respiratory Physiology – Lecture 1-4
Lecture 1: Basic Principles of Gas Exchange in Animals
Supplementary Readings:
• textbook (5th edition, chapter 37, pages 977-994)
• textbook (4th edition, chapter 40, pages 1057-1072)
respiration
• exchange of respiratory gases – oxygen (O2) and carbon dioxide (CO2)
o carbon dioxide à excrete it thought metabolism
• why is there a constant urgent need of O2 in animals?
• Constant O2 à most animals cells need a constant supply of ATP
(energy)
o ATP needs O2
Anaerobic vs Aerobic respiration
Þ Ana without O2
Þ AER with O2 / in the presence of O2
• C6H12O6 à 2CH3COCOOH + 4H à 2CH3CHOHCOOH +
4ATP
Þ ATP à Low ATP à less energy to function properly
• “Respiratory gases”
Þ C6H12O6 + 6O2 = 6CO2 + 6H2OO + 34ATP
Þ To perform all the processes in a constant
manner, there is a need for O2 out.
Three types of respirations
• External respiration
o Transport of O2 into and CO2 out of the body
Þ Breathing à lungs
• Internal Respiration
o Transports O2 into and CO2 out of cells
- cells and tissues that regular it
- CO2 – into the gas exchange membrane to get it out
• Cellular Respiration
o Intracellular catabolic reactions that convert stored energy to ATP
§ Utilization of O2 to produce ATP inside the cell (mitochondria)
External respirations
§ a gas exchange ( = respiratory) membrane is a thin layer of one or two simple epithelia
o fundamental process of physiology
§ physiological process follow laws of physics and chemistry
§ it separates internal tissues from the environmental medium (air or water)
§ external respiration is the process by which:
o environmental O2 --à membrane à tissues dissolved CO2 à membrane à environment.
physics of Diffusion
§ C1 & C2 = regions of high and low
concentrations of solutes
§ A = Diffusion Area
§ X = Distance separating the concentration
regions
§ D = diffusion co-efficient, influenced by Physico-chemical properties of the solute, & temperature.
,Application of Fick’s Law to the diffusion of respiratory gases (e.g., O2)
§ P1 & P2 = regions of high and low partial pressure, respectively
§ A diffusion area
§ X = distance separating the concentration regions
§ D = Diffusion co-efficient, influenced by Physico-chemical properties of the
gas, & temperature
o Gasesà from high to low
o Gas molecules move following the presence gradient not certainly the concentration
gradient.
How small does an animal needs to be to rely on diffusion of O2 alone?
§ Using Fick’s Law
o Vertebrate muscle requires O2 partial pressure – 40mmHg.
o Atmospheric O2 partial pressure = 160mmHg.
§ Rearranging the equation
o The distance inside the tissue where O2 partial pressure reaches a
minimum of 40 mmHg is – 1mm.
§ Diffusion alone is sufficient only for very small animals such as rotifers.
o Diffusion: show presence
o Oxygen will move a very small distance which will not meet the
requirement of our body cells.
§ Solution à internal respiration
As Organisms get large
§ Oxygen requirement increases with mass BUT!!!
§ Oxygen has to be transported over a larger distance
o Diffusion distance increases
o Their surface area gets proportionately smaller.
How could animals prevent respiration from being diffusion limited?
, surface area for
gas exchange
increases
proportionally
with the increase
size.
• thickness (um) on log scale à thickness of gas exchange
membrane
• mammals and birds à thinner cause they have higher
metabolic rate to get more oxygen.
§ helps in diffusion occurring more energy à to
maximize the uptake of the oxygen from air
and water.
Respiration in larger animals requires multiple steps.
§ Most vertebrates gas-transfer system involves:
o Breathing movements à ventilation
o Diffusion of gases across the respiratory epithelia
§ Gases: O2 in, CO2 out
Lecture 1: Basic Principles of Gas Exchange in Animals
Supplementary Readings:
• textbook (5th edition, chapter 37, pages 977-994)
• textbook (4th edition, chapter 40, pages 1057-1072)
respiration
• exchange of respiratory gases – oxygen (O2) and carbon dioxide (CO2)
o carbon dioxide à excrete it thought metabolism
• why is there a constant urgent need of O2 in animals?
• Constant O2 à most animals cells need a constant supply of ATP
(energy)
o ATP needs O2
Anaerobic vs Aerobic respiration
Þ Ana without O2
Þ AER with O2 / in the presence of O2
• C6H12O6 à 2CH3COCOOH + 4H à 2CH3CHOHCOOH +
4ATP
Þ ATP à Low ATP à less energy to function properly
• “Respiratory gases”
Þ C6H12O6 + 6O2 = 6CO2 + 6H2OO + 34ATP
Þ To perform all the processes in a constant
manner, there is a need for O2 out.
Three types of respirations
• External respiration
o Transport of O2 into and CO2 out of the body
Þ Breathing à lungs
• Internal Respiration
o Transports O2 into and CO2 out of cells
- cells and tissues that regular it
- CO2 – into the gas exchange membrane to get it out
• Cellular Respiration
o Intracellular catabolic reactions that convert stored energy to ATP
§ Utilization of O2 to produce ATP inside the cell (mitochondria)
External respirations
§ a gas exchange ( = respiratory) membrane is a thin layer of one or two simple epithelia
o fundamental process of physiology
§ physiological process follow laws of physics and chemistry
§ it separates internal tissues from the environmental medium (air or water)
§ external respiration is the process by which:
o environmental O2 --à membrane à tissues dissolved CO2 à membrane à environment.
physics of Diffusion
§ C1 & C2 = regions of high and low
concentrations of solutes
§ A = Diffusion Area
§ X = Distance separating the concentration
regions
§ D = diffusion co-efficient, influenced by Physico-chemical properties of the solute, & temperature.
,Application of Fick’s Law to the diffusion of respiratory gases (e.g., O2)
§ P1 & P2 = regions of high and low partial pressure, respectively
§ A diffusion area
§ X = distance separating the concentration regions
§ D = Diffusion co-efficient, influenced by Physico-chemical properties of the
gas, & temperature
o Gasesà from high to low
o Gas molecules move following the presence gradient not certainly the concentration
gradient.
How small does an animal needs to be to rely on diffusion of O2 alone?
§ Using Fick’s Law
o Vertebrate muscle requires O2 partial pressure – 40mmHg.
o Atmospheric O2 partial pressure = 160mmHg.
§ Rearranging the equation
o The distance inside the tissue where O2 partial pressure reaches a
minimum of 40 mmHg is – 1mm.
§ Diffusion alone is sufficient only for very small animals such as rotifers.
o Diffusion: show presence
o Oxygen will move a very small distance which will not meet the
requirement of our body cells.
§ Solution à internal respiration
As Organisms get large
§ Oxygen requirement increases with mass BUT!!!
§ Oxygen has to be transported over a larger distance
o Diffusion distance increases
o Their surface area gets proportionately smaller.
How could animals prevent respiration from being diffusion limited?
, surface area for
gas exchange
increases
proportionally
with the increase
size.
• thickness (um) on log scale à thickness of gas exchange
membrane
• mammals and birds à thinner cause they have higher
metabolic rate to get more oxygen.
§ helps in diffusion occurring more energy à to
maximize the uptake of the oxygen from air
and water.
Respiration in larger animals requires multiple steps.
§ Most vertebrates gas-transfer system involves:
o Breathing movements à ventilation
o Diffusion of gases across the respiratory epithelia
§ Gases: O2 in, CO2 out
