Download Human Respiratory System

Human Respiratory System
A system that provides a large surface
area for the diffusion of O2 into the
blood, and the diffusion of CO2 out of
the blood.
Parts of the Respiratory System
Oral and Nasal Cavities
• Structure - openings through which air
enters the system. Nasal cavity is the
chamber behind the nose. It contains hairs,
cilia, and mucus.
• Function - the nose and nasal cavities have
the following functions:
• (A) air is cleansed by the mucus, cilia, and
hair
• (B) air is heated by blood passing through a
large number of capillaries just below the
mucus membranes
• (C) mucus membranes moisten the air
• The cleansing, heating, and moistening of
the air prevents damage to the delicate lung
tissue.
Pharynx
• Structure - cavity behind the nasal cavity
that is common to the respiratory and
digestive systems. It contains two lymph
glands: adenoids and tonsils.
• Function - transports air between the nasal
cavity/mouth and the trachea.
Larynx
• Structure - consists of several pieces of
cartilage. Located inside is elastic tissue
known as vocal cords.
• Function - the vocal cords vibrate as air
goes through them producing sound. The
pitch of the sound produced depends on the
length of the vocal cords.
Trachea
• Structure - a tube about 10 to 17 cm long containing rings
of cartilage which prevent the tube from collapsing. At the
top is located the epiglottis. It is lined with mucus
membrane that is ciliated.
• Function - a connecting tube that leads air to and from the
lungs.
• *Epiglottis - prevents liquids or solids from entering the
lungs.
• *Mucus membrane - produces mucus that traps foreign
materials that are then swept out of the trachea by the cilia.
This material is carried away by food passing down the
esophagus.
Bronchi
• Structure - tubes which branch from the
trachea leading into the two lungs.
• Function - a connecting tube that leads air
to and from the lung.
Bronchials
• Structure - small tubes that branch from the
bronchi inside the lungs.
• Function - connecting tubes that lead from
the bronchi to the bronchioles.
Bronchioles
• Structure - yet smaller tubes that branch
from the bronchials inside the lung.
• Function - connecting tubes that lead from
the bronchials to the alveoli.
Lungs
• Structure:
• Protected by the ribs, sternum, and spine.
• Surrounded by two membranes called pleura.
The pleura isolates the lungs and protects the
delicate tissue. A lubricating fluid is found
between the two layers allowing the lungs to
move freely in the chest cavity during breathing.
• Function - contain a variety of tubes and
chambers where gases are exchanged between the
lungs and the blood.
Diaphragm
• Structure - sheet of muscle that separates
the thorax (chest) and abdomen cavities.
• Function - its movement is responsible for
breathing.
• Inspiration (inhale) - diaphragm contracts
• Expiration (exhale) - diaphragm relaxes
Alveoli
• Structure - millions per lung, giving the lungs
a very large surface area for gas exchange.
They are found at the ends of the bronchioles
and are a cluster of microscopic, one cell thick,
grape-like air sacs. They are moist and
surrounded by capillaries.
• Function - site of gas exchange between the air
in the lungs and the blood in the capillaries.
Alveoli of the Lungs
Process of Breathing
• Definition - breathing is a mechanical process where
gases are exchanged between the lungs and the
atmosphere. Breathing is the first step in
respiration.
• Breathing occurs due to changes in the pressure in
the thorax or chest cavity of the body. This pressure
is controlled by changing the size of the thorax.
Two structures responsible for changing the size of
the thorax are:  ribs and rib muscles (intercostal muscle)
 diaphragm
Inhalation (Inspiration)
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Definition - air enters the lungs
Process - there are six steps to the process:
(1) rib muscle and diaphragm contract
(2) ribs move up and out
(3) diaphragm moves down
(4) thorax increases in size or volume
(5) pressure decreases in the thorax due to increase in
volume. The result is lower pressure inside the thorax
than outside.
• (6) air rushes into the lungs
Exhalation (Expiration)
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Definition - air leaves the lungs
Process - there are six steps to the process:
(1) rib muscle and diaphragm relax
(2) ribs move down and in
(3) diaphragm moves up
(4) thorax decreases in size or volume
(5) pressure increases in the thorax due to decrease in
volume. The result is a higher pressure inside the
thorax than outside.
• (6) air rushes out of the lungs
Rate of Breathing
• Breathing is an involuntary response controlled
by a section of the brain called the medulla
oblongata.
• This structure sends impulses to the intercostal
muscles of the ribs and diaphragm, causing them
to contract which produces inspiration.
• When this impulse stops, the intercostal muscle
and diaphragm relax producing expiration.
• The amount of CO2 in the blood determines the
rate of breathing.
• Two sensors located in the circulatory
system measure the CO2 content of the
blood:
 carotid artery in the neck
 aorta leading from the left
ventricle of the heart
CO2 Level
Rate of Breathing
High
Fast
Low
Slow
* Breathing rates vary with age
and activity.
Stages of Respiration
1. Breathing
(previously discussed)
2. External Respiration
• Definition - exchange of gases between the
alveoli of the lungs and the blood.
• Process - occurs by diffusion
• O2 goes into the blood from the alveoli
• CO2 goes into the alveoli from the blood
3. Gas Transport
• Definition - transportation of gas between the lungs and
body cells.
• Process - the gases enter the blood and combine with
the protein hemoglobin found on the red blood cell
(RBC)
• lung ----> body cells : O2 enters the bloodstream and
combines with the hemoglobin forming oxyhemoglobin
• body cells ----> lung : CO2 enters the bloodstream and
combines with the hemoglobin forming
carboxyhemoglobin
* CO2 also combines with water on
the RBC and in the plasma, this
forms carbonic acid.
Gas Exchange
4. Internal Respiration
• Definition - exchange of gases between the
blood and the cells of the body.
• Process - occurs by diffusion
• O2 goes into the body cells from the blood
• CO2 goes into the blood from the body cells
5. Cellular Respiration
• Definition and Process both covered
previously.
Diseases of the Respiratory System
Bronchitis
• Definition - inflammation of the bronchial
passages. Two forms:
• Acute - severe form which involves an
infection of the air passages.
• Chronic - less severe form which involves
an irritation of the air passages.
• Symptoms - fever, chest pain, severe
coughing and often the secretion of sputum.
Asthma
• Caused by the constriction of bronchial
passages and swelling of their mucus
linings. It is triggered by a hypersensitivity
to various agents within an individual’s
environment.
• Symptoms - attack begins with pressure in
the chest, feeling of suffocation, with severe
bouts of uncontrollable coughing and the
secretion of a thick mucous sputum.
Pneumonia
• Caused by the infection in the alveoli
resulting in the build-up of fluid in the
lungs. Two major forms are bacterial and
viral.
• Symptoms - fever, pain in the chest while
breathing, cough, and blood-streaked
sputum.
Cancer
• Cancer is the uncontrollable
multiplication of cells. Cancer may
occur in any part of the body, and
therefore in any part of the
respiratory system.
Emphysema
• A progressive disease in which the tissues of
the lungs lose their elasticity, and therefore the
volume of air that the lungs are able to handle
continually decreases.
• The deterioration in the lungs is permanent
and irreversible.
• Symptoms - severe coughing, shortness of
breath, and wheezing; developing into
difficulty in breathing. It sometimes results in
disability and death.
Influenza
• A viral infection of the respiratory tract,
especially the trachea. Commonly called
flu. Reduces a person’s resistance making
them susceptible to further infections such
as pneumonia.
• Symptoms - sore throat, nasal discharge,
fever, chills, headache, aching of muscles
and joints, upset stomach
Common Cold
• A viral infection of the upper respiratory
tract.
• Symptoms - sneezing, headaches, sore
throat, nasal discharge
Pleurisy
• Inflammation of the pleura membranes that
surrounds the lungs. Most cases are due to
infections, and many are associated with
pneumonia.
• Symptoms - sharp pain brought on by
breathing and coughing. Patient breaths
shallowly.
Carbon Monoxide Poisoning
• Definition - Carbon monoxide is a chemical
compound consisting of one atom of carbon
and one atom of oxygen (CO). It is an
odorless and tasteless gas.
• Source - It is produced when organic
compounds are burned with an insufficient
air supply.
• Effects - When inhaled, it combines with
the hemoglobin on the RBC, preventing
absorption of oxygen.
• Symptoms - symptoms are normally mild
and include nausea, headache, or fatigue.
Excessive inhalation can be more serious,
even fatal.
• Treatment - remove the individual from the
source of CO. Perform mouth to mouth
resuscitation if necessary.