Introduction Pollution is an undesirable change in the physical, chemical or biological characteristics of our air, land, and water that may or will harmfully affect human life or that of desirable species, our industrial processes, living conditions, and cultural assets (Odum, 1971) In other words, pollution is the unfavorable alteration of our environment, largely as […]
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Introduction •Anemia is defined as a reduction in the hemoglobin concentration of the blood below normal for age and sex OR red cell defect (Table 2.3). •Reduction of hemoglobin is usually accompanied by a fall in red cell count and packed cell volume (PCV), but these may be normal in some patients with subnormal hemoglobin
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Introduction The endocrine system is made up of the cells, tissues, and organs that secrete hormones into body fluid. Hormones diffuse into the bloodstream to act target cells some distance away. The body has two kinds of glands, exocrine (secretes products into ducts) and endocrine (secrete products into body fluids to affect target cells).
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•Distinctions between gustation and olfaction. Gustation used to detect and identify food-related chemicals in near environment. Olfaction used not just to detect food, also detection of enemies and mates. The gustatory system: Taste bud ·Gustatory receptors found in clusters- taste buds, receptors an axonal but generate APs. ·Gustatory receptors on tongue, throat, and mouth synapse
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•Photoreceptors located on retina. •retina contains rods and cones a) Rods used for black-and-white vision when illumination is dim. b) Cones are used for color vision, are shorter than rods. c) Humans have 100 million rods and 3 million cones in each retina. d) Most cones found in fovea. (1) Location where eye forms its sharpest
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Synaptic Transmission The process of information transfer at a synapse Plays role in all the operations of the nervous system 1897: Charles Sherrington- “synapse” Chemical and electrical synapses •1921- Otto Loewi •1959- Gurshan and Potter Six Types of synapses Axodendritic: Axon to dendrite Axosomatic: Axon to cell body Axoaxonic: Axon to axon Dendrodendritic: Dendrite to
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•Neurotransmitters are the chemicals which allow the transmission of signals from one neuron to the next across synapses. •They are also found at the axon endings of motor neurons, where they stimulate the muscle fibers. •They and their close relatives are produced by some glands such as the pituitary and the adrenal glands. •Neurotransmitter levels
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Nerve Action Potential Nerve signals are transmitted by action potentials, which are rapid changes in the membrane potential that spread rapidly along the nerve fiber membrane. Each action potential begins with a sudden change from the normal resting negative membrane potential to a positive potential and then ends with an almost equally rapid change back
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The Sinus Node as the Pacemaker of the Heart •In the discussion in last post, thus far of the genesis and transmission of the cardiac impulse through the heart, we have noted that the impulse normally arises in the sinus node. •In some abnormal conditions, this is not the case. A few other parts of
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Automatic Electrical Rhythmicity of the Sinus Fibers of heart •Some cardiac fibers have the capability of self-excitation, a process that can cause automatic rhythmical discharge and contraction. •This is especially true of the fibers of the heart’s specialized conducting system, including the fibers of the sinus node. •For this reason, the sinus node ordinarily controls
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