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TRANSCRIPT
Gas ExchangeRespiratory System – Chapter 22
Bozeman – Intro to the Respiratory System
Surviving Thin Air
The high mountains of the Himalayas
Have claimed the lives of even the world’stop mountain climbers
The air at the height of the world’s highest peak,Mt. Everest
Is so low in oxygen that mostpeople would pass outinstantly if exposed to it
Surviving Thin Air
Twice a year, flocks of geese migrate over the Himalayas
They are able to fly at such a high altitude because
of the efficiency of their lungs
These birds have blood with hemoglobin with a very
high affinity for oxygen
This adaptation allows them to carry large amounts
of oxygen to their tissues to exchange with carbon
dioxide
Standards
Core
I can outline the 4 major aspects of the process
respiration.
I can describe structure and function of the airway.
I can describe structure and function of alveoli.
I can describe the processes of inhalation and exhalation.
Advanced
I can outline the nervous control of breathing.
So what is Respiration?
The process of gas exchange,
often called respiration is the
interchange of O2 and CO2
between an organism and its
environment
Crash Course – Respiratory System Pt. 1
Mechanisms of Gas Exchange
There are three sequences of gas exchange; how
respiration occurs
1. Breathing
2. Transport of gases by the circulatory system
3. Exchange of gases with body cells
The Four major aspects of respiration
1. Breathing (inhaling and exhaling)
2. External respiration (gas exchange at the lungs)
3. Internal respiration (gas exchange at the tissues)
4. Cellular respiration (making ATP in cells)
22.2 – Animals exchange O2 and CO2
across moist body surfaces Animals have a respiratory surface which is
often moist.
This moist layer allows O2 and CO2 to
diffuse easily and quickly into the
circulatory system
Some animals, like the earthworm, use their
entire skin as a gas-exchange organ
In most animals specialized body parts
provide large respiratory surfaces for gas
exchange
22.3 Gills are adapted for gas exchange
in aquatic environments
In a fish, gas exchange is enhanced by ventilation and the countercurrent flow of
water and blood
22.4 The tracheal system of insects provides
direct exchange between the air and body
cells Land animals exchange gases
by breathing air
Tracheal systems in insects
Transport O2 directly
to body cells through a
network of finely
branched tubes
22.5 Terrestrial vertebrates have lungs
In mammals, air inhaled
through the nostrils, nasal
cavity, passes through the
pharynx and larynx into
the trachea, bronchi, and
bronchioles
22.5 Terrestrial vertebrates have lungs
The bronchioles end in clusters of tiny sacs called
alveoli and this is where gas exchange occurs
Connection: 22.6 Smoking is a deadly assaults
on our respiratory system
Mucus and cilia in the respiratory passages
Protect the lungs
Can be destroyed by smoking
A single drag on a cigarette exposes a person to over 4000 chemicals, 50 of
which are known carcinogens. People die 13-14 years younger.
Smoking can also cause emphysema; alveoli loose their elasticity and
deteriorate reducing lung capacity
22.7 Breathing ventilates the lungs
Breathing: is the alternation of inhalation and
exhalation
The contraction of rib muscles and the
diaphragm
Expands the chest cavity and reduces air
pressure in the alveoli (negative pressure
breathing)
Vital capacity is the maximum volume of air
we can inhale and exhale but our lungs still
hold a residual volume
22.7 Breathing ventilates the lungs
Air flows in one direction; through the more efficient lungs of birds
22.8 - Breathing is automatically
controlled
We can control some of our breathing but we
have automatic control centres that ensure
coordination between the circulatory system
and the respiratory system.
In your brain, there are areas called
Pons
Medulla Oblongata
The Medulla control centre signal the
diaphragm and rib muscles to contract
The pons smooths out the basic rhythm of
breathing set by the medulla
PH and CO2 levels
The medulla control centre monitors the CO2 levels in
the blood and regulates breathing rate in response.
The way it regulates the CO2 levels is by monitoring
pH levels
When CO2 increases your blood and Cerebralspinal Fluid
pH drop slightly
This is because the CO2 goes into the blood and reacts
with water to produce carbonic acid
This results in your medulla control centre sending a
signal to increase respiration and eliminate more CO2
pH and buffers – Negative Feedback Loop
Secondary control over breathing in the
Aorta!
There are sensors in your aorta and carotid artery that monitor
concentrations of O2 and CO2 that send messages to nerves which relay the
information to the medulla.
This may result in conditions of low oxygen, like high elevation.
Hyperventiation – suspends breathing because too much CO2 has removed
from the blood.
22.9 Blood transports respiratory gases
Transport of gases in the body
The heart pumps oxygen-poor blood to the lungs
Where it picks up O2 and drops off CO2
Then the heart pumps the oxygen-rich blood to body cells
Where it drops off O2 and picks up CO2
Gas transport and exchange in the body
Gases diffuse down partial-pressure gradients In the
lungs and the tissues
22.10 Hemoglobin carries O2 and helps
transport CO2 and buffer the blood
Hemoglobin in red blood cells
Consists of four polypeptides chains of two types
Attached to each polypeptide is a chemical group
called heme (green) at which the centre is a iron
group (black)
Every hemoglobin can carry up to four O2
molecules
Transports oxygen, helps buffer
the blood and carries some CO2
The partial pressure of oxygen in the tissue reflects
how much oxygen the cells are using
Crash Course – Respiratory System pt. 2
22.10 Hemoglobin carries O2 and helps
transport CO2 and buffer the blood
Most CO2 enters the red blood cells, where some combines with hemoglobin.
The rest reacts with water molecules forming carbonic acid
Red blood cells contain an enzyme that accelerates this reaction to break
them apart into hydrogen ion and a bicarbonate ions
Hemoglobin will then bind the H+ ion, minimizing the change in blood pH
Is transported as bicarbonate ions in the plasma, where they are carried to
the lungs
This process is reversed in the lungs so the CO2 diffuses from the alveoli to
the exhaled air
Words to know!
Oxyhemoglobin: O2 attached to hemoglobin
Carbaminohemoglobin – CO2 attached to hemoglobin
Reduced hemoglobin – once oxygen is released into
tissues from hemoglobin
Bicarbonate ions – is alkaline and helps buffering pH
Carbonic anhydrase – enzyme that balances the pH
of blood by converting CO2 and H20 into bicarbonate
ions and hydrogen ions
Connection - 20.11 – The human fetus exchanges gases
with the mother’s bloodstream
A human fetus exchanges gases with
maternal blood in the placenta
Fetal hemoglobin has a higher affinity
for oxygen transfer from maternal blood
At birth, increasing CO2 in the fetal
blood
Stimulates the breathing control
centers to initiate breathing
because the baby’s lungs are filled
with amniotic fluid.