Human Anatomy and

Physiology II

Biology 1414

Unit 4

Respiratory Physiology

Objective 1

List and give the percentage of
the main gases of the
atmosphere.

Unit 1 - Objective 1

Main Gases of the

Atmosphere

Gas Symbol
Approximate %

Nitrogen N2
78.6
Oxygen O2
20.9
Carbon Dioxide CO2 0.04
Water Vapor H2O
0.46

Unit 1 - Objective 1

Objective 2

Define partial pressure and be
able to compute partial
pressures of gases in a mixture.

Unit 1 - Objective 2

Definition of Partial

Pressure

Partial pressure refers to the
pressure that is exerted by a
single gas in some given system
(atmosphere, blood, tissue, lung or
experimental mixture). The sum
of the individual partial
pressures produces the total
pressure in the system. This total
pressure is called barometric
pressure The barometric
pressure of the atmosphere is 760
mmHg at sea level.

Unit 1 - Objective 2

Calculation of Partial

Pressure

Partial pressure is directly
proportional to the percentage of
a gas in a mixture. In order to
calculate the partial pressure of a
gas, you will multiply the decimal
equivalent of the percentage of
a given gas by the total pressure
of the system. The general
formula would be:
partial pressure (P) = % of gas X
total pressure

Unit 1 - Objective 2

Calculation of Partial

Pressure Continued

If the percentage of oxygen in the
atmosphere is 20.9% and the total
barometric pressure of the
atmosphere is 760 mmHg, then:
PO2 = 0.209 X 760 mmHg.
This gives an oxygen partial
pressure (PO2) of:
158.84 (159 rounded) mm
Hg

Unit 1 - Objective 2

Calculation of Partial

Pressure Continued

If the percentage of carbon
dioxide in the atmosphere is
0.04% and the total barometric
pressure of the atmosphere is 760
mmHg, then:
PCO2 = 0.0004 X 760
mmHg.
This gives a carbon dioxide partial
pressure (PCO2) of:
0.304 (0.3 rounded) mm Hg

Unit 1 - Objective 2

Objective 3

Distinguish between pulmonary
ventilation, external and
internal respiration using short
definitions.

Unit 1 - Objective3

Definition of Pulmonary

Ventilation

Pulmonary ventilation is the
exchange of air between the
atmosphere and the lungs. This
process is commonly called
breathing and depends on chest
and diaphragm movements, as
well as, clear airways. Inhalation
(inspiration) lowers pressure
inside the lungs which draws in
air. Exhalation does the opposite.

Unit 1 - Objective 3

Definition of External

Respiration

External respiration is gas
exchange between the lung
alveoli and the blood of the
pulmonary circulation. This
process depends on gas partial
pressure differences, the integrity
of lung membranes and blood
flow in and out of the lungs.

Unit 1 - Objective 3

Definition of Internal

Respiration

Internal respiration is the
exchange of gas between the
blood and the cells of the body.
This process generally depends on
the same factors as external
respiration.

Unit 1 - Objective 3

Objective 4

Explain or interpret the movement
of gases between alveolar spaces,
blood and cells due to differences
in partial pressure.

Unit 1 - Objective 4

Movement of Gases in the

Body

Movement of gases between the
alveoli, blood and cells depends on
the partial pressure difference of a
gas across these regions.
According to the Law of Diffusion,
gases always move from a region
of high partial pressure to a
region of low partial pressure. If
your lungs have a higher gas
pressure than your blood, then the
gas will move into your blood and
visa versa.

Unit 1 - Objective 4

Movement of Gases in the

Body

Examine the following slide in
order to observe the gas partial
pressure differences that exist in
different regions of the body.
Predict the direction of oxygen
and carbon dioxide movement
from one region to another using
the gas pressures.

Unit 1 - Objective 4

Movement of Gases in

Body

Unit 1 - Objective 4

Objective 5

Name the ways carbon dioxide
and oxygen are transported by the
blood.

Unit 1 - Objective 5

Carbon Dioxide Transport

Method
Percentage
Dissolved in Plasma 7 - 10
%

Chemically Bound to
Hemoglobin in RBC’s 20 -
30 %

As Bicarbonate Ion in
Plasma 60
-70 %

Unit 1 - Objective5

Oxygen Transport

Method
Percentage

Dissolved in Plasma
1.5 %

Combined with Hemoglobin
98.5 %

Unit 1 - Objective5

Write reactions to show the
formation of each of the following
in the blood. Be able to define
and discuss the functional
significance of each:
oxyhemoglobin,
carbaminohemoglobin,
bicarbonate ion, carbonic acid.

Objective 6

Unit 1 - Objective 6

Oxyhemoglobin Formation

Oxyhemoglobin forms when an
oxygen molecule reversibly
attaches to the heme portion of
hemoglobin. The heme unit
contains iron ( +2 ) which
provides the attractive force. The
process is summarized as follows:

Unit 1 - Objective 6

O

2

+

Hb

HbO

2

Carbaminohemoglobin

Formation

Carbaminohemoglobin forms
when a carbon dioxide molecule
reversibly attaches to an amino
portion of hemoglobin. The
process is summarized as follows:

Unit 1 - Objective 6

CO

2

+

Hb

HbCO

2

Carbonic Acid Formation

Carbonic acid forms abundantly in
the RBC when the enzyme
carbonic anhydrase stimulates
water to combine quickly with
carbon dioxide. The process is
summarized as follows:

Unit 1 - Objective 6

CO

2

+ H

2

0

H

2

CO

3

Bicarbonate Ion

Formation

The bicarbonate ion also forms
abundantly in the RBC when
carbonic acid breaks down to
release a hydrogen ion and
bicarbonate. The process is
summarized as follows:

Unit 1 - Objective 6

H

2

CO

3

H

+

+

HCO

3

Objective 7

Explain what takes place during
the chloride shift and be able to
diagram the chloride shift for
tissue capillaries and pulmonary
capillaries.

Unit 1 - Objective 7

Chloride Shift in Tissue

Capillaries

When RBC’s move through tissue
capillaries, they take in carbon
dioxide and release bicarbonate.
As bicarbonate is released,
chloride (-1) shifts into the
RBC in order to replace the
negative bicarbonate (-1). This
preserves charge balance in the
RBC. To see this, look at the next
slide.

Unit 1 - Objective 7

Chloride Shift in Tissue

Capillaries

Unit 1 - Objective 4

Tissue Capillary

Chloride Shift in

Pulmonary Capillaries

When RBC’s move through
pulmonary capillaries, they take
in bicarbonate and release carbon
dioxide. As bicarbonate (-1) shifts
into the RBC, chloride (-1) shifts
out of the RBC. This also
preserves charge balance in the
RBC. To see this, look at the next
slide.

Unit 1 - Objective 7

Chloride Shift in

Pulmonary Capillaries

Unit 1 - Objective5

Pulmonary Capillary

Objective 8

Given an oxygen dissociation
curve, determine the percent of
hemoglobin saturation with
oxygen for a given PO2 and
PCO2. Discuss the influence of the
Bohr effect on hemoglobin
saturation.

Unit 1 - Objective 8

The Oxygen Dissociation

Curve

Examine the following oxygen
dissociation curve and give the
percent saturation at the following
partial pressures of oxygen:
PO2 Percent
Saturation
100 mm Hg ?
40 mm Hg ?
26 mm Hg ?

Unit 1 - Objective 8

The Oxygen Dissociation

Curve

Unit 1 - Objective 8

The Oxygen Dissociation

Curve

The answers for the previous
activity are as follows:
PO2 Percent
Saturation
100 mm Hg 98
40 mm Hg 75
26 mm Hg 50

Unit 1 - Objective 8

The Bohr Effect

When the carbon dioxide content
of the blood increases, the oxygen
dissociation curve shifts to the
right. This right shift decreases
the ability of hemoglobin to hold
oxygen. Consequently, additional
oxygen is unloaded and made
available to the body. See the
following graph for this effect.

Unit 1 - Objective 8

Bohr Effect

Unit 1 - Objective 8

Bohr Shift Curve

The Bohr Effect

Did you notice that when PCO2
increased from 40 to 80 mm Hg,
oxygen saturation decreased from
75 % to about 65 %. This made an
extra 10% oxygen available to the
tissues. This would come in handy
during increased activity. The
Bohr shift is a very positive
adaptation!

Unit 1 - Objective 8

Objective 9

Cite or recognize four reasons
why oxyhemoglobin is induced to
give off oxygen in tissue
capillaries

Unit 1 - Objective 9

Factors That Induce

Oxygen Unloading From

Hemoglobin

In addition to carbon dioxide
that causes a right shift in the
oxygen dissociation and more
oxygen unloading, there are
additional factors that cause a
similar effect:
1. Increased body
temperature
2. Increased H+ from acids
3. Increased 2,3-
biphosphoglygerate
(BPG)

Unit 1 - Objective 9

Objective 10

Give the location and function of
the respiratory centers and list
five factors that influence the
centers.

Unit 1 - Objective 10

Location of Respiratory

Centers

The pons contains the
pneumotaxic respiratory center
and the apneustic respiratory
center. Both of these centers are
considered secondary
respiratory centers. This means
they do not set the basic
respiratory rhythm. Instead, they
modify the basic respiratory rate.
The medulla contains the
medullary respiratory center
that operates as the primary
breathing center.

Unit 1 - Objective 10

Location of Respiratory

Centers

View the following diagram for the
location of the respiratory centers

Unit 1 - Objective 10

Respiratory Centers

Unit 1 - Objective

Medullary Respiratory
Center

Function of Respiratory

Centers

The pneumotaxic respiratory
center inhibits inhibits inspiratory
time and increases breaths per
minute. The apneustic
respiratory center has not been
clearly defined, but, is postulated
to prolong inspiratory time and
reduces breaths per minute. The
medullary respiratory center
stimulates basic inspiration for
about 3 seconds and then basic
expiration for about 2 seconds
(5sec/breath= 12breaths/min).

Unit 1 - Objective 10

Factors That Influence

Respiration

View the following slide for factors
that influence respiration

Unit 1 - Objective 10

Factors Influencing

Respiration

Unit 1 - Objective