Chapter 13 – Part 4
The Respiratory System
Respiratory Volumes and Capacities
 Respiratory capacities
are measured with a
spirometer
 As a person breathes,
the volumes of air
exhaled can be read on an indicator
 Spirometer testing is useful for evaluating
losses in respiratory functioning and in
following the course of some respiratory
diseases
Respiratory Sounds
 Sounds are monitored with a stethoscope
 Bronchial sounds – Produced by air rushing
through trachea and bronchi
 Vesicular breathing sounds – Occur as air
fills the alveoli; soft sounds that resemble a
muffled breeze
 Diseased respiratory tissue, mucus, or pus
can produce abnormal sounds such as rales
(a rasping sound) and wheezing (a whistling
sound)
External Respiration
 External respiration – the actual
exchange of gases between the alveoli
and the blood
 Oxygen movement into the blood
 Because body cells continually remove O2
from the blood, there is always more O2 in
the alveoli than in the blood
 Oxygen moves by diffusion towards the area
of lower concentration
 Pulmonary capillary blood gains oxygen
External Respiration
 Carbon dioxide movement out of the
blood
 Blood returning from tissues has higher
concentrations of carbon dioxide than air in
the alveoli
 Pulmonary capillary blood gives up carbon
dioxide
 Blood leaving the lungs is oxygen-rich
and carbon dioxide-poor
Gas Transport in the Blood
 Oxygen is transported in the blood in two
ways:
1. Most attaches to hemoglobin molecules
inside the red blood cells to form
oxyhemoglobin (HbO2)
2. A very small amount of oxygen is carried
dissolved in the plasma
 Color change in blood
 Oxygen-rich blood = bright red
 Oxygen-poor blood = dark red
Gas Transport in the Blood
 Carbon dioxide transport in the blood
1. Most is transported in the plasma as
bicarbonate ion (HCO3–)
 Plays a very important role in the blood
buffer system
2. A small amount is carried inside red blood
cells on hemoglobin, but at different
binding sites than those of oxygen
Internal Respiration
 Internal respiration - exchange of
gases between blood and body cells
 An opposite reaction to what occurs in
the lungs
 Carbon dioxide diffuses out of tissue to
blood
 Oxygen diffuses from blood into tissue
Internal Respiration
External Respiration,
Gas Transport, and
Internal Respiration
Summary
Hypoxia
 Hypoxia – Inadequate oxygen delivery
to body tissues
 Impaired oxygen transport
 May be the result of anemia, pulmonary
disease, or impaired or blocked blood
circulation
 Symptoms:
 Easy to recognize in fair-skinned people
because their skin and mucosae take on a
bluish cast (become cyanotic)
 In dark-skinned individuals, this color
change can be observed only in the
mucosae and nailbeds.
Carbon Monoxide Poisoning
 Type of hypoxia
 Odorless, colorless gas that
competes vigorously with O2 for the
same binding sites on hemoglobin
 Crowds out or displaces O2 (hemoglobin binds
to carbon dioxide more readily than to oxygen)
 Leading cause of death from fire
 Dangerous because it kills softly and quietly
 Does not produce the characteristic signs of
hypoxia – cyanosis and respiratory distress
 Instead, the victim becomes confused and has a
throbbing headache
Neural Regulation of Respiration
 Activity of respiratory muscles is transmitted
to the brain by the phrenic and intercostal
nerves
 Neural centers that control rate and depth are
located in the medulla
 The pons appears to smooth out respiratory
rate
 Normal respiratory rate (eupnea) is 12–15
respirations per minute
 Hyperpnea is increased respiratory rate
often due to extra oxygen needs (exercise)
Suppressed Medulla Centers
 If the medulla centers
are completely
suppressed,
respiration stops
completely and death
occurs.
 Can occur with an
overdose of
sleeping pills,
morphine, or
alcohol
Neural Regulation of Respiration
Factors Influencing Respiratory
Rate and Depth
1. Physical factors (Increased body temperature, exercise, talking, coughing)
2. Conscious control (during swimming,
swallowing, singing)
•
Voluntary control of breathing is limited and
the respiratory centers will ignore messages
from our wishes when the O2 supply is
getting too low.
3. Emotional factors (Ever been so scared
that you gasped or were nearly panting?)
Factors Influencing Respiratory
Rate and Depth
 Chemical factors
 Carbon dioxide levels
 Level of carbon dioxide in the blood is the
main regulatory chemical for respiration
 Increased carbon dioxide increases
respiration
 Changes in carbon dioxide act directly on
the medulla oblongata
Factors Influencing Respiratory
Rate and Depth
 Chemical factors (continued)
 It is the body’s need to rid itself of
carbon dioxide (not to take in oxygen)
that is the most important stimulus for
breathing in a healthy person.
Factors Influencing Respiratory
Rate and Depth
 Hyperventilation – A rapid and
deep breathing pattern
 Occurs when carbon dioxide or other
sources of acid begin to accumulate in the
blood and the pH starts to drop
 Different breathing pattern from the
hyperpnea of exercise
 This blows off more carbon dioxide, which
returns blood pH to normal
Hyperventilation
 When brought on by anxiety attacks, it often
leads to brief periods of apnea (cessation of
breathing) until the carbon dioxide builds up in
the blood again
 If breathing stops for an extended period of
time cyanosis can occur
 The individual may get dizzy and faint
 Such attacks can be prevented by
having the person breath into a paper
bag (raises the CO2 levels in the blood)
Factors Influencing Respiratory
Rate and Depth
 Hypoventilation – Extremely slow or
shallow breathing
 Occurs when blood starts to become too
basic
 Allows carbon dioxide to accumulate in the
blood and brings blood pH into normal
range