Compendium Review Movement

Movement:

Neuron brings impulse to synapse with muscle

muscle cell shorten by sliding protein filaments (actin, myosin units)

Movements at protein level cause whole muscle to rapidly shorten or contract

Neurons trigger muscle to contract based on stimuli or sensory input, muscle contracts by sliding filaments, muscle pulls on bone to cause movement across joint

Muscle Cell Structure:

Muscle cells are large and visible

Each cell contains hundreds of myofibrils

Each myofibril contains actin, myoisn, filaments proteins all lined up

Parts of a muscle cell : Sarcolemma- muscle cell membrane, Sarcoplasmic Reticulum- ER in muscle, T tubule penetrate into cells and cotact SR

Calcium Release in muscle:

Motor neuron impulse arrives to axonal terminus, neuro muscular juction synapse passes message onto muscle cell, sarcolemma (muscle cell membrane) undergo action potential all along length of cell membrane and into T-tubule system, voltage change causes releases of Ca+2 ions into muscle cell. Calcium causes actin-myosin units sarcomers to shorten

Shortening of actin myosin units lead to whole muscle contraction, connection of many cells make whole muscle shorten bringing about body movements, movement happens across joints between skeletal elements

Joints:

connect skeletal elements, synovial joints are lubricated mobile joints, skeletal elements linked by synovial jounts move when muscle pull on those skeletal elements.

Flexion- joint angle decreases

Extension-joint angle increases

Adduction- body parts move towards midline

Abduction-body parts move away from midline

Rotation- body part moves around its own axis

Circumduction- body part moves so that cone shape is outlined

Inversion- sole of foot turns inward

Eversion- sole of foot turns outward

Structure of bone:

bone is alive, has nerves, blood supply, cells, connective tissue very organized in layers around blood vessels, cells make bone tissue, dissolve bone tissue, live inside bone tissue

Fetal bone formation: cartilage model forms first, then bony tissue fills around blood vessels, final bone has three parts central shaft diapysis, and 2 ends epiphysis, new bone tissue forms with in cartilage

Medullary Cavity: inside diaphysis is hollow tube, filled with bone marrow where blood cells form.

Calcium Regulation and Bone:

Bone serves as calcium storage, calcium is needed for many aspects of cell metabolism, but especially in muscle cells. Calcium regulation is negative feedback mechanism, release of calcium by degrading bone can be contrery to support role of bone, osteoporosis is a result of calcium need