Ch.5: Synaptic Activity
<span>Introduction<span>Otto Loewi studied the heart of the frog, which-like our own hearts- is supplied by two different peripheral nerves. One, the sympathetic nerve, excites the heart and makes it beat more rapidly; the other , the vagus, shows the heart. The problem was to discover the mechanism by which the effects of nerve impulses in either of these nerves are communicated to the heart muscle. Many believed that the electrical nerve impulse spread from the nerve to the muscle as an electrical wave; Loewi thought otherwise.Loewi tested two isolated frog hearts, one with the sympathetic and vagus nerves intact, the other with the nerves removed. A small tube containing salt water was placed in the heart with the nerves attached. When he stimulated the vagus nerve, the heartbeat slowed, as expected. Then he took salt solution that had been in the stimulated heart and placed it inside the heart without nerves. It too immediately slowed- exactly as if its own (missing) vagus nerve had been stimulated.He repeated the same procedure, stimulating the sympathetic nerve instead. The effect was again as if the nerve of the denervated heart itself were stimulated: the denervated heart began beating faster. These results could not be explained electrically; the nerves must have secreted chemicals into the salt solution that directly affect the muscles of the denervated heart.In one simple experiment, Loewi had demonstrated three important findings: (1) that communication at the gap between nerve and heart muscle was chemical, (2) that each nerve released a different transmitter substance, and (3) that it was the characteristics of the different transmitter substances that caused the increase or decrease in heart rate. This was the first direct experimental evidence of the action of chemical neurotransmitters.<span>Like the junction between nerve and heart muscle that Loewi studied, nerve cells communicate with each other at special junctions called synapses. </span></span></span><span><span> thanks and i hope this helps you.....
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Answer:
The inside of Neptune is very cold, which is about -214 degrees. Hence, no microorganisms could live there. Overall, the environment of Neptune sounds very unfriendly to life as we know it on earth.
The percent of the body surface area burned to the front torso is 36% and front of the right arm is 4.5%.The total body surface area involved in burn is 40.5% calculated by Rule of Nines.
The total body surface area (TBSA) is an easy way to get a rough burn size estimate that can be used when calculating a patient's fluid resuscitation needs.
The Rule of Nines or Wallace Rule of Nines, is a common tool used by healthcare professionals to assess the total body surface area involved in burn patients.
The Rule of Nines is estimated by assigning percentages to different body areas. For instance, the entire head is estimated as 9%, the entire trunk is estimated at 36% and each arm is estimated at 9%.
The total body surface area (TBSA) of a burn can also be calculated with a Lund and Browder Chart.
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The following model health claims can be used in the food labeling to illustrate the association between vitamin D, calcium, and osteoporosis:
1. Sufficient vitamin D and calcium throughout life, as a component of a well-balanced diet, may minimize the threat of osteoporosis.
2. Sufficient calcium and vitamin D as a component of a healthful diet, alongside physical activity, may minimize the threat of osteoporosis in the later stages. Thus, the given statement is True.
The correct answer is (B) Plants wouldn't be able to draw water from the ground through their roots.
Surface tension is the result of cohesion in water molecules. This cohesion is because of the pressence of hydrogen bonds which makes the water molecules attached to each other. This property is helpful for plants to uptake water from the grounds through their roots. As gravity acts on water, and surface tension will be weak the plants would not be able to uptake water.