BIOL 1344 Lecture 18 Outline of Last Lecture I. Gas Transport in the BodyA. Laws Concerning Gas TransportB. Pressures of Air at Sea LevelII. Solubility of GasOutline of Current Lecture I. Nitrogen Below Sea LevelII. Normal / Fast / Slow Breathing EffectsIII. Control of RespirationIV. Introduction of Digestive SystemCurrent LectureAt sea level, nitrogen from the air is not dissolved. However, if a person is diving, pressure doubles for every 33 feet. At this pressure, nitrogen dissolves in blood and forms bubbles which choke blood vessels. This is called nitrogen narcosis or Caisson’s Disease. Scuba tanks replace nitrogen with helium which is nonreactive and will not form these bubbles.Normal breathing is called eupnea. Breathing with increased depth is called hyperpnea while breathing with increased depth and rate like in a state of hyperventilation creates hypocapnia. Hypoventilation is breathing that is too slow (bradypnea) or too shallow (hypopnea) to support the body’s metabolic needs. In this condition, the partial pressure of carbon dioxide increases which causes a state of hypercapnia. Gas exchange rate will be altered in either of these states. During hypoventilation, the amount of oxygen in the air is decreased which is called hypoxia. Control of Respiration: The respiratory center includes the pontine center (or pneumotoxic center) within the pons and the dorsal respiratory group (DRG) and the ventral respiratory group (VRG) within the medulla. There are neuron groups called inspiratory neuron within the VRG which connect through action potentials with expiratory neuron groups also in the VRG. Expiratory neuron groups then have a connection with a neuron group in the DRG and finally connect back to the first group of neurons to make a complete round of inspiration / expiration of breath. The pontine center is responsible for making this a smooth transition, if this center is damaged, erratic breathing is the result. It also control the inflation of the lungs or how much These notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.air goes into the lungs which should be about 500 ml, due to stretch receptors within the lungs, it cannot go above 1000 ml. Chemoreceptors are in the medulla and regulate levels of gases in the air we breathe. Baroreceptors are aortic bodies and carotid bodies which act as stretch receptors and detect pressure within the lungs. Digestive System: the GI tract is about 30 feet long however due to muscle tone it is about a third of this length in a living person. The tract essentially goes mouth (teeth), pharynx, esophagus (upper and lower sphincter), stomach, [pyloric sphincter], duodenum, [sphincter of oddi], jejunum, ileum, [ileo-cecal valve], rectum (internal anal sphincter) and anus (external analsphincter). The upper esophageal sphincter and the external anal sphincter are made up of skeletal muscles so they are under our control while the rest are smooth muscles and work
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