2. Respiration
Gas exchange- also called respiration
Uptake of molecular oxygen from the environment and the
discharge of CO2
Respiration is not only exclusive to this concept; presence of
cellular respiration
Aerobic respiration
Anaerobic respiration
3. Cellular respiration
Chemical breakdown of food to yield ATP
Is a catabolic process
Aerobic Respiration- presence of a complete redox
process due to the presence of O2
More ATP yield
Anaerobic Respiration- absence of O2
Less ATP is produced
4. Glycolysis
Glycolysis- process of breaking down sugar to yield
ATP
Both an aerobic and anaerobic process
Anaerobic- less ATP is produced
Used by bacteria in producing energy; less efficient
Aerobic-more ATP is produced of more products
that can be broken down through oxidative
phosphorylation
8. Yeast Fermentation
Also called alcohol fermentation
Ethanol is a by-product of yeast fermentation
Saccharomyces cerevisiae
9. Gas Exchange in Plants (Photosynthesis)
CO2 is taken in while O2 is released
Factors such as temperature, wind, humidity affect
gas exchange in plants
Different plants employ different strategies in
acquiring CO2 from the environment
Presence of C3, C4 and CAM plants
10. C3, C4 and CAM
Different group of plants have different strategies in
acquiring CO2for photosynthesis
All pathways start from a single CO2 from the
environment
11. C3 pathway
The most basic among the three
A basic 6-C compound is broken down into two 3-C
compound
3-C is more stable than the 6-C compound
12. C4 pathway
C4 plants produce an intermediate 4-C compound
before converting it to the 3-C
Special structure is present in producing the 4-C
compound
Bundle sheath
Employs spatial adaptation
13. CAM pathway
Crassulacean acid metabolic pathway
Common in plants under the family Crassulaceae
Difference to the C4 pathway is the used of temporal
adaptation
CO2 is taken at night when the temperature is low
and the stomata are open
15. Animal Respiration
Respiration or gas exchange is necessary to support
ATP production
May involve both respiratory system and circulatory
system
17. Animal Respiration
Respiratory medium- oxygen source
Air for terrestrial animals
Water for aquatic animals
Oxygen in water is less concentrated compared to air
Oxygen exists in a dissolved form
Many factors affect oxygen concentration in water such as
temperature
18. Respiratory Surface
Respiratory Surface- part of an animal where gas
exchange occurs
Gas exchange occurs entirely through diffusion
Diffusion rate- directly proportional to the SA where
it occurs
Inversely proportional to the square to which molecules must
move
19. Respiratory Surface
Therefore, respiratory surface have thin walls and
have a large SA
Also, water is needed by all living cells to maintain
its plasma membrane
Thus, respiratory surfaces are moist, dissolving first
CO2 and O2 in water
20. Respiratory Surface
Respiratory surface structure:
Depends on the size of the organism
Depends on the organism’s habitat
Depends on its metabolic demands
Endotherm has a larger SA of respiratory surface than a similar-
sized ectotherm
21. Protists and Some Simple Animals
Gas exchange occurs at the entire length of
unicellular organisms
Same for simple animals such as poriferans,
cnidarians and flatworms
Cell in their body is close enough to the respiratory
medium
22. More Complex Animals
Respiratory Surface- does not have direct access to
the respiratory medium
Respiratory surface- thin, moist epithelium
Separates the respiratory medium from blood and capillaries
23. Cutaneous Respiration
Animals such as earthworms and amphibians use the
entire length of their body to respire
Skin is the respiratory organ
Should always be moist, near bodies of water and/or
damp
Why?
25. The Most Common Respiratory Organs
If an animal lacks sufficient body SA for exchange of
gases the solution is an extensively folded respiratory
organ
Most common are tracheal system, gills and lungs
26. Gills: Respiratory adaptations of aquatic animals
Gills- outfolding of the body suspended in water
Can be internal or external
Shape varies
Sea stars- gills have simple shape and distributed all over the
body
Annelids- flaplike gills that extended from each segment or
long feathery gills found on the head or tail
Clams, fish- gills are found in one local region
28. Water as a respiratory medium
Advantage
Cell membranes of respiratory surface are always moist
Disadvantage
Less concentration of O2
High temp, high salinity= low O2 conc
29. Ventilation
Process of increasing contact between the
respiratory medium and respiratory surface
Solution to the low O2 conc in water
Without ventilation a region of high O2 conc and
high CO2 conc can occur
30. Ventilation
Crayfish and lobster- use paddlelike appendages in
driving water over the gills
Fish- gills are ventilated through the passage of
water through the mouth and to the gills
May require large amount of energy
31. Fish Ventilation
High volume of water is needed to ventilate the gills
thereby increasing the energy used
Arrangement of gill capillaries decrease energy use
Blood moves opposite the direction of the water
The process is called countercurrent exchange
32. Countercurrent exchange
There exists a diffusion gradient that favors the
movement of O2 from water to blood in the
capillaries
Very efficient: can remove up to 80% of O2 dissolved
in water
Is also important in temperature regulation and
other physiological processes
35. Terrestrial Respiratory Structures: Tracheal
Systems and Lungs
Air as a respiratory medium
High concentration of O2
Diffusion of O2 and CO2 is faster, ventilation is not much
needed
Partial pressure of gases dictates the rapid transfer of the two
gases involve
36. Air as a respiratory medium
When ventilation is needed, less energy is needed to pump air
Air is much lighter than water
Less volume of air is needed to obtain equal amount of O2 from
H2O
Disadvantage: Respiratory epithelium should always be moist
Solution: highly folded respiratory structure
38. Tracheal Systems
Made up of air tubes that branch throughout the
body; not folded
Largest tubes: called tracheae; open to the outside
Spiracles- outside opening
Tracheoles: finer branch of tracheae, directly
connected to cell surface
39. Tracheal System
Gas exchange is through diffusion across the moist
epithelium at the terminal ends of the system
Circulatory system is not involved
Diffusion is enough to support cellular respiration
Larger insects with higher energy demands ventilate
through rhythmic body movements
40. Tracheal System
Flying insect has high metabolic demand
Wings act as bellows in pumping air through the
tracheal system
Flight muscle cells are packed with mitochondria,
tracheal tubes supply ample amount of O2
41. Lungs
Confined to one location
Gap between respiratory medium and transport
tissue is bridged by the circulatory system
Have dense net of capillaries under the epithelium
that forms the respiratory surface
Evolved in spiders, terrestrial snails, vertebrates
44. Lungs
Amphibians small lungs, rely mainly through skin
Reptiles, birds, mammals rely mainly on their lungs
Turtles: exception: supplement lung breathing
through epithelial surface through the mouth and
anus
Some fish have lungs: lungfishes
Size and complexity of lungs: correlated to an
animal’s metabolic rate
46. Mammalian Respiration
Mammalian Lung Structure: spongy, honeycombed
with moist epithelium
Branching ducts convey air to lungs
Air enters through the nostrils
Filtered by hairs and cilia
Air is warmed, humidified and sampled for odors
47. Mammalian Respiration
Air moves from the nasal passage to the pharynx and
then to the larynx
The act of swallowing moves the larynx upward
tipping the epiglottis over the glottis
Glottis- opening of the windpipe
Larynx- adapted as voicebox
Syrinx- vocal organ of birds
Found at the base of the trachea
Produce sound without the vocal chords found in mammals
48. Mammalian Respiration
Sound: produced when voluntary muscles stretch
and vibrate during the process
High-pitched sound: tight, rapid vibration
Low-pitched sound: less tense, slow vibration
49. Mammalian Respiration
From the trachea: forks into two bronchi
Shaped like an inverted tree
Finer branches are called bronchioles
Epithelial lining is covered with mucus and beating
cilia
Mucus traps contaminant, while, the cilia moves this
to the pharynx where it can be swallowed
51. Ventilating the Lungs
Terrestrial organisms also rely on ventilation
Maintains high O2 and low CO2 at the gas exchange surface
Process of ventilating the lungs is called breathing
Breathing- alternate process of inhalation and exhalation
Two types
Positive pressure breathing
Negative pressure breathing
52. Positive pressure breathing
Frogs ventilate their lungs through positive pressure
breathing
In a breathing cycle:
Muscles lower the oral cavity floor (becomes enlarge and draws
air through the nostrils)
Closing of the mouth and nostril (oral cavity floor rises and
forces air into the trachea)
Air is force out/exhaled (elastic recoil of lungs and muscular
contraction of chest)
53. Negative Pressure Breathing
Works like a suction pump (air is pulled rather than
pushed)
Negative pressure is produced due to action of chest
muscle
Relaxation of chest muscle pushes air; contraction pulls air in
Expansion of lungs is possible due to its double-
walled sac
Inner sac adheres to the lungs
Outer sac adheres to the chest cavity walls
Space in between is filled with fluid
54. Surface Tension
Surface tension- responsible for the behavior of the
lungs
The lungs slide past each other but cannot be pulled
separately
The surface tension couples the movement of the
lungs to the movement of the rib cage
55. Breathing
Inhalation- Contraction of muscles (rib muscles and
diaphragm)
Increases volume of chest cavity
Decreases alveolar air pressure
Rib cage expands (ribs pulled upward; breastbone pushed
forward)
Gas moves from an area of higher partial pressure to
low partial pressure
Air moves from the URT to alveoli of LRT
56. Breathing
Exhalation- relaxation of muscles
Rib muscles and diaphragm relax
Lung volume is reduced
Inc in alveolar air pressure
Shallow breathing- rib muscle and diaphragm are
responsible
Deep breathing- muscles of the back, neck and chest
are responsible
Some animals employ visceral pump- adds to the
piston like action of the diaphragm
57. Breathing
Tidal volume- volume of air inhaled and exhaled in
each breath
Ave human tidal volume is 500 ml
Vital capacity- max tidal volume during forced
breathing
3.4 L female; 4.8 L male
Residual volume- air left in the lungs during
exhalation
Lungs hold more air than the vital capacity
58. Breathing
Age or disease decrease the elasticity of the lungs
Residual volume increases at the expense of vital capacity
Max O2 conc in the alveoli decreases
Gas exchange efficiency is decreased
59. Ventilation in birds
More complex than mammals
Presence of air sacs
Do not function directly in gas exchange; acts as
bellows
Lungs and air sacs- ventilated during breathing
Presence of parabronchi rather than alveoli
Air moves in one direction
Air is completely exchanged
Max O2 conc is higher in birds than in mammals
60. Regulation of Breathing
Breathing – controlled by the medulla oblonagata
and the pons
This ensures that respiration is coordinated with
circulation
Medulla oblongata- major control center of
breathing
Control center in the pons works synergistic with the
control center of the medulla oblongata
61. Regulation of Breathing
Negative feedback- helps maintain breathing
Stretch sensors- found in the lungs send impulses to
the medulla (inhibits the breathing control center)
Medulla- monitors CO2 level of the blood
CO2 conc is detected through slight change in blood and tissue
fluid pH
Carbonic acid lowers pH
Drop in pH increases rate of rate and depth of breathing
62. Oxygen Concentration
Oxygen Concentration- have little effect to breathing
control center
Severe depression of O2 conc stimulates O2 sensors
in the aorta and carotid arteries to send alarm
signals
Breathing rate is increased by the control centers
Increase in CO2 conc is a good indicator of decrease
in O2 conc
63. Hyperventilation
Excessive deep, rapid breathing inc CO2 conc in the
blood
Breathing centers temporarily stops working
Impulses to the rib muscles and diaphragm are
inhibited
Breathing resumes when CO2 conc inc
64. Different Factors Affect Breathing
Nervous and chemical signals affects rate and depth
of breathing
Most efficient if it works in tandem with the
circulatory system
E.g. Exercise: inc cardiac output-inc breathing rate
Enhances O2 uptake and CO2 removal
65. Respiratory pigments: transports gases and
buffers the blood
Low solubility of O2- problem if O2 is transported
via the circulatory system
E.g. Normal human consume 2L of O2 per minute
Only 4.5 ml of O2 can dissolve into a L of blood in the lungs
If 80% dissolved O2 would be delivered, 500 L of blood should
be pumped per minute (a ton per 2 mins)
Unrealistic!!!!
Special respiratory pigments are used
66. Respiratory Pigments
Transports O2 instead of dissolving into a solution
Inc O2 that can be carried in the blood (~200 mL O2
per L in mammalian blood)
Decreases cardiac output (20-25 L per min)
67. Respiratory Pigments
Binds O2 reversibly
Loads O2 from respiratory organ; unloads in other parts of the
body
Hemocyanin- found in hemolymph of arthropods
and many mollusks
Copper- acts as the oxygen-binding component
Hemoglobin- respiratory pigment of all vertebrates
68. Hemoglobin
Consists of four heme subunits
Iron acts as the binding site of O2
Loading and unloading of O2 depends on the
property of each subunits called cooperativity
Affinity is dependent to the conformation of each
subunit
Binding of one O2 molecule to one subunit induces the inc in
affinity of other subunits
Unloading of one O2 molecule decreases the affinity of other
subunits
69. Dissociation Curves of Gases
Cooperativity of heme subunits is shown in a
dissociation curve
Steep slope- slight change in Po2causes substantial
loading or unloading of O2
Because of cooperativity, slight drop in Po2causes a
relatively large inc in O2 to be unloaded
71. The Bohr Shift
A shift to the right of the oxygen hemoglobin
dissociation curve
Brought about by increase CO2 or low blood pH
Decrease in affinity of hemoglobin to O2
Greater efficiency of O2 unloading
72. Carbon Dioxide transport
Hemoglobin- also transports CO2 not only O2
Assists in buffering the blood
Blood released by respiring cells:
7%- transported in the solution of blood plasma
23% - bind to amino group of hemoglobin
70% - transported in the blood in the form of carbonic acid
73. Carbon Dioxide Transport
CO2- converted in the red blood cells into
bicarbonate
Reacts first with water to form carbonic acid (carbonic
anhydrase)
Dissociates into H+
and bicarbonate
H ions- attach to different sites in the Hb and other proteins
Bicarbonate ions- diffuse into the plasma
Movement of blood through the lungs reverses the process
favoring the conversion of bicarbonate to CO2
74. Deep-diving air breathers
Stockpile oxygen- O2 is reserved in the blood and
muscles (e.g. Weddell seal)
High percentage of myoglobin
Dec heart rate and O2 consumption
20-min dive- O2 in myoglobin is used up
Energy is erived from fermentation rather than respiration