Respiration (Extended Response) Flashcards
Outline the process of inhalation. (4 marks)
-diaphragm contracts / moves downwards/flattens
-external intercostal muscles contract
-(muscle contraction) moves the rib cage upwards and outwards
-increases volume of the thorax / lungs
-difference in pressure/decreasing pressure causes air to flow into lungs / lungs inflate
Explain the process of gas exchange taking place in the alveoli. (7 marks)
-O2 diffuses into blood and CO2 diffuses out from blood
-blood entering the alveoli is high in CO2/low in O2
-diffusion (in either direction) take place due to concentration gradients
-concentration gradients maintained by ventilation/blood flow
-large surface area created by many alveoli/spherical shape of alveoli for more efficient diffusion
-rich supply of capillaries (around alveoli) allows efficient exchange
-type I pneumocytes are thin to allow easy diffusion/short distances
-gases must dissolve in liquid lining of alveolus in order to be exchanged
-type II pneumocytes secrete surfactants to reduce surface tension/prevent lungs sticking together
-type II pneumocytes create moist conditions in alveoli
Explain how ventilation and lung structure contribute to passive gas exchange.
(7 marks)
-air carried through trachea AND bronchi/bronchioles AND alveoli
-alveoli increase the surface area/thin walled for gas exchange
-gas exchange carried out through type I pneumocytes
-type II pneumocytes secrete surfactant to reduce surface tension
-moist surface/surfactant allows gases to diffuse in solution
-ventilation/moving blood maintains concentration gradients of oxygen and carbon dioxide
-between air in alveoli and blood in «adjacent» capillaries
-external intercostal muscles/diaphragm contract during inspiration
-lowering air pressure «in lungs»/increasing thorax volume
-relaxation of external intercostal muscles/diaphragm enable «passive» expiration
-internal intercostal «and abdominal muscles» contract «to force» expiration
-expiration due to increasing air pressure «in lungs»/decreasing thorax volume
Outline the process of inspiration in humans.
(4 marks)
-diaphragm and external intercostal muscles contract
-diaphragm moves down/becomes flatter
-external intercostals raise the ribcage/move the ribcage up/out
-muscles/ diaphragm/intercostals increase volume of thorax/expand the thorax decrease in pressure in the thorax
-as volume «of thorax/lungs» increases the pressure decreases
-air enters «lungs» due to decreased pressure/higher pressure outside body
-air flows to lungs through trachea and bronchi/bronchioles
Identify Type I Pneumocytes and Endothelial cells on a diagram (2 marks)
Endothelial cells are the closest layer to blood while Type I Pneumocytes are the outside layer
Explain, with the aid of an annotated diagram, how physical exercise affects the affinity of hemoglobin for oxygen. (6 marks)
-diagram showing normal oxygen dissociation curve (see diagram study set)
-where tissues are respiring there is a higher concentration of CO2
-exercise increases the amount of CO2 in the blood
-increase in CO2 lowers the pH of the blood
-a lower pH causes hemoglobin to release oxygen
-lower pH decreases hemoglobin affinity for O2/changes hemoglobin conformation
-oxygen is released in tissue where it is required for respiration
-this is known as the Bohr effect/shift
-at the lungs the low concentration of CO2 means oxygen attaches to hemoglobin
-«Bohr» effect particularly important during exercise
Discuss the significance of the oxygen dissociation curves for adult hemoglobin and fetal hemoglobin. (6 marks)
-oxyhemoglobin forms when partial pressure of oxygen is high
-respiring tissues have low partial pressure of oxygen
c. Diagram of dissociation curve (see diagram study set)
-«small» decrease in oxygen partial pressure over steep part of curve results in dissociation of oxyhemoglobin/oxygen release to tissues
-fetal hemoglobin is structurally different from adult/maternal hemoglobin
-fetal dissociation curve to left of adult dissociation curve
-fetal hemoglobin has greater affinity for oxygen than adult/maternal blood
-fetus obtains its oxygen from mother’s blood «at placenta»
-at any given partial pressure of oxygen fetus will take up oxygen from mother
-fetal hemoglobin always more saturated with oxygen than maternal blood
Outline the role of the parts of an alveolus in a human lung. (4 marks)
-the (spherical) wall of an alveolus maximizes/allows gas exchange
-pneumocytes I (optimize) gas exchange
-pneumocytes II produce surfactant
-adjacent capillaries enclose alveoli for efficient gas exchange with blood
-surfactant reduces surface tension/prevents collapse of alveolus
-(alveolar) macrophages/ phagocytes help with defense/homeostasis/ response to foreign substances
Outline how ventilation in humans ensures a supply of oxygen. (4 marks)
-ventilation is exchange of gases between lungs and air.
-during inhalation diaphragm contracts AND lowers.
-external intercostal muscles contract, raising ribs upwards and outwards
-increase in volume AND decrease in pressure within thoracic cavity
-air drawn into alveoli bringing fresh supply of oxygen
-oxygen concentration in alveolar sacs is higher than in blood capillaries
-«oxygen concentration gradient» causes oxygen to diffuse out of alveoli into red blood cells in capillaries
Explain how an increase in cell respiration in a tissue causes increased release of oxygen by hemoglobin in the tissue. (6 marks)
-cell respiration consumes O2 / lowers O2 partial pressure in tissues
-(actively) respiring tissues release CO2 / partial pressure of CO2 increases
-CO2 increases acidity / lowers pH of the blood
-decreases hemoglobin’s affinity for O2
-promotes the release of oxygen to respiring cells/tissues
-binding of hydrogen ions/ allosteric effect / conformational change in hemoglobin releases O2 more readily
-more oxygen released at the same partial pressure
-this shifts the oxygen dissociation curve to the right/Bohr shift
-Can also be diagrammed (see diagram study section)
Discuss high altitude training for athletes. (6 marks)
Benefits:
-improved performance /endurance at lower oxygen levels/ altitude
-due to higher concentration erythrocytes/red blood cells/hemoglobin
-more oxygen transported /circulating «due to increase in hemoglobin/RBC number»
-improved metabolic/lung efficiency/gas exchange
-increase in myoglobin /number of capillaries /mitochondria
Risks:
-altitude sickness/stroke/lower immunity
-increased muscle tissue breakdown
-effects are not immediate/not permanent/extended training at high altitude required
-may be unfair to competitors who cannot train at high altitude
Describe what happens in alveoli. (4 marks)
-gas exchange
-oxygen diffuses from air to blood and carbon dioxide diffuses from blood to air
-oxygen binds to hemoglobin in red blood cells
-pressure inside/volume of alveoli increases/decreases / air enters/exits alveoli during inspiration/expiration/ ventilation
-blood flow through capillaries / concentration gradients of gases/oxygen/CO2 maintained
-type II pneumocytes secrete fluid/surfactant / secretion of surfactant to prevent sides of alveolus adhering
Explain, using an oxygen dissociation curve, how hemoglobin supplies oxygen to respiring tissues and how the Bohr shift increases the supply. (6 marks)
-Diagram of oxygen dissociation curve (see diagram study set)
-tissues use O2 for «cellular» respiration thus lowering pO2 at tissue level
-respiring tissues produce CO2
-O2 dissociates more at lower pO2 from Hb «than at higher pO2» thus providing O2 to «respiring» tissues/OWTTE
How Bohr shift increases the supply
-CO2 is converted to hydrogen carbonate ions/HCO3− and H+
-increase in H+ lowers blood pH
-H+ combines with Hb / conformational change in Hb «in red blood cell» freeing some O2
-shifts the oxygen dissociation curve to the right «Bohr shift»
-oxygen dissociation curve steeper at lower pO2 «corresponding to respiring tissues»
-lowers the affinity of hemoglobin for oxygen
-means less oxygen can be carried for same pO2 «as normal»
