Regulation of Breathing
Should we worry if
someone has a temper
tantrum and says they are
going to hold their
breathe until they get their
way?
Recap – Where are we coming from
• External respiration and internal respiration
• Gasses travel through the blood
• Gasses have different partial pressures in
the blood depending on location
• Oxygen and carbon dioxide travel through
the blood in different ways (what are these
ways?)
Regulation of Respiration
• Two types of chemoreceptors are involved in
regulation of respiration
• Chemoreceptors are receptors in our body that
detect chemical change (such as pH change)
• One type detects carbon dioxide levels by sensing
the change in pH levels
• The other type detects oxygen levels
• Carbon dioxide / pH chemoreceptors are the MAIN
RECEPTORS TO REGULATE BREATHING
Carbon dioxide / acid chemoreceptors
• Located in the medulla oblongata
• Stimulated by high carbon dioxide and low pH
levels
• The activated medulla oblongata signals
diaphragm and rib muscles to increase breathing
movements
CONTINUED
Carbon dioxide / acid chemoreceptors
• Normal acidity range is 7.35 – 7.45
• When blood is too acidic, rate of respiration
increases to get rid of excess carbon dioxide.
• When blood is too basic, rate of respiration
decreases to allow carbon dioxide levels to build
up once again
Why Do We Have Oxygen Chemoreceptors?
are people
highduring
altitudes
• •Examples
Oxygen chemoreceptors
areat
needed
times
when
oxygen
levelsthat
decrease
but carbon
dioxide
and
people
inhale
carbon
levels do not change
monoxide
• Can you think of an example where this happens?
Acidosis & Alkalosis
• Acidosis – an increased level of carbon dioxide results
in the formation of carbonic acid. It is caused by
conditions that interfere with gas exchange, such as
pneumonia or emphysema
• Alkalosis – results when more than the usual amount
of carbon dioxide is removed from the blood. It is
caused by an increased respiration rate, such as
anxiety and aspirin poisoning
Can we suffocate by holding out breath?
• People can deliberately hold their breath for a period
of time, despite rising carbon dioxide levels in the
blood
• However, once a person passes out, the medulla
oblongata regains control and stimulates the breathing
rate
• We can not suffocate ourselves by holding our breath!
Pause for Thought
• During mouth-to-mouth resuscitation, exhaled air is
forced into the victim’s trachea. As you know, exhaled
air contains higher levels of CO2 than atmospheric air.
Would the higher levels of CO2 create problems or be
beneficial? Provide your reasons.