Download respiration 11.2 - St John Brebeuf

UNIT B: Human Body Systems
Chapter 8: Human Organization
Chapter 9: Digestive System
Chapter 10: Circulatory System and
Lymphatic System
Chapter 11: Respiratory System:
Section 11.2
Chapter 12: Nervous System
Chapter 13: Urinary System
Chapter 14: Reproductive System
UNIT B Chapter 11: Respiratory System
Chapter 11: Respiratory System
In this chapter, you will learn about the
structure and function of the respiratory
system.
How would a narrowing and swelling of
the airways affect the respiratory
volumes?
How do the typical treatments for asthma
work to reduce the symptoms?
Asthma is a disease in which the airways
become constricted (narrowed) and inflamed
(swollen), both of which can result in difficulty
breathing. It is one of the most common
chronic diseases in children. It is estimated
that 10 to 15 percent of children in Canada
have asthma.
TO PREVIOUS
SLIDE
Why is it so difficult to develop a cure for
asthma?
What are some of the normal defence
mechanisms of the respiratory tract?
UNIT B Chapter 11: Respiratory System
11.2 Mechanism of Breathing
A free flow of air is vitally
important during ventilation
(breathing).
A spirometer is a device used
to record the volume of air
inhaled and exhaled with each
breath.
TO PREVIOUS
SLIDE
Section 11.2
UNIT B Chapter 11: Respiratory System
Section 11.2
Figure 11.7 Measuring ventilation. A spirometer measures the air inhaled and exhaled with each
breath. During inspiration, the pen moves up. During expiration, the pen moves down. Vital capacity
(red) is the maximum amount of air a person can exhale after taking the deepest inhalation possible.
TO PREVIOUS
SLIDE
UNIT B Chapter 11: Respiratory System
Section 11.2
Respiratory Volumes
Tidal volume: the amount of air that is inhaled and exhaled at rest
TO PREVIOUS
SLIDE
UNIT B Chapter 11: Respiratory System
Section 11.2
Inspiratory reserve volume: the additional volume of air that can be
inhaled beyond the tidal volume (e.g., during deep breathing)
Expiratory reserve volume: the addition volume of air that can be
exhaled beyond the tidal volume
TO PREVIOUS
SLIDE
UNIT B Chapter 11: Respiratory System
Section 11.2
Vital capacity: the maximum volume of air that can moved in and
out during a single breath
• Vital capacity = tidal + inspiratory reserve + expiratory reserve
TO PREVIOUS
SLIDE
UNIT B Chapter 11: Respiratory System
Section 11.2
Residual volume: amount of air that remains in the lungs and
airways after a full exhalation
• During normal breathing, only 70% of tidal volume reaches the
alveoli; about 30% remains in the airways. This air is not useful
for gas exchange because it has been depleted of oxygen.
TO PREVIOUS
SLIDE
UNIT B Chapter 11: Respiratory System
Section 11.2
Respiratory volumes depend on various factors.
• Age (decreasing after age 30)
• Gender (10-20% lower in women)
• Physical activity (20-30% higher in conditioned athletes)
• Respiratory disorders
o Some disorders decrease vital capacity or can increase
residual volumes because the individual has difficulty
emptying the lungs
TO PREVIOUS
SLIDE
UNIT B Chapter 11: Respiratory System
Section 11.2
Inspiration and Expiration
To understand ventilation, the following facts should be remembered:
• There is a continuous column of air from the pharynx to the alveoli
in the lungs.
• The lungs lie within the sealed-off thoracic cavity.
o Rib cage: top and sides of the thoracic cavity
o Intercostal muscles: lie between the ribs
o Diaphragm and connective tissue: floor of the thoracic cavity
• The lungs adhere to the thoracic wall through the pleura.
o Space between the two pleurae is minimal due to surface
tension of the fluid between them
TO PREVIOUS
SLIDE
UNIT B Chapter 11: Respiratory System
Inspiration
Inspiration is the active phase of
ventilation.
• Diaphragm: contracts and lowers
• Intercostal muscles: contract
• Rib cage: moves up and out
• As the thoracic volume increases,
the lung volume increases, and air
pressure in alveoli decreases
o Alveolar pressure is lower than
atmospheric pressure outside
lungs, causing air to flow into
airways
TO PREVIOUS
SLIDE
Section 11.2
UNIT B Chapter 11: Respiratory System
Expiration
Expiration is the passive phase of
ventilation.
• Diaphragm: relaxes and moves up
• Intercostal muscles: relax
• Rib cage: moves down and in
• As the thoracic volume decreases,
the lung volume decreases, and air
pressure in alveoli increases
o Alveolar pressure is higher than
atmospheric pressure outside
lungs, causing air to be pushed
out
TO PREVIOUS
SLIDE
Section 11.2
UNIT B Chapter 11: Respiratory System
TO PREVIOUS
SLIDE
Section 11.2
Figure 11.8 Inspiration and expiration compared. a. During inspiration, the thoracic
cavity and lungs expand so that air is drawn in. b. During expiration, the thoracic cavity
and lungs resume their original positions and pressures. Now, air is forced out.
UNIT B Chapter 11: Respiratory System
Section 11.2
Control of Breathing
Ventilation is controlled by a
respiratory centre in the medulla
oblongata of the brain.
• Stimulates inspiration by
automatically sending impulses
to the diaphragm through the
phrenic nerve, and to the
intercostal muscles through the
intercostal nerve
Figure 11.9 Nervous control of breathing. The
respiratory centre automatically stimulates the external
intercostal (rib) muscles and diaphragm to contract via the
phrenic nerve. After forced inhalation, stretch receptors
send inhibitory nerve impulses to the respiratory centre via
the vagus nerve. Usually, expiration automatically occurs
because of the lack of stimulation from the respiratory
centre to the diaphragm and intercostal muscles.
TO PREVIOUS
SLIDE
UNIT B Chapter 11: Respiratory System
Section 11.2
Control of Breathing
• When the respiratory centre
stops sending signals to the
diaphragm and rib cage, the
diaphragm relaxes and
expiration occurs
• Following inhalation, stretch
receptors in the alveolar walls
send inhibitory nerve impulses
via the vagus nerve to the
respiratory centre, which
inhibits the respiratory centre
from sending impulses
TO PREVIOUS
SLIDE
UNIT B Chapter 11: Respiratory System
Control of Breathing
Chemical Input
• The respiratory centre is also sensitive to levels of carbon
dioxide and hydrogen ions in the blood
o When carbon dioxide or hydrogen ion concentrations
increase, the respiratory centre increases rate and depth
of breathing
• Respiration rate is also influenced by cells called carotid
bodies and aortic bodies
o When concentration of blood oxygen decreases, these
bodies signal the respiratory centre to increase rate and
depth of breathing
TO PREVIOUS
SLIDE
Section 11.2
UNIT B Chapter 11: Respiratory System
Section 11.2
Check Your Progress
1. Compare tidal volume and vital capacity.
2. Explain why inspiration is considered the active phase
of ventilation, and expiration the passive phase.
TO PREVIOUS
SLIDE
UNIT B Chapter 11: Respiratory System
TO PREVIOUS
SLIDE
Section 11.2
UNIT B Chapter 11: Respiratory System
TO PREVIOUS
SLIDE
Section 11.2