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LAB 21 - ADAM Respiration CD


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The respiratory is a complex group of organs that removes carbon dioxide from the blood and replaces it with oxygen. Air enters the respiratory system through two paired openings called the external nares or nostrils. Within the nose, the air passes through the nasal cavity then travels through the pharynx. Air then enters the larynx after passing thought the larynx air enters the trachea which is held open by rings of cartilage. Trachea divide into a right and left bronchus which carry the air into the lung.

Respiratory System Organs

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nose.gif (512 bytes) nostrils and nasal cavity - filter, warm, and humidify air.
pharynx - (throat) intersection for esophagus and trachea.
larynx - (Adam's apple) voice box . As air is exhaled, vocal cords vibrate and produce sound.
trachea - tube reinforced by rings of cartilage to maintain shape.
bronchi - large tubes branching from trachea, one to each lung.

wpe2.jpg (13883 bytes) Boyle’s law –– the pressure of a gas in a closed container and at constant temperature varies inversely to the volume of the container. If the volume goes up, the pressure goes down. If the volume goes down, the pressure goes up. Pressure is caused by molecules hitting one another and the sides of the container as they move around within it. Pressure changes occur in the lungs during respiration and gases move from areas of high to low pressure.

O2 Transport
O2 is transported in the red blood cells. Oxygen is not very soluble in water. Hemoglobin can carry 60 times as much oxygen as an equal volume of water, so oxygen binds to hemoglobin molecules.

Hb + O2 WB00678_.gif (615 bytes) Hb.O2
deoxyhemoglobin oxyhemoglobin

CO2 Transport
7% of the CO2 goes into solution of water in blood, the remaining CO2 goes into the red blood cells.

Control of Respiration
The basic rythum of breathing is controlled by respiratory centers located in the medulla and pons of the brainstem. This rythum is modified in response to input from sensory receptors and from other regions of the brain. Respiratory centers in the pons modify inspiration and allow for smooth transitions between inspiration and expiation. Expiratory centers in the medulla function during forced expiation stimulating the internal and abdominal muscles. The basic rythum of breathing is modified by input from the central and peripheral chemoreceptors. They respond to changes in the PCO2 and PO2 of arterial blood. Medullary chemoreceptors are located on the ventral surface of the medulla oblongata. The medullary chemoreceptors detect changes to the H+ concentration of the brain interstitial fluid, an indirect assessment of arterial PCO2. Chemoreceptors in the carotid and aortic bodies are stimulated by a rise in the PCO2, a rise in the H+ concentration, or a decline in arterial blood PO2. Peripheral chemoreceptors detect changes in carbon dioxide and hydrogen ion concentrations. The effect of the peripheral chemoreceptors on respiration is much less than the effect of medullary chemoreceptors.

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