Download Respiratory Ch 22-Student

Ch 22 The Respiration System
The Respiration System
I. Overview
A. Major Function
B. 4 Processes
1. Pulmonary ventilation:
2. External respiration:
3. Transport:
4. Internal respiration:
Circulatory
system
Respiratory
system
II Functional Anatomy of the Respiratory System
Conducting Zone
• Introduction– Major organs
• Nose,
TO
• Lungs: Bronchi and their branches
• Lungs: respiratory bronchioles &
alveoli
= Respiratory Zone
A. The Nose
1. *Functions
2. Parts
a. *External Nose
i) External Nares (nostrils)
b. Nasal Cavity (internal portion)
Root and
Bridge
Dorsum nasi
Ala
Apex
Septal cartilage
Alar cartilages
Naris (nostril)
(a) Surface anatomy
(b) External skeletal framework
Figure 22.2a
b. Nasal cavity … Cribriform plate
of ethmoid bone
i) *Internal NaresSphenoid sinus
Posterior nasal
Aperture (choana)
ii) Vestibule
iii) Vibrissae:
iv) *Olfactory mucosa
v) Respiratory mucosa
• Tissue:
• Seromucous Glands
• Lysozyme:
• Defensins:
• Cilia:
• Sensory receptors
• Nasal Conchae
• Meatus:
Nasal cavity
Nasal conchae
(superior, middle
and inferior)
Nasal vestibule
Nostril
Hard palate
Soft palate
vi. Palate
• Hard
• Soft
• Uvula
*B. Paranasal Sinuses
• *In 4 bones =
• *Functions:
Frontal sinus
Sphenoid sinus
C. Pharynx connects nasal cavity and mouth
to larynx and esophagus
1. Structure and composition:
2. Tissue:
*Pharyngotympanic
(Eustachian) tube opening
3. *Parts:
4. *Pharyngotympanic Tube
5. *Tonsils-- 3
Nasopharynx
Pharyngeal T.
Oropharynx
Palantine T.
Lingual T.
Laryngopharynx
Pharynx
D. Larynx
Epiglottis
1. Functions
a. Airway
b. Sound
Thyroid
Cricoid
2. Basic Anatomy
a. Bony Attachment
b. 9 Cartilages
• Tissue:
i) Thyroid
• *Laryngeal Prominence
ii)
Cricoid
iii) Epiglottis
• Elastic Cartilage
• Aryepiglottic Fold
Laryngopharynx
Hyoid bone
Larynx
Epiglottis
Vocal fold
9 Laryngeal Cartilages …
iv) Arytenoid
Aryepiglottic Fold
(paired)
Cuneiform
• Vocal Cords
Corniculate
v) Corniculate
Arytenoid
(paired)
vi) Cuneiform
(paired)
c. Vocal Folds (cords)
i)
Vocal ligaments
•
ii) Glottis =
False Vocal
Cords
d. Epithelial Tissue– lining cavity
i) Above Vocal C.
ii) Below Vocal C.
e. Vestibular folds = false vocal cords; i)
Location: Superior and lateral to True
ii) Function:
Epiglottis
Vestibular fold
(false vocal cord)
Vocal fold
(true vocal cord)
Glottis
Inner lining of trachea
Cuneiform cartilage
Corniculate cartilage
(a) Vocal folds in closed position;
closed glottis
(b) Vocal folds in open position;
open glottis
2. Basic Anatomy …
g. Intrinsic Laryngeal
Muscles (Lab only)
FUNCTION:
• Arytenoid
- On Arytenoid C.
- Oblique &
Transverse
Thyroarytenoid
• Cricoarytenoid
- On Cricoid C.
• Thyroarytenoid (=
vocalis)
- lateral
• Cricothyroid
- Anterior
E. Trachea = windpipe
1. Location
2. Wall composed of 3 layers
1. Mucosa: tissue =
2. Submucosa:
3. Adventitia:
3. Hyaline Cartilage Rings
4. Trachealis muscle - connects posterior ends of C-cartilage
Function
Esophagus
Mucosa
Trachealis
muscle
Lumen of
trachea
Mucosa
Submucosa
Seromucous gland
in submucosa
Hyaline cartilage
Adventitia
Anterior
F. Bronchi and Subdivisions (bronchial tree)
CONDUCTING ZONE
1. Right and Left Primary Bronchi
• Right: wider, shorter, more vertical
• Enter lungs at Hilium
2. Branching
Superior lobe
of right lung
Middle lobe
of right lung
Inferior lobe
of right lung
Superior lobe
of left lung
Left main
(primary)
Lobar
(secondary)
Segmental
(tertiary)
Inferior lobe
of left lung
a. Lobar Bronchi
(secondary):
b.  segmental (tertiary)
bronchi
c. More Branches
d.  Bronchioles
• Size
• Function:
• Terminal Bronchioles
• Size
• End of
• Feed into respiratory
bronchioles
Bronchial ≠ Bronchiole
F. Bronchi and subdivisions …
3. Histology Characteristics from
bronchi  bronchioles:
Tracheal /Bronchial Wall
• Cartilage rings 
• Pseudostratified columnar

• ↑smooth muscle (complete
ring in bronchioles)
• Elastic tissue-- all
GC = Goblet Cells
GL = Gland
Cart
Plates
3. Histology …
Vein
F. Bronchi & Subdivisions
4. Respiratory Zone
= Respiratory
bronchioles, alveolar
ducts, alveolar sacs
a. alveoli
i) Description
- Alveolar Duct
- Terminal cluster
of Alveoli =
Aveolar Sac .
Sac
Alveolar duct
ii) Function
Respiratory
bronchioles
Terminal
bronchiole
Respiratory
bronchiole
Alveolar
duct
Alveoli
Alveolar
sac
Alveoli
Alveolar duct
Alveolar
sac
4. Respiratory Zone …
b. Respiratory Membrane – gas  liquid
i) Alveolar & Capillary walls + basement membranes (0.5μm)
ii) Alveolar walls =
• Type II cuboidal cells secrete:
Red blood
cell
Nucleus of type I
(squamous
epithelial) cell
Alveolar pores
Capillary
Macrophage
O2
Capillary
CO2
Alveolus
Alveolus
Alveolar
epithelium
Fused basement
membranes of the
Respiratory alveolar epithelium
membrane and the capillary
Red blood cell
endothelium
Alveoli (gas-filled in capillary
Type II (surfactantCapillary
air spaces)
secreting) cell
endothelium
b. Respiratory Membrane …
iii) Alveolar pores =
c. Alveolar Macrophages
d. Pulmonary Capillary Networks
d. Pulmonary Capillary Network …
Terminal bronchiole
Respiratory bronchiole
Smooth
muscle
Elastic
fibers
Alveolus
Capillaries
(a) Diagrammatic view of capillary-alveoli relationships
Figure 22.9a
II. Functional Anatomy …
G. Lungs
1. Lung Structure
• Apex, Base,
• Lobes
• *Cardiac Notch
• *Oblique
Fissure
Lung
Intercostal
muscle
Rib
Parietal pleura
Pleural cavity
Visceral pleura
Trachea
Apex of lung
Thymus
Superior Lobe
Superior Lobe
Middle Lobe
Inferior Lobe
Inferior Lobe
Oblique Fissure
Base of lung
Cardiac notch
(a) Anterior view. The lungs flank mediastinal structures laterally.
Figure 22.10a
1. Lungs Structure …
• Root = bronchi/vascular/nerve bundle
• Hilum = site of entry
Right lung
Parietal
pleura
Visceral
pleura
Pleural
cavity
Root of lung
at hilum
• Left main bronchus
• Left pulmonary artery
• Left pulmonary vein
Left lung
Sternum
Anterior
(c) Transverse section through the thorax, viewed from above. Lungs,
pleural membranes, and major organs in the mediastinum are shown.Figure 22.10c
1. Lungs Structure …
• Bronchiopulmonary Segments
• Served by an individual
segmental bronchus
• 8-9 per side (next slide)
• Disease often
confined to
Oblique
• Lobules
fissure
• Smallest gross
unit
• Served by large
Pulmonary
bronchiole
hilum
• Stroma: the rest
Aortic
impression
Apex of lung
Pulmon
artery
Left m
bronch
Lobule
Bronchiopulmonary Segment (10 on right; 8-9 on left)
Right
superior
lobe (3
segments)
Left superior
lobe
(4 segments)
Right
middle
lobe (2
segments)
Right
inferior lobe (5 segments)
Left inferior
Figure 22.11
lobe (5 segments)
G. Lungs …
2. Blood Supply
• Pulmonary circulation
feeds alveoli
• Systemic circulation
(high pressure, low
volume)
• Bronchial arteries
• Pulmonary veins carry
most venous blood back
to heart
3. Pleaurae = double-layered serosa
• Parietal pleura
• Visceral pleura
• Pleural fluid
Vertebra
Posterior
• Function:
Parietal
pleura
Visceral
pleura
Pleural
cavity
Anterior
Figure 22.10c
III. Mechanics of Breathing
A. Pressure Relationships in Thoracic Cavity
1. Basic Characteristics
• Respiratory Pressures
always relative to
Atmospheric pressure
Patm
• Negative respiratory
pressure
• Positive respiratory
• Zero respiratory pressure
= Patm
Atmospheric pressure
Atmospheric pressure
1. Basic Characteristics ..
- Gases always flow from
higher pressure to lower
Pressure
2. Intrapulmonary
Pressure
But, lungs are elastic and
will collapse if not ‘held’
against thoracic wall!
760
Intrapulmonary
pressure 760 mm Hg
(0 mm Hg)
= intra-alveolar = Ppul) =
pressure in alveoli
• Fluctuates with breathing
(- sucks in; + forces out)
• Always eventually
equalizes with Patm
3. Intrapleural Pressure
Parietal pleura
Visceral pleura
Pleural cavity
= Pip = Pressure in pleural cavity
• Fluctuates with breathing
Intrapleural
pressure
756 mm Hg
(–4 mm Hg)
756
• Always negative pressure
(<Patm and <Ppul)
• 4 less than intrapulmonary
• Keeps lungs ‘sucked’ up
against chest wall
• Resists lungs recoiling power
and alveolar collapse
A. Pressure Relationships …
• If Pip = Ppul the lungs collapse
• (Ppul – Pip) = transpulmonary
pressure
• Keeps the airways open
• As chest cavity expands,
transpulmonary increases to
resist higher recoil of lungs
(4mm at resting exhalation;
6mm at resting inhalation)
Transpulmonary
pressure
760 mm Hg
–756 mm Hg
= 4 mm Hg
756
760
4. Transpulmonary pressure difference
keeps lungs against chest wall…
• Infections or
injuries can let air
into pleural cavity
= collapsed lung
(a.k.a.
atalectasis)
Pleural
Membrane
III. Mechanics of Breathing …
B. Pulmonary Ventilation
• Inspiration/expiration depend on: volume changes in
thoracic cavity
• Boyle’s Law: Pressure (P) varies inversely w/ volume (V):
P1V1 = P2V2
• Increase Volume  ______________ pressure  to
equalize pressure, air must ______________
1. Inspiration
Passive Inhalation– muscle
actions
a. Diaphragm
• contracts: moves down
b. external intercostal
• Contract: lift rib cage
up and out.
c. lung volume: expands
2. Expiration
Passive Exhalation– muscle
actions
a. Diaphragm relaxes
moves:
b. external intercostals relax
Moves:
c. Lung volume: Rib cage
moves down & Lungs recoil
Fig. 11.7, p. 200
Inspiration
Sequence of events
Changes in anteriorposterior and superiorinferior dimensions
Changes in lateral
dimensions
(superior view)
1 Inspiratory muscles
contract (diaphragm
descends; rib cage rises).
2 Thoracic cavity volume
increases.
Ribs are elevated
and sternum flares
as external
intercostals
contract.
3 Lungs are stretched;
External
intercostals
contract.
intrapulmonary volume
increases.
4 Intrapulmonary pressure
drops (to –1 mm Hg).
5 Air (gases) flows into
lungs down its pressure
gradient until intrapulmonary
pressure is 0 (equal to
atmospheric pressure).
Diaphragm
moves inferiorly
during contraction.
Figure 22.13 (1 of 2)
Exhalation
Sequence
of events
Changes in anteriorposterior and superiorinferior dimensions
Changes in
lateral dimensions
(superior view)
1 Inspiratory muscles
relax (diaphragm rises; rib
cage descends due to
recoil of costal cartilages).
2 Thoracic cavity volume
Ribs and sternum
are depressed
as external
intercostals
relax.
decreases.
3 Elastic lungs recoil
External
intercostals
relax.
passively; intrapulmonary
volume decreases.
4 Intrapulmonary pres-
sure rises (to +1 mm Hg).
5 Air (gases) flows out of
lungs down its pressure
gradient until intrapulmonary pressure is 0.
Diaphragm
moves
superiorly
as it relaxes.
Figure 22.13 (2 of 2)
Intrapulmonary
pressure. Pressure
inside lung decreases as
lung volume increases
during inspiration;
pressure increases
during expiration.
Intrapleural pressure.
Pleural cavity pressure
becomes more negative
as chest wall expands
during inspiration.
Returns to initial value
as chest wall recoils.
Volume of breath.
During each breath, the
pressure gradients move
0.5 liter of air into and out
of the lungs.
Inspiration Expiration
Intrapulmonary
pressure
Transpulmonary
pressure
Intrapleural
pressure
Volume of breath
5 seconds elapsed
Figure 22.14
3. Forced inspiration and expiration
Forced inspiration employs pec minor,
sternocleidomastoid, erector spinae
among others to lift faster/expand
further
Forced expiration is uses
abdominal and internal
intercostal muscles
C. Physical Factors Influencing Pulmonary
Ventilation
Conducting
3 factors
1. Airway resistance –
usu. low
• Increases w/:
a. inflammation +
b. smooth muscle
contraction (asthma)
• Drugs: Epinephrine
dilates bronchioles
zone
Medium-sized
bronchi
Respiratory
zone
F=ΔP/R
(remember?)
ΔP = 1-2mm
still enough flow
Terminal
bronchioles
Airway generation
(stage of branching)
C. Physical Factors affecting ventilation …
2. Alveolar Surface Tension
a. Surface tension of H2O: resists increases in surface area
b. Surfactant (bio-soap) of Type II cells reduces surface tension
• Prevents alveolar collapse
• Premature babies (<28 weeks) lack surfactant, require assistance
Alveolus
Type II (surfactantsecreting) cell
Physical Factors affecting ventilation …
3. Lung Compliance
= Air Volume taken in w/ given change
in transpulmonary pressure
a. Normally high:
• High distensibility
• Low surface tension
b. Diminished by
• scar tissue (fibrosis)
• Reduced surfactant
• Decreased flexibility of thoracic
cage
 More energy required for
inspiration
D. Respiratory Volumes & Pulmonary Function Tests
1. RESPIRATORY VOLUMES
 Tidal Volume (TV)
 Inspiratory Reserve Volume (IRV)
 Expiratory Reserve Volume (ERV)
 Residual Volume =
 Vital Capacity =
Figure 13.9
Dead Space
• =
• Anatomical dead space:
volume of conducting zone
conduits (~150 ml)
• Alveolar dead space:
collapsed or obstructed
alveoli
• Total dead space: sum of
above nonuseful volumes
• Part of Tidal Volume
Average values affected by age and gender
Measurement
Respiratory
volumes
Adult male
average value
Adult female
average value
Tidal volume (TV)
500 ml
500 ml
Inspiratory reserve
volume (IRV)
3100 ml
1900 ml
Expiratory reserve
volume (ERV)
1200 ml
700 ml
Residual volume (RV)
1200 ml
1100 ml
Copyright © 2010 Pearson Education, Inc.
Description
Amount of air inhaled or
exhaled with each breath
under resting conditions
Amount of air that can be
forcefully inhaled after a normal tidal volume inhalation
Amount of air that can be
forcefully exhaled after a normal tidal volume exhalation
Amount of air remaining in
the lungs after a forced
exhalation
Figure 22.16b
2. Pulmonary Function Tests
• SPIROMETER
a. Minute Ventilation = Tidal Volume X breaths/minute
b. Forced Vital Capaity
Abnormalities
• Hyperinflation may be due to obstructive disease
• Reduced volumes result from restrictive disease
Figure 22.16a
D. Respiratory Volumes & Pulmonary Function Tests …
c. Alveolar Ventilation
= Alveolar ventilation rate (AVR): gas flow in/out of alveoli
per minute
is thenActual exchange
AVR
(ml/min)
=
frequency
X
(breaths/min)
• Dead space is normally constant
(TV – dead space)
(ml/breath)
IV. Gas Exchange Between the
Blood, Lungs, and Tissues
A. Basic Properties of Gases
• Total Pressure: The sum of
the pressures of each gas
• Partial Pressure
• Proportional to gas %
• example
Basic Properties of Gases …
• Gas in Contact with Liquid
• Gas dissolves into liquid proportional to its partial
pressure
• At equilibrium: partial pressures in gas & liquid same
• Chemical Nature of Gas
• CO2 is 20 times more soluble in
water than O2
• Temperature
• Pressure
B. Composition of Alveolar Gas
• Alveoli gas mix is slightly different from atmosphere
• Gas exchanges in lungs
• Humidification of air
C. External Respiration
Inside the alveoli, gas exchange is
driven by simple diffusion
Low CO2 in air; High O2
High CO2 in blood; Low O2
External Respiration
In LUNGS
• O2 Partial pressure gradient:
• Alveolar Po2 = 104 mm Hg
• Venous blood Po2 = 40 mm Hg
• O2 reaches equilibrium in ~0.25 s
• 1/3 the time RBC in capillary
• CO2 Partial pressure gradient:
• Alveolar Pco2 = 40 mm Hg
• Venous blood Pco2 = 45 mm Hg
Inspired air:
PO2 160 mm Hg
PCO 0.3 mm Hg
Alveoli of lungs:
PO2 104 mm Hg
PCO 40 mm Hg
2
2
External
respiration
Pulmonary
arteries
Pulmonary
veins (PO2
100 mm Hg)
Blood leaving
tissues and
entering lungs:
PO2 40 mm Hg
PCO2 45 mm Hg
Blood leaving
lungs and
entering tissue
capillaries:
PO2 100 mm Hg
PCO2 40 mm Hg
Heart
• CO2 diffuses in equal amounts w/ O2
Systemic
veins
Systemic
arteries
Internal
respiration
O2
CO2
Figure 22.17
Ventilation-Perfusion Coupling
• Overview:
• Ventilation: amount of gas reaching alveoli– controlled by CO2
• Perfusion: blood flow reaching alveoli– Controled by O2
• PERFUSION:
• Mechanism opposite that for systemic vessels
• High pO2 dilates pulmonary arterioles
• This when ventilation is maximal
• VENTILATION:
• High CO2 in Alveoli cause bronchioles to dialate
• Balancing: Ventilation and perfusion must be matched
• Low Alveolar Ventilation = low O2 and high CO2
•  arterioles constrict and bronchioles dilate, vica versa
Thickness and Surface Area of Respiratory
Membrane effects gas exchange
• Respiratory membranes
• 0.5 to 1 m thick
• Large total surface area
O2
Capillary
CO2
Alveolus
Internal Respiration
Inspired air:
PO2 160 mm Hg
PCO 0.3 mm Hg
Alveoli of lungs:
PO2 104 mm Hg
PCO 40 mm Hg
2
2
• Capillary gas exchange in body tissues
• Partial pressures (diffusion gradients)
reversed compared to external
respiration
• O2 leaves blood, CO2 enters blood
External
respiration
Pulmonary
arteries
Pulmonary
veins (PO2
100 mm Hg)
Blood leaving
tissues and
entering lungs:
PO2 40 mm Hg
PCO2 45 mm Hg
Blood leaving
lungs and
entering tissue
capillaries:
PO2 100 mm Hg
PCO2 40 mm Hg
Heart
Systemic
veins
Systemic
arteries
Internal
respiration
O2
CO2
V. Transport of Respiratory Gases by Blood
A. Introduction:
1. Active vs. Inactive Tissues
• Active Tissues:
• CO2, Higher H+, Temp: Higher or Lower?
• Lower O2
• Inactive Tissues:
• O2:
• CO2, H+, Temp:
• CO2 + H20
H2C03
H+ + HCO3-
2. Hemoglobin– four 02 per Hb
• Affinity for O2 changes with:
• # O2 attached
• Local Conditions: as for active and inactive tissues
• Reversibly binds O2– Loading & unloading
V. Transport of Respiratory Gases by Blood …
B. O2 Transport
• 1.5% is:
• 98.5% is:
oxyhemoglobin
Reduced hemoglobin
Alveolus
Fused basement membranes
CO2
Red blood cell
O2 + HHb
HbO2 + H+
O2
O2
O2 (dissolved in plasma)
(b) Oxygen pickup and carbon dioxide release in the lungs
Blood plasma
B. O2 Transport …
1. Association of Oxygen and Hemoglobin
a. Plasma O2 diffusion
b. Loading & Unloading
• In Lungs = Loading: As O2 binds, Hb affinity for O2 :
• At body cells = Unloading: As O2 is
released, Hb affinity for
O2 :
- Because: Hb
c. Influence of PO2 on Hb
saturation
Relationship=
AT LUNGS: Hb = 98%
saturated at Po2 = 100mm
(leaving lung)
Additional
O2 unloaded
to exercising
tissues
O2 Saturation Curve
B. O2 Transport …
1. Association of Oxygen and Hemoglobin …
c. Influence of PO2 on Hb
saturation …
Even if Po2 = 70 mm, Hb
over 90% saturated
If PO2 at approx. 40 as
when leaving body cells–
If get small drop in Po2
causes:
- On steep part of curve
WHY ?  Next slide
Additional
O2 unloaded
to exercising
tissues
O2 Saturation Curve
B. O2 Transport …
1. Association of Oxygen and Hemoglobin …
c.
Influence of PO2 on Hb saturation …
• WHY? Have reserve of
O2 in blood
• if PO2 of inspired air is
below normal,
unloading is:
• for EMERGENCY Or . EXERCISE
Additional
O2 unloaded
to exercising
tissues
O2 Saturation Curve
d. Other Factors Influencing Hb Saturation
i) Active Tissues: temperature
• Modify structure of Hb, affinity for O2 ( unloading)
• Saturation curve shifted:
10°C
20°C
38°C
43°C
Normal body
temperature
d. Other Factors Influencing Hb Saturation …
ii) Active Tissues: H+ and Pco2:
• Weakens ______________________ = Bohr Effect
• Modify structure of Hb, affinity for O2 ( unloading)
• Saturation curve shifted to the right
Decreased carbon dioxide
(PCO2 20 mm Hg) or H+ (pH 7.6)
Bohr Effect –  CO2/H+
encourages O2 unloading
Normal arterial
carbon dioxide
(PCO2 40 mm Hg)
or H+ (pH 7.4)
Increased carbon dioxide
(PCO2 80 mm Hg)
or H+ (pH 7.2)
PO (mm Hg)
2
C. CO2 Transport
3 ways
1. 7 - 10% :
2. 20% :
= Carbaminohemoglobin
• Binds to:
• Catalyst:
3. 70% :
CO2
Carbon
dioxide
+
H2O
Water

H2CO3
Carbonic
acid

H+
Hydrogen
ion
+
HCO3–
Bicarbonate ion
C. CO2 Transport …
3. As Bicarbonate …
• Enzyme in RBCs: Carbonic Anhydrase
• - reversible
• Once produced, it then moves into plasma
• IN LUNGS: reaction reverses to unload CO2
• Additional affect: The H+ created by CO2 reaction with
Water causes Bohr Shift
Tissue cell
Interstitial fluid
CO2
CO2
CO2 (dissolved in plasma)
CO2 + H2O
Slow
H2CO3
HCO3– + H+
CO2
CO2
CO2
CO2
AT BODY CELLS
Fast
CO2 + H2O
H2CO3
Carbonic
anhydrase
CO2 + Hb
HCO3– + H+
HbCO2 (Carbaminohemoglobin)
Red blood cell
HbO2
O2 + Hb
HCO3–
Cl–
Cl–
HHb
Binds to
plasma
proteins
Chloride
shift
(in) via
transport
protein
C. CO2 Transport …
4. Haldane Effect: O2 effects CO2 transport
= The lower the Po2 (and thus HbO2), the more CO2 can be
carried in blood (and vice versa)
• Because: Deoxyhemoglobin reacts more readily with CO2
• OVERALL AFFECT: Bohr Shift and Haldane Effect
• At tissues, as more CO2 enters blood (H+↑)
• More O2 dissociates from Hb (Bohr effect, i.e. CO2 effects O2)
• As HbO2 releases O2, it more readily forms bonds with CO2 to
form carbaminohemoglobin
In the lungs: O2 loaded/CO2 unloaded
Alveolus
Fused basement membranes
CO2
CO2 (dissolved in plasma)
CO2
CO2 + H2O
Slow
H2CO3
HCO3– + H+
HCO3–
Fast
CO2
H2CO3
CO2 + H2O
Carbonic
anhydrase
CO2
CO2 + Hb
Red blood cell
HCO3–
+
H+
HbCO2 (Carbaminohemoglobin)
O2 + HHb
HbO2 + H+
Cl–
Cl–
Chloride
shift
(out) via
transport
protein
O2
O2
O2 (dissolved in plasma)
Blood plasma
(b) Oxygen pickup and carbon dioxide release in the lungs
Figure 22.22b
C. CO2 Transport
5. Influence of CO2 on Blood pH
1. Carbonic Acid-Bicarbonate Buffer System
H2CO3

H+
+
HCO3–
Carbonic
Hydrogen
Bicarbonate ion
acid
ion
a. Alkaline Reserve: the HCO3- in plasma
b. Changes in pH (usually via metabolic factors)
• If H+  in blood: excess H+ removed by combining
with HCO3–
• If H+ : H2CO3 dissociates, releasing H+
c. As CO2 accumulates in blood, pH declines
• Major stimulus for neural control of respiration rates
• Respiratory Sys. Can Change breathing patterns:
Carbonic Acid Buffer System
c. As CO2 accumulates …
Changing breathing patterns by adjusting
respiratory rate or depth:
• Resp. Sys.: a method of controlling blood pH
• slow/shallow  pH– exhale less CO2
• deep/rapid  pH)– exhale more CO2
• D. Urinary System
H2CO3
Carbonic
acid

H+
Hydrogen
ion
+
HCO3–
Bicarbonate ion
VI. Control of Respiration
Pons
Medulla
Pontine respiratory centers
interact with the medullary
respiratory centers to smooth
the respiratory pattern.
Ventral respiratory group (VRG)
contains rhythm generators
whose output drives respiration.
Pons
Medulla
Dorsal respiratory group (DRG)
integrates peripheral sensory
input and modifies the rhythms
To inspiratory
generated by the VRG.
muscles
Diaphragm
External
intercostal
muscles
VI. Control of Respiration …
A. Neural
Mechanisms
Pons
• Involves neurons in
Pons
Medulla
reticular formation Pontine respiratory centers Medulla
Pontine
respiratory
centers
with
the medullary
of medulla and ponsinteract
interact with
the medullary
respiratory
centers
to smooth
1. Medulla
Oblongata
Respiratory
Centers
a. Ventral
Respiratory
Group
 NEXT SLIDE
respiratory
centers
to smooth
the
respiratory
pattern.
the respiratory
pattern.
Ventral
respiratory
group (VRG)
Ventral
respiratory
group (VRG)
contains rhythm generators
contains
rhythm
generators
whose
output
drives
respiration.
whose output drives respiration.
Pons
Pons
Medulla
Medulla
Dorsal respiratory group (DRG)
Dorsal respiratory
group (DRG)
integrates
peripheral sensory
integrates
peripheral
sensory
input
and modifies
the rhythms
input andby
modifies
the rhythms To inspiratory
generated
the VRG.
To inspiratory
muscles
generated by the VRG.
muscles
Diaphragm
Diaphragm
External
External
intercostal
intercostal
muscles
muscles
VI. Control of Respiration …
A.
Neural Mechanisms …
• a. Ventral
Respiratory Group …
• Inspiration:
Certain neuron
send impulses
to:
Pons
Pons
Medulla
Medulla
Pontine respiratory centers
Pontine
respiratory
centers
interact
with
the medullary
interact with
the medullary
respiratory
centers
to smooth
respiratory
centers
to smooth
the
respiratory
pattern.
the respiratory
pattern.
Ventral
respiratory
group (VRG)
Ventral
respiratory
group (VRG)
contains rhythm generators
contains
rhythm
generators
whose
output
drives
respiration.
whose output drives respiration.
Pons
Pons
Medulla
Medulla
Dorsal respiratory group (DRG)
Dorsal respiratory
group (DRG)
integrates
peripheral sensory
integrates
peripheral
sensory
input
and modifies
the rhythms
input andby
modifies
the rhythms To inspiratory
generated
the VRG.
To inspiratory
muscles
generated by the VRG.
muscles
• Expiration: Other
neurons send:
• Rhythm
generating:
Eupnea =
Diaphragm
Diaphragm
External
External
intercostal
intercostal
muscles
muscles
VI. Control of Respiration …
A.
Neural Mechanisms
b. Dorsal Respiratory Group
• Integrates information from peripheral
stretch receptors & chemoreceptors Pons

Pons
Medulla
sends to VRG Pontine respiratory centers Medulla
2. Pons– Pontine
Respiratory
Centers
Fine tunes rhythm
for vocalizations,
sleep, exercise by
influencing VRG
Pontine
respiratory
centers
interact
with
the medullary
interact with
the medullary
respiratory
centers
to smooth
respiratory
centers
to smooth
the
respiratory
pattern.
the respiratory
pattern.
Ventral
respiratory
group (VRG)
Ventral
respiratory
group (VRG)
contains rhythm generators
contains
rhythm
generators
whose
output
drives
respiration.
whose output drives respiration.
Pons
Pons
Medulla
Medulla
Dorsal respiratory group (DRG)
Dorsal respiratory
group (DRG)
integrates
peripheral sensory
integrates
peripheral
sensory
input
and modifies
the rhythms
input andby
modifies
the rhythms To inspiratory
generated
the VRG.
To inspiratory
muscles
generated by the VRG.
muscles
Diaphragm
Diaphragm
External
External
intercostal
intercostal
muscles
muscles
B. Factors Influencing Breathing
Depth and Rate
Arterial PCO2
- modification in response to
changing body
H in
CO
brain extracellular
demands’
fluid (ECF)
2
1. Chemical Factors
a. CO2 diffuses across
blood-brain barrier,
forms ↑H2CO3 = ↑H+ in
brain ECF
Central chemoreceptors
in medulla respond to H+
in brain ECF (mediate 70%
of the CO2 response)
• pH , stimulates
chemoreceptors in
medulla
Afferent impulses
Medullary
respiratory centers
Efferent impulses
b. Arterial pH 
stimulates peripheral
chemoreceptors Initial stimulus
Physiological response
Both =  ventilation
Result
Peripheral chemoreceptors
in carotid and aortic bodies
(mediate 30% of the CO2
response)
Respiratory muscle
Ventilation
(more CO2 exhaled)
Arterial PCO2 and pH
return to normal
c. PO2 is NOT a common stimulus
Brain
• Only if arterial PO2 < 60mm,
peripheral chemoreceptors
 ventilation
Carotid body
Cranial nerve X (vagus nerve)
Aortic bodies in aortic arch
Aorta
Heart
Figure 22.26
2. Higher Brain Influences
Other receptors (e.g.,
pain) and emotional
stimuli via hypothalamus
+
–
Higher brain centers
(cerebral cortex—voluntary
control over breathing)
+
–
Peripheral
chemoreceptors
O2 , CO2 , H+
Central
Chemoreceptors
CO2 , H+
Respiratory centers
(medulla and pons)
+
+
–
–
Stretch receptors in
lungs (Hering-Breuer
(inflation) reflex)
+
Receptors in
muscles and joints
Irritant
receptors
Figure 22.24
3. Respiratory Adjustments: Exercise
• Depends on: intensity and duration of exercise
• Hyperpnea
• Increase in ventilation 10 to 20 fold
• Pco2, Po2, and pH remain surprisingly constant during
exercise
4. Acclimatization to High Altitude
Affect of decreased PO2
1. Substantial  in Po2 stimulates peripheral
chemoreceptors
• Result: minute ventilation increases in a few days to 2–
3 L/min
2. Decline in blood O2 stimulates kidneys to  production of
EPO (erythropoietin)  ↑ RBCs over long-term
C. Homeostatic Imbalances
• STUDENTS DO
• Chronic obstructive
pulmonary disease
END OF PPT
• REVIEW QUESTIONS
• EXTRA SLIDES
Review
A. ID
B. ID
C. What type
of E.T. is
found here?
Review Questions
The _____________
pseudostratified ______
ciliated columnar
________ epithelium of
mucus and gives
the nasal cavity helps move _________
stratified _________
squamous epithelium in the
way to ________
friction
oropharynx to protect against ___________
from
food.
How many lobar bronchi are there?
5 = 3 right + 2 left lobes
Review Questions
The ___________
respiratory membrane
________ is where respiratory
alveoli to the blood
gases diffuse from air in the ________
plasma.
Intrapleural (Pip) pressure is always _____
less than
intrapulmonary pul) pressure, otherwise the lungs
_____________(P
would do what?
Collapse (atalectasis)
Review Questions
Which of the following physical factors would
negatively effect pulmonary ventilation?
A.
B.
C.
D.
E.
Increased resistance to flow
Increased lung compliance
Decreased alveolar surface tension
A and C only
All of the above
_______
Dead _______
space is the portion of gas in the lungs that
does not participate in active gas exchange.
Review Questions
In a mix of gases, the
partial pressures
________
_________ of
each gas and its
solubility
___________
in the
liquid determine the
direction and quantity of
diffusion.
How does rapid, shallow
breathing effect alveolar
respiration rate, i.e.
actual gas exchange?
Reduces it.
Review Questions
What brain regions have primary
control over respiration?
Pons and Medulla
The primary stimulus for
regulating respiration rates is
CO2 and
the concentration of _____
its eventual production of ___
H+
ions.
Long term acclimation is
regulated by what organs?
kidneys
Review Questions
As CO2 enters the blood, what happens to blood pH?
Decreases (H+ increases)
What happens to the ability of Hb to hold onto O2 as
CO2 levels increase?
Decreases (Bohr effect)
O2 on
The Haldane effect describes the influence of ____
CO2
the capacity of blood to carry _____.
Middle lobe
of right lung
Superior lobe
of left lung
Left main
(primary)
bronchus
Lobar
(secondary)
bronchus
Segmental
(tertiary)
bronchus
Inferior lobe
of right lung
Inferior lobe
of left lung
Superior lobe
of right lung