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86 Cards in this Set
- Front
- Back
What are the 4 primary functions of the respiratory system?
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1) Exchange of gases between atm and blood
2) Homeostatic regulation of body pH 3) Protection from inhaled pathogens and irritating substances 4) Vocalization |
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What is lost from the body through the respiratory system besides CO2?
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Water and heat loss
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Distinguish between cellular respiration and external respiration
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CELLULAR RESPIRATION: Take O2 and nutrients -> CO2, water, and ATP as products
EXTERNAL RESPIRATION: take in O2 and take out CO2 |
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Distinguish between inspiration and expiration.
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Inspiration: Movement of air into the lungs
Expiration: Movement of air out of the lungs |
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Name the structures of the upper and lower respiratory system, following an O2 molecule from air to the exchange surface of the lungs. Briefly describe the anatomy of each section.
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UPPER: Mouth, nasal cavity, pharynx, larynx
LOWER: trachea, left and rich lung, right and left bornchus, diaphragm From pharynx -> larynx -> trachea -> left primary bronchus -> secondary bronchus -> bronchioles -> alveoli |
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What bones and muscles form the thoracic cage? The floor? Name them.
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Thorax is bounded by the bones of the spine (sternocleidomastoids and scalenes) and rib cage (intercostal muscles)
Diaphragm (skeletal muscle) |
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Name the three sacs enclosed within the thorax. What is in each sac?
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Pericardial sac: heart
Pleural sacs: lungs |
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What is the relationship between the lungs, the pleura, and the pleural fluid?
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The lungs are like the air-filled ballons; the balloon is the pleural membrane, and inside the ballon are fluid.
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What purpose does pleural fluid serve?
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Moist, slippery surface so that the opposing membranes can slide across one another as the lungs move within the thorax.
Holds the lungs tight against the thoracic wall |
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Which air passages of the respiratory system are collapsible?
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Bronchioles, because they have only smooth muscle.
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List three functions of the upper airways and bronchi in addition to simply being passageways.
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1) Warming to body temperature so that core body temperature doesn't change and alveoli aren't damaged b/c of cold air
2) Adding water vapor until air is 100% moist and exchange epithelium doesn't dry out 3) Filtering out foreign material, so that viruses, bacteria, and inorganic particles do not reach the alveoli |
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Describe and give the functions of the two types of epithelial cells in alveoli. What kind of epithelia are these two cell types?
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Type 1: Alveolar cell for gas exchange (exchange epithelia)
Type II: Surfactant cells (ciliated epithelia) |
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Trace a drop of blood through the pulmonary circulation from the Right ventricle to left atrium.
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RV -> PUlmonary trunk -> Pulmonary arteries -> lung capillaries -> Pulmonary veins -> LA
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Compare pulmonary blood flow, blood pressure, and capillary filtration to that of the systemic circuit.
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Blood flow: Rate is much higher than the rate in other tissues because lungs receive entire cardiac output of the right ventricle
BP: Low; 25/8 mm Hg, because of low resistance (shorter total length of pulmonary blood vessels and large cross-sectional area of pulmonary arterioles ) Capillary filtration: LOw because of low mean blood pressure |
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Describe the association of the alveoli and the circulatory system.
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Very close; blood vessels fill 80-90% of space between alveoli, forming continous sheet of blood in close contact -> rapid gas exchange
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List the 4 integrated processes of external respiration (3 exchanges and 1 transport).
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1: Atmosphere to lung (ventilation)
2: Lung to blood 3: Transport of gases in the blood 4: Blood to cells |
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What thoracic structures are not contained in the sacs?
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?
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Distinguish between atmospheric pressure and partial pressure.
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Partial pressure: pressure of a single gas
Patm x Percent of gas in the atmosphere |
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Distinguish between lung volumes and lung capacities.
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Lung volumes:
1) Tidal volume (insp - exp) 2) Inspiratory reserve volume (additional volume you can inspire to full capacity (above tidal volume) 3) expiratory reserve volume: amount of air forcefully expired after tidal volume 4) residual volume: amount that you cannot expire out Lung capacities: sum of 2 ore more lung volumes Vital capcity: sum of inspiratory reserve volume, tidal volume, expiratory reserve volume, and residual volume = Total lung capacity Or inspiratory capacity: inspiratory reserve volume + tidal volume Functional residual capacity: expiratory reserve volume + residual volume |
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What is inspiration and expiration?
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Inspiration: movement of air in the lungs
Expiration: movement of air out of lungs |
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What is active vs. passive expiration?
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Passive: Expiration during quiet breathing involves passive elastic recoil rather than active muscle contraction
Active expiration: voluntary exhalations and when ventilation exceeds 30-40 breaths per minute |
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What is total pulmonary ventilation and alveolar ventilation?
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Total pulmonary ventilation: volume of air moved into and out of the lungs each minute
breaths/min x tidal volume = total pulmonary ventilation MINUTE VOLUME Alveolar ventilation: amount of fresh air that reaches the alveoli each minute Alveolar ventilation = ventilation rate x (tidal volume - dead space) |
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What is restrictive and obstructive lung disease?
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Obstructive: Diseases in which air flow is diminished because of increased airway resistance
Restrictive: Decrease in lung compliance, because more work must be expanded to stretch a stiff lung; like fibrotic lung diseases |
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What is hyperventilation and hyperpnea?
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Hyperventilation: Alveolar ventilation increases above normal levels (BUT NOT INCREASED METABOLISM -> like emotional hyperventilation, or blowing up a balloon)
Hyperpnea: Increased respiratory rate and or volume in response to increased metabolism, like exercise |
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What is anatomic dead space and physiological dead space?
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Anatomic dead space: some air that enters the respiratory system does not reach the alveoli because some remains in trachea and bronchi; do not exchange gases with the blood
Physiological dead space: atm pressure is the same, not put into the body |
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How does increasing water vapor pressure in a mixture of gases affect the concentration of those gases if nothing else changes?
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Decreases everything else's Partial pressure
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In which air passage(s) of the respiratory system is resistance to flow (normally) greatest?
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Trachea and bronchi (unless there is bronchoconstriction)
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At what point in a respiratory cycle is intrapleural pressure greatest? least? equal to atmospheric pressure?
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Greatest at the end of expiration and lowest at end of inspiration
Never equal to atmospheric pressure |
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What is the role of surfactant in the alveoli? What happens if it is lacking?
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Surfactant: Reduces surface tension - if it is lacking, then takes more work to expand the lungs and alveoli
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What local factors influence resistance in the bronchioles? In the pulmonary arterioles?
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Bronchioles: Parasymp, symp, CO2
Pulmonary arterioles: decreased O2 around alveoli constricts alveoli, diverting blood to better ventilated alveoli |
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Define hematocrit.
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Ratio of red blood cells to paslma indicated by hemotcrit and expressed as a percentage of the total blood volume
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Describe the structure and contents of the mature RBC.
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Structure: No nucleus, biconcave disks, filled with enzymes and hemoglobin, no mitochondria (use glycolysis), no ER, flexible, modify in response to osmotic changes in the blood.
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How is the lack of a nucleus related to the short life span of a RBC?
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They can't make new enzymes and renew membrane components, so they lose flexibility and are more likely to rupture.
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Why does the erythryocyte need to be flexible?
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To respond to osmotic changes
To squeeze through narrow capillaries of the circulation |
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Describe or draw the structure of hemoglobin.
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Tetramer with 4 globins centered on a heme (iron) group.
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Why must we have adequate iron in the diet to make hemoglobin?
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Iron: part of hemoglobin
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what is the average life span of an RBC?
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120 +/- 20 days
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How are old RBCs destroyed and what happens to the RBC components?
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They are destroyed by rupturing as they try to squeeze through narrow capillaries, or are engulfed by scavenging macrophages
Many components are recycled: like amino acids from globin chains, iron |
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What is the relationship between heme, bilirubin, and bile?
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Spleen and liver convert remnants of heme groups to a colored pigment called bilirubin. Bilirubin is carried by plasma albumin to the liver, where it is metabolized and incoprorated into a secretion called bile. Then bile is secreted into the digestive tract, and it leaves body in feces
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What is relative polycythemia?
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Person's RBC count is normal, but hematocrit is elevated because of low plasma volume (DEHYDRATION)
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By what mechanism do gases move between the alveoli and the plasma?
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simple diffusion
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List the 4 rules for diffusion of gases.
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Diffusion rate is proportional to surface area x concentration gradient x membrane permeability / membrane thickness
Most important: concentration gradient |
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Why do respiratory physiologists commonly use partial pressures to express gas concentrations in solution?
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Allows direct comparison with partial pressure of the gases in the air, which is important for establishing whether there is a concentration gradient between the alveoli and the blood.
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When a gas is placed in contact with a liquid, what 3 factors determine how much gas will dissolve in the liquid?
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1) Pressure gradient of the gas
2) Solubility of the gas in the liquid 3) Temperature |
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Which is more soluble in body fluids: oxygen or CO2?
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Co2
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Fill in the "Normal" values for the following partial pressures in a person at sea level:
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PO2: Alveoli: 100
Arterial blood: 95 Resting cells: 40 Venous blood: 40 PCO2: Alveoli: 40 Arterial blood: 40 Resting cells: 46 Venous blood: 46 |
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Define hypoxia and hypercapnia.
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Hypoxia: a state of too little oxygen
Hypercapnia: doesn't always go with hypoxia, but elevated concentrations of carbon dioxide SIGNS |
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List 4 pathological changes in the alveolar-blood exchange surface that result in low arterial content.
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Emphysema: destruction of alveoli means less surface area for gas exchange.
Fibrotic lung diesease: thickened alveolar membrane slows gas exchange, and loss of compliance may decrease alveolar ventilation. Pulmonary edema: FLuid in interstitial space increases diffusion distance; Arterial PCO2 may be normal due to higher CO2 solubility in water. Asthma: Increased airway resistance decreases alveolar ventilation |
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List 2 main reasons alveolar PO2 may be lower than normal
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Altitude and alveolar ventilation problems (like hypoventilation, like decreases compliance, increased airway resistance)
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The more soluble a gas is in a particular liquid, the ___ the parital pressure required to force the gas into solution.
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LOWER
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What 2 cell layers must gases cross to go from the alveoli to the plasma?
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Alveolar epithelium and capillary endothelial cells
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How much of the alveolar epithelium must be incapacitated before arterial PO2 drops?
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1/3
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What is pulmonary edema and how does it alter gas exchange?
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Fluid in interstitial space increases diffusion distance
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List 2 ways that gases are transported in the blood
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Dissolved in plasma or bound to hemoglobin
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__ % of oxygen in a given volume of blood will be carried bound to hemoglobin.
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98
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The amount of O2 bound to Hb depends primarily on what 2 factors?
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PO2 of plasma
Total number of binding sites |
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What is the 'corpuscle' in the term mean corpuscular Hb?
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cell
amount of hemoglobin per RBC |
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Describe the differences between adult and fetal hemoglobin.
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Adult: two alpha, two beta chains
Fetus: different isoform of hemoglobin, two gamma chains, two alpha chains; can get more O2 from maternal blood |
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Explain how oxygen-hemoglobin binding obeys the law of mass action.
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Hb + O2 -> <- HbO2
As Hb goes up, HbO2 goes up |
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As dissolved O2 diffuses into RBCs, what happens to the PO2 of the surrounding plasma?
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Lowers Po2, causing more O2 from alveoli to flow in
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In the oxyhemoglobin dissociation curve, the ___ determines the ___.
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PO2 determines percent saturation of Hb.
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Below PO2 of 60 mm Hg, where the curve is steeper, small changes in PO2 cause relatively __ releases of O2 from hemoglobin
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Large
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An increase in pH ___ hemoglobin's affinity for O2.
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increases
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An increase in temperature ___ hemoglobin's affinity for O2.
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decreases
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An increase in PCO2 ___ hemoglobin's affinity for O2.
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decrease
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The metabolite 2,3 DPG ___ hemoglobin's affinity for O2. What triggers an increase in 2,3 DPG?
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decreases; an increases in 2,3 DPG = high altitude, anemia
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FEtal Hb has an ___ affinity for oxygen.
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Increased
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A left shift in the curve indicates ___ binding affinity.
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Increased
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A right shift in the curve indicates ___ binding affinity.
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Decreased
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Why is it important that Co2 be removed from the body?
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Hypercapnia causes pH disturbance, which can denature proteins
also depress CNS function, causing confusion, coma or even death. For these reasons, CO2 is potentially toxic waste product that must be removed by the lungs |
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List the three ways CO2 is transported in the blood.
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1) Dissolved in blood
2) RBC: converted to bicarbonate 3) RBC: bound to hemoglobin |
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Write the equation, including the enzyme, in which Co2 is converted into bicarbonate ion and H+.
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CO2 + H2O -> carbonic anhydrase <- H2CO3 -> <- H+ + HCO3 –
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What 2 purposes does does the conversion of CO2 to HCO3- serve?
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1) provides additional means of CO2 transport from cells to lungs
2) HCO3- acts as a buffer for metabolic acids and stabilizes body pH |
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What is the chloride shift?
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Transport process that exchanges HCo3- for Cl- that remove free H+ and HCO3-. The transfer of HCO3- into the plasma makes the buffer available to moderate pH
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What is a buffer?
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moderate pH changes caused by production of metabolic acids.
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Compare the rhythmicity and control of breathing to that of the heartbeat.
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Both rhythmic
Yet skeletal muscles (unlike autorhythmic cardiac muscles) are not able to contract spontaneously, but must be inititaed by somatic motor neurons, controlled by the CNS Contraction of diaphragm and other muscles initiated by spontaneously firing network of neurons in the brain stem Input by chemoreceptors for CO2, O2, and H+ |
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Compare the types of efferent neurons leaving the respiratory control center and the CV control center.
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Efferent neurons leaving respiratory control center = somatic motor neurons (inspiration + expiration)
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What role do each of the following play in the control of breathing?
a) medulla oblongata: b) pons: c) cerebrum: |
Medulla oblongata: respiratory neurons in the medulla control inspiratory and expiratory muscles
Pons: Neurons in the pons integrate sensory information and interact with medullary neurons to influence ventilation Cerebrum: spontaneously discharging neurons and various chemoreceptor and mechanoreceptor-linked reflexes and higher brain centers |
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Describe neural control of quiet respiration.
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18.17
Sensory input from mechanical and chemosensory neurons -> Nucleus tractus solitarus in pons (which contains dorsal respiratory group) -> controls muscles of inspiration, diaphragm, intercostal nerves to the intercostal muscles Dorsal respiratory group -> respiratory neurons -> initiation and termination of inspiration -> pontine respiratory groups Ventral respiratory group - basic pacemaker for respiratory rhythm, keep airways open for breathing Ramping up, positive feedback loop up until the end of inspiration; then shut off and elastic recoil of inspiratory muscles and lung VRG - inactive during quiet breathing until activated during forced breathing, activate internal intercostal and abdominal muscles |
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List the location and chemical factor(s) monitored by each group of respiratory chemoreceptors.
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Peripheral chemoreceptors - carotid and aortic arteries near baroreceptors (change BP) sense changes in the PO2, pH, PCO2 of the plasma
Central chemoreceptors - in brain, respond to changes in concentration of CO2 in the cerebrospinal fluid; on ventral surface of medulla, close to neurons involved in respiratory control |
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Explain the strategic significance of location of chemoreceptors.
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??
Maybe, that inspiration and expiration continuously by sensory input In the carotid and aortic bodies, neurotransmitters initiate action potentials in sensory neurons leading to the brain stem respiratory networks, signaling them to increase ventilation |
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Using the oxyhemoglobin dissocation curve in FIg. 18-9, explain the adaptive significance of the fact that the peripheral chemoreceptors do not respond to decrease in PO2 until PO2 drops below 60 mm Hg.
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B/c until 60 mm Hg, not really big changes in hemoglobin saturation
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An increase in PCO2 will trigger an __ in ventilation.
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Increase
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If PCO2 is chronically elevated (chronic hypercapnia) and hypoxia, is CO2 the primary chemical drive for ventilation? Explain.
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No, ventilation falls back toward normal rates as the chemoreceptor response adapts to low CO2...UNLESS there is a low arterial PO2 that remains intact...bc then low PO2 becomes the primary chemical stimulus for ventilation
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Write the reflex response to an inhaled irritant.
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write
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Give 2 examples of how higher brain centers can alter ventilation.
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1) Voluntary control of ventilation (holding breath) - but overriden by elevated PCO2 and cerebrospinal fluid activates chemoreceptor reflex
2) Limbic system (emotional and autonomic activities of fear and excitement) - neural pathway goes directly to somatic motor neurons, bypass control network in brain stem |