Download The Respiratory System

The Respiratory System
Ventilation to Gas Exchange
The Respiratory System

Respiration takes place in 5 steps:
1.) Pulmonary ventilation, breathing
2.) External respiration, air into and out
of the lungs
3.) Transport of respiratory gases, blood stream
4.) Internal respiration, gas exchange in capillary
5.) Cellular respiration, use of O2 by cells
The Respiratory System

The organs of the
respiratory system
are divided into the
upper and lower
respiratory organs.
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The Respiratory System

The organs of the upper respiratory tract are
lined with mucous membranes.

The mucous functions as a debris trap.

The mucous membrane also serves to warm up
the air on its way into the lungs.
Upper Respiratory Organs

The nose is an external appendage on
the face which is made up of bone and
cartilage.
 The
nose is lined with small hairs that are
responsible for trapping large particles.
 The
nose connects to the lungs and is the
primary entry point for air.
Upper Respiratory Organs

The nasal cavity is the vault like
opening behind the nose.
 The
nasal cavity is responsible for warming
air before entry into the lungs.
 The
olfactory senses are based in the
nasal cavity.
 It
is also a resonating chamber for speech.
Upper Respiratory Organs

The nasal conchae divides the nasal
cavity into a system of groove like
passageways.
 Air
is filtered down through these grooves.
 These
grooves help warm the air more
efficiently and filter out more particles.
Upper Respiratory Organs

The paranasal sinuses are a series of
chambers in the skull which reduce the
weight.
 These
sinuses are responsible for draining
fluids out of the nasal cavity.
 These
also act as resonating chambers for
speech.
Upper Respiratory Organs

The pharynx is a tube of cartilage
which is the passage way for air into the
lungs.
 The
epiglottis is a trap door which stops
food from entering the lungs.
Upper Respiratory Organs

The larynx is the tube of cartilage that
attaches to the lungs.
 Within
the larynx there are two pairs of
vocal folds, there is a set of false vocal
chords over top of the true vocal chords.
 These
vocal chords expand and contract
as well as vibrate to produce sounds (your
voice).
Upper Respiratory Organs

Larynx (cont.)
 The
slit between the vocal chords is the
glottis which is where sound originates
from.
 The
first ring of hyaline cartilage which
attaches to the trachea is made up of
cricoid cartilage which is the sight of a
tracheotomy.
Lower Respiratory Organs

The trachea is the portion of the
respiratory tract that splits off at the
same point as the esophagus.
 The
trachea is made up of 16-20
incomplete C rings which are completed by
smooth muscle and elastic CT.
 The
trachea divides at the carina in the left
and right bronchus.
Lower Respiratory Organs

The bronchial tree Is the “tubing” which
branches down into each of the lungs.
 The
primary bronchus is the first
branching that occurs to each lung.
 The
secondary bronchus is branching
which leads to each lobe of the lungs.
Lower Respiratory Organs

Bronchial tree
(cont.)

The tertiary bronchi
branch off into the
bronchials which
branch off into
terminal
bronchioles.
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Lower Respiratory Organs

Bronchial tree (cont.)
 As
this branching occurs the cartilage
decreases and the smooth muscle
increases to allow for more expansion.
 The
expansion and contraction of these
bronchi is an important tool to doctors.
Lower Respiratory Organs

Bronchial tree (cont.)
 Bronchodilators
are much like epinephrine
and are used to treat asthma.
 Bronchoconstrictors
are histamines that
are used to help treat air borne allergies.
Lower Respiratory Organs

The lungs are the organs where the
bronchial tree is located.
 The
lungs are covered by pleural (serous)
membranes.
 These
membranes act as a lubricant for
the lungs as they expand and contract.
Lower Respiratory Organs

Lungs (cont.)
 There
is a right and a left lung and each is
divided into lobes.
 The
right lung has three lobes.
 The
left lung has two lobes.
Lower Respiratory Organs

Lungs (cont.)
 Each
of the lobes of the lungs is divided up
into lobules is wrapped in elastic CT
which allow for stretching when they
become filled with air.
 Each
lobule contains a terminal bronchiole.
Lower Respiratory Organs

Lungs (cont.)
 Each
terminal bronchiole is subdivided into
branches called respiratory bronchioles,
which are subdivided into alveoli.
 These
alveoli meet up with capillaries and
allow for gas exchange.
Lower Respiratory Organs

Lungs (cont.)

There are two types of cells in the walls of alveoli:
1.) Type I alveolar cells make up the
majority of the structure.
2.) Type II alveolar cells are responsible for
creating surfactant, which is a substance that
stops your lungs from collapsing.
Physiology of Pulmonary
Ventilation

Atmospheric pressure is required for
inhalation and the pressure inside is equal to
the pressure outside.

The diaphragm is curved upward when at
rest.

Upon contraction the center of the diaphragm
pushes down expanding the volume of the
chest cavity.
Physiology of Pulmonary
Ventilation

This expansion of the chest cavity
causes the pressure within to decrease.

Air rushes into the cavity to equalize the
pressure.

P1V1=P2V2
Physiology of Pulmonary
Ventilation

Contraction of the intercostal muscles
(muscles between the ribs) also help in
expansion and contraction of the chest
cavity.

The elastic recoil of the tissue in the
chest cavity and lungs allow for exhaling
of gases.
Physiology of Pulmonary
Ventilation

The process of exhaling causes
extreme pressure to push on the walls
of the small alveoli.

Surfactant helps to break the surface
tension of the air as it is being pushed
out of the lungs.
Physiology of Pulmonary
Ventilation

In times of extreme contraction and
stress the surfactant isn’t enough to
stop a complete contraction of the
alveoli, this is called a collapsed lung.

Respiratory Distress Syndrome
(RDS) occurs in newborns. It is a
collapsed lung due to a lack of
surfactant in the alveoli.
Physiology of Pulmonary
Ventilation

The air volume of your lungs is measured by
a spirometer.

The tidal volume of a persons lungs is the
amount of air that enters and exits the lungs
while inhaling and exhaling respectively.

The average person has a tidal volume of
500ml.
Physiology of Pulmonary
Ventilation

Inspiratory Reserve Volume (IRV) is
the amount air that can be forcibly
inhaled after the tidal volume, basically
a deep breath.

In the average person this is
approximately 3000ml.
Physiology of Pulmonary
Ventilation

Expiratory Reserve Volume (ERV) is
the amount of air that can be forcibly
exhaled after the normal tidal volume,
pushing air out after you exhale.

This is about 1100ml for the average
person.
Physiology of Pulmonary
Ventilation

Vital Capacity (VC) is the maximum
amount of air that can be exhaled after
a maximum inhalation.

VC = TV + IRV + TV + ERV

An Average persons vital capacity is
about 5100ml.
Physiology of Pulmonary
Ventilation

The lungs are NEVER without some air,
unless they are collapsed.

The residual volume (rv) is the amount
of air that always remains in the lungs
no matter how much you try and exhale.

The average residual volume is 1200ml.
Physiology of Pulmonary
Ventilation

There are modified respiratory movements
which occur in addition to normal breathing
as a result of reflexes.

A cough sends a blast of air which clears the
upper respiratory system of blockages.

A sneeze forcefully expels air through the
nose in response to dust in the mouth or
nose.
Physiology of Pulmonary
Ventilation

A laugh is a deep breath released in a
series of short convulsive expirations.

A hiccup is a spasm of the diaphragm.

A yawn is a deep inspiration through an
open mouth, which ventilates the
alveoli.
Control of Breathing

It is controlled in the respiratory center
of the brain, which is located in the pons
and medulla of the brain stem.

Its location in the brain stem shows that
it is a primitive neurological command
that is why you can breathe with out
even thinking about it.
Control of Breathing

Breathing speed is regulated by chemoreceptors located in major arteries.

These chemo-receptors measure levels of
oxygen and carbon dioxide.

If the levels of O2 are too low or the levels of
CO2 are too high a signal is sent to the brain
stem to increase the breathing rate.
Control of Breathing

There are required levels of oxygen and
carbon dioxide in the blood which keep
homeostatic levels.

If a person begins to hyperventilate (quick
shallow breathing) oxygen levels will increase
and can cause problems in the gas levels in
the blood.

Breathing into a paper bag rich in carbon dioxide
is a way to equalize gas levels.
Control of Breathing

There are a few factors which influence the
control of breathing:
1.) Stretchiness of the tissue (decreases with
age)
2.) Low blood oxygen (decreases when cells
are working strenuously)
3.) High blood CO2 (rises when cells are
working strenuously)
4.) Low Blood pH (normal is 7.4)
External Respiration

The definition of external respiration is
the exchange of oxygen and carbon
dioxide between the alveoli and lung
capillaries.

Dalton’s Law states that the pressure
of a gas determines the rate at which it
will diffuse from a region.
External Respiration

Air is a mixture of 74% nitrogen, 21% oxygen
and 0.04% carbon dioxide.

In a mixture of gases the amount of pressure
each gas creates is called its partial pressure.

A gases partial pressure is directly related to
the concentration of that gas in a mixture.
External Respiration

Diffusion of gases across a membrane
proceeds from where a gas is in high
partial pressure to low partial pressure.

This idea is why oxygen diffuses into
the capillaries and out the alveoli and
the opposite is true for carbon dioxide.
External Respiration
ALVEOLI
CAPILLARY
PCO2 = 40mmHg
PCO2 = 45mmHg
PO2 = 104mmHg
PO2 = 40mmHg
External Respiration

The rate of diffusion also depends on
other factors like:
 Surface
area available for gas exchange
 Diffusion
distance
 Breathing
rate and depth
Internal Respiration

The definition of internal respiration is the
exchange of oxygen and carbon dioxide
between capillaries and body tissues.

All of the same partial pressure rules hold
true here as well.

The tissues have oxygen at a lower pressure
and carbon dioxide at a higher pressure.
Transport of Gases in the Blood

Oxygen binds to hemoglobin in the
blood to form the compound
oxyhemoglobin.

The rate at which oxygen is released
from this compound is depends on:
 Blood
temp.
 Blood pH
 CO2 levels
Transport of Gases in the Blood

Carbon Monoxide is much better at
binding to hemoglobin then oxygen is.

This is why carbon monoxide is so
dangerous, if all of the hemoglobin is
bound to the useless carbon monoxide
then hypoxia of essential tissues
results.
Transport of Gases in the Blood

Carbon Dioxide is usually transported
as carbaminohemoglobin and
bicarbonate ions, very rarely is it
transported as carbon dioxide.

When carbon dioxide is transported as
CO2 it usually reacts with the water in
the blood to form carbonic acid which
could lower the pH of the
blood…dangerous!!!
Life Span Changes

Exposure to pollutants such as SMOKE
increases the risk of respiratory illnesses.

Loss of cilia and thickening of the mucous
can cause increased illness as one ages.

Vital capacity decreases with age…you get
out of breath easier as you age.