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Physio Exam 2
Week 6 Info
| Question | Answer |
|---|---|
| What is the total pressure of atmospheric gasses at sea level? | 760 mmHg |
| What is partial pressure? | One gas components' pressure in a mixture of multiple gasses |
| What is the fractional composition of dry atmospheric air? | O2: 20.93% CO2: 0.04% N2: 79.03% |
| What is Henry's law? | The amount of a given gas that dissolves in a liquid is directly proportional to the partial pressure of that gas in equilibrium with that liquid |
| Where is systemic arterial PO2 and PCO2? | In the blood |
| What determines how much O2 is transported in the blood? | Systemic arterial PO2 |
| What is the most important regulator of ventilation? | Systemic arterial PCO2 |
| How do you get true pressure? | Subtract the water vapor pressure |
| What gas continuously diffuses out of the alveoli into the blood? | Oxygen |
| What gas continuously diffuses from the blood into the alveoli? | CO2 |
| What is the typical value at rest of alveolar PO2? | 104mmHg |
| What is the typical value at rest of alveolar PCO2? | 40mmHg |
| What are alveolar PO2 and PCO2 influenced by? | The rate of alveolar ventilation (pump=breathing) |
| Why is it that when alveolar ventilation increases, the alveolar PCO2 decreases? | Because the CO2 that enters the alveoli is washed out faster |
| Why is it that when alveolar ventilation increases, the alveolar PO2 increases? | The O2 that leaves the alveoli is refilled faster |
| What is hypoventilation? | Alveolar ventilation is too low |
| What is hyperventilation? | Alveolar ventilation is too high |
| Why are alveolar PO2 and PCO2 important? | Because they determine the PO2 and PCO2 in the pulmonary venous blood that leaves the lungs and becomes systemic arterial blood |
| Partial pressures of gases in the respiratory system are affected by... | Altitude |
| Partial pressures in the alveoli will be proportional to what? | The prevailing atmospheric pressure |
| What affects ventilation? | Exertion |
| Increased oxygen consumption in exercise will do what to the alveolar PO2? | Lower the alveolar PO2 |
| Why does increased oxygen consumption in exercise lower alveolar PO2? | Because tissues require a greater portion of the oxygen entering the alveoli during inspiration |
| When is oxygen not carried away from alveoli into pulmonary capillaries? | When the ventilation rate is increases to sustain alveolar PO2 during exercise |
| In a person at rest, the blood passes through the capillary in about how many seconds? | 0.75s |
| What is the basic principle of diffusion? | The flow is proportional to the partial pressure difference |
| If alveolar PO2 is 104, what will it be when it becomes blood in pulmonary vein? | 103.9 (always barely under) |
| Does equilibration happen very fast or very slow? | Very fast |
| During exercise, where is the blood at in relation to equilibrium for O2? | Almost complete equilibrium |
| If the alveolar PCO2 is 40, what will it be when it becomes blood in pulmonary vein? | 40.3 (always higher) |
| The PO2 of the blood leaving the alveoli will almost be... | Equal to the alveolar PO2, but never higher |
| The PCO2 of the blood leaving the alveoli will almost be... | Equal to the alveolar PCO2, but never lower |
| When is the blood leaving the alveoli not equilibrated with the alveoli air? | When diffusion is impaired |
| What happens to the PO2 of the blood leaving the lungs when a V/Q mismatch occurs? | Lowered PO2 |
| What is V/Q? | Each alveolus receives a certain amount of air (ventilation, V) and a certain amount of blood flow (perfusion, Q) |
| What is the PO2 of pulmonary venous blood level in disease states when blood flows through parts of the lungs that are not ventilated? | Much less than 100mmHg |
| What are characteristics of emphysema (smoking)? | Destruction of alveolar walls and collapse of lower airways |
| O2 diffuses ffrom alveolar air into what? | Capillary blood and dissolves into plasma |
| The amount of oxygen dissolved in the blood is directly proportional to what? | PO2 |
| Can enough O2 be transported in dissolved form? | No |
| Hemoglobin is found within what type of blood cells? | Red blood cells |
| Each hemoglobin consists of what? | Globin (4 polypeptide chains) 4 heme groups, each containing one Fe |
| Each Fe in hemoglobin can bind to one what? | O2 |
| More O2 is bound to hemoglobin when... | The PO2 is raised |
| The PO2 does not only determine how much O2 is dissolved but also... | How much is bound to hemoglobin |
| What is O2 capacity? | When the amount of O2 combined with Hb at 100% saturation |
| What is the equation for O2 capacity? | O2 capacity= (O2 capacity/gram Hb) * Hb content |
| What is the O2 capacity/gram Hb constant? | 1.34 ml O2/gram Hb |
| What 2 steps are needed for calculating the amount of O2 combined with Hb? | 1. Calculate the O2 capacity 2. Calculate the amount of O2 combined with Hb |
| What does the shift to the right on the graph mean? | That for any given value of PO2, Hb has decreased affinity for oxygen and will more easily release O2 |
| The more metabolically active a tissue is, what happens to O2 released from Hb? | The more O2 is released from Hb |
| What happens to DPG levels in people living in high altitudes? | DPG levels increase, so unloading of O2 to peripheral tissues is increased |
| What forms from combining CO and Hb? | Carbovyhemoglobin |
| What is CO poisoning? | PO2 is nomal and the control systems do not respond |
| What are the 3 forms that CO2 is carried in the blood to the lungs? | 1. Dissolved CO2 2. As carbamino compounds 3. As bicarbonate |
| How is plasma bicarbonate and H+ combined to yield carbonic acid and is then converted to RBCs? | By CA into dissolved and diffusible CO2 |
| What is respiratory acidosis? | In lung disease or hypoventilation, arterial PCO2 and H+ both increase and the blood becomes more acidic |
| What is respiratory alkalosis? | Hyperventilation decreases arterial PCO2 and H+ |
| What nerves are used during quiet breathing? | Phrenic nerves |
| What 3 parts are used for vigorous breathing? | Phrenic nerves, intercostal muscle innervation, and abdominal muscle innervation |
| Where are the bursts of action potentials produced during vigorous breathing? | In the respiratory center of the medulla |
| What does the interaction between inspiratory neurons and expiratory neurons produce? | Rhythmicity of breathing |
| What is dorsal respiratory group (DRG)? | Primarily control inspiration via innervation of the diaphragm and external intercostal muscles |
| What is ventral respiratory group (VRG)? | Primarily control expiration via innervation of the internal intercostal and abdominal muscles |
| What does the pons do in respiration? | Makes rhythm more regular |
| What do pulmonary stretch receptors do? | Protects; if there is too much stretch, further inspiration is inhibited (The Hiring-Breuer reflex) |
| What does the hypothalamus do in respiration? | Changes the rhythm for temperature regulation |
| What does the limbic system do in respiration? | Emotional stimulus ie. anxiety leads to hyperventilation |
| What does the cortex do in respiration? | Breathing can be controlled willingly |
| What are chemoreceptors responsible for in respiration? | arterial PCO2, PO2, and pH |
| What is the most important variable in the control of ventilation? | CO2 |
| How is arterial PCO2 changed? | By adding CO2 to inspired air |
| What happens to ventilation when arterial PCO2 increases? | Ventilation is increased |
| What happens to ventilation when arterial PCO2 decreases? | Ventilation is decreased? |
| When arterial PCO2 is 30mmHg, what happens to ventilation? | Ventilation stops |
| Where are central chemoreceptors located? | In the medulla |
| Where are peripheral chemoreceptors located? | In the carotid and aortic bodies |
| When arterial PCO2 increases, what happens to action potential frequency in afferent nerves? | Action potential frequency in afferent nerves increases |
| How is arterial PCO2 controlled? | Via negative feedback |
| During initial disturbance, where arterial PCO2 increases, how does the respiratory center in medulla respond? | It increases ventilation in order to get rid of CO2 |
| How much of an effect is there when arterial PO2 decreases from 100 to 60 mmHg? | Small effect |
| How much of an effect is there when arterial PO2 decreases below 60 mmHg? | Very strong effect |
| How much of an effect is there when arterial PO2 increases above 100mmHg? | Hardly any effect |
| Why is arterial PCO2, around its normal value, much better regulated than PO2? | -PCO2 is controlled for acid-base balance -PO2 is not very critical (above 60mmHg) because of Hb saturation |
| The chemoreceptors responsible for when a patient will not breathe until the PCO2 is high enough are... | Central and peripheral chemoreceptors |
| The chemoreceptors responsible for arterial PCO2 being much better regulating than arterial PO2 are... | Only aortic and carotid bodies |
| When arterial PO2 decreases, the action potential frequency in afferent nerves... | Increases |
| Are central receptors sensitive to changes in PO2? | No |
| What is metabolic acidosis? | A change in arterial H+ concentratoin due to build-up of acids in the body ie. additon of lactic acid to the body during vigorous exercise |
| What is metabolic alkalosis? | Results from removal of acids from the body ie. result of vomiting |
| What happens to ventilation when pH decreases? | Ventilation increases |
| What happens to ventilation when pH increases? | Ventilation decreases |
| When the arterial pH decreases, action potential frequency in afferent nerves... | Increases |
| Are central receptors sensitive to blood pH? | No |
| What does the hyperventilation from acidosis do to H+ concentration? | Lowers concentration back to normal |
| What does the hypoventilation from alkalosis do to H+ concentration? | Increases concentration back to normal |
| Are changes in PCO2, PO2, or pH responsible for the increases ventilation during moderate exercise? | No |
Created by:
saradrake46
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