St. John’s BIO 1050: Human Biology
Instructor: Dr. Galina N. Fomovska
Respiration System
Chapter 10
Lecture 11
Respiration
The entire process of gas exchange between air in
atmosphere and body cells is called RESPIRATION
Events of RESPIRATION include:
1. Movement of Air into and out of the lungs (breathing or
ventilation)
2. Exchange of gases between the air in the lungs and blood
capillaries (external respiration)
3. Transport of gases in blood from lungs to the body cells and
back
4. Exchange of gases between blood in capillaries and body
cells (internal respiration)
5. O2 utilization and CO2 production at cellular level (cellular
respiration)
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10.1 The Respiratory System
Respiratory System
ORGANS
Nose
Pharynx
Larynx
Trachea
Bronchus
(bronchi)
Bronchioles
CONDUCTING DIVISION
FUNCTION: the respiratory system is responsible for the
process of ventilation (breathing), which includes
INSPIRATION and EXPIRATION.
Lungs: structures involved in gas exchange
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– RESPIRATORY DIVISION
10.2 The Upper Respiratory Tract
Organs of the upper respiratory tract
• Nose
• Filter, warm, and
moisture the air, has
odor receptors
• Pharynx
• commonly called the
throat, three part
• Larynx
• passes air between
the pharynx and
trachea, houses
vocal cords..
Figure 10.2 The upper respiratory tract.
sinus
nasal cavity
hard
palate
nares
sinus
tonsil
Pharynx
nasopharynx
uvula
mouth
tongue
oropharynx
tonsils
epiglottis
glottis
larynx
laryngopharynx
esophagus
trachea
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10.3 The Lower Respiratory Tract
Organs of the lower respiratory tract
1. Trachea
2. Bronchial tree
Nasal cavity
filters, warms, and moistens air
NO GAS EXCHANGE IN
TRACHEA and
BRONCHOIAL TREE
Upper
Respiratory
Tract
Pharynx
passage way where pathway
for air and food cross
Glottis
space between the vocal chords;
opening to larynx
Larynx
(voice box) ; produces sound
Trachea
(wind pipe) ; passage of air
to bronchi
3. Lungs
Bronchus
passage of air to lungs
GAS EXCHANGE
HAPPENS in ALVEOLI in
LUNG
Lower
Respiratory
Tract
Bronchioles
passage of air to alveoli
Lung
contains alveoli (air sacs);
carries out gas exchange
Diaphragm
skeletal muscle; functions
in ventilation
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10.3 The Lower Respiratory Tract
The bronchial tree
• The bronchial tree starts with two main bronchi
that lead from the trachea into the lungs.
• The bronchi continue to branch until they are
small bronchioles about 1 mm in diameter with
thinner walls (~65 thousand terminal
bronchioles!).
NO GAS EXCHANGE IN BRONCHIAL TREE
• Bronchioles eventually lead to elongated sacs
called alveoli.
GAS EXCHANGE HAPPENS in ALVEOLI
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10.3 The Lower Respiratory Tract
The Lung
The secondary bronchi, bronchioles, and alveoli make up the
lungs.
GAS EXCHANGE HAPPENS in ALVEOLI
There are 300 million alveoli in
the lungs that greatly increase
surface area.
• Alveoli are enveloped by
blood capillaries.
• The alveoli and capillaries are
one layer of epithelium to
allow exchange of gases.
• Alveoli are lined with
surfactant that act as a film to
keep alveoli open.
alveoli
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10.4 Mechanism of Breathing
Boyle’s Law
• Ventilation is governed
by Boyle’s Law.
• At a constant
temperature the
pressure of a given
quantity of gas is
inversely proportional
to its volume.
Figure 10.7 The relationship between air pressure
and volume.
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10.4 Mechanism of Breathing
Two phases of breathing/ventilation
I. Inspiration
• The diaphragm and
intercostal muscles
contract.
• The diaphragm flattens
and the rib cage moves
upward and outward.
• Volume of the thoracic
cavity and lungs increase.
• The air pressure within the
lungs decreases (became
less than atmospheric
pressure).
• Air flows into the lungs.
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10.4 Mechanism of Breathing
Two phases of breathing/ventilation
II. Expiration
• The diaphragm and
intercostal muscles relax.
• The diaphragm moves
upward and becomes
dome-shaped.
• The rib cage moves
downward and inward.
• Volume of the thoracic
cavity and lungs
decreases.
• The air pressure within the
lungs increases.
• Air flows out of the lungs.
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Different volumes of air during breathing
• Tidal volume – the small amount of air that usually moves in
and out with each breath
• Vital capacity – the maximum volume of air that can be moved
in plus the maximum amount that can be moved out during one
breath
• Inspiratory and expiratory reserve volume – the increased
volume of air moving in or out of the body
• Residual volume – the air remaining in the lungs after
exhalation
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10.5 Control of Ventilation
Respiration Control
I. Nervous control
– Respiratory control center in the brain (medulla
oblongata) sends out nerve impulses to contract
muscle for inspiration (causes us to breathe 12 to
20 times a minute).
II. Chemical control
– Two sets of chemoreceptors sense the drop in pH: one set
is in the brain and the other in the circulatory system.
Both sets of chemoreceptors are sensitive to
carbon dioxide levels that change blood pH due
to metabolism.
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Kahoot “Respiratory Structure,
Function, and Control”
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10.6 Gas Exchanges in the Body
Exchange of gases in the body
• Oxygen and carbon dioxide are exchanged.
• The exchange of gases is dependent on diffusion.
Partial pressure is the amount of pressure each
gas exerts (PCO2 or PO2).
Oxygen and carbon dioxide will diffuse from the
area of higher to the area of lower partial
pressure.
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Animation
“Change in partial pressure
of oxygen and carbon”
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10.6 Gas Exchanges in the Body
External respiration
External respiration is the exchange of gases
between the lung alveoli and the blood capillaries.
• PCO2 is higher in the lung capillaries than the air,
thus CO2 diffuses out of the plasma into the lungs.
• The partial pressure pattern for O2 is just the
opposite, so O2 diffuses the red blood cells in the
lungs.
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10.6 Gas Exchanges in the Body
The movement of oxygen and carbon
dioxide in the body
alveolus
plasma
H+ + HCO–3
External respiration
Hb H+
CO2
pulmonary
capillary
HCO–3
RBC
H2CO3
CO2
Hb O2
H2O
RBC
O2
Hb CO2
pulmonary
capillary
O2
alveolus
CO2 exits blood
CO2
a.
plasma
O2 enters blood
O2
lung
pulmonary artery
pulmonary vein
heart
tissue cells
systemic vein
systemic artery
HCO–3
H+ + HCO–3
plasma
plasma
systemic
capillary
RBC
Figure 10.11
Movement of gases
during external and
internal respiration.
CO2
O2
RBC
systemic
capillary
Hb H+ H2CO3
CO2
H2O
Hb
Internal respiration
Hb CO2
tissue
fluid
CO2 enters blood
b.
tissue
cell
tissue
cell
tissue
fluid
O2 exits blood
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10.6 Gas Exchanges in the Body
Internal respiration
Internal respiration is the exchange of
gases between the blood in the capillaries
outside of the lungs and the tissue fluid.
• PO2 is higher in the capillaries than the tissue
fluid, thus O2 diffuses out of the blood into
the tissues.
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Animation “External and Internal
respiration”
Kahoot
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10.7 Respiration and Health
Upper respiratory tract
infections
• Sinusitis – blockage of sinuses
• Otitis media – infection of the middle ear
• Tonsillitis – inflammation of the tonsils
• Laryngitis – infection of the larynx that leads
to loss of voice
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10.7 Respiration and Health
Lower respiratory tract disorders
• Pneumonia – infection of the lungs with thick,
fluid build up
• Tuberculosis – bacterial infection that leads to
tubercles (collections of encapsulated bacteria)
• Pulmonary fibrosis – lungs lose elasticity
because fibrous connective tissue builds up in
the lungs, usually because of inhaled particles
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10.2 The Upper Respiratory Tract
• Air from the nose enters the pharynx and passes through
• The nasal cavities, which filter and warm the air
• The pharynx, the opening into parallel air and food
passageways; the upper region of the pharynx, the
nasopharynx, is connected to the middle ear by auditory
tubes (eustachian tubes); the epiglottis blocks entry of
food into the lower respiratory tract
• The larynx, the voice box that houses the vocal cords; the
glottis is the small opening between the vocal cords; the
tonsils are lymphoid tissue that helps protect the respiratory
system
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10.3 The Lower Respiratory Tract
• The trachea (windpipe) is lined with goblet cells and
ciliated cells.
• The bronchi enter the lungs and branch into smaller
bronchioles.
• The lungs consist of the alveoli, air sacs surrounded by
a capillary network; alveoli are lined with a surfactant
that prevents them from closing. Each lung is enclosed
by a membrane called a pleura.
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10.6 Gas Exchanges in the Body
• Both external respiration and internal respiration depend on
diffusion. Hemoglobin activity is essential to the transport of
gases and, therefore, to external and internal respiration.
• External Respiration
• CO2 diffuses out of plasma into lungs; carbonic anhydrase
accelerates the breakdown of HCO3– ions in red blood cells.
• O2 diffuses into the plasma and then into red blood cells in the
capillaries. O2 is carried by hemoglobin, forming
oxyhemoglobin.
• Internal Respiration
• O2 diffuses out of the blood into the tissues.
• CO2 diffuses into the blood from the tissues. CO2 is carried in
the plasma as bicarbonate ions (HCO3–); a small amount links
with hemoglobin to form carbaminohemoglobin.
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Suggested animation: Excellent summary
of the human respiratory system by
Britannica Encyclopedia (~1-hr long):
https://www.youtube.com/watch?v=yWnlhc
qJlRk
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Checkup Qs
1. What are the parts and functions of the upper
and lower respiratory system?
2. What is the mechanism for expiration and
inspiration?
3. How is breathing controlled by the nervous
system and through chemicals?
4. Where and how is exchange of gases
accomplished?
5. What are some common respiratory infections
and disorders?
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