Transcript PowerPoint Presentation - Liberty Union High School District

Ch 40
Respiratory System
AP Biology
2006-2007
Function
 Need O2 in

for cellular respiration = ATP
 Need CO2 out

food
waste product
O2
AP Biology
ATP
Autonomic Breathing Control
 Medulla sets rhythm & pons moderates it
 Nerve sensors in
aorta & carotid arteries detect
O2 & CO2 levels in blood

measure blood pH
 CO2 = pH (acid)
AP Biology
Lung Anatomy




trachea
bronchi
bronchioles
alveoli
AP Biology
Lung Structure
spongy texture
 alveoli

 small air sacs for more
surface area
 more O2 absorption

moist lining
 mucus to trap dust,
pollen, particles

cilia
 move mucus upward to
clear out lungs
AP Biology
Mammalian Breathing
 Negative pressure

Air is pulled into lungs during inhalation

How: diaphragm moves down
& expands chest cavity
 Air pulled INTO lungs
 Air moves from high to low pressure
AP Biology
Mechanics of breathing
 Air enters nostrils

filtered by hairs, warmed & humidified
 Pharynx  glottis  larynx (vocal cords) 
trachea (windpipe)  bronchi  bronchioles
 air sacs (alveoli)
 Epithelial lining covered by cilia & thin film
of mucus
AP Biology
Alveoli
 Gas exchange across thin epithelium of
millions of alveoli

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total surface area in humans ~100 m2
Moving gases into bloodstream
 Inhale

O2 passes from
alveoli to blood by
diffusion
 Exhale

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CO2 passes from
blood to alveoli by
diffusion
Medulla monitors blood
 Monitors CO2 level of blood

measures pH of blood
 CO2 + H2O  H2CO3 (carbonic acid)
 if pH decreases then
increase breathing & excess
CO2 is eliminated in
exhaled air
AP Biology
Diffusion of gases
 Concentration & pressure drives
movement of gases into & out of blood
in lungs & body tissue
capillaries in lungs
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capillaries in muscle
O2
O2
O2
O2
CO2
CO2
CO2
CO2
blood
lungs
blood
body
Hemoglobin
 Why use a carrier molecule?

O2 not soluble enough in H2O for animal needs
 blood alone could not provide enough O2 to animal cells
 hemocyanin in insects = copper (bluish)
 hemoglobin in vertebrates = iron (reddish)
 Reversibly binds O2

loading O2 at lungs or gills & unloading at cells
heme group
AP Biology
cooperativity
Cooperativity in Hemoglobin
 Binding O2

binding of O2 to 1st subunit causes shape
change to other subunits
 conformational change

increasing attraction to O2
 Releasing O2

when 1st subunit releases O2,
causes shape change to
other subunits
 conformational change

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lowers attraction to O2
O2 dissociation curve for hemoglobin
lowers affinity
of Hb for O2
 active tissue
(producing
CO2) lowers
blood pH
& causes Hb
to release
more O2
AP Biology
% oxyhemoglobin saturation
Bohr Shift
 drop in pH
Effect of pH (CO2 concentration)
100
90
80
70
60
50
40
30
20
10
0
pH 7.60
pH 7.40
pH 7.20
More O2 delivered to tissues
0
20
40
60
80 100
PO2 (mm Hg)
120
140
O2 dissociation curve for hemoglobin
temperature
lowers affinity
of Hb for O2
 active muscle
produces heat
% oxyhemoglobin saturation
Bohr Shift
 increase in
Effect of Temperature
100
90
80
20°C
37°C
70
60
50
40
30
20
10
0
More O2 delivered to tissues
0
AP Biology
43°C
20
40
60
80
PO2 (mm Hg)
100
120
140
Transporting CO2 in blood
 Dissolved in blood plasma as bicarbonate ion
Tissue cells
carbonic acid
CO2 + H2O  H2CO3
CO2
carbonic
anhydrase
bicarbonate
H2CO3  H+ + HCO3–
AP Biology
Carbonic
anhydrase
CO2 dissolves
in plasma
CO2 combines
with Hb
Plasma
CO2 + H2O H2CO3
H2CO3
H+ + HCO3–
Cl–
HCO3–
Gills: getting O2 out of water
 Gills are gas exchange
membranes outside of
the body

thin tissue
water
 high surface area
lots of blood vessels
 gas exchange

 O2 into blood
 CO2 out to water
AP Biology
gills
Counter current exchange system
 Water carrying gas flows in one direction,
blood flows in opposite direction
AP Biology
How counter current exchange works
70%
front
40%
100%
back
15%
water
60%
30%
counter90%
5%
current
blood
50% 70%
100%
50% 30%
concurrent
water
5%
blood
 Blood & water flow in opposite directions

AP Biology
maintains diffusion gradient over whole length
of gill capillary
maximizing O2 transfer from water to blood
Optimizing gas exchange
 Why high surface area?
maximizing rate of gas exchange
 CO2 & O2 move across cell membrane by
diffusion

 rate of diffusion proportional to surface area
 Why moist membranes?
moisture maintains cell membrane structure
 gases diffuse only dissolved in water

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Evolution of gas exchange structures
Aquatic organisms
external systems with
lots of surface area
exposed to aquatic
environment
Terrestrial
moist internal
respiratory tissues with
lots of surface area
AP Biology
Gas Exchange on Land
 Advantages of terrestrial life

air has many advantages over water
 higher concentration of O2
 O2 & CO2 diffuse much faster through air
 respiratory surfaces exposed to air do not have to
be ventilated as thoroughly as gills
 air is much lighter than water & therefore
much easier to pump
 expend less energy moving air in & out
 Disadvantages

keeping large respiratory surface moist
causes high water loss
 reduce water loss by keeping lungs internal
AP Biology