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34 Cards in this Set

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  • Back
what percent of oxygen is bound to Hb?
98.5%
what percent of CO2 is bound to Hb?
30%
what percent of CO2 is bound to bicarbonate?
60%
most Hb combines with oxygen to form?
oxyhemoglobin
where is oxyhemoglobin formation favored?
in the lungs
where is dissociation of oxyhemoglobin into Hb and free molecules of oxygen favored?
in the tissue cells
what is the main determinant of the percent Hb saturation?
partial p of oxygen
what does Hb do?
it promotes the net transfer of oxygen at both alveolar and tissue levels
what four factors shift the curve to the right, unloading more oxygen to the tissues?
an increase in the parital P of CO2, increase in the acidity, increase in temp. and increaes in 2,3 bisphosphoglycerate
what is the 2-step reversibile process which is favored at tissue cells involiving the combination of CO2 and water?
carbonic anhydrase transoforms CO2 and water into H2CO3 then to H+ and HCO3
what is the chloride shift?
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
what is the Haldone effect?
oxygen removal from Hb at tissue cells increases the ability of Hb to bind CO2 and H+
what is hypoxic hypoxia?
low Po2 in arterial blood (at high altitudes, emphaysema, pneumonia)
what is anemia hypoxia?
reduced oxygen carrying capacity in the blood, decreased availability of Hb, CO poisoning
what is circulatory hypoxia?
too little oxygenated blood deleivered to tissues, MI, hemmorhage
what is histotoxic hypoxia?
oxygen delivered to tissues is normal, but cells CAN'T use it, something wrong with cells, CN poisoning
what is hyperoxia?
above normal arterial Po2 levels, o2 supplementation
what is hypercapnia?
excess co2 in arterial blood, cause hypoventilation
what is hypocapnia?
below normal co2 in arterial blood, cause: hyperventiation
what is hyperpnea?
increased need for 02 delivery and co2 during times of increased metabolic need, exercise, fever
what does excess co2 cause?
H+ and HCO3- increases which increases acidity and may cause respiratory acidosis
what are the respiratory centers found in the brain?
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
what are the inspiratory neurons that signal inspiratory muscles (diaphragmn and external intercostals)
phrenic and intercostal neurons
what does the dorsal respiratory group do?
they are mostly inspiratory neurons, descending fibers terminate on inspiratory motor neurons, responsible for inspiration, connected to VRG
what does the ventral respiratory group do?
composed of both inspiratory and expiratory neurons, both INACTIVE during quiet breathing, utilized during increased demand for ventilation
what does the pre-botzinger complex do?
region in upper end of medullary respiratory center, believed to establish basic respiratory rhythm, neurons have pacemaker activity
what is the function of the pneumotaxic center (pons)?
sends impulses that switch off inspiratory neurons, limits duration of inspiration
what is the function of the apneustic center (pons)?
prevents inspiratory neurons from being switched off, provides extra boost to inspiratory drive
what is the function of the Hering-Breuer reflex?
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
what determines the magnitude of ventilation?
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
what do peripheral chemoreceptors do?
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
what is the function of central chemoreceptors?
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
what is apnea?
transient interruption in ventilation
what is dyspnea?
subjective feeling of shortness of breath