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BIOL 273 - Unit 5- Respiratory System

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University of Waterloo
BIOL 273
Vivian Dayeh

Unit 5 The Respiratory SystemThe exchange surface must be thin and moist to allow gases to pass from air into solution and yet at the same time must be protected from dying out as a result of exposure to airSome animals have behavioural adaptations that restrict them to humid environments and nighttime activitiesA more common solution to dehydration is anatomical an internalized respiratory epithelium ie Human lungs o It creates a humid environment for the exchange of gases with the blood and protects the delicate exchange surface from damage o air flow requires a muscular pump to create pressure gradientsmore complex respiratory systems consist of two separate components o a muscledriven pump o a thin most exchange surfacethere are 4 primary functions of the respiratory system 1 exchange of gases between the atmosphere and the blood brings in O and eliminates CO from the body 222 Homeostatic regulation of body pH the lungs can alter body pH by changing CO levels 23 Protection from inhaled pathogens and irritating substances the respiratory epithelium is well supplied with defense mechanisms to trap and destroy potentially harmful substances before they can enter the body 4 Vocalization air moving across the vocal cords creates vibrations used for speech singing and other forms of communicationThe respiratory is also a significant source of water loss and heat loss from the body which must be balanced using homeostasis Principles of air flow o Flow takes place from regions of higher pressure to regions of lower pressure o A muscular pump creates pressure gradients o Resistance to air flow is influenced primarily by the diameter of the tubes through which the air is flowingAir is a less viscous compressible mixture of gases while blood is a noncompressible liquidCellular Respirationrefers to the intracellular reaction of oxygen with organic molecules to produce carbon dioxide water and energy in the form of ATPExternal respirationthe movement of gases between the environment and the bodys cells can be divided into 4 integrated processes I The exchange of air between the atmosphere and the lungs known as ventilation or breathingInspirationinhalation the movement of air into the lungsExpirationexhalation the movement of air out of the lungsThe process of ventilation takes place by the mechanics of breathing II The exchange of O and CO between the lungs and the blood 22III The transport of O and CO by the blood 22IV The exchange of gases between blood and the cellsExternal Respiration requires coordination between the respiratory and circulatory systems The Respiratory System consists of structures involved in ventilation and gas exchange 1 The Conducting system of passages or airways that lead from the external environment to the exchange surface of the lungs 2 The Alveoli alveolus are a series of interconnected sacs and their associated pulmonary capillaries they form the exchange surface where oxygen moves into the blood and carbon dioxide moves out 3 The bones and muscles of the thorax and abdomen that assist in ventilationThere are two parts to the respiratory system 1 Upper Respiratory tract consists of the mouth nasal cavity pharynx and larynx 2 Lower Respiratory tract consists of the trachea two primary bronchi their branches and the lungs aka the thoracic portion because it is enclosed in the thorax The Thorax Fig 172The thorax is bounded by the bones of the spine and rib cage and their associated musclesThoracic cage is made up of the thoracic bones and muscles o Chest wall the ribs and spineDiaphragm a domeshaped sheet of skeletal muscle forms the floor of the thoracic cageIntercostal muscles muscles associated with the rib cage used for breathing connect the 12 pairs of ribs Sternocleidomastoids and the scalenes run from the head and neck to the sternum and first two ribsFunctionally the thorax is a sealed container filled with 3 membranous bags or sacs o Pericardial sac contains the heart
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