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34 Cards in this Set
- Front
- Back
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what percent of oxygen is bound to Hb?
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98.5%
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what percent of CO2 is bound to Hb?
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30%
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what percent of CO2 is bound to bicarbonate?
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60%
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most Hb combines with oxygen to form?
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oxyhemoglobin
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where is oxyhemoglobin formation favored?
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in the lungs
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where is dissociation of oxyhemoglobin into Hb and free molecules of oxygen favored?
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in the tissue cells
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what is the main determinant of the percent Hb saturation?
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partial p of oxygen
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what does Hb do?
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it promotes the net transfer of oxygen at both alveolar and tissue levels
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what four factors shift the curve to the right, unloading more oxygen to the tissues?
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an increase in the parital P of CO2, increase in the acidity, increase in temp. and increaes in 2,3 bisphosphoglycerate
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what is the 2-step reversibile process which is favored at tissue cells involiving the combination of CO2 and water?
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carbonic anhydrase transoforms CO2 and water into H2CO3 then to H+ and HCO3
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what is the chloride shift?
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RBC plasma membrane passively facilitates diffusion of bicarbonate and chloride ions via HCO3- - Cl- carrier, HCO3- is moved to the plasma and Cl- is moved to RBC, it buffers the blood
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what is the Haldone effect?
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oxygen removal from Hb at tissue cells increases the ability of Hb to bind CO2 and H+
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what is hypoxic hypoxia?
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low Po2 in arterial blood (at high altitudes, emphaysema, pneumonia)
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what is anemia hypoxia?
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reduced oxygen carrying capacity in the blood, decreased availability of Hb, CO poisoning
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what is circulatory hypoxia?
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too little oxygenated blood deleivered to tissues, MI, hemmorhage
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what is histotoxic hypoxia?
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oxygen delivered to tissues is normal, but cells CAN'T use it, something wrong with cells, CN poisoning
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what is hyperoxia?
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above normal arterial Po2 levels, o2 supplementation
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what is hypercapnia?
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excess co2 in arterial blood, cause hypoventilation
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what is hypocapnia?
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below normal co2 in arterial blood, cause: hyperventiation
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what is hyperpnea?
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increased need for 02 delivery and co2 during times of increased metabolic need, exercise, fever
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what does excess co2 cause?
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H+ and HCO3- increases which increases acidity and may cause respiratory acidosis
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what are the respiratory centers found in the brain?
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medullary respiratory center: pre-botzinger complex, dorsal respiratory group, ventral respiratory group
2 respiratory centers in Pons: influence output from medullary respiratory center: pneumontaxic center, and apneustic center |
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what are the inspiratory neurons that signal inspiratory muscles (diaphragmn and external intercostals)
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phrenic and intercostal neurons
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what does the dorsal respiratory group do?
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they are mostly inspiratory neurons, descending fibers terminate on inspiratory motor neurons, responsible for inspiration, connected to VRG
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what does the ventral respiratory group do?
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composed of both inspiratory and expiratory neurons, both INACTIVE during quiet breathing, utilized during increased demand for ventilation
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what does the pre-botzinger complex do?
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region in upper end of medullary respiratory center, believed to establish basic respiratory rhythm, neurons have pacemaker activity
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what is the function of the pneumotaxic center (pons)?
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sends impulses that switch off inspiratory neurons, limits duration of inspiration
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what is the function of the apneustic center (pons)?
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prevents inspiratory neurons from being switched off, provides extra boost to inspiratory drive
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what is the function of the Hering-Breuer reflex?
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it is composed of stretch receptors in lungs activated with large TVs (greater than 1 L) during inspiration, signals travel from receptor to medullary center by afferent neurosn, inhibiting the inspiratory center, expiratory center then dominates
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what determines the magnitude of ventilation?
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depends on three factors: P02, PC02, and H+
CO2 generated H+ in brain is the primary regulator, peripheral and central chemoreceptors detect chemical changes in the blood |
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what do peripheral chemoreceptors do?
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monitor arterial P02
carotoid and aortic bodies, stimulated only when arterial P02 is life-threateningly low (<60 mmHg) highly responsive to arterial H+, high arterial H+ stimulates ventilation |
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what is the function of central chemoreceptors?
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located in medulla, monitor increased H+ in brain ECF, CO2 generated H+ in brain: normally primary regulator of ventilation, elevated H+ in brain ECF directly stimulates central chemoreceptors to increase ventilation by stimulating respiratory center
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what is apnea?
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transient interruption in ventilation
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what is dyspnea?
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subjective feeling of shortness of breath
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