When you hold your breath which of the following gas changes in blood would first lead to the urge to breathe?
Falling O2 concentration
Rising CO2 concentration
Falling CO2 concentration
Rising CO2 and falling O2 concentration
Lungs are made up of air-filled sacs, the alveoli. They do not collapse even after forceful expiration, because of
Residual Volume (RV)
Inspiratory Reserve Volume (IRV)
Tidal Volume (TV)
Expiratory Reserve Volume (ERV)
The partial pressure of oxygen in the alveoli of the lungs is
equal to that in the blood
more than that in the blood
less than that in the blood
less than that of carbon dioxide
Lungs do not collapse between breaths and some air always remains in the lungs which can never be expelled because
there is a negative pressure in the lungs
there is a negative intrapleural pressure pulling at the lung walls
there is a positive intrapleural pressure
pressure in the lungs in higher than the atmospheric pressure
Reduction in pH of blood will
reduce the blood supply to the brain
decrease the affinity of hemoglobin with oxygen
release bicarbonate ions by the liver
reduce the rate of heart beat
Name the chronic respiratory disorder caused mainly by cigarette smoking
asthma
respiratofy acidosis
respiratory alkalosis
emphysema
Approximately seventy percent of carbon dioxide absorbed by the blood will be
transported to the lungs
as bicarbonate ions
in the form of dissolved gas molecules
by binding to RBC
as carbamino-haemoglobin
The figure shows a diagrammatic view of human respiratory system with labels A, B, C
and D. Select the option, which gives correct identification and main function and/or
characteristic.
inspired air
A-trachea-long tube supported by complete cartilaginous rings for conducting
8-pleural membrane-surround ribs on both sides to provide cushion against rubbing
C-alveoli-thin walled vascular bag-like structures for exchange of gases
D-lower end of lungs-diaphragm pulls it down during inspiration
Which one of the following is the correct statement for respiration in humans?
duration of inspiration
Cigarette smoking may not lead to inflammation of bronchi
Neural signals from pneumotoxic centre in pons region of brain can increase the
Workers in grinding and stone breaking industries may suffer, from lung fibrosis
About 90% of carbon dioxide (CO2) is carried by haemoglobin as carbamino haemoglobin
People who have migrated from the planes to an area adjoining Rohtang Pass about six
months back
have more RBCs and their haemoglobin has a lower binding affinity to O2
are not physically fit to play games like football
suffer from altitude sickness with symptoms like nausea, fatigue, etc.
have the usual RBC count but their haemoglobin has very high binding affinuty to O2
A large proportion of oxygen is left unsused in the human blood even after its uptake by
the body tissues. This O2
raises the PCO2 of blood to 75 mm of Hg
is enough to keep oxyhaemoglobin
helps in relasing more O2 to the epithelial tissues
acts as a reserve during muscular exercise
What is true about RBCs in humans?
transported in dissolved state in blood plasma
They carry about 20-25 per cent of CO2
They transport 99.5 per cent of O2
They transport about 80 per cent oxygen only and the rest 20 per cent of it is
They do not carry CO2 at all
Which two of the following changes (1-4) usually tend to occur in the plain dwellers when
they move to high altitudes (3,500 m or more)?
(1) Increase in red blood cell size
(2) Increase in red blood cell production
(3) Increased breathing rate
(4) Increase in thrombocyte count Changes occurring are
(2) and (3)
(3) and (4)
(1) and (4)
(1) and (2)
What is vital capacity of our lungs?
Inspiratory reserve volume plus tidal volume
Total lung capacity minus expiratory reserve volume
Inspiratory reserve volume plus expiratory reserve volume
Total lung capacity minus residual volume
The haemoglobin of a human foetus
has a lower affinity for oxygen than that of the adult
its affinity for oxygen is the same as that of an adult
has only 2 protein subunits instead of 4
has a higher affinity for oxygen than that of an adult
People living at sea level have- around 5 million RBC per cubic millimeter of their blood
whereas those living at an altitude of 5400 metres have around 8 million. This is because
at high altitude:
amount of O2 to survive
people get pollution-free air to breathe and more oxygen is available
atmospheric O2 level is less and hence more RBCs are needed to absorb the required
there is more UV radiation which enhances RBC production
people eat more nutritive food, therefore more RBCs are formed
Which one of the following statements is incorrect ?
The residual air in lungs slightly decreases the efficiency of respiration in mammals
The presence of non-respiratory air sacs, increases the efficiency of respiration in birds
In insects, circulating body fluids serve to distribute oxygen to tissues
The principle of countercurrent flow facilitates efficient respiration in gills of fishes
In the tissues, high concentrations of carbon doxide
increases the affinity of haemoglobin to both oxygen and hydrogen
increases the affinity of haemoglobin to oxygen but decreases its affinity to hydrogen
decreases the affinity of haemoglobin to oxygen but increases its affinity to hydrogen
decreases the affinity of haemoglobin to both oxygen and hydrogen.
During winter a person died during sleep, the room was closed and a container with burnt
charcoal was found in the room. What may be the possible reason of his death?
non-availability of oxygen
Hb has more affinity to combine with carbon monoxide
Hb has more affinity to combine with nitrogen
combined effect of 1. and 3.
The respiratory centre in the brain is stimulated by
CO2 concentration in venous blood
O2 concentration in artery blood
CO2 concentration in artery blood
O2 concentration in venous blood.
Which of the following match is correct?
Emphysema : reduction of surface area of alveoli and bronchi
Pneumonia : occupational disease with asbestos
Silicosis : inflammation of alveoli
Asthma : excessive secretion of bronchial mucus
When a man inhales air containing normal concentration of O2 as well as CO he suffers from suffocation because
CO reacts with O2 reducing its percentage in air
haemoglobin combines with CO instead of O2 and forms carboxyhaemoglobin
CO affects diaphragm and intercostal muscles
CO affects the nerves of the lungs.
Respiration is controlled by
medulla oblongata
cerebellum
hypothalamus
cerebrum
Chemosensitive area of respiratory centre medulla is affected by
less CO2 and H+ ions
less O2 and H+ ions
excess CO2 and H+ ions
excess O2 and H+ ions.
Oxygen binding to haemoglobin in blood is
directly proportional to the concentration of CO2 in the medium
inversely proportional to the concentration of CO2 in the medium
directly proportional to the concentration of CO in the medium
independent of the concentration of CO in the medium.
Carbon dioxide (CO2) diffuses into blood from tissue site and passes to alveolar site in the form of
bicarbonate; 70%
bicarbonate; 20 - 25%
carbaminohaemoglobin; 60 - 70%
carbaminohaemoglobin; 7%.
Hiccups can be best described as
forceful sudden expiration
forceful contraction of intercostal muscles during deep breathing
vibration of the soft palate during breathing while sleeping
jerky incomplete inspiration.
The volume of 'anatomical dead space’ air is normally
230 mL
210 mL
190 mL
150 mL.
Oxyhaemoglobin dissociates into oxygen and deoxyhaemoglobin at
low O2, pressure in tissue
high O2, pressure in tissue
equal O2, pressure inside and outside tissue
all times irrespective of O2, pressure
A person sitting at rest experiences a temporary cessation of breathing after forced deep breathing for a few minutes.This is due to:-
too much CO2 in the blood
too much O2 in the blood
very little CO2 in the blood
both high O2 and very little CO2 in the blood
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