Download Chapter 9 Outline Notes

Chapter 9 Outline Notes
Gas Exchange and Smoking (by Rafael Limongi)
9.1- Gas exchange
Human gas exchange system (basics)
The human gas exchange system links the circulatory system with
the atmosphere. It:
• cleans and warms the air that enters during breathing
• maximize the surface area for diffusion of oxygen and carbon
dioxide between the blood and atmosphere
• minimize the distance for this diffusion
• maintain adequate gradients for this diffusion
Gross Structure of Human Gas Exchange
System
• In humans, the gas exchange surface is the alveoli, located in the
lungs.
• Small, thin, yet very extensive network
• Air passes through the trachea and bronchi to supply many
branching bronchioles which terminate in alveoli where gas
exchange occurs.
• The human gas exchange system’s surface area is in total 70 m^2.
a
Plan Diagrams for Trachea, Bronchus, Bronchiole, and
Alveoli
b
Describe The Functions of Cartilage, Cilia, Goblet Cells,
Mucous Glands, Smooth Muscle, and Elastic Fibres
• Cartilage in the walls of the trachea and bronchi provides support
and prevents the tubes collapsing when the air pressure inside them
is low.
• Cillated epithelium is found lining the trachea, bronchi and some
bronchioles. It is a single layer of cells whose outer surfaces are
covered with many thin extensions (cilia) which are able to move.
They sweep mucus upwards towards the mouth, helping to prevent
dust particles and bacteria reaching the lungs.
• Goblet cells are also found in the ciliated epithelium. They secrete
mucus, which traps dust particles and bacteria.
c
• Smooth muscle cells are found in the walls of the trachea, bronchi
and bronchioles. This type of muscle can contract slowly but for
long periods without tiring. When it contracts, it reduces the
diameter of the tubes. During exercise it relaxes, widening the
tubes so more air can reach the lungs.
• Elastic fibres are found in the walls of all tubes and between the
alveoli. When breathing in, these fibres stretch to allow the alveoli
and airways to expand. When breathing out, they recoil, helping to
reduce the volume of alveoli and expel air out of the lungs.
Describe the Process of Gas Exchange
Between the Alveoli and The Blood
• Breathing brings fresh supply of air into lungs, with a high oxygen
concentration and low carbon dioxide concentration.
• Blood is brought into the lungs with a lower concentration of
oxygen and a higher concentration of carbon dioxide than the
alveoli.
• Oxygen diffuses down its concentration gradient from the air in the
alveoli to the blood, and carbon dioxide diffuses down its
concentration gradient in the opposite direction.
• The blood is constantly flowing through and out of the lungs, so, as
the oxygenated blood leaves, more deoxygenated blood enters to
maintain the concentration gradient with each new breath.
d
9.2 - Smoking
Describe the effects of tar and carcinogens in
tobacco smoke on the gas exchange system
• The tar and various other carcinogens found in tobacco smoke can
pose various detrimental affects to the gas exchange system
• These carcinogens can cause mutations to the division of cells,
resulting in cancer, mainly lung cancer in smokers
• Tar stimulates the goblet cells and mucous glands to produce more
mucus. Also, it destroys and weakens cilia, causing mucus to
accumulate and obstruct bronchioles.
• With this accumulating mucus, infections such as pneumonia occur,
further constricting airways.
a
Describe The Short Term Effects of Nicotine and
Carbon Monoxide on the Cardiovascular System
• Nicotine reduces supply of oxygen, also increasing chance of blood
clots. Carbon monoxide decreases the quantity of oxygen
transported in the blood by around 5-10%
• Makes it harder for blood to reach extremities
b