External respiration
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Transcript External respiration
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