Download 37.1: The Respiratory System

Why a respiratory system?
• Need O2 in
– for cellular respiration
– make ATP
• Need CO2 out
food
– waste product
O2
ATP
CO2
Passageways and Lungs
• Respiratory system consists of a pair of lungs & a
system of tubes that carry air to them
• Breathing is just one of the functions that the
respiratory system carries out
The path air takes
• Air enters
through the
nasal cavity
– It passes
through the
pharynx and
larynx into the
trachea
The path air takes
– The trachea
forks to form
two bronchi
– Each bronchus
branches into
numerous
bronchioles
• The bronchioles
end in clusters of
tiny sacs called
alveoli- 1 cell
layer thick wall
Lungs
• Structure
spongy texture
• high surface area
• more absorption of O2
– alveoli
• small air sacs
– moist lining
• mucus traps dust,
pollen, particles
– covered by cilia
• hair-like extensions of
cells
• move mucus upward to
clear out lungs
Moving gases into bloodstream
• Inhale
– O2 passes from alveoli
to blood
– by diffusion
• Exhale
– CO2 passes from blood
to alveoli
– by diffusion
capillaries
(circulatory system)
Gas exchange: Diffusion of gases
• Gases move by diffusion from high to low
concentration
– capillaries are thin-walled tubes of circulatory
system
– alveoli are thin-walled sacs of respiratory system
capillaries in lungs
capillaries in muscle
O2
O2
O2
O2
CO2
CO2
CO2
CO2
External respiration: exchange of
gases between alveoli and blood
blood
lungs
Internal respiration: exchange of
gases between blood and cells
blood
body
The Mechanics of Breathing
• Breathing ventilates the lungs
• The action of your diaphragm and the muscles
between your ribs enable you to breathe in and
breathe out
• Breathing is the alternation of inhalation (active) and
exhalation (passive)
Control of Respiration
• Breathing is usually an
involuntary process
• Partially controlled by an
internal feedback
mechanism that involves
signals being sent to the
medulla oblongata about
the chemistry of your
blood
– measure blood pH
• CO2 = pH (acid)
Control of Respiration
– coordinate breathing,
heart rate & body’s
need for energy
• Will send nerve signals to
the rib muscles and
diaphragm
• Nerve signals cause these
muscles to contract, and
you inhale
Breathing and Homeostasis
• Homeostasis
– keeping the internal environment
of the body balanced
– need to balance O2 in and CO2 out
– need to balance energy (ATP)
production
O2
ATP
CO2
Breathing and Homeostasis
• Exercise
– breathe faster
• need more ATP
• bring in more O2 & remove more
CO2
• Disease
O2
– poor lung or heart function =
breathe faster
• need to work harder to bring in
O2 & remove CO2
ATP
CO2
Cleaning dirty air
• To prevent foreign
material from reaching
the respiratory system is
lined with ciliated (hair)
cells that secrete mucus
• The cilia constantly beat
upward in the direction
of your throat, where
foreign material can be
swallowed or expelled by
coughing or sneezing