BGYB30H3 Lecture 18 Notes Endocrinology 1-Nov 10

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BGYB30H3 Lecture 18 Notes
-smooth muscle is found in the walls of hollow organs and tubes in blood vessels
-contraction changes shape of organs and moves materials in, out, or around the body
-smooth muscle has low fatigue, low oxygen consumption, less energy required to generate
force
-smooth muscles are small and have a single nucleus in spindle fibres
-neurotransmitters and sex hormones control smooth muscles
-smooth muscles integrate signals and act based on the majority of neurotransmitters
-smooth muscles may hyperpolarize or depolarize depending on the signal
-smooth muscles may depolarize without a graded or action potential or a change in
membrane potential
-in a single unit cell smooth muscle, cells contract as a unit through being connected by gap
junctions, which conducts electrical synapses
-multi-unit smooth muscle involves cells associated with variscosities with no gap junctions,
allowing fine control of contractions
-smooth muscle in the uterus goes from multi-unit to single unit during pregnancy
-smooth muscle has longer actin and myosin filament
-rate of cross bridge cycling is slower in smooth muscle to allow longer contractions
-there is less sarcoplasmic reticulum than skeletal muscles
-caveolae concentrates calcium in the smooth muscle
-smooth muscles lack troponin and sarcomeres
-smooth muscles have oblique bundles that extend diagonally
-ÁZvZu}}Zuµo}vU](}uPo}µoZv}v[PZ}
-myosin moves slowly and lengthens the contraction period by decreasing the rate of
crossbridge cycling
-myosin light chain kinase regulates contractions
-lack of sarcomere allows myosin to move longer distances with actin sliding over it
- a reflex is the integration of sensory info to control muscles/glands
-input is integrated in the spinal cord or the brain to cause an output
-feedforward allows the body to anticipate stimuli and begin a response prior to the stimulus
-reflexes can be classified by the
x by being viscera or somatic
x number of neurons in the pathway
x learned through conditioning or innate
x originates in the spinal cord or the brain
-autonomic reflexes are sometimes caused by the spinal cord or modulated by descending
tracts from the brain
-spinal reflexes include
x urination
x defecation
-brain stem reflexes include
x Sneezing
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Document Summary

Smooth muscle is found in the walls of hollow organs and tubes in blood vessels. Contraction changes shape of organs and moves materials in, out, or around the body. Smooth muscle has low fatigue, low oxygen consumption, less energy required to generate force. Smooth muscles are small and have a single nucleus in spindle fibres. Smooth muscles integrate signals and act based on the majority of neurotransmitters. Smooth muscles may hyperpolarize or depolarize depending on the signal. Smooth muscles may depolarize without a graded or action potential or a change in membrane potential. In a single unit cell smooth muscle, cells contract as a unit through being connected by gap junctions, which conducts electrical synapses. Multi-unit smooth muscle involves cells associated with variscosities with no gap junctions, allowing fine control of contractions. Smooth muscle in the uterus goes from multi-unit to single unit during pregnancy. Smooth muscle has longer actin and myosin filament.

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