Breathing and Exchange of Gases Flashcards
Difference between breathing and respiration
Breathing: The process of exchange of oxygen from the atmosphere with carbon dioxide
produced from the cells.
Respiration: Oxidation of glucose to form carbon dioxide, water and energy.
What are the various respiratory organs in different invertebrates
Coelenterates: cell surface gaseous exchange , they are in contact with the environment, so
simple diffusion across their body surface happens.
Earth worms: they respire through their moist cuticles ,the cells are thin, vascular and moist
that diffusion takes place.
Insects: they have network of tubes which is also known as tracheal system, small openings
through the tubes are known as spiracles where gas exchange happens.
Aquatic arthropods: They use highly vascularised organs such as gills, they are also plate like
and filament out.
What are the various respiratory organs used in vertebrates
Fishes: use gills
Amphibians:
Frogs: use moist skin, buccal cavity and lungs
Breathing and exchange of gases 2
Tadpole: use gills.
Reptiles, birds and mammals: use lungs.
What is nasal chamber lined by
pseudo stratified ciliates columnar epithelium, which also has goblet cells which produce mucus. This also contains sensory neural epithelium
3 types of pharynx
nasopharynx, oropharynx and
laryngopharynx.
What is trachea lined by
it’s lined
by incomplete rings of hyaline cartilage, this makes sure that this does not easily
collapse.
At which vertebrae does the wind pipe divide into right and left
5th thoracic vertebrae
What is lecithin
Lecithin is a surfactant, it reduces tension between air and alveolar fluid thus protecting from
the collapsing of lung alveoli. It is secreted by type 2 alveolar epithelial cells.
Distinguish right and left lung
The right side lung is shorter by 2.5 cm due to the diaphragm which has to accommodate
the liver.
Left lung is narrower due to a cardiac notch which accommodates the heart, the heart is
slightly tilted to the left.
The left lung has 2 lobes, this is divided by oblique fissure. The right lung has 3 lobes,
these are divided by horizontal and oblique fissures.
Left lung- left inferior and left superior lobes.565grams.
Right lung- Right inferior , right middle and right superior lobes.625grams.
What are conducting and respiratory part
From the external nostrils to the bronchioles is known as conducting part, but from the
alveolar ducts to alveoli form the exchange or the respiratory part.
Stages of breathing
- Breathing: also known as pulmonary ventilation.
- Diffusion of gases between alveoli and blood.
- Transport of gases : gases transported through the blood.
- Diffusion of gas between blood and tissue.
- Utilising the oxygen: cellular respiration takes place to produce energy. It’s a
biochemical reaction that occurs inside the cells.
Inspiration
The pressure in the lungs is reduced so that the air moves from outside to inside.
The diaphragm muscles contract, this causes an increase in the volume of thoracic cavity,
in antero-posterior axis.
Since the volume increases, the pressure decreases and air flows from high to low
pressure.
The external intercostal muscles contract, these causes the ribs to lift up and the sternum
up and outward. This also causes an increase in the volume of thoracic cavity, in the
dorsal ventral axis.
Muscles involved in forceful expiration
Forceful expiration in when the internal intercostal muscles and abdominal muscles
contract. This pulls the ribs downward and inward causing a decrease in pressure.
Rate of breathing
12 to 16 times per minute.
Spirometer
instrument used to measure the volume of air through respiratory
movements.
Tidal volume
the volume of air inspired or expired during normal breathing.
Approx. 500ml. Since breathing rate is 12 to 16 times, 6000 to 8000 ml of air per minute.
Inspiratory reserve volume
Additional volume of air a person can inspire through
forcible expiration. Approx.2500 to 3000ml.
Expiratory reserve volume
Additional volume of air a person can expire through
forcible expiration. Approx.1000 to 1100 ml.
Residual volume
Volume of air remaining in the lungs even after forceful
expiration. Aprrox. 1100 to 1200ml.
Inspiratory capacity
it is the volume of air a person can inspire after normal
expiration. IC = TV + IRV (3000 to 3500 ml)
Expiratory capacity
Expiratory capacity: it is the total volume of air a person can expire after normal
inspiration. EC = TV + ERV (1500 to 1600 ml)
Functional residual capacity
volume of air that will remain in the lungs after
normal expiration. FRC = RV + ERV (2100 to 2300 ml)
Vital capacity
Maximum volume of air a person can inspire after forcible
expiration, or maximum volume of air a person can expire after forcible inspiration.
VC = RV + IRV + ERV (4000 to 4600 ml)
Total lung capacity
total volume of air in lungs after maximum inspiration
TLC = RV + IRV + ERV + TV ( 5100 to 5800 ml)
Partial pressure
pressure exerted by a single gas in a moisture of gases. Diffusion happens
from high to low partial pressure.
Factors affecting rate of diffusion
Solubility of gas: high solubility , faster diffusion rate. Carbon dioxide is more soluble
than oxygen by 20 to 25 times so it has higher diffusion rate.
Partial pressure: Diffusion from high to low partial pressure
Thickness of membrane: more the thickness, lesser diffusion rate, that’s why alveolar
membrane has thin walls.
3 layers of alveolar membrane
Thin squamous epithelium of alveoli
Endothelium of alveolar capillaries.
Basement substance between epithelium and endothelium.
Total thickness of all 3 layers combined = 0.2 to 0.3µm
Partial pressure at various parts of the body
Oxygen
Atmospheric air = 159
Alveoli = 104
Deoxygenated blood = 45
Oxygenated blood = 95
Tissues = 40
Expired air = 120
Carbon dioxide
Atmospheric air = 0.3
Alveoli = 40
Deoxygenated blood = 45
Oxygenated blood = 40
Tissues = 45
Expired air = 27
How much oxygen is transported by various methods
3% of oxygen is carried as dissolved state through plasma.
97% of the oxygen is carried by the RBCs of the blood in the form of oxyhaemoglobin.
Transport of oxygen
Haemoglobin is made of 2 parts, Haem and Globin,
Haem is iron containing part.
Globin is protein containing part.
This red pigments binds with oxygen in reversible form forming oxyhaemoglobin.
One molecule of haemoglobin can carry 4 molecules of oxygen.
There are 4 peptide chains, each chain has a haem group, each group has iron atom,
the oxygen atom binds with iron, so maximum 4 molecules of oxygen.
15g of haemoglobin in 100ml of blood.
The capacity of 1g of haemoglobin to combine with o2 is 1.34 ml, so about 20 ml of
oxygen in 100ml of blood.
Shift to right of oxygen dissociation curve
Shift to right: It indicates dissociation of oxygen from haemoglobin in tissues.
Conditions responsible for this shift are:
Low partial pressure of oxygen
High partial pressure of carbon dioxide
High H+ ion concentration, decrease in pH , increase in acidity
High temperature.
Shift to left of oxygen dissociation curve
Shift to left: It indicates association of oxygen and haemoglobin in alveoli.
Conditions responsible for this shift are:
High partial pressure of oxygen
Low partial pressure of carbon dioxide
Less H+ ion concentration, increase in pH, decrease in acidity
Low temperature
Foetal haemoglobin
The haemoglobin present in foetal has higher affinity for oxygen compared to adult haemoglobin. The oxygen dissociation curve for foetal will be more towards the left.
% of carbon dioxide transportation
7% of Carbon dioxide is carried in dissolved state in plasma, But only 3% of oxygen was
carried, this is because the solubility of carbon dioxide is more that solubility of oxygen.
70% of the carbon dioxide is transported in the form of bicarbonate through plasma.
The rest 20 to 25% of carbon dioxide is transported through RBC in the form of carb
amino haemoglobin
How much carbon dioxide is delivered to alveoli
Approx. 4ml of carbon dioxide delivered to alveoli by every 100ml of deoxygenated
blood.
Respiration regulation
Neural regulation: regulated by neural or nervous system ,2 centres present in brain for
respiration regulation are:
Respiratory rhythm centre: in medulla (hind brain) ,can either cause expiration or
inspiration.
Pneumotaxic centre: present in pons(hind brain) , moderates the function of respiratory
rhythm centre, signal from this centre can reduce the duration of inspiration and
expiration.
Strong signals from pneumotaxic centre can result in shallow and fast breathing.
Chemical regulation:
A chemo sensitive area: next to rhythm centre, sensitive to chemicals , contains
chemoreceptors
chemo sensitive area gets activated when there is an increase of carbon dioxide or H+ion
concentration, which leads to the activation the rhythm centre, which alters the rate of
respiration.
Chemoreceptors found in:
Aortic bodies: located on the aortic arch
Carotid bodies: present in carotid arteries, these arteries supply blood to the brain.
Low blood pH increases rate of respiration.
How long does inspiration and expiration last
Inspiration lasts 2 seconds.
Expiration lasts 3 seconds.
Infants breathe about 44 times per minute
Asthma
a. Caused due to allergic reactions that affect the respiratory tract , allergens cause
allergy.
b. Coughing , wheezing ,difficulty in breathing are common symptoms.
Emphysema
a. Chronic disorder
b. Due to excessive cigarette smoking or inhalation of toxic substances over long
times.
c. Wall of alveoli damaged
d. Loss of elasticity in wall
e. This disease can be prevented by quitting smoking.
Occupational respiratory disorder
a. Due to continuous exposure to harmful substances , gases, fumes and dust, usually
in a person working in industrial sites.
i. Pneumoconiosis: due to inhalation of mineral dust, inflammation,coughing etc.
Common example for this dust is silica and asbestos.
b. Symptoms might include serious lung damage, causing inflammation, swelling .
c. It’s advices to avoid prolonged exposure to harmful gases and to wear protective
masks while working in industrial sites.
Number of cartilage in larynx
9 cartilage
3 paired, 3 unpaired
Vocal cords
True vocal cords: vibration of these cords produce sound
False vocal cords: do not participate in sound production
Hiccup
Due to sudden spasmodic contraction of diaphragm followed by sudden closure of glottis
Negative and positive pressure breathing
Mammals have negative pressure breathing as they can breathe and eat at the same time, frogs have positive pressure breathing
Asphyxia
Increase in carbondioxide concentration in tissues
Hypoxia
Lack of proper oxygen supply to tissue
4 types of hypoxia:
Hypoxia hypoxia
Anaemic hypoxia
Stagnant hypoxia
Histotoxic hypoxia
Hypoxia hypoxia
Partial pressure of oxygen is low , usually in high altitudes
Anaemic hypoxia
Amount of oxygen carrying haemoglobin is reduced
Stagnant hypoxia
Intense vasoconstriction or poor cardiac output
Histotoxic hypoxia
Due to cyanide poisoning
Pneumonia
Bacterial infection on lungs resulting in accumulation of mucus
Carbon monoxide poisoning
Carbon monoxide combines with haemoglobin instead of oxygen, so tissues are supplied with poisonous carbon monoxide
SARS
Severe acute respiratory syndrome
Cyanosis
Colour of skin and mucous membrane becomes bluish due to deficiency of oxygen
Pleurisy
Inflammation of pleural membrane
Hay fever
Acute irritatative inflammation of mucous membrane of upper respiratory passage
Caissons disease or bend’s disease or dysbarrism
Respiratory disorder in divers
Atelectasis
Collapse of alveoli, due to a sense of surfactant
Anoxia
Absence if oxygen in inspired gases, arterial blood or tissues
Hypercapnia
Increased carbon dioxide concentration in blood
Eupnea
Normal breathing
Hypopnea
Slow breathing
Hyperpnea
Rapid breathing
Apnea
No breathing
Dyspnea
Painful breathing
Orthopnea
Difficult breathing except in upright position
