Breathing and Exchange of Gases NCERT Flashcards
CO2 is harmful and released during ______ reactions.
catabolic reactions
The process of exchange of O2 from atmosphere with CO2 produced by the cells is called ______.
breathing
Breathing, commonly known as
Respiration
Mechanisms of breathing depend upon-
habitats and levels of organization
_______ exchange O2 with CO2 by simple diffusion over their entire body surface.
Lower invertebrates like sponges, coelenterates, flatworms, etc.
Earthworm breathe by ________
Moist cuticle
Insects have a network of tubes called _______.
Tracheal tubes
The mode of respiration through gills is known as
Branchial respiration
______ structures called Gills.
Gills are used by:
Special vascularised;
Aquatic arthropods, molluscs, and fishes
Vascularised bags called ______ are used by the terrestrial forms for the exchange of gases.
lungs
Among vertebrates:
_______ use gills
_______ use lungs
fishes;
reptiles, birds, and mammals
Amphibians like frogs respire through lungs and ___________
Moist skin
Mammals have a ______ respiratory system.
well-developed
Nasal chamber opens into a common passage for food and air called.
Pharynx
Pharynx opens through ________ into _________
Larynx into Trachea
The cartilaginous box helping in production of sound is
Larynx
Larynx is called.
sound box
During swallowing, glottis can be covered by a thin elastic cartilaginous flap called.
Epiglottis
Epiglottis prevents the entry of food into _______
Larynx
Trachea is a straight tube extending up to _______
mid-thoracic cavity
Trachea divides into right and left primary bronchi at the level of _____ thoracic vertebrae.
5th thoracic vertebra
Bronchi further undergo repeated sub-divisions and end up in very thin __________
Terminal bronchioles
Terminal bronchioles give rise to?
Alveoli
Originating from terminal bronchioles are very thin, irregular-walled and vascularised bag like structures called
Alveoli
The double-layered membrane which covers lungs is ________.
Pleural membrane
The fluid that reduces friction on lung surface is
Pleural fluid
Outer pleural membrane stays in contact with which lining?
Thoracic lining
The part of respiratory system constituting external nostrils upto terminal bronchioles is called
Conducting part
The exchange part of respiratory system constitutes both __________ and __________
Alveoli and alveolar ducts
The part of respiratory system involved in transportation of air to alveoli, its humidification, and removal of foreign particles is
Conducting system
Actual diffusion of oxygen and carbon dioxide between blood and atmospheric air occurs at which system?
Exchange part of respiratory system
The lungs are situated in an airtight chamber called
Thoracic chamber
Thoracic chamber is formed dorsally by
Vertebral column
The thoracic chamber is formed ventrally by _______.
Sternum
Thoracic chamber is formed laterally by
Ribs
Thoracic chamber on lower side is formed by
Diaphragm
The movement of air into and out of lungs is carried out by creating a ___________ gradient between lungs and atmosphere
Pressure
Contraction of diaphragm increases volume of thoracic chamber in which axis?
Antero-posterior axis
The contraction of external intercoastal muscles increases the volume of thoracic chamber in which axis?
Dorso-ventral axis
Intra-pulmonary pressure ________ when pulmonary volume increases
decreases
Increased intra-pulmonary pressure with respect to atmospheric pressure leads to
Expiration
Device that can be used for the clinical assessment of pulmonary functions is
Spirometer
The volume of air inspired or expired during a normal respiration is called
Tidal volume
The approximate tidal volume for a healthy adult individual is
500 mL
The additional volume of air a person can inspire by forceful inspiration is
Inspiratory reserve volume
Average IRV for a healthy adult individual is
2500-3000 mL
The additional volume of air a person can expire by forceful expiration is
Expiratory reserve volume
Average volume of ERV is
1000-1100 mL
Volume of air remaining in lungs even after a forcible expiration is called
Residual volume
Average RV for a healthy adult individual is
1100-1200 mL
Total volume of air a person can inspire after a normal expiration is called
Inspiratory capacity
Inspiratory capacity is the sum of
TV+IRV
Tidal volume and expiratory reserve volume summed together gives __________
Expiratory capacity
The volume of air that will remain in lungs after a normal expiration is called
Functional residual capacity
Functional residual capacity is the sum of _____ and ___
ERV and RV
The maximum volume of air a person can breathe in or out after a forced expiration or inspiration is called
Vital capacity
Vital capacity is the sum of
ERV, TV and IRV
Total volume of air accomodated in the lungs at the end of a forced inspiration is known as
Total lung capacity
The sum of RV, ERV, TV and IRV is equal to
Total lung capacity
The primary site for exchange of gases in lungs is
Alveoli
Apart from pressure gradient, rate of diffusion of gases also depends on thickness of membranes and _______
Solubility of gases
The partial pressure of oxygen in alveoli is
104 mm Hg
The partial pressure of carbon dioxide in alveoli is
40 mm Hg
The partial pressure of carbon dioxide in deoxygenated blood is
45 mm Hg
Thin squamous epithelium of alveoli, endothelium of alveolar capillaries and basement substance together constitute the _______________ of lungs.
Diffusion membrane
The diffusion membrane is made up of three major layers namely, the thin squamous epithelium of alveoli, the endothelium of alveolar capillaries and the ________.
basement substance
The solubility of which gas is 20-25 times higher than that of oxygen during respiration?
Carbon dioxide
The medium for transport of oxygen and carbon dioxide is
Blood
The percentage of oxygen transported by RBCs is
97%
3% of oxygen is transported through
Plasma
20-25% of carbon dioxide is transported through
RBCs
70% of carbon dioxide is carried in the form of
Bicarbonate
The percentage of carbon dioxide transported in a dissolved state through plasma is
7%
The red-colored iron containing pigment present in RBCs is
Haemoglobin
Oxygen binds with Hb in a reversible manner to form
Oxyhaemoglobin
Maximum number of oxygen molecules that can be carried by a molecule of Hb are
Four
Binding of oxygen with Hb is primarily dependent on partial pressure of which gas?
Oxygen
The shape of oxygen dissociation curve under normal physiological conditions is
Sigmoid
High pO2, low pCO2, lesser H+ concentration, and lower temperature are the favorable conditions for formation of which Hb complex?
Oxyhaemoglobin
Oxyhaemoglobin is formed in
Alveoli
Low pO2 , high pCO2 , high H+ concentration and higher temperature are the favourable conditions for
Dissociation of oxyhaemoglobin
Dissociation of oxygen from oxyhaemoglobin takes place in ______
Tissues
The volume of oxygen that every 100 mL of oxygenated blood can provide to tissues under normal physiological conditions is
5 mL
Carbon dioxide is carried by Hb as
Carbamino-Hb
The major factor affecting the binding of carbon dioxide to haemoglobin is
pO2
Dissociation of CO2 from carbamino-Hb occurs when pCO2 is ______ and pO2 is ______
Low pCO2; high pO2
The enzyme that facilitates formation of bicarbonate ions is
Carbonic anhydrase
Due to high pCO2 at tissue site, CO2 diffuses in blood and forms __________ and ______
HCO3-, and H+
In which form carbon dioxide is trapped at tissue level?
Bicarbonate
Every 100 ml of deoxygenated blood delivers approximately ____ of CO2 to the alveoli.
4 mL
Respiratory rhythm centre is present in which part of brain?
Medulla
The centre primarily responsible for the regulation of respiration is
Respiratory rhythm centre
Pneumotaxic centre is located in
Pons
The duration of inspiration can be reduced by which centre in brain?
Pneumotaxic centre
The chemosensitive area located near rhythm center is highly sensitive to
CO2 and H+ ions
Difficulty in breathing causing wheezing that occurs due to inflammation of bronchi and bronchioles is characteristic of _______
Asthma
The chronic disorder in which alveolar walls get damaged is
Emphysema
The major cause of emphysema is
Cigarette smoking
Occupational lung disorders eventually lead to
Lung damage
Occupational lung disorders can be prevented by using _______
Protective masks
