Unformatted text preview: mmogwnmmgsvgo senses. pltcoceco AquVOCOQO 10v122w ."x>x= these conditions. However, when the body is active, energy demands of the tissues increase. These demands must
be met, even at the expense of suspending operation of the gastrointestinal organs. Under these conditions
parasympathetic activity decreases and sympathetic activity increases. This results in increased activity of the
heart, which helps increase blood ﬂow to the skeletal muscles. The major areas of the brain that regulate autonomic fimction include the W, rags and W3
W. The hypothalamus m the fight-or-tlight response to elicit widespread activation of the
sympathetic nervous system when a person is in danger or otherwise excited. The hypothalamus also contains the
regulatory centers for WW, We and water balance all of which are regulated in some way by
autonomic neurons. The 113 oblon and nuns contain chioxmﬂar and W that control the heart,
blood vessels, and smooth muscle in the respiratory airways and regulate e automatic breathing patterns that do not require conscious thought Click the Home Menu Button
.."‘,..,.....""°‘“...."""....;, 7 WW 7‘1““. ‘ °"“"7 7“”77777'7'77’“"5"”"ﬂ" Click the somatic nervous system button: The
M [g thinly mum-tryouts! somatic nervous system controls only one type of
m m" mmmmﬁmd effector organ — skeletal muscle. In the somatic nervous systems, a single motor neuron travels from the central
4 t , nervous system to a skeletal muscle cell. When a motor
‘ neuron is activated it stimulates all the muscle ﬁbers in l its unit to contract.
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mam “""°""°'"""“‘°""‘“" "M“ Go to the next screen: Both the axon terminal of
W I? n. mum-humw an. the motor neuron and the portion of the plasma
mm” 3‘3“? “immw °' membrane of the skeletal muscle called the motor end
W at m- um Wm plate are spectalized at the neuromuscular junction.
. When an action potential arrives at the axon terminal of a
. motor neuron voltage gated calcium channels open and
. calcium enters the cytosol.
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m... Go to the next screen: The entry of calcium
to: mom triggers the release by exocytosis of acetylcholine, which diffuses to and binds to nicotinic cholinergic
receptors at the motor end plate opening cation
channels. Sodium enters the cell producing an end-plate
potential that generates currents throughout the plasma
membrane of the skeletal muscle cell depolarizing the
membrane to threshold to generate an action potential.
The action potential spreads along skeletal muscle cell Mover-Adi
momma ; Page 4 of 5 ...
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- Spring '07