tendons

Muscle Spindles

Muscle spindles: Provide information concerning muscle length and the rate of change in length. When the muscle stretches.
intrafusal fibers: modified fibers which run parallel to the normal fiber
extrafusal: normal fibers

Golgi Tendon Organs

Proprioceptors located in tendons near the myotendinous junction and are in series, that is, attached end to end, with extrafusal muscle fibers.

Cardiovascular System

Heart

atrium and a ventricle: pumps' chamber

Valves

Conduction System

sinoatrial (SA) node: - the intrinsic pacemaker—where rhythmic electrical impulses are normally initiated
atrioventricular (AV) node: the impulse is delayed slightly before passing into the ventricles;
atrioventricular (AV) bundle: conducts the impulse to the ventricles
left bundle branch and right bundle branch: divide into the Purkinje fibers and conduct impulses to all parts of the ventricles.
myocardium: heart muscle
sympathetic and parasympathetic nervous systems: the components of the autonomic nervous system
bradycardia: resting heart rate fewer than 60 beats/min
tachycardia: resting heart rate more than 100 beats/min

Electrocardiogram

electrocardiogram: electrical activity of the heart can be recorded at the surface of the body
P-wave and QRS complex: recordings of electrical depolarization (the electrical stimulus that leads to mechanical contraction).
Depolarization: the reversal of the membrane electrical potentia
Repolarization: T-wave is caused by the electrical potential generated as the ventricles recover from the state of depolarization

Blood Vessels

Arteries

Regulates of blood flow to the capillaries. Arterioles have strong, muscular walls that are capable of closing the arteriole completely or allowing it to be dilated many times their size, thus vastly altering blood flow to the capillaries in response to the needs of the tissues

Capillaries

Facilitate exchange of oxygen, fluid, nutrients, electrolytes, hormones, and other substances between the blood and the interstitial fluid in the various tissues of the body. The capillary walls are very thin and are permeable to these, but not all, substances

Veins

Venules collect blood from the capillaries and gradually converge into the progressively larger veins, which transport blood back to the heart.

Blood

hemoglobin: The transport of oxygen, the iron–protein molecule carried by the red blood cells.
Red blood cells: contain a large quantity of carbonic anhydrase, which catalyzes the reaction between carbon dioxide and water to facilitate carbon dioxide removal.

Respiratory System

trachea: the first-generation respiratory passage, and the right and left main bronchi are the second-generation passages.
alveoli: where gases are exchanged in respiration

Exchange of Air

Pleural pressure is the pressure in the narrow space between the lung pleura and the chest wall pleura.
Alveolar pressure is the pressure inside the alveoli when the glottis is open and no air is flowing into or out of the lungs

Exchange of Respiratory Gases

The process of diffusion is a simple random motion of molecules moving in opposite directions through the alveolar capillary membrane.

Reference