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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
Respiratory System Organs
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
trachea - tube reinforced by rings of cartilage to maintain shape.
bronchi - large tubes branching from trachea, one to each lung.
||Boyles 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 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
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
ZOOLOGY 310 GUIDE TO ADAM