Respiration

1
Respiration
2
Respiratory Systems
- becomes necessary when organisms are too large
for gas exchange to occur by simple diffusion
- a gas will follow a diffusion gradient from an
area of higher concentration to an area of lower
concentration
O2
CO2
Direct diffusion
ENVIRONMENT
CELLS
Respiratory system
Circulatory system
BLOOD
3
Vertebrate Respiratory Systems
- depend on the environment in which gas exchange
must occur
- in water, vertebrates generally use aquatic
respiration with gills
- on land, vertebrates generally use terrestrial
respiration with lungs
- aquatic respiration can be supplemented with
cutaneous, tracheal and / or cloacal respiration
- aerial respiration can be supplemented with or
replaced by cutaneous respiration (lungless
salamanders)
4
The pharynx is the major respiratory structure in
early vertebrates.
Water high in O2 and low in CO2 enters pharynx
via mouth and / or spiracle
This water is forced across gills and out
external gill slits
Blood low in O2 and high in CO2 is pumped into
gills where gas exchange takes place
What mechanism makes gases move from water
to blood or blood to water?
Diffusion gradient
5
Deoxygenated blood from heart meets oxygenated
water in a counter - current exchange mechanism
that results in highly oxygenated blood leaving
gills and entering dorsal aorta
6
Counter - current exchange mechanism
Highly oxygentated water enters gills from
pharynx
150
120
50
30
100
30
60
110
20
140
140
20
deoxygentated blood enters gills from heart
- all numbers represent partial pressure (PO2) of
oxygen
- the counter current mechanism allows the
maintenance of a strong diffusion gradient for a
maximum amount of time.
7
Understanding partial pressures
How do we measure concentrations of gases in air
and water so we know what diffusion gradients
exist?
We measure the partial pressure made up by each
contributing gas.
Air pressure or barometric pressure (reported by
the weatherman) is the total weight of the air on
a pan of mercury of a given size.
Total air pressure and is usually just under 30
Hg or 760 mm Hg
The gases that make up the atmosphere contribute
differently to the total air pressure They
contribute their partial pressure.
PERCENT OF ATMOSPHERE
PARTIAL PRESSURE
GAS
80
610 mm Hg
N2
150 mm Hg
O2
20
3 mm Hg
CO2
0.3
8
What about partial pressure of gases in water?
- the partial pressure of a gas dissolved in a
liquid is the partial pressure of that gas in the
atmosphere above the liquid, assuming that the
liquid is saturated.
- so, if the PO2 of the atmosphere over the water
is 150 mm Hg, then the water that our shark is
swimming in has a PO2 150 mm Hg
PO2 150 mm Hg

• but the oxygen is dissolved in the water, and the
  water is only 0.7 O2
• by volume

PO2 150 mm Hg
9
Counter - current exchange mechanism
150
120
50
30
100
water
30
60
110
140
20
In the counter-current exchange mechanism, the
gases are dissolved in fluids.
140
20
blood
But a pressure gradient is maintained across the
entire gill
Consider the case of having the fluids flow in
the same direction.
water
150
150
120
100
85
85
85
20
20
50
70
85
85
85
blood
The pressure gradient is lost long before blood
is saturated.
10
Why might evolution favor aerial breathing?
Oxygen is about 30 time more abundant in air than
in water.
Air is much lighter than water.
Acquiring needed oxygen from air rather than
water could save lots of energy.
A possible evolutionary scenario.
Some fish supplement aquatic respiration by
gulping air into swim bladder normally used for
bouyancy control.
They do this especially when O2 in water becomes
depleted.
Exaptation of the swim bladder as a respiratory
organ appears to be characteristic of the
Choanata.
Choanata include lungfishes and tetrapods.
11
Lungs/ gas bladder develop as a ventral
outpocketing of the achenteron
It may be dorsal or ventral to the digestive tract
Fig. 16.1
Liem, Bemis, Walker Grande.
12
Choanata
Outpocketing of digestive tract
Teleostomi
Lungs or gas bladders are present in all
Teleostomi
13
Members of the Choanata include lungfishes and
tetrapods.
All have lungs for gas exchange
All have a breathing nose not just a smelling
nose.
14
(No Transcript)
15
Marieb Fig. 22.1
16
(No Transcript)
17
Lungs are filled with air by expansion of the
pleural cavity
Gas exchange takes place in alveoli
18




19
(No Transcript)
20
(No Transcript)
21
Marieb Fig. 22.9
22
In alveoli
Inside cells
CO2 rich
CO2 poor
Cellular respiration
C6 H12 O6 6O2
6CO2 6H2 O E
O2 rich
O2 poor
23
(No Transcript)
24
Emphysema- a condition in the lungs, where the
walls between the alveoli loose their ability to
stretch and recoil

• Chronic Obstructive Pulmonary Disease (COPD)
• Patients experience shortness of breath, trouble
  breathing, and fatigue
• 2 types
• Primary and secondary

• Causes
• Protein deficiencies allow enzymes to attack the
  elastic structures in your lungs.
• Exposure to toxic chemical fumes
• Smoking temporarily paralyzes the cilia in the
  bronchial tube, this causes the irritants to
  remain in the tube and filter through the lungs

25
So what exactly happens?

• The alveoli become weakened and break
• Elasticity within the lung tissue is lost causing
  air to be trapped in the air sacs and impairing
  the exchange of oxygen and carbon dioxide
• The support of the airways is lost, causing more
  obstruction

26
(No Transcript)
27
Treatment

• Many drugs relieve symptoms and prevent further
  complications but they never fully cure emphysema
• Inhaled and oral steroids
• Supplemental oxygen
• Surgery (long volume reduction surgery)
• Transplants
• Pulmonary rehabilitation

WORKS CITED

• http//www.mayoclinic.com/health/emphysema/
• http//www.lungusa.org/site/apps/s/content.asp?cd
  vLUK9O0Eb34706ct67284
• http//emphysema.org/
• http//www.nlm.nih.gov/medlineplus/emphysema.html