The Respiratory System
By:
Olga Pavlenko,
Ray Peniera,
Talia Torres
And
Melissa Yu
What is the respiratory system?
Respiration, or gas exchange is the uptake
of molecular oxygen from the
environment and the discharge of carbon
dioxide to the environment.
Respiratory Surface
The respiratory surface is the part of the
animal’s body where gases are exchanged
with the surrounding environment.
Animals do not move oxygen and carbon
dioxide across membranes by active
transport so movement of these gases
between respiratory surface and the
environment occurs by diffusion.
Respiratory Medium
The respiratory medium is the source of
oxygen for terrestrial animals.
Respiratory
medium
(air of water)
O2
CO2
Respiratory
surface
Organismal
level
Circulatory system
Cellular level
Energy-rich
molecules
from food
Figure 42.19
Cellular respiration
ATP
The Parts of The Respiratory System
Nasal Cavity
The air passage
behind the nose
that plays an
important role in
breathing
The human inhales
oxygen and exhales
carbon dioxide
through the nasal
cavity
Pharynx
An area in the vertebrate throat where air
and food passages cross.
It extends from the mouth and nasal
cavities to the larynx, where it continues
to the esophagus.
Larynx
The voice box containing the vocal cords.
It is located between the pharynx and the
trachea.
Trachea
A thin-walled,
cartilaginous tube
passing from the
larynx to the
bronchi that carries
air to the lungs.
It is also known as
the windpipe.
Bronchi
The two branches of breathing tubes that branch from
the trachea that lead to the lungs.
At the end of each bronchus is a bronchiole, which is
one of the fine branches that transport air to the alveoli.
Diaphragm
The main breathing
muscle, that contracts
when inhaling, and
releases when
exhaling.
A sheet of skeleton
muscle that forms the
bottom wall of the
chest cavity.
Lungs
Two, spongy, saclike
respiratory organs in
most vertebrates,
occupying the chest
cavity together with
the heart and
functioning to remove
carbon dioxide from
the blood and provide
it with oxygen.
Carbon Dioxide Transport
in Blood
1. Carbon dioxide produced by body tissues diffuses into the interstitial
fluid and the plasma.
2 .Over 90% of CO2 diffuses into the red blood cells, which leaves 7% in
the plasma as dissolves CO2.
3. Some CO2 is picked up and transported by hemoglobin.
4. However, most CO2 reacts with water in red blood cells, forming
carbonic acid (H2CO3), a reaction catalyzed by carbonic anhydrase
contained within
red blood cells.
5. Carbonic acid dissociates into a biocarbonate ion (HCO3–) and a
hydrogen ion (H+).
6. Hemoglobin binds most of the \H+ from H2CO3 preventing the H+
from acidifying the blood and thus preventing the Bohr shift.
Carbon Dioxide Transport
in Blood (continued)
7. Most of the HCO3– diffuse into the plasma where it is carried in the
bloodstream to the lungs.
8. In the HCO3– diffuse from the plasma red blood cells, combining
with H+ released from hemoglobin and forming H2CO3.
9. Carbonic acid is converted back into CO2 and water.
10. CO2 formed from H2CO3 is unloaded from hemoglobin and
diffuses into the interstitial fluid.
11. CO2 diffuses into the alveolar space, from which it is expelled during
exhalation. The reduction of CO2 concentration in the plasma drives
the breakdown of H2CO3 Into CO2 and water in the red blood cells
(see step 9), a reversal of the reaction that occurs in the tissues (see
step 4).
Carbon Dioxide Transport
Control of Breathing in Humans
The main breathing control centers are located in regions of the
brain, the medulla, and the pons.
Aided by the control center in the pons, the medulla center sets the
basic breathing rhythm.
Secondary control over breathing is exerted by sensors in aorta and
carotid arteries that monitor O2 and CO2 concentrations in the
blood as well as pH.
During deep breathing, a negative feedback mechanism prevents the
lungs from over expanding; stretch sensors in the lung tissue send
nerve impulses that inhibit the medulla’s control center.
Control of Breathing in Humans
(Cont.)
The medulla’s control center regulates breathing activity in response
to changes in pH of the tissue fluid (cerebrospinal fluid) bathing the
brain.
When the O2 level is severely depressed O2 sensors in the aorta and
carotid arteries in the neck send alarm signals to the breathing
control centers, which respond by increasing breathing rate.
Normally a rise in CO2 concentration is a good indication of a fall
in O2 concentration because CO2 is produced by the same process
that consumes O2-cellular respiration
The breathing center responds to a variety of nervous and chemical
signals and adjusts breathing rate and depth to meet changing
demands.
The Role of Partial Pressure Gradients
Gases diffuse down pressure gradients in
the lungs and other organs. Diffusion of a
gas, whether present in air or dissolved in
water, depends on differences in a quantity
called partial pressure.
A gas always diffuses from a region of
higher partial pressure to a region of lower
partial pressure.
How the pressure gradient is maintained
1.
2.
3.
4.
Blood arriving at the lungs via the pulmonary arteries has a lower PO2 and
a higher PCO2 than the air in the alveoli. As blood enters the alveolar
capillaries, CO2 diffuses from the blood to the air in the alveoli.
Meanwhile O2 in the air dissolves in the fluid that coats the epithelium
and diffuses into the blood.
When the blood leaves the lungs in the pulmonary veins, its PO2 has
been raised and its PO2 has been lowered. After returning to the heart,
this blood is pumped through the systemic circuit.
In the tissue capillaries, gradient of partial pressure favor the diffusion of
O2 out of the blood and CO2 into the blood. This is because cellular
respiration removes O2 from and adds CO2 to the interstitial fluid.
After the blood unloads O2 and loads CO2, it is returned to the heart
and pumped to the lungs again, where it exchanges gases with air in the
alveoli.
Inhaled air
Exhaled air
160 0.2
O2 CO2
120 27
Alveolar spaces
O2 CO2
104
Alveolar
epithelial
cells
40
O2 CO2
Blood
entering
alveolar
capillaries
40
O2
CO2
O2
Alveolar
capillaries
of lung
45
O2 CO2
104
40
O2 CO2
Pulmonary
veins
Pulmonary
arteries
Systemic
arteries
Systemic
veins
Heart
CO2
Tissue
capillaries
O2
Blood
entering
tissue
capillaries
Blood
leaving
tissue
capillaries
40
Blood
leaving
alveolar
capillaries
45
O2
CO2
100
40
O2 CO2
O2 CO2
Tissue
cells
<40 >45
O2 CO2
Respiratory pigments
A protein that transports oxygen in blood.
The pigments increase amount of oxygen
that can be carried in blood.
Oxygen transport
A diversity of respiratory pigments have evolved in different kinds
of animal taxa.
A type of respiratory pigment that uses copper as its oxygenbinding component is called hemocyanin, which is found in the
hemolymph of arthropods and molluscs.
Hemoglobin consists of 4 subunits, each with a cofactor called
heme group consisting of an iron atom at its center. Each
hemoglobin molecule can carry molecules of O2. They must bind
O2 reversibly, loading O2 in the lungs, and unloading it in other
parts of the body. This process depends on cooperatively between
subunits of hemoglobin molecule.
Oxygen Transport (cont.)
Binding of O2 to a subunit induces the
others to change shape slightly, with the
result that there affinity for O2 increases.
When one subunit unloads its O2, the
other three quickly unload, too as a shape
change lowers their affinity for O2.
Bibliography
http://library.thinkquest.org/5777/resp2.htm
http://library.thinkquest.org/2935/Natures_Best/Nat_Best_High_Level/Re
spiratory_Net_Pages/Respiratory_title.html
http://users.rcn.com/jkimball.ma.ultranet/BiologyPages/P/Pulmonary.ht
ml
http://www.emc.maricopa.edu/faculty/farabee/BIOBK/BioBookRESPSYS.ht
ml
http://www.getbodysmart.com/ap/respiratorysystem/menu/menu.html
http://www.nhlbi.nih.gov/health/dci/Diseases/hlw/hlw_respsys.html
http://www.cdli.ca/~dpower/resp/main.htm
http://www.webmd.com/lung/how-we-breathe
http://www.biotopics.co.uk/humans/resyst.html
http://www.ivyrose.co.uk/HumanBody/Respiratory/Respiratory_System.php
Activities
(1) Name the Function of each of
the following:
Nasal Cavity: _______________________
Pharynx:____________________________
Larynx: ____________________________
Trachea (Windpipe): __________________
Lungs: _____________________________
Bronchi: ___________________________
Bronchioles: ________________________
Diaphragm: _________________________
(2)
Identify the following parts:
(3) Match the Term with its
Definition
_____. Respiratory medium
_____. Nasal Cavity
_____. Pharynx
_____. Larynx
_____. Trachea
_____. Bronchi
_____. Bronchioles
_____. Diaphragm
_____. Lungs
_____. Breathing Control Centers
_____. Partial Pressure Gradients
_____. Respiratory Pigment
a. Area in vertebrate throat that extends from the
mouth and nasal cavities to the larynx, where it
continues to the esophagus.
b. Voice box containing vocal chords between the
pharynx and trachea
c. A protein that transports oxygen in blood.
d. Branch at ends of Bronchi.
e. Air passage behind the nose.
f. Source of oxygen for terrestrial animals.
g. Two, spongy, saclike respiratory organs in most
vertebrates, occupying the chest cavity together with
the heart.
h. Located in regions of the brain, the medulla, and the
pons.
i. A sheet of skeleton muscle that forms the bottom
wall of the chest cavity.
j. Diffuse gas in the lungs and other organs.
k. The two branches of breathing tubes that branch
from the trachea that lead to the lungs.
l. A thin-walled, cartilaginous tube passing from the
larynx to the bronchi, also known as the windpipe.
Answers to the Activities
Activity (1)
The nasal cavity conditions the air to be received by the other areas of the
respiratory tract. The air passing through the nasal cavity is warmed or
cooled within 1 degree of body temperature.
The part before the trachea that air passes through. It is important in
vocalization.
Sound is made in larynx, and that is where pitch and volume are controlled.
The strength of expiration from the lungs also contributes to loudness.
A thin-walled, cartilaginous tube that carries air from the larynx to the
lungs and bronchi.
Spongy, saclike respiratory organs that remove carbon dioxide from the
blood, and replaces it with oxygen.
The subdivisions of the trachea that convey air to and from the lungs.
Small terminal branches of the bronchi in the lungs. It lacks cartilage, and is
lined with smooth muscle, which controls the lumen size.
When breathing, the diaphragm contracts and flattens down, thus
increasing the capacity of the chest, and causing air to be drawn into the
lungs.
Activity (2)
1.
2.
3.
4.
5.
6.
7.
8.
9.
Nasal cavity
Oral cavity
Pharynx
Larynx
Trachea
Bronchi
Lung
Heart
Ribs
Activity (3)
f.
e.
a.
b.
l.
k.
d.
i.
g.
h.
j.
c.