PET3322 Fall 2012 Final Exam Study GuideCh. 23- The Respiratory System-Excessive CO2 produces acidity and can be toxic to cells.-Conducting Zone- nose, nasal cavity, pharynx, larynx, trachea, bronchi, broncioles, and terminal bronchioles; filter, warm, moisten and conduct air.-Respiratory Zone- (where gas exchange occurs) respiratory bronchioles, alveolar ducts, alveolar sacs, and alveoli.-Nose--open to pharynx through internal nares or choane-Ducts from the paranasal sinuses (which drain mucus) and the nasolacrimal ducts (which drain tears) also open into the nasal cavity-Nasal conchae moisten, warm and trap dust particles in air.-Pharynx- (throat)-starts at internal nares and extends to the level of the cricoid cartilage, the most inferior cartilage if the larynx (voicebox)-Larynx- (voicebox)-connects laryngopharynx with trachea-epiglottis- during swallowing, the pharynx and larynx rise and cause the epiglottis to move down and form a lid over the glottis, closing it off.-Voice production--ventricular folds- false vocal cords-vocal folds- true vocal cords-Bronci--At the superior border of 5th thoracic trachea divides into left and ride primary broncus (this internal ridge is called the carina)-Air passages undergo 23 orders of branching in the lungs-Secondary bronchi split to supply each lobe-Path: Trachea primary bronchi secondary bronchi tertiary bronchi bronchioles terminal bronchioles microscopic resp. bronchioles-bronchioles consist of cuboidal epithelium, have a complete layer of circular smooth muscle and lack cartilage support and mucus-producing cells-Lungs- seperated from each other by the heart and other structures of the mediastinum, which divides the thoracic cavity into two anatomically distinct chambers. As a result, if trauma occurs to one lung and it collapses, the other one may remain expanded.-Alveoli- -An alveolus is a cup shaped outpouched line by simple squamousepithelium and supported by a thin elastic basement membrane-An alveolar sac consists of 2+ alveoli that share a common opening-Terminal bronchiolesresp bronchiolesalveolar ductsalveolar sacsalveoli-Air blood barrier is composed of:-Alveolar and capillary walls-Their fused basal membranes-Alveolar walls:-Area single layer of type 1 epithelial cells-Permit gas exchange by simple diffusion-Secrete angiotensin converting enzyme (ACE)Pulmonary Ventilation-The process of gas exchange in the body, called respiration, has 3 basic steps:1)Pulmonary ventilation- or breathing, is the inhalation (inflow) and exhalation (outflow) of air and involves the exchange of air between the atmosphere and alveoli of lungs2)External (pulmonary) respiration- is the exchange of gases between the alveoli of the lungs and the blood in the pulmonary capillaries across the pulmonary membrane. -Blood gains O2 and loses CO23)Internal (tissue) respiration- is the exchange of gases between blood in the systemic capillaries and tissue cells. -Blood loses O2 and gains CO2-Within cells, the metabolic reactions that consume O2 and give off CO2 during the production of ATP are termed cellular respiration.Pressure Changes During Pulmonary Ventilation-Air moves into the lungs when the air pressure inside the lungs is less than the air pressure in the atmosphere.-Air moves out of the lungs when the air pressure inside the lungs is greater than the air pressure in the atmosphere.-Negative respiratory pressure < Patm-Positive repiratory pressure > Patm-The first step in expanding the lungs during normal quiet breathing involves contraction of muscles of inhalation, the diaphragm (75%) and external intercostals (25%, elevate ribs). Scalenes and sternocleidomastoids also during exercises or forced breathing.-During quiet inhalation, the pressure between the two pleural layers in the pleural cavity, called intrapleural (intrathoracic) pressure, is always subatmospheric.-Exhalation- -Passive process (quite exhale)-Active only during forceful breathing (exercise, playing an instrument)-Abdominal and internal intercostal contractOther Factors Affecting Pulmonary VentilationA. Surface tension of alveolar fluid-Surface tension arises at all air-water surfaces because the polar water molecules are more strongly attracted to each other than to gas molecules in the air.-In the lungs, surface tension causes the alveoli to assume the smallest possible diameter-Surface tension also accounts for 2/3 of lung elastic recoil which decreases the size of alveoli during exhalation-Surfactant reduces its surface tension to less than that of water-Deficiency in premature babies increases surface tension so that the alveoli collapse at the end of each exhalation and great effort is needed in the next inhalation to reopen the collapsed alveoli.B. Compliance of the lungs-refers to how much effort is required to stretch the lungs and chest wall-High compliance = stretches easilyC. Airway resistance-Like bloodflow, rate of airflow depends on both the pressure difference and the resistance. -Airflow= DP/ Resistance-Greatest resistance in medium sized bronchi-inhalation, walls expand, bronchioles expand, less resistance.-Opposite for exhalationLung Volumes and Capacities-Tidal Volume (VT)- volume of one breath-Minute Volume (MV)- total volume inhaled and exhaled in one minuteMV= 12 breaths/min x 500mL/breath = 6 liters/min-Anatomic (respiratory) dead space- the conducting airways with air that does not undergo respiratory exchange (150mL)-Alveolar Ventilation rate (AVR)- measure the flow of fresh gases into and out of the alveoli during a particular time-AVR = frequency x (TV-dead space)-Slow deep breathing AVR. Rapid shallow breathing AVRExchange of Oxygen and Carbon Dioxide-Total pressure exerted by a mixture of gases is the sum of the pressures exerted independently by each gad in the mixture-Each gas exerts its own pressure as if no other gas were present-Daltons Law- the partial pressure (Px) of each gas is directly proportional to its percentage in the mixture-Atmospheric pressure = 760 mmHgO2 = 20.93% = 160 mmHGCO2 = 0.0003% = 0.3 mmHgN2 = 79.04% = 600 mmHg-Henry’s Law- the quantity of gas that will dissolve in a liquid is proportional to the partial pressure of the gas and its solubility-More gas molecules are soluble at a higher pressure- P solubility-Although CO2 has a lower partial pressure gradient:-It has 20x more soluble membranes than O2-It diffuses in equal amounts with oxygen-While O2 is
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