Upload
channing-carlson
View
20
Download
0
Embed Size (px)
DESCRIPTION
Respiration. Chapter 24. Types of Respiratory Systems. Respiration is the uptake of oxygen and the simultaneous release of carbon dioxide. Most primitive animal phyla obtain oxygen directly from their environments through diffusion. More advanced phyla have specific respiratory organs: - PowerPoint PPT Presentation
Citation preview
TYPES OF RESPIRATORY SYSTEMS
• Respiration is the uptake of oxygen and the simultaneous release of carbon dioxide.• Most primitive animal phyla obtain oxygen
directly from their environments through diffusion.• More advanced phyla have specific respiratory
organs:• Gills, tracheae, and lungs
GAS EXCHANGE IN ANIMALS
Flatworm
CO2 O2
Body wall
CO2
Tracheoles
Spiracles
Trachea
O2
O2
CO2
SpiracleTerrestrial arthropod
Gill filament
Blood vesselsFish
Gill
CO2
O2
O2
TracheaMammalian lung Blood vessels
Alveoli
Mammal
CO2
RESPIRATION IN AQUATIC VERTEBRATES
• Water always moves past a fish’s gills in one direction.
Gill raker Gill archGill raker Gill arch
Water
Gill filamentsLamellae withcapillary networks
Water
Direction of water flowDirection of blood flow
Vein
Water
Artery
Water
Water
Gill filaments
Blood (85%O2 saturation)
Countercurrent exchange Concurrent exchange
Water (50%O2 saturation)Water (100%
O2saturation)Blood (50%O2 saturation)
No furthernet diffusion
50%
60%
70%
80%
90%
(b)
Blood (0%O2 saturation)
Water(15%O2 saturation)
Blood (0%O2 saturation)
10%
20%
30%
40%
50%
60%
70%
80%
85% 100%
90%
80%
70%
50%
40%
30%
20%
10%15%
30%
40%
50%
60%
(a)
Water(100%O2saturation)
RESPIRATION IN AQUATIC VERTEBRATES
• Moving the water past the gills in the same direction permits countercurrent flow.• This process is an
extremely efficient way of extracting oxygen.
• Blood flows through a gill filament in an opposite direction to the movement of water.
• The blood in the blood vessels always encounters water with a higher oxygen concentration, resulting in the diffusion of oxygen into the blood vessels.
RESPIRATION IN TERRESTRIAL VERTEBRATES
• Lungs are less efficient than gills because new air that is inhaled mixes with old air already in the lung.• But there is so much more oxygen in air than in
water.
RESPIRATION IN TERRESTRIAL VERTEBRATES
• The lungs of mammals possess on their inner surface many small chambers called alveoli, which greatly increases surface area for the diffusion of oxygen.
(a) Amphibian (b )Reptile (c) Mammal
Alveoli
Alveoli
Bronchiole
Bronchiole
RESPIRATION IN TERRESTRIAL VERTEBRATES
• Flying creates a respiratory demand for oxygen that exceeds the capacity of the saclike lungs of even the most active mammal.• Birds have evolved the most efficient lung.• An avian lung is connected to a series of air sacs
outside of the lung.LungTrachea
Anteriorair sacs
(a)
Posteriorair sacs
(b)
Trachea Inspiration
Posteriorair sacs
Parabronchi of lungAnteriorair sacs
Inspiration Expiration
ExpirationCycle 1
Cycle 2http://youtu.be/kWMmyVu1ueY
Avian lungs
Mammalian lungs
Uniform pool
Cross current
Counter current
Fish gills
Blood(c)
RESPIRATION IN TERRESTRIAL VERTEBRATES
• This creates a unidirectional flow of air through the lungs.• Blood flow and airflow are not opposite but
flow at perpendicular angles in crosscurrent flow.
THE MAMMALIAN RESPIRATORY SYSTEM
• In the mammalian respiratory system, air passes in and out of the lungs, which are housed in the thoracic cavity.• Air is warmed and
filtered as it flows through the nasal cavity.
• It passes next through the pharynx, then the larynx (or voice box), then to the trachea, or windpipe.
Nasal cavity
Nostril
Glottis
Larynx
Trachea
Right lung
Pharynx
Epiglottis
Left lung
Leftbronchus
THE MAMMALIAN RESPIRATORY SYSTEM
• From there, air passes through several branchings of bronchi in the lungs and then to the bronchioles.• The tissue of the
lungs is divided into tiny air sacs called alveoli; through these thin-walled cells, gas exchange with the blood occurs.
Blood flow
Smooth muscle
Bronchiole
Pulmonary arteriole
Pulmonary venule
Alveolarsac
Alveoli
Capillary networkon surfaceof alveolus
THE MAMMALIAN RESPIRATORY SYSTEM
• The mammal respiratory apparatus is simple in structure and functions as a one-cycle pump.• A diaphragm muscle separates the thoracic
cavity from the abdominal cavity.• Each lung is covered by a thin, smooth
membrane called the pleural membrane.• This membrane adheres to another pleural
membrane lining the walls of the thoracic cavity, basically coupling the lungs to the thoracic cavity.
THE MAMMALIAN RESPIRATORY SYSTEM
• Air is drawn into the lungs by the creation of negative pressure.• The active pumping of air in and out is
called breathing.• During inhalation, muscular contraction
causes the chest cavity to expand.• During exhalation, the ribs and diaphragm
return to their original position.
KEY BIOLOGICAL PROCESS: BREATHING
14
<Plung > Pair
Before inhalation, the air pressure in thelungs (Plung) is equal to the atmosphericpressure (Pair).
During inhalation, the diaphragmcontracts, and the chest cavity expandsdownward and outward. This increasesthe volume of the chest cavity and lungs,which reduces the air pressure inside thelungs, and the air from outside the bodyflows into the lungs.
During exhalation, the diaphragm relaxes,decreasing the volume of the chestcavity. The pressure increases in thelungs, forcing air out of the lungs.
321
Diaphragmrelaxed
Plung
Pair Pair
Inhalation
Chestcavityexpands
Diaphragmrelaxed
Plung
Exhalation
Pair
Diaphragmcontracts
Plung Pair
Plung
Plung = Pair
HOW RESPIRATION WORKS: GAS EXCHANGE
• Oxygen moves through the circulatory system carried by the protein hemoglobin.• Hemoglobin molecules contain iron, which binds
oxygen in a reversible way.Heme group Beta (β) chains
Oxygen (O2)
Iron (Fe++)
Alpha () chains
HOW RESPIRATION WORKS: GAS EXCHANGE
• Hemoglobin molecules act like little sponges for oxygen.• At the high O2 levels that occur in the blood
supply at the lung, most hemoglobin molecules carry a full load of O2.
• In the tissues, the O2 levels are much lower, so hemoglobin gives up its bound oxygen.
• In the presence of CO2, the hemoglobin assumes a different shape that gives up its oxygen more readily.
HOW RESPIRATION WORKS: GAS EXCHANGE
• CO2 must also be transported by the blood.• About 8% simply dissolves in the plasma.• 20% is bound to hemoglobin but at a different
site than where O2 binds.• The remaining 72% diffuses into the red blood
cells.
• In order to maintain the gradient for CO2 to leave the tissues and enter the plasma, the CO2 levels in the plasma must be kept low.
HOW RESPIRATION WORKS: GAS EXCHANGE
• The enzyme carbonic anhydrase combines CO2 with water to form carbonic acid (H2CO3).• This acid dissociates into bicarbonate (HCO3
–) and H+.• Bicarbonate also acts as buffer in the blood
plasma.• In the lungs, the reverse reaction takes place,
and CO2 is released.
THE NATURE OF LUNG CANCER
• Lung cancer is one of the leading causes of death among adults.• Mutations to two tumor-suppressing genes are
implicated in the development of cancer.• Rb codes for Rb protein, which acts as a
brake on cell division.• p53 codes for p53 protein, which detects
damaged or foreign DNA and prevents its replication.
THE NATURE OF LUNG CANCER
• Smoking causes lung cancer.• The annual incidence of
lung cancer is much higher for smokers than for nonsmokers.• Changes in the
incidence of lung cancer have mirrored changes in smoking habits.
• Many types of mutagens are found in cigarette smoke that can damage genes.• The p53 gene is damaged in 70% of lung
cancers.• Smoking also leads to nicotine addiction.
INCIDENCE OF LUNG CANCER IN MEN AND WOMEN
1
Per
cap
ita
cig
aret
te c
on
sum
pti
on
Lu
ng
can
cer
dea
th r
ates
per
100
,000
Lu
ng
can
cer
dea
th r
ates
per
100
,000
Per
cap
ita
cig
aret
te c
on
sum
pti
on
3000
2500
2000
1500
1000
500
1900
10
20
30
40
50
60
70
80
90
10Males
Cigaretteconsumption
30years Lungcancerdeaths
Time
Females3000
2500
2000
1500
1000
500
100
90
80
70
60
50
40
30
20
10
201020001910 1920 1930 1940 1950 1960 1970 1980 1990
Cigaretteconsumption
30yearsLungcancerdeaths
1900 1910 1920 1930 1940 1950 960 1970 1980 1990 2000 2010
Time