Slide 1 : The respiratory system
Structure of the respiratory system
What is respiration?
ventilation
gas exchange
between air and blood
between blood and cells (oxygen)
exchange and transport of carbon
dioxide
Slide 2 :
Slide 3 :
Slide 4 : General functions of upper tract
Take in, moisten air
Trap irritants/infectious particles
cilia
mucous membranes
Paranasal sinuses- resonant chambers
Pharynx- passageway for food and air
Larynx- breathing and speech
Slide 5 :
Slide 6 : Trachea branches into bronchi
Trachea is ciliated and woth goblet cells
Cartilaginous rings hold it open
Bronchial tree branches off into bronchioles,
terminating in alveoli
Slide 7 :
Slide 8 : What is the mechanism of breathing?
Inspiration, expiration
thoracic cavity changes in size- how?
Phrenic nerve stimulation causes diaphragm
to contract (and drop)
Thoracic cavity enlarges, air pressure drops
and atmospheric pressure forces air in
External intercostals may contract, elevate
sternum
Pleural membranes moves out (and together)
Slide 9 :
Slide 10 : Expiration
Lots of elastic tissue in lungs and thoracic wall
Recoil helps return tissues to original configu-
ration
Alveoli enlarge during inspiration, contract
during expiration
Slide 11 :
Slide 12 : What are the respiratory volumes and capacities?
Components of normal breathing, at rest and
under exertion
Capacities will vary with age, sex, body size-
and state of health
Slide 13 :
Slide 14 : Restrictive disorders- vital capacity is reduced;
FEV is normal
Obstructive disorders- FEV is reduced, vital
capacity is normal, e.g., asthma
Bronchoconstriction
Inflammation
Emphysema- destruction of alveoli
COPD- obstructive and restrictive; chronic
bronchitis and emphysema
Slide 15 : Breathing is normally rhythmic and involuntary
Respiratory muscles are under voluntary
control
Respiratory centers in pons and medulla
oblongata
Dorsal group- basic rhythmicity
Ventral group- when deeper breathing is
required
Both act on diaphragm and respiratory muscles
Slide 16 : Inflation reflex prevents lungs from over-
inflating
Stretched lung tissues stimulate stretch
receptors in visceral pleura and within
lungs
Signal ultimately reaches pons (pneumotaxic
area) which modulates inspiratory
activity
Slide 17 :
Slide 18 : What factors affect breathing?
Respiratory control centers are sensitive to
carbon dioxide and hydrogen levels
If those rise (in blood), breathing rate increases
Low blood oxygen can also be detected
Hyperventilation lowers blood carbon dioxide
levels; can lead to blood alkalosis
(slows breathing rate)
Slide 19 :
Slide 20 : How does gas exchange occur?
Both alveoli and capillaries are lined with simple
squamous epithelium
Respiratory membrane is formed between them;
gases diffuse across it
Diffusion is due to differential partial pressures
of oxygen and carbon dioxide
Slide 21 :
Slide 22 : In blood, oxygen is transported by hemoglobin
(combines with heme group)
In tissues, oxygen is released
High temperatures, acidic conditions reduce
affinity of oxygen for hemoglobin
Carbon dioxide also binds to hemoglobin, but
to a different site
Only about 23% of carbon dioxide is transported
this way
Slide 23 : Most carbon dioxide is formed into bicarbonate
Carbonic anhydrase in red blood cells catalyzes
this reaction
Chloride ion plays a role, too
Slide 24 :
Slide 25 :
Slide 26 : Disorders of the respiratory system
Infections
Chronic inflammation (asthma)
Degenerative disease, e.g., emphysema
Lung cancer
Genetic disorders
Slide 27 : Interaction of respiratory and other systems
Loading of oxygen (and carbon dioxide) requires
blood transport and specilaized functions
of red blood cells
Utilization and regulation of voluntary muscles
Sensitivity to pH (acidosis, alkalosis)
Response to exercise?
Response to high altitude?