7[1].3 the concept of gaseous exchange

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Transcript of 7[1].3 the concept of gaseous exchange

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LEARNING LEARNING OUTCOMESOUTCOMES

To describe the process of gaseous To describe the process of gaseous exchange across the surface of the exchange across the surface of the alveolus & blood capillaries in the lungs;alveolus & blood capillaries in the lungs;

To explain the transport of respiratory To explain the transport of respiratory gases;gases;

To explain the process of gaseous To explain the process of gaseous exchange between the blood & body exchange between the blood & body cells;cells;

To distinguish the composition of inhaled To distinguish the composition of inhaled & exhaled air.& exhaled air.

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Gaseous exchange Gaseous exchange occurs across the occurs across the surface of the surface of the alveolusalveolus & & blood blood capillariescapillaries in the in the lungs.lungs.

Occurs by the Occurs by the process of diffusion process of diffusion & involves & involves oxygen & oxygen & carbon dioxide.carbon dioxide.

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Process of Gaseous Exchange at the Process of Gaseous Exchange at the AlveolusAlveolus

Inhaled airInhaled air in alveolus – in alveolus – more more oxygen, less carbon dioxideoxygen, less carbon dioxide compare to the qtts. in the compare to the qtts. in the blood capillaries of the lung.blood capillaries of the lung.

The The partial pressure of O2partial pressure of O2 is is higherhigher in the air of the in the air of the alveolusalveolus compare to the partial compare to the partial pressure of O2 in the blood pressure of O2 in the blood capillaries.capillaries.

The The higherhigher partial pressurepartial pressure of of oxygen oxygen in the alveolusin the alveolus causes causes the oxygen the oxygen to dissolveto dissolve in the in the layer of moisture on the wall of layer of moisture on the wall of the alveolus & the alveolus & diffuse outdiffuse out of of the alveolus into the blood the alveolus into the blood capillariescapillaries

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During respirationDuring respiration, CO2 , CO2 is produced. The is produced. The blood blood capillaries in the body capillaries in the body transport the CO2 to transport the CO2 to the alveolus.the alveolus.

The The partial pressure of partial pressure of CO2CO2 in the in the blood blood capillariescapillaries entering the entering the alveolus is alveolus is higherhigher than than the partial pressure of the partial pressure of CO2 in the alveolusCO2 in the alveolus

The The CO2 in the blood CO2 in the blood capillaries diffuses outcapillaries diffuses out of the blood capillaries of the blood capillaries into the alveolus & is into the alveolus & is expelled during expelled during exhalation.exhalation.

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Transport of Respiratory Gases

The The oxygenoxygen from the blood capillaries from the blood capillaries has to has to be transported to the body cellsbe transported to the body cells that need it. that need it.

The The oxygen diffusesoxygen diffuses into the RBCs & into the RBCs & combines combines with haemoglobinwith haemoglobin to form to form oxyhaemoglobinoxyhaemoglobin..

Haemoglobin + Oxygen Haemoglobin + Oxygen Oxyhaemoglobin Oxyhaemoglobin

Transport Transport from lungs to the whole bodyfrom lungs to the whole body in the in the form of form of oxyhaemoglobinoxyhaemoglobin

Oxyhaemoglobin is not stableOxyhaemoglobin is not stable. The . The oxyhaemoglobin breaks down & releases the oxyhaemoglobin breaks down & releases the oxygen to diffuse into the celloxygen to diffuse into the cell

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In the blood, In the blood, some CO2some CO2 is transported in the is transported in the form of form of carbonic acidcarbonic acid

Some are combines with haemoglobinSome are combines with haemoglobin to to form form carbaminohaemoglobincarbaminohaemoglobin in the in the RBCsRBCs..

A large part of the CO2A large part of the CO2 is transported to the is transported to the alveolus in the form of alveolus in the form of bicarbonate ionsbicarbonate ions in in the the blood plasmablood plasma..

The The CO2 are transportedCO2 are transported to the alveolus by to the alveolus by these 3 ways.these 3 ways.

At the alveolusAt the alveolus in the lungs, the CO2 is in the lungs, the CO2 is released from its compound & diffuse into released from its compound & diffuse into the alveolus, to be expelled during exhalationthe alveolus, to be expelled during exhalation

Transport of Respiratory Gases

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Gaseous Exchange at Gaseous Exchange at Body CellsBody Cells

Occurs Occurs between the blood capillaries & body between the blood capillaries & body cellscells

The The body cellsbody cells - lack of O2, - lack of O2, bloodblood - - high high partial pressure of O2partial pressure of O2 O2 diffuse out of O2 diffuse out of the bloodthe blood capillaries into the body cells capillaries into the body cells

Body cells – high conc. of CO2 Body cells – high conc. of CO2 product of product of cellular respirationcellular respiration

Body cellsBody cells – – high partial pressure of CO2high partial pressure of CO2, , blood – low partial pressure of CO2 blood – low partial pressure of CO2 CO2 CO2 diffuses out of the body cellsdiffuses out of the body cells into the blood into the blood capillariescapillaries

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Composition of Composition of Inhaled & Exhaled AirInhaled & Exhaled Air

Components of Components of airair

Inhaled airInhaled air Exhaled airExhaled air

OxygenOxygen 21%21% 16%16%

Carbon dioxideCarbon dioxide 0.03%0.03% 4%4%

NitrogenNitrogen 78%78% 78%78%

Water vapourWater vapour Varies (depends on Varies (depends on the humidity of air)the humidity of air)

More (usually More (usually saturated)saturated)

Dust particlesDust particles VariesVaries Usually noneUsually none

Temperature Temperature (heat)(heat)

Varies (follows Varies (follows atmospheric atmospheric

temp.)temp.)

Body temperatureBody temperature

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EXERCISE 7.3EXERCISE 7.31.1. How different is the partial pressure of How different is the partial pressure of

oxygen & carbon dioxide between the oxygen & carbon dioxide between the alveolar space & alveolar capillaries alveolar space & alveolar capillaries during gaseous exchange? (2 marks)during gaseous exchange? (2 marks)

2.2. How different is the partial pressure of How different is the partial pressure of oxygen & carbon dioxide in the blood oxygen & carbon dioxide in the blood entering the alveolus with the blood entering the alveolus with the blood leaving the alveolus? (2 marks)leaving the alveolus? (2 marks)

3.3. How is oxygen transported in blood? How is oxygen transported in blood? (1 mark)(1 mark)

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QUIZ 7.3QUIZ 7.31.1. Compound formed by binding of carbon Compound formed by binding of carbon

dioxide with haemoglobin.dioxide with haemoglobin.

2.2. Compound formed by binding of carbon Compound formed by binding of carbon monoxide with haemoglobin.monoxide with haemoglobin.

3.3. Respiratory pigment in red blood cells.Respiratory pigment in red blood cells.

4.4. How many ways are CO2 transported in How many ways are CO2 transported in the blood? List them.the blood? List them.

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