Hour 2-Gaseous Exchange Dah Edit
Transcript of Hour 2-Gaseous Exchange Dah Edit
-
7/30/2019 Hour 2-Gaseous Exchange Dah Edit
1/25
Powerpoint@lecture Slides Are Prepared By Biology Lecturer, KMPk
mailto:point@lecturemailto:point@lecture -
7/30/2019 Hour 2-Gaseous Exchange Dah Edit
2/25
7.1 Gaseous exchange and
control in mammals
-
7/30/2019 Hour 2-Gaseous Exchange Dah Edit
3/25
-
7/30/2019 Hour 2-Gaseous Exchange Dah Edit
4/25
4
1
dissolved
in blood
plasma
2
as Carbamino
haemoglobin
3
as bicarbonate
ions
(HCO3-)
CO2 transportation in blood
CO2is transported between respiring tissues and
the lungs in 3 different ways:
-
7/30/2019 Hour 2-Gaseous Exchange Dah Edit
5/25
At the end of this topic, student should be
able to:
c. describe the oxygen dissociation curve
of haemoglobin
d. compare oxygen dissociation curve of
haemoglobin and myoglobin
e. explain Bohr effect due to partialpressure of carbon dioxide
-
7/30/2019 Hour 2-Gaseous Exchange Dah Edit
6/25
6
Oxygen dissociation curves of
haemoglobin
The curve shows
the relative
amounts of oxygen
bound to
haemoglobin
exposed to
solutions withdifferent PO2
-
7/30/2019 Hour 2-Gaseous Exchange Dah Edit
7/25
7
Oxygen dissociation curves
of haemoglobin
When the partial
pressure of oxygen
is high as in lungcapillaries,
haemoglobin has a
high affinity for
oxygen to form
oxyhaemoglobin
Campbell 9th edition, page 907
-
7/30/2019 Hour 2-Gaseous Exchange Dah Edit
8/25
8
Oxygen dissociation curves
of haemoglobin
When the partial
pressure of
oxygen is low asin respiring
tissues, the
oxyhaemoglobin
dissociates and
oxygen is
liberated
Campbell 9th edition, page 907
-
7/30/2019 Hour 2-Gaseous Exchange Dah Edit
9/25
9
Compose of a single
polypeptide chain with
an iron atom that can
bind to an O2
molecule
Have higher affinity
for oxygen thanhemoglobin
-
7/30/2019 Hour 2-Gaseous Exchange Dah Edit
10/25
10
When O2 levels fall in
muscle cells, myoglobinwill contain O2 after the
hemoglobin supplies
have been exhausted
Function :
store O2in the muscle
-
7/30/2019 Hour 2-Gaseous Exchange Dah Edit
11/25
11
its O2 dissociation
curve is displaced
well to the left of
hemoglobin
it only begins to
release O2 when
the partialpressure of O2 is
below 20 mm Hg
-
7/30/2019 Hour 2-Gaseous Exchange Dah Edit
12/25
12
in this way, it acts as
a store of O2 in resting
muscle (only releasing
it when supplies of
HbO2 have been exhausted)
the myoglobin-oxygen
dissociation curve is
hyperbolic rather than
sigmoid
-
7/30/2019 Hour 2-Gaseous Exchange Dah Edit
13/25
At low PO2levels,
maternal hemoglobin
gives up oxygen to
fetal hemoglobinacross the placenta
The curve is shift to
the left shows that
fetal hemoglobin has a
higher affinity for
oxygen than mother at
the same PO2.
-
7/30/2019 Hour 2-Gaseous Exchange Dah Edit
14/25
E.g:
At 40mmHg, fetal
hemoglobin is
almost 90%
saturated while
maternalhemoglobin is only
75% saturated.
-
7/30/2019 Hour 2-Gaseous Exchange Dah Edit
15/25
- The effect of pH on
hemoglobin's
affinity for oxygen
- This is the result of
H+ binding to
hemoglobin
-
7/30/2019 Hour 2-Gaseous Exchange Dah Edit
16/25
Bohr Effect/shift
It is shown
graphically by a
shift of the
oxyhemoglobindissociation curve
to the right.
-
7/30/2019 Hour 2-Gaseous Exchange Dah Edit
17/25
Partial pressure of O2
high in lung capillaries,
haemoglobin has a high
affinity for O2
to form
oxyhaemoglobin
Partial pressure of O2
low in respiring tissues,
oxyhaemoglobin
dissociates and O2
liberated
-
7/30/2019 Hour 2-Gaseous Exchange Dah Edit
18/25
Partial pressure of CO2
increases, pH also
decreases (increase of
H+), haemoglobin has a
low affinity for O2
-
7/30/2019 Hour 2-Gaseous Exchange Dah Edit
19/25
19
Increase in CO2pressure willshift the O2
dissociationcurve to the
right
This effectknown as
Bohr Shift
-
7/30/2019 Hour 2-Gaseous Exchange Dah Edit
20/25
The red line on the
graph represents the
oxygen dissociation
curve at a normal pH(pH = 7.4).
BOHR EFFECT
-
7/30/2019 Hour 2-Gaseous Exchange Dah Edit
21/25
BOHR EFFECT
The green line
represents the
curve in the blood
of exercising
tissues, shifted to
the right of the
normal curve.
-
7/30/2019 Hour 2-Gaseous Exchange Dah Edit
22/25
The black line
represents the
curve in the bloodat the lungs,
shifted to the left
of the normal
curve.
BOHR EFFECT
-
7/30/2019 Hour 2-Gaseous Exchange Dah Edit
23/25
Remember!!!
Higher PCO2= Higher [H+]
= Lower pH = Shift
oxygen dissociation
curve to the RIGHT
-
7/30/2019 Hour 2-Gaseous Exchange Dah Edit
24/25
What is the Oxygen Dissociation Curves?
What does a right shift indicate?
What are the causes of a right shift? Why is the fetus haemoglobin curve shifted to the
left?
What is myoglobin?
-
7/30/2019 Hour 2-Gaseous Exchange Dah Edit
25/25
17.3 Gaseous exchange and
control in plants
17.2 Role of chemoreceptors in
controlling breathing