Gaseous Exchange

Question 1

Define gaseous exchange

Answer 1

Uptake of molecular oxygen from the environment and discharge of carbon dioxide to the environment by cells

Question 2

What is a respiratory medium?

Answer 2

The source of oxygen

(Air for land animals, water for aquatic)

Question 3

What is a respiratory surface?

Answer 3

The boundary between the external environment and body interior

Question 4

Define ventilation

Answer 4

Movement of air between the gas exchange medium and respiratory system to maintain appropriate concentrations of oxygen and carbon dioxide in the body.

Question 5

Define respiration

Answer 5

Chemical reactions by which food is broken down to release energy in cells

Question 6

Compare the suitability of air and water as a gas exchange media in animals

Answer 6

1. Air is richer than water in oxygen
2. Air has a lower density and is less viscous than water
3. Air has a dehydrating effect on surfaces
4. Slight temperature increase causes oxygen to diffuse out of water while oxygen in air remains relatively stable
5. Water’s high density prevents collapse of respiratory structures such as gill filaments while in absence of lung surfactants alveolar sacs collapse
6. Unidirectional water flow during ventilation in aquatic animals is energetically less costly than tidal ventilation in lungs
7. Countercurrent flow of water with respect to blood flow over gill lamellae improves oxygen extraction efficiency
8. Carbon dioxide is highly soluble in water making it easier to eliminate than in air

Question 7

Why does a fish placed out of water soon suffocate?

Answer 7

• The gill lamellae lack structural strength and rely on water for their support thus in air its gills collapse into a mass of tissue reducing the diffusion surface area of the gills
• Gill lamellae surface dries and oxygen in air fails to dissolve and diffuse into blood

Question 8

State Fick’s law

Answer 8

The rate of diffusion is proportional to the surface area across which diffusion occurs and inversely proportional to the square of the distance through which molecules must move

Question 9

Give the significance of large organisms having a small surface area to volume ratio

Answer 9

• Small SA/V ratio decreases the rate of gaining unwanted substances eg toxic substances
• Enables slow heat loss during cold weather
• Causes slow entry of useful substances eg oxygen

-Causes slow heat loss during hot weather

Question 10

How do organisms minimize the limitations of body sizes?

Answer 10

Small organisms:
- Live in habitats where harmful substances easily get diluted before harming the body

• Allowing body enzyme systems function at varying temperatures

Large organisms:
-Development of an efficient transport system
- Improved oxygen carriage by pigments
- Development of ventilation mechanisms
- High metabolic rate

Question 11

Give characteristics of effective gaseous exchange surfaces

Answer 11

1. Large SA/V ratio
2. Thin
3. Moist
4. Permeable to respiratory gases
5. Operated in a way that maintains a high concentration gradient

Question 12

Define non-directional ventilation

Answer 12

Passive process by which respiratory medium flows past gas exchange surface in an unpredictable pattern.

Passive ventilation relies on water and air currents

Eg skin breathers like toads, earthworms

Question 13

Define bi-directional (tidal) ventilation

Answer 13

Active mechanism by which external medium moves in and out of respiratory system in a back and forth movement.

For example tidal ventilation

Occurs in;
Lung breathers like mammals, amphibians, etc

Question 14

Define unidirectional ventilation

Answer 14

Active mechanism by which respiratory medium flows in at one point, and exits via another.

[Blood flow relative to medium flow]

(1) Same Direction- Concurrent eg dogfish, shark
(2) Opposite Direction- Countercurrent eg bony fish
(3) At an angle- Crosscurrent eg bird lungs

Question 15

Why do Air breathers use bi-directional ventilation while water breathers use unidirectional ventilation?

Answer 15

Air breathers use bi-directional ventilation since air has low density and is less viscous while water breathers use unidirectional flow to save respiratory energy.

Question 16

Give adaptations of the cell surface membrane as the gas exchange surface of unicellular organisms like amoeba

Answer 16

• The cell surface membrane has a sufficiently large surface area to volume ratio enables efficient diffusion of gases.
• Being aquatic, the cell membrane is always moist to dissolve respiratory gases to enable their diffusion.
• The cell surface membrane is permeable to respiratory gases

Question 17

What adaptations does the earthworm have to using its entire body surface (skin) as a gas exchange surface?

Answer 17

• Skin surface is moist to enable dissolving of respiratory gases for efficient diffusion.
• Skin is thin to reduce the diffusion distance such that there is increased rate of diffusion of respiratory gases.
• The epidermal tissue is highly vascular to deliver and carry respiratory gases such that a high concentration gradient for the gases is maintained

Question 18

Give the advantages and disadvantages of external gills in tadpoles and lugworms

Answer 18

• Increased surface area for diffusion
• They offer great resistance because they are highly branched, hence external gills are ineffective except in smaller animals.
• Easily get damaged since the thin epithelium required for gas exchange is thin and delicate.

Question 19

Adaptations of the gas exchange site in insects include?

Answer 19

• Tracheae are kept open by circular bands of chitin to enable continual air movement to reach and leave tracheoles.
• Tracheae highly branch to form tracheoles that reach every cell to ventilate respiring cells directly.
• Tracheoles are moist to enable dissolution of respiratory gases for increasing their diffusion.
• Tracheae are impermeable to gases to maintain a high diffusion gradient in the air that reaches the tracheoles.

Question 20

State the adaptations of gill filaments in bony fish to their functions

Answer 20

• Gill filaments have folds called secondary lamellae that increase the surface area for gas exchange.
• The gill lamellae contain a network of capillaries for carrying away oxygen or bringing in Carbon dioxide for expulsion.
• There is counter current flow i.e. water and blood in the gills flow in opposite directions to maintain a favourable concentration gradient for diffusion of respiratory gases.
• Gill filaments are moist to enable dissolution of respiratory gases for efficient diffusion.
• Gills filaments are thin-walled to provide a short distance for diffusion of respiratory gases.
• Tips of adjacent gill filaments overlap = increases the resistance to the flow of water over gill surfaces and slows down the movement of water= more time for gaseous exchange to take place

Question 21

Give adaptations of the lungs to gas exchange

Answer 21

• Lungs have many saccular alveoli which provide a large surface area for gas exchange.
• Diffusion of respiratory gases is made faster by the shortened distance due to (1) alveoli and capillary walls being only one cell thick
(2) epithelial cells are flattened so are very thin
(3) capillaries are pressed against alveoli.
• The moistened alveolar surface enables dissolution of respiratory gases to increase the rate of diffusion.
• Alveolar surface is internal to reduce water evaporation.
• High concentration gradients of the gases, maintained by ventilation and flow of blood in the extensive capillary network.
• Air is warmed as it passes through the nostrils, to increase diffusion rate.

Question 22

What are the adaptations of the gas exchange structures of plants to their function?

Answer 22

• When the stomata open, production and consumption of oxygen and carbon dioxide in the leaf is sufficient to maintain a concentration gradient steep enough to facilitate gas exchange with the atmosphere.
• Large intercellular air filled spaces in the spongy mesophyll act as a reservoir for gaseous exchange.
• The cortical air spaces of roots and stems are continuous up and down and also in a sideways direction, thus allowing gas transport throughout the stem and root tissues.
• Root hairs lack a waxy cuticle and have moist surfaces to facilitate rapid diffusion of gases through the cell wall.
• Mangrove species that grow in water logged soils with less air content develop breathing roots above the ground level to increase gas exchange.
• Root hairs are numerous to increase the surface area for gas exchange.
• In the stem, lenticels consist of loosely packed cells at the opening to enable diffusion of respiratory gases.

Question 23

Describe gaseous exchange in unicellular organisms such as protozoa e.g. amoeba

Answer 23

The medium of gas exchange is fresh water and the gas exchange surface is the plasma membrane.
Along their concentration gradients, dissolved oxygen diffuses from the water across the permeable plasma membrane into the cytoplasm while dissolved carbon dioxide diffuses into water.

Question 24

Describe gaseous exchange in Spirogyra

Answer 24

In filamentous algae, the medium of gas exchange is fresh water and gas exchange occurs across the plasma membrane by diffusion.

(i) In the dark, no photosynthesis occurs in the chloroplast, no oxygen is made. Dissolved oxygen diffuses from the water across the cell membrane into the mitochondria while dissolved carbon dioxide diffuses into water, along their concentration gradients.

(ii) In the light, photosynthesis in chloroplasts releases oxygen, some of which diffuses into the mitochondria, the excess diffuses out.

Question 25

Describe gas exchange in plants

Answer 25

In plants, different structures (roots, stems, leaves, flowers, fruits) care for their own gas exchange needs; therefore the medium of gas exchange varies depending on environmental location of each plant part.

Plants respire all the time, but photosynthesis only occurs when there is light.

This means that the net gas exchange from a leaf depends on the light intensity.

Question 26

What is net gas exchange in plants dependent on?

Answer 26

Light intensity

In darkness no photosynthesis occurs, hence in the absence of photosynthesis there is a net release of carbon dioxide and a net uptake of oxygen.

In bright light during the day, the rate of photosynthesis is much higher than the rate of respiration hence there is a net release of oxygen and a net uptake of carbon dioxide

In Dim light during early morning and evening, photosynthesis greatly decreases hence the release of oxygen also decreases while respiration occurs normally hence the release of carbon dioxide increases causing compensation point.

Question 27

What is compensation point?

Answer 27

The light intensity at which the photosynthetic intake of carbon dioxide is equal to the respiratory output of carbon dioxide

Question 28

Why do most plants lack specialized organs for gas exchange?

Answer 28

(i) Each plant part takes care of its own gas exchange needs without dependence on a liquid transport system.

(ii) Roots, stems, and leaves respire at rates much slower than occurs in animals. Only during photosynthesis are large volumes of gases exchanged, and each leaf is well adapted to take care of its own needs.

(iii) The diffusion distance for gases is very short, even in a large plant because each living cell in the plant is located close to the surface. In stems, middle placed cells are dead while the only living cells are organized in thin layers just beneath the bark.

(iv) The loose packing of parenchyma cells in leaves, stems, and roots provides an interconnecting system of air spaces which exposes one surface of most of the living cells in a plant to air.

(v) Both the cell walls and plasma membranes are permeable to oxygen and carbon dioxide, enabling diffusion of the gases across. Carbon dioxide diffusion may be aided by aquaporin channels inserted in the plasma membrane.

Question 29

Why do most animals have specialized respiratory systems?

Answer 29

(i) Animal bodies are large with a small surface area to volume ratio, which limits the efficiency of diffusion alone in supplying oxygen and exit of carbon dioxide.

(ii) Outermost integuments of most parts on animal bodies are impermeable to respiratory gases.

(iii) Animal bodies are active therefore depend on fast metabolic rates to supply metabolites, which necessitates fast mechanisms for supplying oxygen and disposal of carbon dioxide.

(iv) Animal tissues are thickened layers of cells, for which diffusion alone would be ineffective.

Question 30

How does air enter the plant body?

Answer 30

Through;
Lenticels; pores in woody plants that form between the atmosphere and the cambium layer of stems and trunks

Stomata; typically found on the epidermis of leaves, but can occur on herbaceous stems.

Question 31

Give adaptations of the leaves to gaseous exchange

Answer 31

(i) Spongy mesophyll cells are loosely packed to accommodate much air which increases the concentration gradient of gases to enable faster diffusion.

(ii) Spongy mesophyll cells are covered by a thin film of water to dissolve respiratory gases to enable faster diffusion.

(iii) Palisade mesophyll cells are tightly packed with thin walls to reduce diffusion distance.

(iv) High stomatal density in upper leaf surface increases rate of diffusion of gases.

(v) Differences in thickness of guard cell walls enables the thin outer wall to bulge out and force the thicker inner wall into a crescent shape to open stomata when full turgor develops while regaining of shape when guard cells lose turgor causes stomatal aperture to close.

(vi) Floating leaves (e.g. water lilies) generally lack stomata in lower epidermis but very many stomata in the upper epidermis to maximise gas exchange with air at the upper surface.

(vii) Leaves of hydrophytes have very thin or no cuticle to reduce or prevent any barrier to the diffusion of gases into the leaves.

(viii) In land plants, stomata are spread out over leaves, to increase the rate of diffusion of waste gases produced by the leaf, which stops the build-up of excreted products that would slow gas exchange.

(ix) Leaves are thin, which increases diffusion rates of gases.

(x) Leaves have a very large surface area, which increases diffusion rate of gases.

(xi) Sunken in stomata and sub stomatal spaces enable leaves to minimise stomatal transpiration while maintaining gaseous exchange.

(xii) Some plants e.g. water lilies have elongated petioles to enable lamina maintain access to atmospheric air for gaseous exchange.

Question 32

Give adaptations of roots and stems to gaseous exchange functions

Answer 32

(i) Internally, stems of hydrophytes have large intercellular / air spaces / aerenchymatous tissue to accommodate much air which increases concentration gradient for faster diffusion of gases.

(ii) Black Mangroves which live in oxygen deficient mud have pneumatophores (breathing roots projecting up) with air filled spongy tissue connected to lenticels (pits) for faster diffusion of oxygen to all cells.

(iii) Mangroves which live in oxygen deficient mud water have relatively short roots to remain in close to oxygen rich mud surface to avoid the oxygen deficient deeper layers of mud.

(iv) Red Mangroves which live in oxygen deficient mud have air-rich pneumatophores in prop roots to supplement the oxygen uptake.

(v) Stems of submerged plants have little or no cuticle to reduce the barrier for gas diffusion.

(vi) Stems of hydrophytes have large air spaces to enable floating to expose leaves above water for access to atmospheric air.

(vii) Some aquatic plants elongate stems to enable stomata access atmospheric air for gaseous exchange.

Question 33

Describe gas exchange in earthworms

Answer 33

Earthworms exchange oxygen and carbon dioxide with water or air directly through their moist skin.

Dissolved oxygen diffuses into tiny blood vessels under the skin surface, where it loosely combines with haemoglobin that moves it through bloodstream to tissues. Carbon dioxide released by tissues attaches to haemoglobin then detaches to diffuse out of the skin.

Question 34

Explain how earthworms solely use the skin for gas exchange yet their bodies are quite large

Answer 34

(i) Earthworms have low metabolic rate, therefore require relatively low oxygen supply for aerobic respiration.

(ii) Moist surface with dense network of blood capillaries under the skin enable efficient gas exchange between air and blood.

(iii) Earthworm circulatory system contains haemoglobin in blood to increases the oxygen carrying capacity of blood.

(iv) Long, thin body provides large surface area compared to body size, efficient for gas exchange.

(v) Blood capillaries are very close to the skin surface to reduce the diffusion distance for gases.

Question 35

Define positive pressure breathing

Answer 35

Actively creating a positive (increased) pressure in the breathing apparatus higher than atmospheric pressure, to establish the air pressure gradient

e.g. Frogs gulp air into the mouth, then close the mouth and nostrils, and raise the floor of the mouth upwards to decrease volume of mouth cavity and increase pressure in the mouth cavity higher than atmospheric pressure.

Question 36

Define negative pressure breathing

Answer 36

Actively creating a negative (decreased) pressure in the breathing apparatus lower than atmospheric pressure, to establish the air pressure gradient

e.g. contraction of diaphragm and rib cage in mammals increases volume to create a lower pressure within the lungs than atmospheric pressure.

Question 37

Describe the respiratory system of insects

Answer 37

• 10 pairs of spiracles, located laterally on the body surface.
• 2 pairs are thoracic and 8 pairs are abdominal.
• The spiracles are guarded by fine hairs to keep the foreign particles out and by valves that function to open or close the spiracles as required.
• The spiracles open into small spaces called the atria that continue as air tubes called the tracheae.
• The tracheae are fine tubes that have a wall of single layered epithelial cells.

-The cells secrete spiral cuticular thickenings called taenidia around the tube that gives support to the tubes.

• The tracheal tubes branch further into finer tracheoles that enter all the tissues and sometimes, even the cells of the insect.

-The ends of the tracheoles that are in the tissue are filled with fluid and lack the cuticular thickenings.

• Main tracheal tubes join together to form three main tracheal trunks; dorsal, ventral and lateral.

Question 38

Describe the process of insect ventilation and gaseous exchange

Answer 38

• Increased CO2 is detected by chemoreceptors, causing relaxation of the abdominal muscles, increased volume and lowering of pressure.

• The spiracle valves open and air rich in oxygen is drawn into the tracheal system.

• Spiracles valves then close and oxygen is forced along the tracheal system into the fluid-filled tracheoles, which are in direct contact with the tissue fluid. Gaseous exchange occurs along concentration gradients of oxygen and carbon dioxide.

• Air is expelled out when muscles contract and flatten the insect body, decreasing the volume of the tracheal system.

• During increased metabolic activity, the water potential of tissue lowers (hypertonic) due to accumulation of wastes like lactic acid, causing osmotic efflux of water from the tracheoles into tissues. Air fills the tracheoles and oxygen diffusion through tracheoles is faster.

• In resting tissues, the water potential of tissue fluid increases (hypotonic), causing the fluid to fill the tracheoles.

Question 39

Explain gaseous exchange in aquatic insects

Answer 39

= Aquatic insects also use tracheal system for gas exchange.

= Some insect larvae (“wigglers”) like mosquito, have a siphon/breathing tube that connects the tracheal system to the water surface for obtaining oxygen and disposal of carbon dioxide.

= Some insects that can submerge for long periods carry an air bubble from which they breathe.

= Some insects have spiracles at the tips of spines. When the spines pierce the leaves of underwater plants oxygen is obtained from the bubbles formed by photosynthesis within the leaves.

= Some aquatic insect larvae have gills into which oxygen diffuses from the water, then into a gas-filled tracheal system for transport through the body.

Question 40

Fossil insects have been discovered that are larger than insects occurring on earth today. What does this suggest about the atmospheric composition at the time when these fossil insects lived?

Answer 40

The earlier atmosphere contained more oxygen than the present atmosphere

Question 41

Give a disadvantage of concurrent flow in dog fish

Answer 41

The partial pressure of blood may equilibrate with that of the respiratory medium thus requiring facilitated diffusion to occur

Question 42

What are the advantages of countercurrent flow?

Answer 42

(1) Enables blood of the gill lamellae to extract maximum oxygen from the water for the entire period the water flows across the gill filaments.

(2) Under conditions permitting adequate oxygen uptake, the counter-current fish expends less energy in respiration compared to parallel flow.

Question 43

How is parallel flow improved?

Answer 43

When the flow of water is very rapid compared to blood flow rate, to ensure a higher saturation of the blood by the time it leaves the respiratory surface.

Question 44

What is a respiratory pigment?

Answer 44

Any molecule that increases the oxygen carrying capacity of blood

Question 45

Why are respiratory pigments necessary?

Answer 45

= Because oxygen has low solubility in aqueous solution.
= To enable pickup of molecular oxygen at sites of high oxygen tension and deposition at sites of low oxygen tension.
= To enable blood to carry a much greater quantity of oxygen
= To enable quick removal of oxygen from respiratory surfaces, thus maintaining a concentration gradient down which O2 can diffuse.

Question 46

Describe cutaneous gaseous exchange in frogs

Answer 46

Oxygen from atmospheric air dissolves in moisture / mucus at the outer skin surface, then diffuses through the thin skin into the underlying dense capillary network while carbon dioxide diffuses out of the skin.

• Cutaneous respiration is actually more significant than pulmonary (lung) ventilation in frogs during winter, when their metabolisms are slow while lung function becomes more important during the summer as the frog’s metabolism increases.

Question 47

Describe buccal cavity (mouth) gaseous exchange

Answer 47

The muscles of the mouth contract to lower the surface of the mouth hence reducing its pressure than that of the atmosphere.

Air rich in oxygen is inhaled through the nostrils into the mouth cavity.

Oxygen diffuses into the dense capillary network under the buccal cavity lining and is transported by the red blood cells.

Carbon dioxide diffuses from the blood tissues to the buccal cavity; then exhaled through the nostrils when the mouth floor is raised.

Question 48

Describe lung ventilation in frogs

Answer 48

INHALATION
1. Mouth and glottis closed
2. Sternohyoid muscles contract
3. Petrohyoid muscles relax
4. Floor of buccal cavity lowers
5. Volume of buccal cavity increases while pressure of buccal cavity decreases below atmospheric pressure
6. Atmospheric air rushes into the buccal cavity via open external nostrils
7. Nostrils close
8. Petrohyoid contract and sternohyoid relax; floor of buccal cavity raised
9. Volume decreases pressure increases above lung pressure and air forced through open glottis into lung
10. Oxygen diffuses into lung capillaries while carbon dioxide diffuses out of lung capillaries into alveoli.

EXHALATION
•Sternohyoid muscles contract while petrohyoid muscles relax.

•Floor of buccal cavity lowers to increase buccal cavity volume while decreasing pressure below lung pressure.

•Air rich in CO2, from lungs is forced out into the buccal cavity through glottis. At the same time, atmospheric air enters the buccal cavity via external nostrils

•Thus during pulmonary respiration, the buccal cavity receives mixed air, which is again pushed into the lungs.

•Therefore, oxygenation of amphibian blood by the lungs being inefficient is supplemented by cutaneous respiration—the exchange of gases across the skin.

Question 49

Describe gas exchange in bony fish

Answer 49

INHALATION
• Contraction of the mouth muscles lowers the floor of the mouth, increasing buccal cavity volume as pressure decreases.

• Water rushes to fill the buccal cavity, and at the same time, water’s pressure outside presses against and closes opercular valves.

• Operculum muscles contract; causing operculum to bulge; and increase opercular volume but decreases opercular cavity pressure.

• Mouth contracts to decrease buccal cavity volume while increasing pressure, which forces/sucks water into opercular cavity which is at lower pressure;

• As water flows over gill filaments in opposite direction to flow of blood (countercurrent flow) O2 diffuses into blood capillaries to combine with haemoglobin while CO2 diffuse into the flowing water along concentration gradients.

EXHALATION
• Mouth muscles are fully contracted with mouth valve tightly closed.
• Opercular muscles relax to decrease opercular cavity volume and increase pressure.
• Pressured water in opercular cavity forces opercular valves to open as water exits.

Question 50

State adaptations of the bony fish gill structure

Answer 50

• Thin
  -Permeable
  -Moist
  -Has afferent blood vessels (carry deoxygenated blood to the capillaries in the secondary lamellae)
• Has efferent blood vessels (carry oxygenated blood from capillaries back to the gill arch)
• Countercurrent flow of blood relative to water through the gills

Question 51

Under what circumstances may a fish suffocate in water?

Answer 51

(i) When the oxygen in the water is depleted by another biotic source such as bacteria/decomposers.

(ii) When oxygen greatly diffuses out of water due to increase in water’s temperature.

Question 52

State the major features of the human respiratory system

Answer 52

1. Trachea, the two bronchi and bronchioles held open by C-shaped cartilaginous rings
2. Ciliated epithelium, goblet cells that secrete mucus
3. Spongy and elastic lungs
4. Air sacs and alveoli
5. Blood vessels that are branches of the pulmonary artery and vein
6. Each lung enclosed by two membranes; the inner and outer pleural membrane
7. The membranes are enclosed in a space called the pleural cavity containing a fluid that lubricates free lung movement
8. Alveoli have squamous epithelium with liquid surfactant on inner surface and blood capillaries on outer surface

Question 53

Give adaptations of the lungs to their function

Answer 53

• Large SA
• Moist
  -Liquid surfactant
• Highly vascularized
• Elastic
• Pleural fluid
• C-shaped cartilaginous rings

Question 54

Give the functions of lung surfactant

Answer 54

1. Reduces alveolar surface tension
2. Speeds up the diffusion of respiratory gases
3. Kills bacteria that reach the alveoli
4. Prevents collapse of the alveoli

Question 55

Describe ventilation and gaseous exchange in man

Answer 55

INSPIRATION:

• The external intercostal muscles contract while the inner intercostals relax at the same time causing the rib cage to move upwards and outwards.

• Diaphragm muscles contract and flatten / move downwards.

• These movements increase the volume of the thoracic cavity; and lung volume.

• Alveolar lung pressure decreases below atmospheric pressure causing air to rush into lungs through the nostrils, into nasal passages, pharynx, larynx, trachea, main bronchi, bronchioles, alveolar ducts, and into alveoli.

• Air dissolves in the moisture lining the alveolar epithelium, oxygen then diffuses into blood capillaries and into the red blood cells while carbon dioxide diffuses from blood capillaries into alveolar air along the concentration gradients.

EXPIRATION

• Internal intercostal muscles contract
• External intercostal muscles relax causing rib cage to move downwards and inwards
• Diaphragm muscles relax to move upwards
• The volume of thoracic cavity and lungs decreases causing increased lung pressure above atmospheric pressure
• Carbon dioxide rich air but with low oxygen is carried by red blood cells in capillaries, diffuses into the alveoli and is forced out of the lungs

Question 56

Define total lung capacity

Answer 56

The volume of air contained in the lung at the end of maximal inspiration. The total volume of the lung.

Question 57

What is vital capacity?

Answer 57

The amount of air that can be forced out of the lungs after a maximal inspiration

Question 58

What is tidal volume?

Answer 58

Volume of air normally breathed in when the body is at rest

Question 59

Define residual volume

Answer 59

The amount of air left in the lungs after a maximal exhalation can’t be expired

Question 60

What is expiratory reserve volume?

Answer 60

The amount of additional air that can be pushed out after the end expiratory level of normal breathing

Question 61

Define inspiratory capacity

Answer 61

The maximal volume that can be inspired following a normal expiration

Question 62

What is alveolar dead space?

Answer 62

The volume of inspired air that is not used for gas exchange as a result of reaching alveoli with no blood supply

Question 63

Anatomical dead space is?

Answer 63

Space within the airways that does not permit gas exchange with blood

Question 64

What is alveolar ventilation rate?

Answer 64

Amount of air reaching the alveolar space per minute

Question 65

Minute ventilation (pulmonary ventilation) is?

Answer 65

Total volume of air inhaled and exhaled

Question 66

Define ventilation rate

Answer 66

This is the number of breaths taken in one minute

Question 67

When a person becomes adjusted to low partial pressure of oxygen what happens?

Answer 67

• Increase in number of red blood cells
• Increased amount of haemoglobin
• Increased ventilation rate
• Increased cardiac frequency