Respiration

1
Respiration
2
Gas Exchange requires moist surfaces

• P. 871

Gills (left), Alveoli (right)
3
Gas Exchange

• 42.18

4
Gill Structure and Function

1. Gills are skin projections into which coelomic
   fluid moves.
2. Parapodia are used for gills, swimming, crawling.
3. Long, flattened page-like tissues.
4. Feathery gills under exoskeleton.

• 42.19

5
Insects

• Have spiracles leading to trachea (branched
  tubes)
• Air sacs are present near organs
• Pix 42.22

6
Gills in Fish

• 42.20

Water is pumped through the mouth and over gill
arches. Each gill arch has 2 filaments made of
plate like lamellae.
7
Countercurrent Exchange

• 42.21

Blood picks up more and more oxygen as the water
has higher and higher concentrations. (oxygen
poor vessels on right, oxygen rich vessels on
left)
8
Bird Respiration

• 42.25

Air sacs maximize oxygen withdrawal from air.
9
Negative Pressure Breathing

• 42.24

Air is pulled (not pushed) into the lung. On
inhalation the volume of the thoracic cavity is
increased- decreasing pressure-air rushes in.
10
Terminology

• Tidal Volume-volume inhaled and exhaled per
  breath.
• Vital Capacity-Maximum tidal volume (forced).
• Residual volume-the air that cannot be expelled
  from the lungs.

11
Breathing Control Centers
Two regions of the brain-medulla oblongata and
pons. Medulla set rhythm, monitors carbon dioxide
levels in blood (mostly using pH) and adjust
breathing as needed. CO2 water forms carbonic
acid-lowers pH. Low pH triggers increased
breathing rate and depth. Very low O2 sensors in
aorta and carotid respond with signal to
breathing centers-breathing rate
increases. Hyperventilation- very deep breathing
may purge blood of carbon dioxide-stops impulses
to expand thorax until levels build up. Bypasses
usual set-up-Co2 and O2 levels are related.

• 42.26

12
Gas Exchange
Gas diffuses down pressure gradients. Partial
Pressures are the portions of atmospheric
pressure contributed by individual gases. e.g.
air is 21 oxygen. Pressure of atmosphere is 760
mmHg PP of O2 is .21 x 760 160mmHg

• 42.27

13
More Partial Pressure

• Gas will always diffuse from a higher partial
  pressure to a lower partial pressure.
• At the lung the PO2 in the blood is low and the
  PO2 in the lung is higher so oxygen moves into
  the blood.
• At the lung the PCO2 in the blood is higher than
  in the lung, so carbon dioxide moves into the
  lung from the blood.
• This works at the tissues too.

14
Hemoglobin Dissociation Curve

• 42.28

Hemoglobin is a respiratory pigment (protein)
which carries oxygen. Arthropods have hemocyanin.
15
Hemoglobin

• Made of four subunits, each with a cofactor
  called a heme group and each with an iron atom at
  the center.
• The binding of oxygen with one subunit causes a
  shape change which causes the other three to bind
  more easily. This is cooperativity.
• This is seen in the dissociation curve for
  hemoglobin over different partial pressures of
  oxygen. When the partial pressure falls the
  hemoglobin hangs onto the oxygen until it is
  pretty low, then lets go of all of it at once.
• The Bohr shift shows an increase in o2 release
  when the pH is lower-more carbon dioxide.

16
Blood CO2 Transport
CO2 is carried to the lungs in a variety of
ways. 7 is carried in the blood plasma 23 binds
to amino groups of hemoglobins 70 is carried as
bicarbonate ions in the blood. CO2 diffuses into
blood plasma then into RBCs where it is
converted to bicarbonate CO2 first reacts with
water (enzyme here is carbonic anhydrase) to form
carbonic acid. Most H attach to hemoglobin.
Bicarbonate diffuses out into plasma.

• 42.29

17
Hemoglobin Curves

• In fetus

18
Special Adaptations

• Oxygen storage in blood and muscle may be
  doubled.
• Less left in lung 36 to 5 in seal
• Spleen is large and may store huge amounts of
  blood.
• Lots of myoglobin- an oxygen storing protein- in
  muscle
• Conserve oxygen
• ATP from fermentation