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67 Cards in this Set

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Functions of muscle
generation of movement, prevention of movement (posture maintenance - reflex action), generation of 3/4 of body heat.
force and motor unit recruitment concept
more motor units are recruited when more force is required. (motor unit = muscle fibre + nerve that enervates it.)
appendicular skeleton
portion of the skeleton which forms the appendages: shoulders, hips, limbs.
26 bones of the vertebral columnar portion of the axial skeleton. protect the spinal cord and serve as an attachment point for the other bones of the body
intervertebral disk
cartilaginous disk between the vertebrae which serves as a shock absorber - strong attachment point between the vertebrae, and allow for some spinal movement.
ruptured disk
compression of the spinal column causes two vertebrae to push together, crushing the hard ourter portion of the cartilage, tearing it. this can cause the soft inner portion of the disk to herniate, pushing out of the ruptured area. This can cause pinching of a spinal nerve.
connective tissue that attaches muscle to bone
connective tissue that attaches bone to bone, primarily to strengthen and stabilize joints
makes up most of the ligaments, tendons and other connective tissue. Is produced by fibroblast cells. the living cells in connective tissue. makes joints tough but flexible.
covers the surface of bone not covered by cartilage and contains blood vessels, nerves, and cells which create new bone
end of muscle
contraction of a muscle to shorten the distance and decrease the angle between two attached bones
contraction of a muscle to increase the angle between the two attached bones
compact bone
The very hard dense part of the bones in the human skeletal system, which is generally made primarily of mineral crystals (mostly calcium phosphate and calcium carbonate) which surround collagen fibres. Blood vessels also occur throughout compact bone to continually nourish it, and to carry waste and other products away from bone to the rest of the body. has a central hollow cavity.
medullary cavity
hollow space in a bone surrounded by compact bone. Is generally filled with yellow marrow, composed of energy storing fat cells
spongy bone
a spongy appearing, but hard bone type at the ends of bones, containing many pockets, which hold the red marrow that produces red and white blood cells.
bone forming cells that can secrete cartilage, but also deposit calcium to form bone. these are the second stage of bone forming cells.
bone forming cells that can secrete cartilage, but also deposit calcium to form bone. these are the second stage of bone forming cells.
the fetal stage of bone cells, which produce only a cartilage framework, eventually replaced by bone.
mature bone cells that direct the deposit and removal of calcium
arise from a type of white blood cell. remove existing hardened bone and dissolve calcium deposits, digest cartilage. followed by osteoblasts which replace the bone.
Caused when there is an imbalance in the body between the level of bone production, and the rate of absorption of bone by the body, resulting in the overall loss of bone mass. Generally more severe in
women, osteoporosis generally occurs after menopause and may be in part due to changes in hormone levels, and can result in a loss of more than 1/3 of bone mass. This causes bones to break easily and be excessively brittle.
muscle fibre
muscle cell - elongated cells filled with thousands of myofibrils. muscle cells contain more than one nucleus.
very long thin fibres that make up muscle cells.
striated muscle.
muscle that has a striped / lined appearance due to the presence of sarcomeres which allow it to contract.
segment of a myofibril fibre, from one z-ine to the next. the repeating units that make up muscle cells and contain the contractive units.
the protein which makes up the thin filaments of the sarcomeres of muscle.
A protein within the sarcomere structure of skeletal muscle tissue, myosin makes up the thick filaments of the sarcomeres, and contains the "cross bridge" elements that are largely responsible for the contraction mechanism.
tropomyosin, troponin
closely related set of proteins of muscle that are involved in the regulation of muscle contraction. closely associated with the thin filaments, when moved aside by calcium, allow cross bridges to join to actin binding sites to contract muscles.
sarcoplasmic reticulum
a complex system of membrane bound storage saces (modified endoplasmic reticulum) which collects and stores calcium.
small protrusions of the myosin thick filaments which stick out to the side of the thick filaments and are responsible for the binding to the actin molecules of a thin filament to cause contraction.
neuromuscular transmission
process by which the action potential of a neuron produces an action potential in a muscle cell. transmitted across a synapse, just like neuron-neuron, only the neurotransmitter is always acetylcholine
twitch contraction
the force developed by a muscle cell in response to a single action potential
a sustained muscle contraction of maximal strength caused by cumulative action potentials causing cumulative releases of calcium and thus cumulative duration + strength of contraction due to raised Ca++ levels. (Ca++ doesn't have time to diffuse out between action potentials, thus strength and duration of contraction increases.) usually 3-4 times stronger than a single contraction.
length-tension curve
balance between how much strength can be generated by a muscle versus the given length (stretching or shortening) of that muscle.
motor unit
a motor neuron ( a neuron that causes movement) and the muscle cells that it directly controls.
contraction time
speed at which a muscle can shorten is inversely proportional to the force that it requires to shorten it. thus small loads can be applied more quickly than large loads.
isometric contraction
the muscle itself stays the same length because opposing muscles are contracted without changing the position muscle ends attached to the bones or the bones themselves. Muscle movements where movement doesn't take place are generally referred to as isometric contractions.
isotonic contraction
same + tone: constant force is applied, changing the muscle in length, contractions in which MOVEMENT occurs.
rigor mortis
myosin cross bridges of the thick filaments of muscle cells become locked to the thin actin filament binding sites, causing a sustained contraction. The ATP required to release the cross bridges from the filaments is quickly used up after death.
most rapid source for ATP replenishment for muscles, 3 - 5 times the amount of phosphocreatin is in cells, than ATP.
breaking down of glucose from glycogen stores. does not require oxygen, but is much more efficient with oxygen. as anaerobic reaction yields only two ATP for each glucose molecule.
aerobic metabolism
oxidative metabolism that requires oxygen to create ATP from multiple energy sources - the predominant form of muscular enery production
TYPE I Skeletal muscle fibre
SLOW OXIDATIVE. high endurance. contracts slowly. has high capacity for aerobic production of ATP, can make it as fast as it is burned. store almost no glycogen, supplied by many blood vessels. lots of mitochondria. store oxygen locally in myoglobin.
Type IIb skeletal muscle fibre
FAST GLYCOLYTIC: fast oxidative muscle fibre. less common than type I. fast contracting, limited aerobic capacity, moderate power, fatigued at moderate rate. Use ATP faster than can make it.
iron containing oxygen storage cells in type I oxidative muscle.
stored energy source for muscles.
can be metabolized to ATP to create energy for muscles. anaerobically only makes two ATP
decline of muscle performance over time during sustained heavy exercise, caused by loss of potassium from cells, altered hydrogen ion concentration, and depletion of acetylcholine in motor neurons such that they can no longer produce muscle cell action potential.
cardiac muscle
found only in the heart, specialized electrical connections and differently shaped muscle cells, not nearly as long as skeletal muscle cells.
intercalcated disc
Within the myocardial or cardiac (heart) muscle cells, an intercalcated disk is the tissues of the adjoining ends of two myocardial cells, and includes the physical connections called desmosomes, as well as the gap junctions that allow transmission of action potentials between cells.
areas of physical attachment of the intercalcated disc.
gap junction
proteins that span the two membranes of the intercalcated disc, allowing direct passage of ions permitting action potential transmission between cells.
one large multinucleated cell without individual cell membranes... i.e. this is the way that the heart behaves - sync.
myocardial infarction
heart attack. caused by interrupted or compromised blood supply to the heart which can damage or kill myocardial cells.
1/1000 second
smooth muscle
found around blood vessels and hollow organs, is not striated. Is an involuntary muscle. Plays a key role in determining blood pressure. spindle shaped cells and much smaller than skeletal muscle cells.
slow wave potentials
in smooth muscle, these slow rhytmic electrical activities last several seconds each, and are caused by cyclical changes in sodium tranport rates of smooth muscle. Very efficient. Smooth muscle never fully relaxes, only altering the degree of contraction, unlike skeletal muscle cells which must relax from time to time, or run out of energy.
sliding filament mechanics of muscle contraction.
muscles are made up of many thousands of interspersed thick myosin filaments and thin actin filaments. The actin filaments are closely linked to the troponin / tropomyosin chemicals. Sliding filament mechanicism begins when an action potential occurs. calcium is released from the sarcoplasmic reticulum where it is stored. The calcium binds to the troponin/tropomyosisn, causing a position shift in the fibres of the thin filaments. This allows the cross bridges of the thick filaments to bind to the actin binding sites of the thin filaments, causing the thick and thin filaments to slide opposite to each other, contracting the muscle. The increased calcium levels in the cytosol of a muscle is what caused the contraction. Contraction strength is proportional to calcium levels. A contraction ends when calcium is transported from the cytosol back to the sarcoplasmic reticulum (thus causing troponin / tropomyosin to again inhibit myosin crossbridges from attaching to the actin thin filaments.
twitch summation / tetanus phenomenon
A twitch is the singular response of force by a muscle cell, in response to a singular action potential. This muscular response has a set magnitude, and a set duration, and outlasts the action potential that initiated it. However, if a second action potential stimulates a force response by the same muscle cell while the first response is still ongoing, a greater force is generated by the cell, for a longer duration than if only one action potential had occurred. In tetanus, imagine that many action potentials occur one after another - the action potential generated is MUCH larger (generally about three or four times larger), and has a far longer duration than the normal response to only one action potential. Therefore, a single muscle cell can be made to give a far greater muscular output, simply by regulating the frequency of stimulation of the cell. This "tetanus" occurs because the rapidity of the action potentials means that there is no time for the intracellular calcium concentration to disperse, (which would allow the muscle cells to return to their original relaxed positions) creating the sustained maximum strength contraction.
different energy sources for muscle
a) Stored ATP - primary direct source of energy in muscle cell. ATP releases energy when breaks down to ADP + Pi. Is is stored in small quantities -it can be used up in 10 sec of maximal exercise

b) Phosphocreatine - first and most rapid ATP replenishment. Represents stored energy 3 -5 X to stored ATP. Used up in 30 - 40 sec of maximal exercise.

c) Glycolysis - proceeds withough oxygen. One glucose breaks down to2 lactic acid and 2 ATP. Mainly used during first 3 - 5 mins of heavy exercise.

d) Aerobic metabolism - glucose, fatty acid, and a.a can break down to produce ATP. Requires oxygen and is the predominant form of long-term energy prodction in muscle cell. High ATP yeild - one glucose can produce 38ATP.
diff types of skeletal muscle fibres, examples, which types of activities best for each
type one - best for maintaining posture - sustainable for long periods.

tupe II. non sustained, forceful movements. arm muscles, etc.
compare & contrast action potential in cardiac versus skeletal muscle - relate to force produced.
cardiac muscle cell lasts much longer, prolonged plateau phase of depolarization. constant force, tetanus not possible.
how can the degree of tension in smooth muscle be modulated?
degree of neural stimulation, depolarization., inhibition / hyperpolarization.
cardiac muscle functionally similar to skeletal and smooth muscle?
specialized for contraction.
bone is dynamic tissue. explain.
constantly being replaced, repaired, esp. when under stress. requires a constant balance between activity of osteoclasts,which dissolve the calcium deposits, break down cartilage, and osteoblasts, responsible for new bone formation. bones get bigger when exposed to exercise, compression and mechanical stress. This produces electrical currents which stimulate osteoblasts. new bone tissue deposited to counteract stress in correct places. Can change shape of bone. broken bones that heal at an angle may be straightened over time. homoeostatic mechanism to distribute loads and stresses evenly.
review synovial joint
fibrous capsule surrounds joint, cartilage protects bone ends. synovial fluid lubricates between in synovial cavity. synovial membrane encloses synovial fluid.