respiratory control center

regulation of respiration

-objective: to maintain normal levels of PO2 & PCO2 in arterial blood -respiratory control system: 3 basic elements; sensors, central controller, effector

hypoxemia

decreased oxygenation of arterial blood; normal PaO2 is 80-100 mmHg %

hypoxia

decreased oxygenation of cells in the tissues; oxygen saturation normal is 95-100%; the percentage of the available hemoglobin that is bound to oxygen and can be measured using a device called an oximeter

hypercapnia

increased carbon dioxide concentration in the arterial blood; normal PaCO2 is 35-45 mmHg

lung receptors

irritant receptors, stretch receptors, J-receptors

J-receptors

located near capillaries and alveoli and respond to increased pulmonary capillary pressure

central chemoreceptors

located near the medulla oblongata; most sensitive to pCO2 in the blood; very slightly sensitive to PO2

hypoxemia is caused by

problem in oxygen delivery to alveoli, problem in diffusion of oxygen from alveoli to blood, problem in perfusion of pulmonary capillaries

medulla oblongata

sends out nerve impulses to contract muscles for inspiration; stops sending out nerve impulses so muscles relax and expiration occurs

chemical control of breathing- central chemoreceptors

senses change in the pH of cerebrospinal fluid; carbon dioxide can diffuse across the blood-brain barrier; CO2 in blood dissociates into CARBONIC ACID; decreased pH stimulates respiratory center to increase depth and rate of respirations; sensitive to small changes in pH of CSF; become insensitive to small changes in pH with long-term inadequate ventilations (COPD)

stretch receptors

sensitive to increased volume of lungs (Hering-Breuer Reflex)

irritant receptors

sensitive to noxious aerosols, gases, particulate matter

chemoreceptors

structures that are sensitive to changes in PO2 and pCO2 and pH of the blood; 2 types are central and peripheral chemoreceptors

peripheral chemoreceptors

the carotid bodies and the aortic bodies; primarily respond to changes in PaO2; have more impact on the cardiovascular system; oxygen levels must drop well below normal before the peripheral receptors influence ventilation (60mmHg); also respond to PCO2 levels and pH; are the major stimulus when the central chemoreceptors are reset by chronic hypoventilation