Transcript Respiratory

Respiration
Anatomy and Physiology
Respiration
• Respiration is the
exchange of gases
between the atmosphere
and the body; it can mean
the exchange between
capillary and cell
• Breathing is a part of it;
only in medicine is
breathing called
respiration
Organs of the Respiratory System
• Nose—air enters and
leaves
• Nasal cavity—hollow
space lined with
mucous membrane
• Sinuses– air filled
spaces which reduce
the weight of the skull
Sinuses
Organs of the Respiratory System
• Pharynx—behind the
mouth; passageway
for air (and food)
• Larynx-enlargement of
the trachea;
passageway for air and
houses vocal cords
• Epiglottis closes this
off when swallowing
Organs of the Respiratory System
• Trachea—is the
windpipe
• Primary bronchi—the
two branches off the
trachea
• Secondary bronchibranches off the
primary bronchi
• Bronchioles: smaller
branches
Organs of the Respiratory System
• Bronchioles end in the
alveoli
• Alveoli are small air
sacs surrounded by
capillaries
• Gas exchange occurs
here between the air in
the alveolus and the
capillary
Alveoli (air sacs)
“Bathed” in capillaries
Organs of the Respiratory System
• Lungs are large,
spongy organs in the
thoracic cavity
• Right and left lungs
• The bronchi and
smaller bronchioles
are inside
• Covered by two
membrane layers:
visceral pleura and
parietal pleura
Breathing
•
•
•
•
Is a mechanical action
Moving air in and out
Inhalation and Exhalation
Is a result of pressure changes due to
change in size of the thoracic cavity
Inhalation
• Diaphragm contracts
and moves down
• The ribs move up and
out
• This expands the size
of the chest cavity
• Pressure inside cavity
is now lower than
outside; air rushes in
Exhalation
• Diaphragm relaxes,
moving back up
• The ribs move down and
in
• This decreases the size of
the chest cavity
• Pressure inside the cavity
is now higher than
outside, forcing air out
Control of Breathing
• Rhythmic, involuntary, will continue even if
person is unconscious
• Respiratory muscles are under voluntary
control
• Respiratory center is in the pons and
medulla oblongata
• Nerve impulses stimulate the diaphragm
and inspiratory muscles
Control of Breathing
• Chemoreceptors monitor levels of CO2 and
•
•
•
•
hydrogen ions
When these concentrations rise, respiration rate
and volume are increased.
Low oxygen has little effect—must be very very
low to trigger respiration
If you hold your breath, CO2 and H+ increase,
stimulating breathing
Hyperventilation gets rid of CO2, so no stimulus to
breathe
Gas Exchange in Alveoli
• Wall of alveolus is a
thin layer of simple
squamous epithelium
• Each cell is near a
capillary
Gas Exchange in Alveoli
• By diffusion
• With gases, we talk
about regions of
higher pressure and
lower pressure instead
of higher and lower
concentration
• Gas molecules will go
from high to low
Gas Exchange in Alveoli
Transporting the gases
• Most oxygen is carried
by hemoglobin
• A small amount is
dissolved in the
plasma
• CO2 is carried three
ways: dissolved in
plasma, carried by
hemoglobin, or in the
form of a bicarbonate
ion HCO3-
Carbon Monoxide CO
• Is deadly because it
combines more
effectively with
hemoglobin than
oxygen does
• Takes oxygen’s place,
and cells become
oxygen deficient
Carbon Monoxide CO