Required Readings

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University of Toronto Scarborough
Biological Sciences
Connie Soros

TEXTBOOK NOTES FOR REQUIRED READINGS Tracheal Blockage: - Objects that become stuck in the larynx or trachea are expelled by coughing - If the victim cannot breathe nor speak, the Heimlich maneuver is used to help the victim - If the blockage remains, rescuers may perform a tracheostomy. In this procedure an incision is made through the anterior tracheal wall and a tube is inserted - A tracheometry may be required (1) when the larynx becomes blocked by a foreign object, inflammation, or sustained laryngeal spasms, (2) when a portion of the trachea has been crushed, or (3) when a portion of the trachea has been removed during treatment for laryngeal cancer Respiratory Changes at Birth: - Before deliver, pulmonary arterial resistance is high because the pulmonary vessels are collapsed - The rib cage is compressed, and the lungs and conducting passageways contain only small amounts of fluid and no air - The first inspired air enters the passageways with enough force to push the contained fluids out of the way and inflate the entire broncheal tree and most of the alveoli - The same drop in pressure that pulls air into the lungs pulls blood into the pulmonary circulation; the changes in blood flow that occur lead to the closure of the foramen ovule, the embryonic interatrial connection, and the ductus arteriosus, the fetal connection between the pulmonary trunk and the aorta - Surfactant covering the alveolar surfaces prevents their collpase The Teeth: - Mastication (chewing) breaks down tough connective tissues and plant fibers and helps saturate the materials with salivary secretions and enzymes - The bulk of each tooth consists of a mineralized matrix similar to bone. This material, called dentine differs from bone because it does not containing living cells. Instead, cytoplasmic processes extend into the dentine from cells in the central pulp cavity - The pulp cavity is spongy and highly vascular. It receives blood vessels and nevers via a narrow tunnel, the root canal, located at the base, or root, of the tooth - The dental artery, dental vein, and dental nerve enter the root canal through the apical foramen to service the pulp cavity - The root of the tooth is anchored into a bony socket, or alveolus - Collagen fibres of the periodontal ligament extend from the dentine of the root to the alveolar bone, creating a strong articulation known as a gomphosis - A layer of cement covers the dentine of the root, providing protection and firmly anchoring the peridontal ligament. The cement is very similar in histological structure to bone, and less resistant to erosion than dentine - The neck of the tooth marks the boundary between the root and the crown - The crown is the visible portion of the tooth that projects above the soft tissue of the gingiva - Epithelial cells of the gingiva sulcus form tight attachments to the tooth above the neck, preventing bacterial access to the lamina propria of the gingiva or the relatively soft cement of the root. If this attachment breaks down, bacterial infection of the gingiva, termed gingivitis, may occur - The dentive of the crown is covered by a layer of enamel - Enamel contains densely packed crystals of calcium phophate and is the hardest biologically manufactured substance - Types of teeth: there are four types of teeth, each with specific functions: - 1. Incisors: are blade-shaped teeth found at the front of the mouth. Useful for clipping or cutting, as when nipping off the tip of a carrot stick. Have a single root - 2. The cuspids (canines): conical with a sharp ridgeline and pointed tip. Used for tearing or slashing. Have a single root - 3. Bicuspids (premolars): have one or more roots. Premolars have flattened crowns with prominent ridges. Used for crushing, mashing, and grinding - 4. Molars: have very large flattened crowns with prominent ridges and typically have three or more roots. Used for crushing and grinding Dental Succession: - During development, two sets of teeth begin to form. The first to appear are the deciduous teeth, also called the primary teeth, milk teeth, or baby teeth. These are the temporary teeth of the primary denteition - There are usually 20 deciduous teeth, five on each side of the upper and lower jaws - The larger adult jaws can accommodate more than 20 permanent teeth, and 3 additional molars appear on each side of the upper and lower jaws as the individual ages - The permanent root count: 32 - On each side of the upper jaw, the primary dentition consists of two incisors, one cuspid, and a pair of deciduous molars. These are gradually replaced by permanent dentition - The adult molars take the place of the deciduous moars, and the definitive adult molars extend the tooth row as the jaw enlarges - The third molars, wisdom teeth, may not erupt before age 21, if they appear at all A Denal Frame of Reference: - The upper and lower rows of the teeth form a curving dental arcade - The term labial or buccal refers to the outer surface of the dental arcade, adjacent to the lips or cheeks - Mesial or distal refers to the opposing surfaces between the teeth in a single dental arcade - The occlusal surfaces of the teeth face their counterparts on the opposing dental arcade. They perform the actual clipping, tearing, crushing, and grinding actions Mastication: - During mastication, food is forced back and forth between the vestibule and the rest of the oral cavity, crossing and recrossing the occlusal surfaces. This movement results in part from the action of the masticatory muscles, but control would be impossible withouth the aid of the buccal, labial, and lingual muscles - After all the chewing, the tongue begins compacting the debris into small oval mass or bolus, that be swallowed - The pharyngeal constrictors push the bolus towards the esophagus - The palatopharyngeus and stylopharyngeus muscles elevate the larynx - The palatal muscles raise the soft palate and adjacent portions of the pharyngeal wall - The pharyngeal muscles cooperate with muscles of the oral cavity and esophagus to initiate the swallowing process, or deglutition Advances in the Treatment of Renal Failure: - One normal kidney is sufficient to filter the blood and maintain homeostasis - Renal failure wonʼt develop unless both kidneys are damaged - In hemodialysis, a dialysis machine containing an artificial membrane is used to regulate the composition of blood - For temporary kidney dialysis, a silicone rubber tube called a shunt is inserted into a medium- sized artery and vein - While connected to the dialysis
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