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med lecturesfinal
chapter 12
| Question | Answer |
|---|---|
| chemoreceptors are specialized tissue that respond to chemicals.... | CO2,H+,O2, and pH |
| ___________ are probaly the single most important mechanism by which ventilation is regulated | chemoreceptors |
| what are the two types of chemoreceptors? | central and peripheral |
| what are the 2 types of peripheral chemoreceptors | carotid bodies, and aortic bodies |
| where are carotid bodies located, and what are they stimulated by? | they are located at the bifurcation of the common carotid artery and are subject to nervous stimulation |
| where are aortic bodies located and what are they simulated by? | they are located within the arch of the aorta and are stimulated by the vagus nerve |
| peripheral chemoreceptors will respond to..... | increase in CO2, increase in H+, decrease in pH, decrease in PO2, decrease in blood flow, and increase in temp |
| What is the most important mechanism of peripheral chemoreceptors? | there response to a low pO2. This sets them apart from the central chemoreceptors. |
| When is stimulation of peripheral chemoreceptors max? | when PO2 is 40-60 torr, stimulation= increase in RR, and increase in tidal volume |
| peripheral chemoreceptors will be stimulated only with a _____________ in PC02, or ______________ in pH, this stimulation is directly caused by an_____________ in H+ and indirectly caused by CO2 | very large increase, decrease, increase |
| stimulation of peripheral chemoreceptors to decreased blood flow will cause an increase in___________and______________ | HR and BP |
| where are the central chemoreceptors located? | In the medulla ( not in the medullary respiratory center!) |
| What are the central chemoreceptors in contact with? | CSF and arterial blood |
| central chemoreceptors do not respond to what levels in the blood? | O2 |
| central chemoreceptors respond directly to what concentration in the CSF | H+ concentration (ph) |
| When central chemoreceptors are stimulated due to H+ increase(decrease ph) in CSF what happens | increase in ventilation |
| when H+ are low (high pH) chemoreceptors cause | ventilatory drive and volume to diminish |
| Blood brain barrier | protective mechanism for the brain that seperates CSF and blood |
| blood brain barrier membrane | extremly selectively permeable, relatively impermeable to ions and readily permeable to gases (CO2) |
| what diffuses easily across the blood brain barrier | CO2 |
| H+ and HCO3 can get by the blood brain barrier slowly with | active transport |
| an increase in PCO2 in the blood of the in the blood brain barrier leads to | an increase in PCO2 in CSF and increase of H+ in CSF |
| an increase in PCO2 and H+ in CSF will stimulate the central chemoreceptors to do what | increase their respiratory rate and tidal volume |
| Factors influencing PCO2 of CSF | cerebral blood flow, CO2 production rate, CO2 content in artery/vein, and alveolar ventilation |
| Interaction between the central and peripheral chemoreceptors | ventilation normally under control by central chemoreceptors, in presence of disease peripheral c.r may play the dominant role |
| Hering-Breuer Reflex | not normally activated, activated in response to over or under inflation of the lungs, impacts VT and RR, activated to decrease WOB |
| 2 reflexes of Hering Breuer Reflex | inflation reflex and deflation reflex |
| inflation reflex | inhibits inspiration |
| deflation reflex | stimulates inspiration when lung volume is low, my be responsible for hyperventilation seen in patients with restrictive lung diseases |
| J receptors | located in the interstitial tissue of the alveolar capillary membrane, they are stimulated by an increase in AC membrane thickness(PNA,pulmonary edema, fibrosis) resutls in increase RR possible hyperventilation or hypocarbia |
| 3 basic function of the kidneys | 1) excrete fixed acids (H+)2) Regulate electrolyte concentrations (HCO3-,Na+,Ca+,Cl-)3) regulate blood and fluid volumeall accomplished via nephron network in the kidney |
| electrolyte | charged particle within a solution |
| Urine formation 3 steps | 1) glomerular filtration2)tubular reabsorption3)tubular secretion |
| Glomerular filtration depends on the adequacey of_____________ to the kidneys | perfusion (because it is a hydrostatic process) |
| kidneys need what percentage of cardiac output, because they have a high O2 consumption, and high metabolic rate, anything that effects cardiac output will affect the filtrate ( ex. diuretics, epi) | 20% |
| Tubular reabsorption happens via | active or passive transport |
| what pe is percentage of fluid that passes into the glom. filtrate is reabsorbed back into the tubular cells of the kidney and then back into blood | 99% |
| Tubular secretion happens via | active transport |
| Tubular secretion is | a process by which renal tubular cells secrete electrolytes into the filtrate in exchange for the reabsorption of other electrolytes that the body demands |
| What is the most abundant electrolyte? | Sodium |
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