Why oxygen is import Most animals satisfy their energy
requirement by oxidation of food, in the processes forming carbon
dioxide and water Oxygen is most abundant element in the earths
crust (49.2%) In atmosphere Per liter water (15 0 C, 1 atm) O2
20.95% 7.22 ml CO2 0.03% 1019.0 ml N2 78.09% 16.9 ml Argon 0.93%
Total100% Slide 2 760 mm Pressure at sea level Mercury (Hg)
Pressure exerted by atmospheric air above Earths surface Vacuum
Slide 3 Oxygen is added to atmosphere: Photosynthesis (dominant)
Photodissociation of water vapor Oxygen is removed from atmosphere:
Living organism respiration Oxidizing of organic matter, rocks,
gases and fossil fuels Oxygen and carbon dioxide in physical
environment Slide 4 "Global warming" is a real phenomenon: Earth's
temperature is increasing. True False Slide 5 Slide 6 Slide 7 Fig.
11-2, p.464 Slide 8 Slide 9 Solubility of oxygen decreases with
increasing water temperature and salinity Temperature Fresh water
Sea water ml O 2 /L water 0 10.297.97 10 8.026.35 15 7.225.79 20
6.575.31 30 5.574.46 Normoxic water: 100% saturated with oxygen
Hypoxic water contains less oxygen than normoxic water Anoxic water
contains no dissolved oxygen Oxygen and carbon dioxide in physical
environment Slide 10 Slide 11 Slide 12 Transport O 2 and CO 2 in
living systems Diffusion is common mechanism for transport both O 2
and CO 2 across the body surface To maximize the rate of gas
transfer Large respiratory surface area Small diffusion distance
Slide 13 Slide 14 bronchial tree The lungs contain many branching
airways which collectively are known as the bronchial tree Slide 15
The trachea and all the bronchi have supporting cartilage which
keeps the airways open. Bronchioles lack cartilage and contain more
smooth muscle in their walls than the bronchi, for airflow
regulation The airways from the nasal cavity through the terminal
bronchioles are called the conducting zone. The air is moistened,
warmed, and filtered as it flows through these passageways. Slide
16 Slide 17 The pulmonary arteries carry blood which is low in
oxygen from the heart to the lungs. These blood vessels branch
repeatedly, eventually forming dense networks of capillaries that
completely surround each alveolus. oxygen and carbon dioxide are
exchanged between the air in the alveoli and the blood in the
pulmonary capillaries. Blood leaves the capillaries via the
pulmonary veins, which transports the oxygenated blood out of the
lungs and back to the heart. Slide 18 Alveoli ~ 300 million air
sacs. Large surface area (60 80 m 2 ). Each alveolus is 1 cell
layer thick. Total air barrier is 2 cells across (0.5 m). 3 types
of cells: Alveolar type I: Structural cells. Alveolar type II:
Secrete surfactant. Slide 19 Ventilation Mechanical process to move
air in and out of the lungs. O 2 of air is higher in the lungs than
in the blood, O 2 diffuses from air to the blood. C0 2 moves from
the blood to the air by diffusing down its concentration gradient.
Gas exchange occurs entirely by diffusion. Diffusion is rapid
because of the large surface area and the small diffusion distance.
Slide 20 Three types of cells: 1. simple epithelium cells 2.
alveolar macrophages 3. surfactant-secreting cells The wall of an
alveolus is primarily composed of simple epithelium, or Type I
cells. Gas exchange occurs easily across this very thin epithelium.
The alveolar macrophages, or dust cells, creep along the inner
surface of the alveoli, removing debris and microbes. The alveolus
also contains scattered surfactant-secreting, or Type II, cells.
Slide 21 Water in the fluid creates a surface tension. Surface
tension is due to the strong attraction between water molecules at
the surface of a liquid, which draws the water molecules closer
together. Surfactant, which is a mixture of phospholipids and
lipoproteins, lowers the surface tension of the fluid by
interfering with the attraction between the water molecules,
preventing alveolar collapse. Without surfactant, alveoli would
have to be completely reinflated between breaths, which would take
an enormous amount of energy. Slide 22 The wall of an alveolus and
the wall of a capillary form the respiratory membrane, where gas
exchange occurs. Slide 23 Slide 24 Summary The lungs contain the
bronchial tree, the branching airways from the primary bronchi
through the terminal bronchioles. The respiratory zone of the lungs
is the region containing alveoli, tiny thin-walled sacs where gas
exchange occurs. Oxygen and carbon dioxide diffuse between the
alveoli and the pulmonary capillaries across the very thin
respiratory membrane. Slide 25 Three main factors: 1.The surface
area and structure of the respiratory membrane. 2. Partial pressure
gradients 3. Matching alveolar airflow to pulmonary capillary blood
flow Slide 26 Fig. 11-17, p.480 Atmospheric pressure (the pressure
exerted by the weight of the gas in the atmosphere on objects on
the Earths surface760 mm Hg at sea level) Lungs (represents all
alveoli collectively) Pleural sac (space represents pleural cavity)
Thoracic wall (represents entire thoracic cage) Airways (represents
all airways collectively) 756 mm Hg 760 mm Hg Atmosphere 760 mm Hg
Intrapleural pressure (the pressure within the pleural sacthe
pressure exerted outside the lungs within the thoracic cavity,
usually less than atmospheric pressure at 756 mm Hg) Intra-alveolar
pressure (the pressure within the alveoli760 mm Hg when
equilibrated with atmospheric pressure) Slide 27 Fig. 11-18, p.481
Thoracic wall Numbers are mm Hg pressure. Transmural pressure
gradient across thoracic wall = atmospheric pressure minus
intrapleural pressure Transmural pressure gradient across lung wall
= intra-alveolar pressure minus intrapleural pressure 760 756 760
756 Lung wall Airways Pleural cavity (greatly exaggerated) Lungs
(alveoli) Slide 28 Slide 29 Fig. 11-20, p.482 Accessory muscles of
inspiration (contract only during forceful inspiration) Muscles of
active expiration (contract only during active expiration) Internal
intercostal muscles Abdominal muscles Major muscles of inspiration
(contract every inspiration; relaxation causes passive expiration)
Diaphragm External intercostal muscles Ribs Sternum Scalenus
Sternocleidomastoid Slide 30 Fig. 11-21a, p.483 Contraction of
external intercostal muscles causes elevation of ribs, which
increases side-to-side dimension of thoracic cavity Inspiration
Before inspiration Elevation of ribs causes sternum to move upward
and outward, which increases front-to-back dimension of thoracic
cavity Contraction of diaphragm Contraction of external intercostal
muscles External intercostal muscles (relaxed) Diaphragm (relaxed)
(a) Lowering of diaphragm on contraction increases vertical
dimension of thoracic cavity Elevated rib cage Sternum Slide 31
Fig. 11-21bc, p.483 Active expiration (c) (b) Contraction of
internal intercostal muscles flattens ribs and sternum, further
reducing side-to-side and front-to-back dimensions of thoracic
cavity Contraction of abdominal muscles causes diaphragm to be
pushed upward, further reducing vertical dimension of thoracic
cavity Relaxation of diaphragm Return of diaphragm, ribs, and
sternum to resting position on relaxation of inspiratory muscles
restores thoracic cavity to preinspiratory size Position of relaxed
abdominal muscles Contraction of abdominal muscles Relaxation of
external intercostal muscles Contraction of internal intercostal
muscles Passive expiration Slide 32 Slide 33 Fig. 11-23, p.486 An
alveolus H 2 O molecules Slide 34 Fig. 11-26, p.489 Slide 35 Fig.
11-27, p.490 Slide 36 Slide 37 Slide 38 Slide 39 Slide 40 Factors
affecting the exchange of oxygen and carbon dioxide during internal
respiration: 1.The available surface area 2. Partial pressure
gradients. 3. The rate of blood flow in a specific tissue. Slide 41
Oxygen and Carbon Dioxide Transportation The blood transports
oxygen and carbon dioxide between the lungs and other tissues
throughout the body. These gases are carried in several different
forms: 1. dissolved in the plasma 2. chemically combined with
hemoglobin 3. converted into a different molecule Slide 42 Slide 43
Hemoglobin and 0 2 Transport 280 million hemoglobin/ RBC. Each
hemoglobin has 4 polypeptide chains and 4 hemes. Each heme has 1
atom iron that can combine with 1 molecule O 2 Each hemoglobin can
combine with 4 molecule O 2 Combine reversibly with O 2 depend on P
O2 Slide 44 the affinity of hemoglobin for oxygen decreases as its
saturation decreases Hemoglobin's affinity for oxygen increases as
its saturation increases Slide 45 Hemoglobin Oxyhemoglobin: Normal
heme contains iron in the reduced form. Reduced form of iron can
share electrons and bond with oxygen. Deoxyhemoglobin: When
oxyhemoglobin dissociates to release oxygen, the heme iron is still
in the reduced form. Slide 46 Hemoglobin Hemoglobin production
controlled by erythropoietin. Production stimulated by P 02
delivery to kidneys. Loading/unloading depends: P 02 of
environment. Affinity between hemoglobin and 0 2. Slide 47 Oxygen
dissociation curve describes the relation between percent of
saturation and the partial pressure of oxygen (S-shape, sigmoid) At
high P O 2, a large amount of O2 is bound At low P O 2, only small
amount of O2 is bound Oxyhemoglobin Dissociation Curve Slide 48
Hemoglobin saturation is determined by the partial pressure of
oxygen S-shaped curve Slide 49 Slide 50 Slide 51 Oxyhemoglobin
Dissociation Curve Loading and unloading of 0 2. Steep portion of
the curve, small changes in P 02 produce large differences in %
saturation (unload more 0 2 ). Decreased pH, increased temp., and
increased 2,3 DPG, increase CO 2 affinity of Hb for 0 2 decreases.
Shift to the right greater unloading. Bohr effect Slide 52 Slide 53
Muscle Myoglobin Slow-twitch skeletal fibers and cardiac muscle
cells are rich in myoglobin. Has a higher affinity for 0 2 than
hemoglobin. Acts as a go-between in the transfer of 0 2 from blood
to the mitochondria within muscle cells. May also have an 0 2
storage function in cardiac muscles. Slide 54 Human fetal
hemoglobin contains chains, which has a high O2 affinity than adult
hemoglobin In humans, the oxygen affinity of blood decrease for
about 3 months after the birth Slide 55 Slide 56 Slide 57 This
reaction is catalyzed by the enzyme carbonic anhydrase. Slide 58 C0
2 transported in the blood: HC0 3 - (70%). Dissolved C0 2 (7%).
Carbaminohemoglobin (23%). HCO 3 - is high in plasma than in
erythrocytes CO 2 enters and leaves the blood as molecular CO 2
rather than HCO 3 - C0 2 Transport Slide 59 Chloride Shift at
Systemic Capillaries H 2 0 + C0 2 H 2 C0 3 H + + HC0 3 - At the
tissues, C0 2 diffuses into the RBC, reaction shifts to the right.
Increased [HC0 3 - ] in RBC, HC0 3 - diffuses into the plasma with
assistance of band III protein. RBC becomes more +. Cl - diffuses
in (Cl - shift). HbC0 2 formed, give off 0 2. Slide 60 At Pulmonary
Capillaries H 2 0 + C0 2 H 2 C0 3 H + + HC0 3 - At the alveoli, C02
diffuses into the alveoli, reaction shifts to the left. Decreased
[HC0 3 - ] in RBC, HC0 3 - diffuses into the RBC. RBC becomes more
-. Cl - diffuses out (Cl - shift). Hb0 2 formed, give off HbC0 2.
Slide 61 Slide 62 Slide 63 Summary O2 is transported in two ways:
dissolved in plasma, and bound to hemoglobin as oxyhemoglobin The
O2 saturation of hemoglobin is affected by: PO2, pH, temperature,
PCO2, and DPG CO2 is transported in three ways: dissolved in
plasma, bound to hemoglobin as carbaminohemoglobin, and converted
to bicarbonate ions Oxygen loading facilitates carbon dioxide
unloading from hemoglobin. This is known as the Haldane effect.
When the pH decreases, carbon dioxide loading facilitates oxygen
unloading. The interaction between hemoglobin's affinity for oxygen
and its affinity for hydrogen ions is called the Bohr effect. Slide
64 Fig. 11-40, p.513 Respiratory control centers in brain stem Pons
Medulla Pre-Btzinger complex Dorsal respiratory group Ventral
respiratory group Pons respiratory centers Medullary respiratory
center Apneustic center Pneumotaxic center Slide 65 Fig. 11-41,
p.513 Input from other areas some excitatory, some inhibitory
Diaphragm Phrenic nerve Not shown are intercostal nerves to
external intercostal muscles. Spinal cord Medulla Inspiratory
neurons in DRG (rhythmically firing) + + Slide 66 Fig. 11-42, p.514
Sensory nerve fiber Aortic bodies Carotid bodies Heart Sensory
nerve fiber Aortic arch Carotid artery Carotid sinus Slide 67
Arterial P O2 < 60 mm Hg Peripheral chemoreceptors Medullary
respiratory center Central chemoreceptors No effect on + __
Emergency life-saving mechanism + VentilationArterial P O2 Fig.
11-43, p.515 Slide 68 Fig. 11-44, p.516
