Respiratory Physiology
4 Parts of Respiration
• Pulmonary ventilation- air moving
into and out of lungs
• External respiration- gas exchange;
blood - alveoli
• Respiratory gas transport- transport
of gases via bloodstream
• Internal respiration- gas exchange;
blood - cells
3D view of moving diaphragm
Respiratory Capacities
• tidal volume- normal quiet breathing, ~500 ml of air
(1 pint) into and out of lungs/breath
• inspiratory reserve volume - more air can be forcibly
inhaled than during normal breathing ~2100 — 3200
ml (a 2-3 Liter bottle of soda)
• expiratory reserve volume- more air can be forcibly
exhaled than during normal breathing ~1700 ml
• residual volume -after forcible exhalation about 1200
ml of air remains in lungs and cannot be voluntarily
exhaled = (1 liter bottle of soda)
• vital capacity total amount of exchangeable air
Spirometers…slightly better than ours
Gas Exchange
• Occurs across the alveolar capillary membrane
• Alveoli
–
–
–
–
Thin flaps of tissue that are inflated by air
Have holes so air can fill sac if bronchioles are clogged
Produce surfactant
Lined with “dust cells” white blood cells to prevent illness
Oxygen Transport in Blood
• Accomplished via blood
– RBC  carry O2 on hemoglobin
– Plasma (liquid part of blood)  has O2 dissolved in it
• Works because the
likes O2  high affinity
• But CO has a higher
affinity
https://www.youtube.com/watch?v=5LjLFrmKTSA
https://www.youtube.com/watch?v=XTMYSGXhJ4E
If…
• Oxygen level are low in the blood  hypoxic
• Low O2 can lead to a person becoming
cyanotic which causes necrosis
CO2 in blood…
• When CO2 enters blood RBC
join…
• Carbonic acid is unstable and
breaks into H+ & HCO3-
HCO3- is a GREAT buffer…
but if too much H+
accumulates…
CO2 in blood…
Oxygen transport in blood
https://www.youtube.com/watch?v=5LjLFrmKTSA
Page 454 in text book
http://www.youtube.com/watch?v=df3RL0KiUg
Neural Regulation of
Breathing
• Rhythm is set by the pons
and medulla (parts of the
brainstem)
– Pons- assists medulla by
sending sensory input to
the medulla
– Medulla- sets basic rhythm 12-18
breaths/min; sends message to
diaphragm & intercostals to contract
via the phrenic nerve (hiccups)
• Eupnea- normal breathing
(phrenic nerve)
• Hyperpnea- deeper, more vigorous
breathing (exercise)
Your Medulla + Alcohol =
• Alcohol is a depressant
• Alcohol inhibits the medulla’s function
• Too much inhibits your reflexes…
no gag or cough reflex… don’t drink
when passed out!!!
https://www.youtube.com/watch?v=7Wbq2tWomSk
Other factors that influence
Respiratory Rate
1. Physical factors
 Temp, talking, coughing, sneezing, hiccupping,
exercising
2. Conscious Control
 Singing, swimming underwater, swallowing
3. Emotional Factors
 Sad crying, fear, anxiousness
4. Chemical Factors
 Many but most important is CO2 concentration
Regulation of Breathing in Controlled
Chemoreceptors
• Chemoreceptors sense a chemical
change in blood composition
– Inc. or dec. of H+ in blood
• When an inc. of H+ is detected 
medulla to breathes more
• When a dec. of H+ is detected 
medulla breathes less
Spirometer
Lab Data
Class Averages
Class
Males Females
Athletes Non
Horn
Players
Non
Tidal 910
1180 820
970
835
1150
890
ERV 2080
2670 2010
2370 1950
3050
2120
IRV 1570
1860 1420
1700 1380
1200
1700
Respiratory Capacities
• tidal volume- normal quiet breathing, ~500 ml of
air (1 pint) into and out of lungs/breath
• inspiratory reserve volume - more air can be
forcibly inhaled than during normal breathing
~2100 — 3200 ml (a 2-3 Liter bottle of soda)
• expiratory reserve volume- more air can be
forcibly exhaled than during normal breathing
~1700 ml
• residual volume -after forcible exhalation about
1200 ml of air remains in lungs and cannot be
voluntarily exhaled = (1 liter bottle of soda)