Explain the mechanism of breathing with neat labelled sketches.
Breathing involves two stages : inspiration during which atmospheric air is drawn in and expiration by which the alveolar air is released out. The movement of air into and out of the lungs is carried out by creating a pressure gradient between the lungs and the atmosphere. The diaphragm and a specialised set of muscles – external and internal intercostal muscles between the ribs help in the mechanism of breathing. The given figure shows thoracic cavity Inspiration:
Inspiration is initiated by the contraction of diaphragm which increases the volume of thoracic chamber in the antero-posterior axis. The contraction of external inter ¬costal muscles lifts up the ribs and sternum causing an increase in the volume of the thoracic chamber in the dorsal-ventral axis. This increase in the thoracic volume leads to similar increase in pulmonary volume. An increase in pulmonary volume decreases the intra-pulmonary pressure to less than the atmospheric pressure which forces the air from outside to move into the lungs, i.e., inspiration. Relaxation of the diaphragm and intercostal muscles cause the diaphragm and sternijm to go back to their normal positions and thus reduce the thoracic volume and thereby the pulmonary volume. This results in an increase in intra-pulmonary pressure to slightly above the atmospheric pressure causing the expulsion of air from the lungs i.e., expiration.
The given figure shows thoracic cavity during expiration:
For completion of respiration process, write the given steps in sequential manner.
(a) Diffusion of gases (O2 and CO2) across alveolar membrane.
(b) Transport of gases by blood.
(c) Utilisation of O2 by the cells for catabolic reactions and resultant release of CO2 .
(d) Pulmonary ventilation by which atmos-pheric air is drawn in and C02 rich alveolar air is released out.
(e) Diffusion of 02 and CO2 between blood and tissues.
What will be the p02 and pCO2 in the atmospheric air compared to those in the alveolar air?
(i) pO2 lesser, pCO2 higher
(ii) pO2 higher, pCO2 lesser
(iii) pO2 higher, pCO2 higher
(iv) pO2 lesser, pCO2 lesser
What is tidal volume? Find out the tidal volume (approximate value) for a healthy human in an hour.
Diffusion of gases occurs in the alveolar region only and not in the other parts of respiratory system. Why?
Complete the missing terms
(a) Inspiratory Capacity (1C)=_____+IRV
(b)_____= TV + ERV
(c) Functional Residual Capacity (FRC) = ERV +_____
Have you heard about hypoxia? Try to gather information about it, and discuss with your friends.
Arrange the following terms based on their volumes in an ascending order:
(a) Tidal Volume (TV)
(b) Residual Volume (RV)
(c) Inspiratory Reserve Volume (1RV)
(d) Expiratory Capacity (EC).
Match the following and mark the correct options
Animal Respiratory Organ
A.Earthworm (i)Moist cuticle
B.Aquatic Arthropods (ii)Gills
C.Fishes (iii)Lungs
D.Birds/Reptiles (iv)Trachea
(a) A-(ii), B-(i), C-(iv), D-(iii)
(b) A-(i), B-(iv), C-(ii), D-(iii)
(c) A-(i), B-(iii), C-(ii), D-(iv)
(d) A-(i), B-(ii), C-(iv), D-(iii)
Name the organs of respiration in the following organisms:
(a) Flatworm ____________
(b) Birds ____________
(c) Frog____________
(d) Cockroach____________
A major percentage (97%) of O2 is transported by RBCs in the blood. How is the remaining percentage (3%) of O2 transported?
Name the important parts involved in creating a pressure gradient between lungs and the atmosphere during normal respiration.
Compared to O2 , diffusion rate of CO2 through the diffusion membrane, unit difference in partial pressure is much higher. Explain.
The oxygen – haemoglobin dissociation curve will show a right shift in case of ,
(a) High pCO2 (b) High pO2
(c) Low pCO2 (d) Less H+ concentration.
What is the amount of O2 supplied to tissues through every 100 mL of oxygenated blood under normal physiological conditions?
Arrange the following terms based on their volumes in an ascending order:
(a) Tidal Volume (TV)
(b) Residual Volume (RV)
(c) Inspiratory Reserve Volume (1RV)
(d) Expiratory Capacity (EC).
Define oxygen dissociation curve. Can you suggest any reason for its sigmoidal pattern?
A fluid filled double membranous layer surrounds the lungs. Name it and mention its important function.
Distinguish between
(a) IRV and ERV
(b) Inspiratory capacity and expiratory capacity.
(c) Vital capacity and total lung capacity.
Differentiate between
(a) Inspiratory and expiratory reserve volume
(b) Vital capacity and total lung capacity
(c) Emphysema and occupational respiratory disorder.