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26 Cards in this Set

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What are the functions of the skeletal system?
Support; protection of internal organs; locomotion (movement); production of blood cells; mineral storage
How are bones formed?
Osteoblasts form collagen and lay down hydroxyapatie crystals and become osteocytes.
Into what two regions is the human skeleton divided?
Axial skeleton, appendicular skeleton.
Describe the axial skeleton.
Made up of 80 bones, it includes the sull, vertebrae, ribs, and sternum.
Describe the appendicular skeleton.
Made up of 126 bones, it includes the pectoral girdle, pelvic girdle, and is associated with limbs.
Which connective tissue connects bone to bone?
Ligaments.
Which type of arthritis is common in older people as a normal part of aging?
Osteoarthritis.
Which type of arthritis can occur in people of any age?
Rheumatoid arthritis.
Describe achondroplasia.
Bones do not grow to proper length; results in dwarfism.
Describe spina bifida.
In the vertebral column, a spinal foramen doesn't close, and part of the spinal cord is exposed.
About how many skeletal muscles are there in the human body?
About 700.
What are the four characteristics of muscle?
Able to contract

Able to be stimulated (by a nervous impluse)

Able to stretch

Able to relax
To what mechanism is muscle movement attributed?
Contractile proteins. They change form b y contracting or elongating, due to actin and myosin that interact to cause contraction when powered by ATP.
What do muscle cells consist of?
Sarclemma (cell membrane)

Several nuclei

Sarcoplasmic reticulum

Several myofibrils- parallel arrangements of many actin and myosin microfilaments
Describe myosin.
Thick filaments composed of two protein coils.
Describe actin.
Thin filaments composed of three proteins (actin, tropomyosin, troponin)
Describe the way a muscle contracts.
Nerve impulse is sent to muscle cell.

The end of the nerve forms a neuromuscular junction with a muscle cell.

The space between the nerve and sarcolemma is the synapse.

A chemical (acetylcholine) is realeased from the end of the nerve cells and passes the impulse through the synapse to the sarcolemma.

Impulse passes along the sarcolemma to T tubules.

Impulse passes into sarcoplasmic which releases calcium ions

Calcium ions bind to troponin, resulting in movement of the tropomyosin to expose the receptor sites on actin

Myosin head binds to now exposed receptor sites on actin form a cross-bridge.

ATP in myosin head splits to realease energy causing a power stroke.

Myosin head pulls on the actin filaments to shorten the sarcomere and the muscle contracts.
What does most of the energy for muscle contraction come from?
ATP
What if a sudden spurt of muscular activity is needed to create additional ATP molecules?
Creatine phosphate is used.
What if there is no oxygen in the muscles?
Lactic acid forms.
What is tetany?
Occurs when the muscle does not have time to relax from the preceeding contraction. The muscle goes into a sustained state of contraction. E.g. holding a heavy weight continually.
What are muscle cramps?
Pain during or immediately after exercising due to involuntary tentany in muscle.
What is muscle soreness?
Soreness in muscles which appear hours after exercise. Tears in muscle tissue are irritated by lactic acid.
What is muscle atrophy?
The disuse of muscle, resulting in reduction in size. Often occurs when a muscle is kept in a cast.
What is myasthenia gravis?
Muscular paralysis where no nerve impulses reach muscle. Muscles of face affected in early stages.
What is muscular dystrophy?
A genetic disease that continually leaks out Ca++ into the muscle, causing the mucles to cease functioning.