Title: CHAPTER 22 Respiration: The Exchange of Gases
1CHAPTER 22Respiration The Exchange of Gases
2MECHANISMS OF GAS EXCHANGE
- Gas exchange is the interchange of O2 and CO2
between an organism and its environment - It is also called respiration
3Overview Gas exchange involves breathing, the
transport of gases, and the servicing of tissue
cells
- Gas exchange is essential because energy
metabolism requires O2 and produces CO2
O2
4Animals exchange O2 and CO2 through moist body
surfaces
- O2 enters an animal and CO2 leaves by diffusion
through a respiratory surface - Respiratory surfaces are made up of living cells
5Lungs
capillaries (circulatory system)
- trachea
- bronchi
- bronchioles
- alveoli
alveoli
6The human respiratory system
- In humans and other mammals, air enters through
the nasal cavity - It passes through the pharynx and larynx into the
trachea - The trachea forks to form two bronchi
- Each bronchus branches into numerous bronchioles
7The human respiratory system
- The bronchioles end in clusters of tiny sacs
called alveoli - Alveoli form the respiratory surface of the lungs
- Oxygen diffuses through the thin walls of the
alveoli into the blood
8Connection Smoking is one of the deadliest
assaults on our respiratory system
- Mucus and cilia in the respiratory passages
protect the lungs - Pollutants, including tobacco smoke, can destroy
these protections - Smoking kills about 430,000 Americans each year
9Connection Smoking is one of the deadliest
assaults on our respiratory system
- Smoking causes lung cancer and contributes to
heart disease - Smoking also causes emphysema
- Cigarette smoke makes alveoli brittle, causing
them to rupture - This reduces thelungs capacity for gas exchange
10Breathing ventilates the lungs
- Breathing is the alternation of inhalation
(active) and exhalation (passive)
11Negative pressure breathing
- Diaphragm moves down expands chest cavity pulls
air into lungs
inhale
exhale
12Automatic Brain Control
- You dont have to think to breathe!
- medulla pons
- measure blood pH
- ?CO2 ?pH (acid)
- coordinate breathing, heart rate bodys need
for energy - Medulla oblongata
- will stimulate
- diaphragm to contract.
13TRANSPORT OF GASES IN THE BODY
- Blood transports the respiratory gases, with
hemoglobin carrying the oxygen - The heart pumps oxygen-poor blood to the lungs
- In the lungs it picks up O2 and drops off
CO2(external respiration) - In the tissues, cells pick up CO2 and drop off
O2-(Internal respiration) - Gases diffuse down pressure gradients in the
lungs and the tissues
14Gas exchange Diffusion of gases
- Gases move by diffusion from high to low
concentration - capillaries are thin-walled tubes of circulatory
system - alveoli are thin-walled sacs of respiratory system
capillaries in lungs
capillaries in muscle
blood
lungs
blood
body
15Gas exchange in the body
16Hemoglobin is a protein in red blood cells
- It carries most of the oxygen in the blood
Hemegroup
Iron atom
O2 loadedin lungs
O2
O2 unloadedin tissues
O2
Polypeptide chain
17Hemoglobin helps transport CO2 and buffer the
blood
- Hemoglobin helps buffer the pH of blood and
carries some CO2 - Most CO2 in the blood combines with water to form
carbonic acid - The carbonic acid breaks down to form H ions and
bicarbonate ions - These help buffer the blood
18Transport of CO2
- Most CO2 is transported to the lungs in the form
of bicarbonate ions
19Connection The human fetus exchanges gases with
the mothers bloodstream
- A human fetus depends on the placenta for gas
exchange - A network of capillaries exchanges O2 and CO2
with maternal blood that carries gases to and
from the mothers lungs - At birth, increasing CO2 in the fetal blood
stimulates the fetuss breathing control centers
to initiate breathing
Placenta, containingmaternal blood vesselsand
fetal capillaries
Umbilical cord,containing fetalblood vessels
Amnioticfluid
Uterus
20Breathing and Homeostasis
- Homeostasis
- keeping the internal environment of the body
balanced - need to balance O2 in and CO2 out
- need to balance energy (ATP) production
- Exercise
- breathe faster
- need more ATP
- bring in more O2 remove more CO2
- Disease
- poor lung or heart function breathe faster
- need to work harder to bring in O2 remove CO2
21Disorders of the Respiratory system
- Asthma a severe allergic reaction in which
contraction of the bronchioles makes breathing
difficult - Bronchitis an inflammation of the lining of the
bronchial tubes. The passageways to the alveoli
become swollen and clogged with mucus - Emphysema lungs lose their elasticity,
deterioration of the lung structure - Pneumonia alveoli become filled with fluid.
Caused by bacterial or viral infection - Lung Cancer a disease in which tumors form in
the lungs as a result of irregular and
uncontrolled cell growth