1. Physiology of Respiration
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2. Respiratory Volumes and Capacities
Tidal Volume (TV): (know this) - total air moved with each breath
Normal breathing moves about 500 ml
Inspiratory reserve volume (IRV): deep breath
Amount of air that can be taken in forcibly over the tidal volume
Usually around 3,100 ml
Expiratory reserve volume (ERV):
Amount of air that can be forcibly exhaled after a tidal expiration
Approximately 1,200 ml
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3. Respiratory Volumes and Capacities
Vital capacity (VC): (know this)
The total amount of exchangeable air
Vital capacity = TV + IRV + ERV
Avg. 4,800 ml in men; 3,100 ml in women
Residual volume: Air remaining in lung after expiration (about 1,200 ml)
Allows gas exchange between breaths;
keeps alveoli inflated
spirometer –measures respiratory capacities
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4. 6,000 5,000 Inspiratory reserve volume 3,100 ml 4,000 Milliliters (ml)
Figure 13.9 Idealized tracing of the various respiratory volumes of a healthy young adult male.
6,000
5,000
Inspiratory
reserve volume
3,100 ml
4,000
Vital
capacity
4,800 ml
Milliliters (ml)
3,000
Total lung
capacity
6,000 ml
Tidal volume 500 ml
Expiratory
reserve volume
1,200 ml
2,000
1,000
Residual volume
1,200 ml

5. Gas Transport in the Blood
Oxygen Transport: (two methods)
Most attaches to hemoglobin to form oxyhemoglobin (HbO2)
small dissolved amount is carried in the plasma
Carbon dioxide: (three methods)
Dissolved in solution (plasma)
Dissolved in water as carbonic acid and subsequently as bicarbonate ion (HCO3–) (buffering)
It must dissociate to a gas in order for it to diffuse into the alveoli
Bound to hemoglobin
Hemoglobin has different binding sites for CO2
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6. Internal respiration in the body tissues
Figure 13.11b Diagrammatic representation of the major means of oxygen (O2) and carbon dioxide (CO2) loading and unloading in the body.
(b)
Internal respiration in the body tissues
(systemic capillary gas exchange)
Oxygen is unloaded and carbon
dioxide is loaded into the blood.
Tissue cells
CO2 O2
Loading
of CO2
Unloading
of O2
CO2 +H2O
H2CO3
H++ HCO3−
Water
Carbonic
acid
Bicar-
bonate
ion
HbO2
Hb + O2
Plasma
Systemic capillary
Red blood cell

7. External respiration in the lungs (pulmonary gas exchange)
Figure 13.11a Diagrammatic representation of the major means of oxygen (O2) and carbon dioxide (CO2) loading and unloading in the body.
(a)
External respiration in the lungs
(pulmonary gas exchange)
Oxygen is loaded into the blood
and carbon dioxide is unloaded.
Alveoli (air sacs) O2
CO2
Loading
of O2
Unloading
of CO2
Hb + O2
HbO2
HCO3−+ H+
H2CO3
CO2+ H2O
(Oxyhemoglobin
is formed)
Bicar-
bonate
ion
Carbonic
acid
Water
Plasma
Red blood cell
Pulmonary capillary

8. Breathing control centers: Pons centers Medulla centers
Figure Breathing control centers, sensory inputs, and effector nerves.
Breathing control centers:
Pons centers
Medulla centers
Afferent
impulses to
medulla
Efferent nerve impulses from
medulla trigger contraction
of inspiratory muscles.
Phrenic nerves
Intercostal nerves
Breathing control centers
stimulated by:
CO2 increase in blood
(acts directly on medulla
centers by causing a
drop in pH of CSF)
Nerve impulse
from O2 sensor
indicating O2
decrease
Intercostal
muscles
Diaphragm
O2 sensor
in aortic body
of aortic arch
CSF in
brain
sinus

9. Neural Regulation of Respiration
Nerves: the phrenic and intercostal nerves
Control diaphragm and external intercostals
Receptors pick up on chemical composition of Oxygen and CO2 and make adjustments
Medulla:
Sets breathing rate and depth of breathing
Controls overinflation of alveoli
Stretch receptors in alveoli too
Pons—coordinates/smoothens respiratory rate
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10. Factors Influencing Respiratory Rate and Depth
Chemical :
Increased levels of carbon dioxide causes:
decreased or acidic pH of CSF
an increase in rate and depth of breathing
The body’s need to rid itself of CO2 is the most important stimulus for breathing
Acts directly on the medulla oblongata
This idea is changing as more research is being done:
One hypothesis is that the prolonged stretch of the diaphragm is the stimulus
Changes in Oxygen are monitored by chemoreceptors in the aorta and carotid
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11. Factors Influencing Respiratory Rate and Depth
Physical factors/Emotional Factors
Increased body temperature/Exercise
Talking/Coughing
Fear, anger, excitement
Conscious control: holding your breath
Respiratory centers override this when oxygen gets too low and pH drops
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12. Summary of Respiration
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