17 BREATHING AND EXCHANGE OF GASES QUESTION

CHAPTER NOTES

In which of the following gaseous exchange between O₂ and CO₂ occurs through general body surface?

(A) Sponges

(B) Coelenterates

(D) All

Match the followings correctly.

(A) A-IV, B and C-III, D-I, E-II

(B) A- IV, B – III C and D -I, E – III

(D) A-III, B and C-I, D-II, E-IV

Amphibians e.g. frogs respire –

(A) Through moist skin

(B) Lungs

(D) Trachea

Which is the correct sequence of air passages in man?

(A) External Nostril→ Nasal passage→Internal nostril→ Pharynx →Larynx→ Trachea → Bronchi → Bronchioles → Alveoli

(B) Nose→ Larynx→ Pharynx→ Bronchioles→ Bronchi → Alveoli

(D) Nose → Larynx→ Bronchi→ Pharynx→ Trachea→ Bronchioles →Alveoli

Which is correct about nasopharynx?

(A) Internal nostrils open into nasopharynx

(B) It is the common passage for both air and food

(D) All

Which of the following options is wrong about the larynx (sound box)?

(A) It is a bony box

(B) Glottis is the opening into the larynx

(D) All

Trachea divides into right and left primary bronchi at ______ thoracic vertebra.

(A) 4

(B) 5

(D) 9

Incomplete cartilaginous rings support all of the following except-

(A) Trachea

(B) Primary, secondary and tertiary bronchi

(D) Initial bronchioles

Which of the following has the smallest diameter?

(A) Trachea

(B) Terminal bronchiole

(D) Secondary bronchus

Lungs are comprised by –

(A) Only alveoli

(B) Pleura

(D) Network of bronchi, bronchioles and

Sites of gaseous exchange in lungs are –

(A) Alveoli

(B) Tracheoles

(D) Pleura

I. It is double layered and covers the lungs

Fluid between the layers reduces friction on lung-surface

III. Outer layer is in contact with thoracic wall

Inner layer is in contact with lungs The above features refer to –

(A) Pericardium

(B) Peritoneum

(D) None

The part starting with the external nostrils upto the terminal bronchioles constitute the –

(A) Respiratory or exchange part of respiratory system

(B) Inspiratory part

(D) Expiratory part

Respiratory or exchange part of the respiratory system consists of-

(A) The parts starting with external nostrils upto terminal bronchioles

(B) Alveoli and their ducts

(D) All bronchioles

The conducting part of the respiratory system has functions.

(A) Filter, warm and moisten the air

(B) Gaseous exchange

(D) Warm the air

The chamber formed dorsally by the vertebral column, ventrally by sternum, laterally by ribs and on the lower side by dome-shaped diaphragm is –

(A) Abdominal cavity

(B) Thoracic cavity

(D) Cranial cavity

Respiration involves following steps –

I) Diffusion of gases O₂ and CO₂ across alveolar membrane

II) Transport of gases by blood

III) Utilization of O₂ by cell for catabolic reactions and resultant release of O₂

IV) Pulmonary ventilation by which atmospheric air is drawn in and CO₂ rich alveolar air is released out

V) Diffusion of O₂ and CO₂ between blood and tissues

The correct sequence of steps is __

(A) I)→ II)→III)→ IV)→V)

(B) V)→ IV)→III)→ II)→I)

(D) III)→II)→ V)→I)→ IV)

Study the given diagram and identify A, B, C and D.

(A) A- Epiglottis, B -Alveoli, C- Bronchus, D – Diaphragm

(B) A- Epiglottis, B -Alveoli, C – Bronchioles, D – Diaphragm

(D) A-Sound box, B-Alveoli, C- Bronchioles, D – Diaphragm

The lungs expand in inspiration/inhalation because –

(A) Diaphragm contracts upward

(B) The volume of thoracic cavity increases

(D) Diaphragm relaxes

The process of exhalation / expiration is begun mainly due to –

(A) The contraction of intercostal muscles

(B) The contraction of the diaphragm

(D) Low pressure in thoracic cavity

Which of the following statements about the mechanism of ventilation/breathing is false

(A) As the diaphragm relaxes, air is expelled from the respiratory system

(B) During inspiration the lungs act as suction pump

(D) For quiet breathing external intercostal muscles and diaphragm play an important role.

Inspiration occurs when there is a negative pressure in the lungs with respect to atmospheric pressure. This negative pressure is achieved when –

(A) Intrapulmonary pressure is less than the atmospheric pressure

(B) Intra pulmonary pressure is greater than the atmospheric pressure

(D) Intrapleural pressure becomes more than the intra-alveolar pressure

Expiration takes place when the intrapulmonary pressure is –

(A) Greater than the atmospheric pressure

(B) Lesser than the atmospheric pressure

(D) Equal to intrapleural pressure

Which of the following sequences is correct to initiate inspiration?

The contraction of external intercostal muscles raises the ribs and sternum

Volume of thorax increases in the dorso-ventral axis

III. Intrapulmonary pressure decreases

IV. Diaphragm contraction

Air rushes into lungs

Volume of thorax increases in the anterio-posterior axis

(A) I, II, IV, V, III, VI

(B) I, II, III, IV, V

(D) VI, I, II, III, V

Which of the following sequences is correct to initiate expiration?

Relaxation of external intercostal muscles and return of diaphragm and sternum to their normal position

Air expelled from lungs

III. Volume of thorax decreases

Intrapulmonary pressure increases

(A) I, III IV, II

(B) II, IV, III, I

(D) I, II, III, IV

On an average, a healthy human breathes ______ times /minute-

(A) 20 – 40

(B) 1-6

(D) 16-25

Additional muscles for forceful breathing are –

(A) Diaphragm and external intercostal muscles

(B) Abdominal muscles and internal intercostal. muscles

(D) External and internal intercostal muscles

Following illustration depicts the mechanism of breathing. In which of the following option all the parts A. B, C and D are correctly labelled?

(A) A-Air entering into lungs; B- Ribs and sternum raised; C- Diaphragm contracted; D-Volume of thorax raised

(B) A – Air expelled from lungs; B – Ribs and sternum return to original position; C – Diaphragm relaxed; D – Volume of thorax decreased

(D) A-Air expelled from lungs; B- Ribs and sternum raised; C- Diaphragm contracted; D-Volume of thorax decreased

Match the following –

(A) 1 – C, 2 – E, 3 – B, 4 – F, 5 – D, 6 -A

(B) 1 – E, 2 – F, 3 – C, 4 – B, 5 -A, 6 – D

(D) 1 – E, 2 – C, 3 – B, 4 – F, 5 -A, 6 – D

Match the following –

(A) 1 – C, 2 – D, 3 – B, 4 – A, 5 – E

(B) 1 – C, 2 -A, 3 – B, 4 – E, 5 – D

(D) 1 – E, 2 -A, 3 – B, 4 – E, 5 – D

Arrange the following in order of increasing volume –

1. Tidal volume 2. Residual volume

3. Expiratory reserve volume 4. Vital capacity

(A) 1 < 2 < 3 < 4

(B) 1 < 4 < 3 < 2

(D) 1 < 4 < 2 < 3

Different respiratory volumes are given below-

Tidal Volume= 500 ml II. Residual Volume= 1000 ml

III. Inspiratory Reserve Volume= 2500 ml

IV. Expiratory Reserve Volume = 1000 ml

The functional residual capacity (FRC) is-

(A) 3500 ml

(B) 2000 ml

(D) 3000 ml

Expiratory capacity is equal to –

(A) TV+ ERV

(B) ERV+ IRV

(D) ERV+ RV

A spirometer cannot be used to measure –

(A) IC

(B) RV

(D) IRV

The maximum volume of air you can forcefully exhale after taking the deepest possible breath is called

(A) Tidal volume

(B) Total respiratory volume

(D) Vital capacity

Exchange of gases –

(A) Occurs between the alveoli and pulmonary blood capillary

(B) Occurs between blood and tissues

(D) All

Which of the following factors affect the diffusion of gases?

(A) Partial pressure of diffusing gases

(B) Solubility of gases

(D) All

Which of the following statements about the partial pressure of CO₂ is true?

(A) It is higher in alveoli than in pulmonary artery

(B) It is higher in the systemic arteries than in tissues

(D) It is higher in the pulmonary veins than in pulmonary arteries

The partial pressure of CO₂ in the venous blood is –

(A) Greater than in the tissue spaces

(B) Lesser than in the tissue spaces

(D) Less than in alveoli

A section of an alveolus with a pulmonary capillary indicates the presence of major layers constituting diffusion membrane-

(A) 3

(B) 2

(D) 10

Partial pressures (in mmHg) of O₂ in atmospheric air, alveoli deoxygenated blood, oxygenated blood and tissues are-

(A) 40, 95, 40, 104, 159

(B) 104, 40, 40, 95, 159

(D) 195, 104, 95, 40, 40

Partial pressure (in mm Hg) of CO₂ in atmospheric air, alveoli, deoxygenated blood, oxygenated blood and tissues are-

(A) 0.3, 40, 45, 40, 45

(B) 40, 45, 40, 45, 0.3

(D) 0.3, 45, 45, 40, 40

Name the blood vessels A to D-

In comparison to solubility of O₂ in blood the solubility of CO₂ is –

(A) 20 – 25 times lesser

(B) Slightly higher

(D) 20 – 25 times higher

Study the given figure and identify A to C.

The barrier between the air in alveolus and blood in pulmonary capillary consists of 3 layers and its total thickness is-

(A) 1 mm

(B) more than 1 mm

(D) 2 mm

Total percentage of O₂ transported by hemoglobin or RBC is –

(A) 3%

(B) 97%

(D) 100%

Besides RBC blood plasma also carries O₂ in solution. The percentage is –

(A) 3%

(B) 97%

(D) 25%

CO₂ is transported –

(A) By RBC

(B) As bicarbonates

(D) All

The majority of CO₂ is transported as –

(A) Carbonates

(B) Bicarbonates

(D) Dissolved state in blood

Blood carries the CO₂ in 3 forms. The correct percentages of CO₂ in these forms are

Each molecule of hemoglobin when fully saturated carries how many molecules of O₂

(A) 1

(B) 2

(D) 20

Dissociation curve is associated with –

(A) Carbonic anhydrase

(B) CO

(D) Oxyhemoglobin

Binding of O₂ with hemoglobin is primarily related to-

(A) pO₂

(B) pCO₂

(D) None

Besides pO₂ the other factor(s) affecting the binding of O₂ with hemoglobin is/are –

(A) pCO₂

(B) H⁺nk.

(D)All

Oxygen dissociation curve is –

(A) J-shaped

(B) S-shaped

(D) Zig-zag

Which of the following statements is wrong?

(A) O₂ binds with hemoglobin in a reversible manner to form oxyhemoglobin.

(B) Every 100 mL of oxygenated blood can deliver around 5 ml of O2 to the tissue

(D) None

What will be the pO₂ and pCO₂ in the atmospheric air compared to those in the alveolar?

(A) pO₂ lesser, pCO₂ higher

(B) pO₂ higher, pCO₂ lesser

(D) pO₂ lesser, pCO₂ lesser

Which of the following would have the same O₂ content? \

(A) Blood entering the lungs – blood leaving the lungs

(B) Blood entering the right side of the heart – blood leaving the right side of the heart

(D) Blood entering the tissue capillaries – blood leaving the tissue capillaries

CO₂ dissociates from carbaminohaemoglobin when –

(A) pO₂ ↓, pCO₂↓

(B) pO₂ ↑, pCO₂↑

(D) pO₂ ↑, pCO₂↓

Which of the following situations would result in the greatest degree of O₂ saturation for hemoglobin, assuming pO₂ remains constant –

(A) Increased CO₂ levels, decreased temperature

(B) Increased CO₂ levels, increased temperature

(D) Decreased CO₂ levels, increased temperature

Which of the following factors favour the formation of oxyhaemoglobin in lungs?

(A) pO₂ ↓, pCO₂↑, H+↑, Temperature↑

(B) pO₂ ↑, pCO₂↑, H⁺↓, Temperature↑

(D) pO₂ ↓, pCO₂↑, pH↑, Temperature↓

All of the following favour the dissociation of oxyhaemoglobin to deliver O2 to tissues except-

(A) pO₂ ↑

(B) pCO₂↑ OR H⁺↑

(D) pO₂ ↓

The transport of CO₂ by the blood is primarily dependent on –

(A) The solubility of CO₂in blood

(B) The presence of carbonic anhydrase in RBCs

(D) The ability of other blood proteins

Which of the following statements is false?

(A) pO₂ is the major factor which affects the binding of CO₂ with haemoglobin

(B) pCO₂ is low and pO₂ is high as in the tissues, more binding of CO₂ with Hb occurs

(D) Every 100 mL of deoxygenated blood delivers approximately 4 mL of CO₂ to the alveoli.

Which of the following equation is correct?

Which of the following is incorrect about the given graph.

(A) Increase in partial pressure of CO₂ shift the curve to right.

(B) At low temperature the curve shifts to left.

(D) Decrease in partial pressure of oxygen shifts the curve to right.

Assertion- The maximum pO₂ in alveoli is considerably less than in the atmosphere.

Reason- Lungs in mammals do not completely empty with each breath and inhalation occurs through the same airways as exhalation, so each inhalation mixes fresh air with oxygen depleted residual air.

A) Both assertion and reason are true and reason is correct explanation of assertion.

B) Both assertion and reason are true and reason is not correct explanation of assertion.

C) Assertion is true but reason is false.

D) Both assertion and reason are false.

How does an increase in the CO₂ concentration in the blood affect the pH of CSF?

(A) pH↑

(B) pH↓

(D) pH may increase or decrease.

Assertion – A drop in the blood pH causes an increase in heart rate.

Reason- Increased Heart Rate increases the rate at which CO₂ is delivered to the lungs, where CO₂ is removed.

A) Both assertion and reason are true and reason is correct explanation of assertion.

B) Both assertion and reason are true and reason is not correct explanation of assertion.

C) Assertion is true but reason is false.

D) Both assertion and reason are false.

Respiratory process is regulated by certain specialized centres in the brain. One of the following listed centres can reduce the inspiratory duration upon stimulation –

(A) Medullary inspiratory centre

(B) Pneumotaxic centre

(D) Amnestic centre

Pneumotaxic centre is present in –

(A) Pons

(B) Medulla oblongata

(D) Cerebellum

The breathing centre initiates ventilation in response to –

(A) A decrease in air pressure

(B)A decrease in O₂

(D) The rate of gas exchange in the alveoli

All of the following factors play role in the regulation of respiratory rhythm except –

(A) CO₂

(B) H⁺ conc.

(D) None of the above is correct

Receptors associated with aortic arch and carotid artery can recognize changes in and conc. and send necessary signal to _ for remedial action.

(A) O₂, CO₂, Pneumothorax

(B) CO₂, H⁺, rhythm centre

(D) O₂, H⁺, Pneumothorax

Respiratory centre of brain is stimulated by-

(A) CO₂ content in venous blood

(B) CO₂content in arterial blood

(D) O₂ content in venous blood

Asthma is caused by –

(A) Infections of lungs

(B) Infection of trachea

(D) Infection in nose

One reason for emphysema is –

(A) Cigarette smoking

(B) Drug addiction

(D) Heavy exercise

Emphysema is characterised by –

(A) Permanent enlargement and destruction of alveolar area leading to reduction in respiratory surface

(B) Inhibition of respiratory centre

(D) Spasm of muscles of trachea

Why do human beings have difficulty breathing at high elevations?

(A) O₂ makes up lower percentage of air there

(B) The temperature is lower there

(D) pO₂ is lower there

Which of the following diseases are occupational respiratory disorder?

(A) Silicosis, Fibrosis and asbestosis

(B) Emphysema and mountain sickness

(D) Asthma and Hepatitis

If an injury tore a small hole in the membrane surrounding lungs, what effect on lung function would you expect?

(A) Pneumothorax with lung collapse

(B) Pneumothorax without lung collapse

(D) Silicosis without lung collapse

Match the items given in column I with those in column II and select the correct option given below:

Column I Column II

Tidal volume I. 2500 – 3000 mL

Inspiratory Reserve volume II. 1100 – 1200 mL

Expiratory Reserve volume III. 500 – 550 mL

Residual volume IV. 1000 – 1100 mL

(a) A – III; B – II; C – I; D – IV

(b) A – III; B – I; C –IV; D – II

(d) A – I; B – IV; C – II; D – III

Lungs are made up of air-filled sacs, the alveoli. They do not collapse even after forceful expiration, because of

(a) inspiratory reserve volume.

(b) tidal volume.

(d) residual volume.

Name the chronic respiratory disorder caused mainly by cigarette smoking.

(a) Emphysema

(b) Asthma

(d) Respiratory alkalosis

When you hold your breath, which of the following gas changes in blood would first lead to the urge to breathe?

(a) Rising CO2 concentration

(b) Falling CO2 concentration

(d) Falling O2 concentration

Name the pulmonary disease in which alveolar surface area involved in gas exchange is drastically reduced due to damage in the alveolar walls.

(a) Emphysema

(b) Pneumonia

(d) Pleurisy

Due to increasing air-borne allergens and pollutants, many people in urban areas are suffering from respiratory disorder causing wheezing due to :

(1) benign growth on mucous lining of nasal cavity.

(2) inflammation of bronchi and bronchioles.

(3) proliferation of fibrous tissues and damage of the alveolar walls.

(4) reduction in the secretion of surfactants by pneumocytes.

Tidal Volume and Expiratory Reserve Volume of an athlete is 500 mL and 1000 mL respectively. What will be his Expiratory Capacity if the Residual Volume is 1200 mL?

(1) 1500 mL

(2) 1700 mL

(3) 2200 mL

(4) 2700 mL

Select the correct statement.

(1) Expiration occurs due to external intercostal muscles

(2) Intrapulmonary pressure is lower than the atmospheric pressure during inspiration.

(3) Inspiration occurs when atmospheric pressure is less than intrapulmonary pressure.

(4) Expiration is initiated due to contraction of diaphragm.

The maximum volume of air a person can breathe in after a forced expiration is known as :

(1) Expiratory Capacity

(2) Vital Capacity

(3) Inspiratory Capacity

(4) Total lung Capacity

The Total Lung Capacity (TLC) is the total volume of air accommodated in the lungs at the end of a forced inspiration. This includes :

(1) RV; IC (Inspiratory Capacity); EC (Expiratory Capacity); and ERV

(2) RV; ERV; IC and EC

(3) RV; ERV; VC (Vital Capacity) and FRC (Functional Residual Capacity)

(4) RV (Residual Volume); ERV (Expiratory Reserve Volume); TV (Tidal Volume); and IRV (Inspiratory Reserve Volume)

Match the following columns and select the correct option :

Column – I Column – II

(a) Pneumotaxic (i) Alveoli Centre

(b) O₂ Dissociation (ii) Pons region of curve brain

(d) Primary site (iv) R.B.C. of exchange of gases

(1) (a)-(i), (b)-(iii), (c)-(ii), (d)-(iv)

(2) (a)-(ii), (b)-(iii), (c)-(iv), (d)-(i)

(3) (a)-(iii), (b)-(ii), (c)-(iv), (d)-(i)

(4) (a)-(iv), (b)-(i), (c)-(iii), (d)-(ii)

Identify the wrong statement with reference to transport of oxygen

1) Low pCO₂ in alveoli favours the formation of oxyhaemoglobin

2) Binding of oxygen with haemoglobin is mainly related to partial pressure of O₂.

3) Partial pressure of CO₂ can interfere with O₂ binding with haemoglobin

4) Higher H+ conc. in alveoli favours the formation of oxyhaemoglobin

Select the correct events that occur during inspiration

a) Contraction of diaphragm b) Contraction of external inter-costal muscles

c) Pulmonary volume decreases d) Intra pulmonary pressure increases

1) Only (d)

2) (a) and (b)

3) (c) and (d)

4) (a), (b) and (d)

The partial pressures (in mm Hg) of oxygen and carbon dioxide at alveoli (the site of

diffusion) are:

1) 2)

3) 4)

Select the favourable conditions required for the formation of oxyhaemoglobin at the alveoli.

1) Low , high , more , higher temperature

2) High , high , less , higher temperature

3) Low , low , more , higher temperature

4) High , low , less , lower temperature

Which of the following is not the function of conducting part of respiratory system?

1) It clears inhaled air from foreign particles

2) Inhaled air is humidified

3) Temperature of inhaled air is brought to body temperature

4) Provides surface for diffusion of O₂and CO₂

Under normal physiological conditions in human being every 100 ml of oxygenated blood can deliver _________ ml of O₂ to the tissues.

1) 2 ml

2) 5 ml

3) 4 ml

4) 10 ml

CHAPTER NOTES

17 BREATHING AND EXCHANGE OF GASES QUESTION