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BREATHING AND www.anandmani.com
EXCHANGE OF GASES
8MAR
•
Respiratory Volume
◦
Transport
• Disorders

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RESPIRATORY ORGANS

co
Lower invertebrates like sponges, flatworms, exchange Pharynx MECHANISM OF BREATHING
gases through simple diffusion by body surface • It is a common passage for food and air

NORMAL BREATHING
• Divided into nasopharynx, oropharynx, and laryngopharynx Inspiration Expiration
• Pharynx opens into larynx by slit-like aperture glottis Atmospheric air rich in oxygen drawn Alveolar air rich in carbon
Flap Epiglottis prevents entry of good to the 9bM#_

Abdominal
→
into lungs dioxide expelled out from
called
-

Earthworms use
Larynx
the lungs is
moist cuticle
(cutaneous • Also called as sound box as helps in sound production It is an active process It is a passive process
Insects use

Breathing
respiration) • Glottis is guarded by the epiglottis (leaf-shaped cartilage of
tracheal tubes the larynx); during swallowing, epiglottis closes the glottis to Inspiration occurs when intra-pulmonary Expiration occurs when intra-
prevent the entry of food into it pressure is less than the atmospheric pressure. pulmonary pressure is high than
• Epiglottis acts as a flap; made of thin elastic cartilage
It is due to negative pressure in the lungs the atmospheric pressure

1kMs
Trachea It is initiated by- Contraction of diaphragm It is initiated by- Relaxation
for forceful inspiration
→
Aquatic arthropods Terrestrial • Also called as wind pipe th (NEET 2020) of diaphragm
• Divides in the region of 5 thoracic vertebra
and molluscs use gills animals use • The trachea, bronchi (primary, secondary, tertiary),
(branchial respiration) lungs (pulmonary and initial bronchioles are supported by posteriorly Increase in volume of thoracic chamber in Inter-costal muscles return the
itincomplete C-shaped cartilaginous rings of hyaline the anterio-posterior axis diaphragm and sternum to their
respiration) cartilage (NEET 2013) ↓ normal position (Ltcm)
HUMAN RESPIRATORY SYSTEM LUNGS
INCOMPLETE CARTILAGINOUS
R1N9*-_ µContraction of external inter-costal muscles Reduction in the volume of
and lifting up of the ribs and sternum thoracic chamber and overall
= Pkuraiᵗy ( Elem ) pulmonary volume
→
Respiratory tract = Increase in the volume of thoracic chamber Increase in intra-pulmonary
lungs
→
in the dorso-ventral axis pressure to more than the
atmospheric pressure
Overall increase in thoracic volume leads to It leads to expulsion of air
6259M 575 increase in pulmonary volume and decrease from the lungs
""
⊖
THORA gm in intra-pulmonary pressure to less than
cN 0 Structural and atmospheric pressure (Odisha NEET 2019)
functional unit of It forces atmospheric air to come into
the lungs
Umg Alveoli
-

Diagram showing pleura, pleural cavity and mediastinum and diphragm RESPIRATORY VOLUMES AND CAPACITIES Breathing rate per min -
12-16

Pulmonary ventilation timid

✓✓
1 Breathing- Atmospheric air drawn in and
alveolar air (CO2 rich) is released out
Respiratory
Volumes Definition Volume of air
(NEET 2018)
Human respiratory system
Air volume inspired (inhaled) or ☐500 ml;
Human respiratory system starts with a pair of nostrils; leads to nasal Diffusion of gases (O2 and CO2) across Tidal Volume (TV)
passage 2 alveolar membrane ✓ expired (exhaled) per breath
( NORMAL BREATHING
)
6000-8000
ml/ mïñütë
Inspiratory
Nasal passage opens into pharynx Extra volume of air one inhales
Reserve Volume 2500-3000 ml

:
Pharynx opens through larynx which opens into trachea
3 Transport of gases by blood (IRV) (inspires) by forced inspiration

Expiratory Extra volume of air one exhales by

Reserve Volume 1000-1100 ml
Diffusion of O2 and CO2 between blood forced expiration
Trachea is a straight tube extending upto mid-thoracic region then divides
into right and left primary bronchi Ts
4 and tissues (ERV)
Volume of air remaining in lungs
Residual Volume after forced exhalation
Primary bronchi further divides into secondary and tertiary bronchi and Utilisation of O2 by cells for catabolic 1100-1200 ml
5 (RV)
•

finally into terminal bronchioles; bronchioles give rise to numerous alveoli reactions and release of CO2 (cellular It prevents collapsing of lungs
(vascular bag like structures for exchange of gases) (NEET 2013) respiration) (NEET 2017)
Flowchart showing steps of respiration -

Respiratory Volume is measured

by spirometer
spirometer cant measure →
Right
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Respiratoryact
Nostrils → Nasal Chamber →
Nasopharynx → Pharynx
↓
Trachea ← larynx _ Glottis
↓

Bronchial true
↓
tree
Respiratory
 Pressure exhibited by a
gas in presence of Anothergas*=

Respiratory Respiratory Atmospheric Blood

Alveoli (Deoxygenated) Blood Air
Capacities (Shows gas air (oxygenated) Tissues
the capacity of O2 159 104 40 95 40 Alveolar wall Basement
the lungs) (one-celled thick) substance
CO2 0.3 40 45 40 45
Total volume of air one inhales after
normal exhalation Partial pressures (in mm Hg) of oxygen and carbon dioxide at Alveolar cavity
Inspiratory
3000-3500 ml different parts involved in diffusion in comparison to those in atmosphere
Capacity (IC) It is the sum of tidal volume and
inspiratory reserve volume (TV+IRV) Solubility of times
20-25
Total volume of air one exhales after 102 is 02 Blood
normal inhalation more
than
capillary Red blood
Expiratory cell
-

Capacity (EC)
It is the sum of tidal volume and 1500-1600 ml 05 - OF
expiratory reserve volume (TV+ERV) A diagram of a section of an alveolus with a pulmonary capillary
(NEET 2019)
(AIPMT 2011)
Volume of air remaining in lungs FRCS TLC cant bu TRANSPORT OF GASES
after normal exhalation (expiration) Measured
by spiromI-w
✓ Functional
Residual Capacity
It is the sum of expiratory reserve
volume and residual volume (ERV+RV). 2100-2300 ml
97% through blood (Oxyhaemoglobin) -

(FRC) It is the volume of air required to O2

keep the lungs functioning in the 3% through plasma ✓

Transport of gases
normal condition
Maximum volume of air one can = =
inhales after forceful exhalation 20-25% through blood (Carbamino- ✓
haemoglobin) (AIPMT 2010)
Vital Capacity or maximum volume of air one -

%
(VC) can exhale after forceful inhalation 3500-4500 ml
(AIPMT 2009) It is the sum of expiratory reserve Diagrammatic representation of the exchange of gases at the alveolus 70% bicarbonate (AIPMT 2011,

=
volume, tidal volume and inspiratory and the body tissues with blood and transport of oxygen and carbon dioxide CO2 NEET 2014)
reserve volume (ERV + TV + IRV) The pCO2
The partial Oxygen diffuses is higher in
Total volume of air The pO2 is
✓ Total Lung
pressure of from alveoli to deoxygenated Thus CO2 from 7% through plasma
It is the sum of vital capacity and oxygen (pO2) lower in deoxygenated
5000-6000 ml blood (45 deoxygenated
Capacity (TLC) is higher in deoxygenated blood as
residual volume (VC+RV) / (ERV + mm Hg) as blood diffuses
alveoli (104 blood (40 a law of
TV + IRV + RV) compared to into alveoli
mm Hg) mm Hg) diffusion alveoli (40
Volume of air present in the mm Hg)
✓ ✓
respiratory tract (nostrils to terminal
Dead air volume 150 ml Exchange of gases between alveoli and blood (external respiration)
bronchi) not involved in the gaseous Partial pressure of CO2
exchange. It is called dead space Partial pressure of O2
EXCHANGE OF GASES ✓✓
AlVE0L[-_→
Diffusion membrane (Thickness

SIMPLE sq epithelium
Squamous epithelium of it
is less than a millimetre)

alveoli
Factors affecting
it
binding of oxygen
Basement substance
✓
= ✓ Hydrogen ion
Endothelium of alveolar it concentration Temperature
E- capillaries

Alveoli of lungs (primary site for an exchange of O2 and CO2)

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Transport of Gases
97-1
-
.

by oxy haemoglobin
① Transport of Oz ↳ 3-1 .

Plasma

Hb 1- Oz = 11602

Igm Hb transports -

134 ml Oz
100mL →
Blood → 12 -

16 gm Hb

100mL blood transport → 5mi Oz in

normal condition

15mL Oz in
strenuous exercise
 } {
"" """ °
"" "" "" " "" " " "° "" " " " "

letter
left Riqnt_
P0z↑

ÉÉ&:
& plan
plate
poor
right amp ,
Temp ↑
Haldcnuejbct
'
Bohr effect
1 High pH ↑
Hamburg ur phenomenon
i.
pso
low pH
P 02

when percentage
Pso value :-P 02
saturation of Hb is 50%
 CARBONIC ANHYDRASE
Transportes Hbt LOL
I Hbco _

7- %
-
Plasma

20-25-1 .
→ Carbamino Haemoglobin
Bicarbonate

)
70-1 . →
Nat a-

HbtC0→HbC0mT ↓

cHig
co *
poisoning

Chloride #tHAnommon*
Bohr effect : - Dissociation of 0×4 haemoglobin due to
High ( 02 lone ↑
100mL blood transpo Is 4m10↳
-

,,,µg_µµu¥÷
* Haldane cfbct : →

When deoxygenated blood reaches alveoli

p 102 ↓ PO 2 ↑

01144m will bind with

H
 Factors affecting the binding of O2 with haemoglobin REGULATION OF RESPIRATION AND DISORDERS OF RESPIRATORY SYSTEM Normal Alveoli Emphysema Alveoli
Conditions favourable for association Conditions favourable for dissociation Neural System Action on Respiratory Rhythm Location
✓
High pO2 (NEET 2020) Low pO2
Medulla of ←
✓Low pCO2 Respiratory rhythm center Regulation
High pCO2 brain
✓ Low H+ concentration
(NEET-I 2016)
High H+ concentration =
Pneumotaxic center (can
moderate the functions of Moderation Pons of brain
- Low temperature High temperature respiratory rhythm centre) =

SHIFT -
LEFT SHIFT RIGHT
PROCESS OF RESPIRATION REGULATION
Percentage saturation of haemoglobin with oxygen

100 Chemosensitive center Another way of respiratory Diagrammatic representation of healthy and emphysema alveolar sac
present beside rhythm rhythm regulation
center
80
-

Signalling
SILICOSIS
the rhythm
Change in concentration of H+
60 center Sensitive to _
ASBESTOSIS
to make
adjustments H+ and CO2
and CO2
-
to+ eliminate Certain industries involving Defence mechanism of body
40 H and CO2
Recognized by the receptors grinding or breaking stones is unable to cope with
=
associated with aortic arch and
20 Increased carotid artery
Activation of
←
concentration
rhythm center of H+ and
Send signals to the rhythm center
0 20 40 60 80
100
CO2
Occupational
=
to adjust the respiratory rhythm
Partial pressure of oxygen (mm Hg) Respiratory Disorders
Oxygen dissociation curve
TRANSPORT OF CARBON DIOXIDE DISORDERS OF RESPIRATORY SYSTEM Long exposure leads to
Carbonic anhydrase Carbonic anhydrase
Damaging the lungs profliferation of fibrous
CO2 H2 O H2 CO3 HCO3 H Allergic reaction tissues called fibrosis

a Difficulty in
Factors affecting the binding of CO2 Inflammation
0
Asthma breathing
I
of bronchi and

_HEtNthwJ
Conditions favourable for dissociation Conditions favourable for association causing bronchioles
wheezing
_

High pO2 (Major factor) Low pO2 (Major factor)

Low pCO2 (Major factor) High pCO2 (Major factor)

+
Low H concentration High H+ concentration

Emphysema, Major cause Damaged Decreased

Low temperature High temperature

Occurs at alveoli Occurs in tissue

a pulmonary
disease
is cigarette
=
smoking
=
alveolar wall
and chronic I
respiratory
surface
disorder (NEET 2015)

Bicarbonate ion and H+ combines to CO2 diffuses into RBC or plasma and
form H2CO3 which is broken down forms bicarbonate ion and H+ in the
into CO2 and H2O in the presence of presence of carbonic anhydrase
carbonic anhydrase

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