Respiratory Systems

Question 1

What is internal respiration?

Answer 1

Metabolism

Energy being made available to cells

Question 2

What is external respiration?

Answer 2

Delivery of oxygen to tissues and cells

Removal of carbon dioxide

Question 3

How does gas move across biological membranes?

Answer 3

Diffusion

Question 4

Define partial pressure.

Answer 4

Pressure of a single gas in a gas mixture

Question 5

What are physical factors influencing the rate of diffusion?

Answer 5

Partial pressure gradient
Diameter of the gas molecules
Temperature
Solubility of the gas in liquid
Thickness of the gas exchange surface
Surface area of the gas exchange surface

Question 6

What does a respiratory system consist of?

Answer 6

Specialised body surfaces for gas exchange
Mechanisms to ventilate the environmental face of this surface
Mechanisms to perfuse the internal face of this surface

Question 7

What is the primary role of a respiratory system?

Answer 7

Meet the metabolic demands of the organisms

Question 8

What is ventilation?

Answer 8

Convection of respiratory medium over the gas exchange surfaces (active or passive)

Question 9

What is the purpose of ventilation?

Answer 9

Maintain partial pressure gradient at respiratory system

Fresh oxygen delivered and carbon dioxide removed

Question 10

What is the intrapleural pressure at rest (with respect to atmospheric pressure)?

Answer 10

Negative with respect to atmospheric pressure

Question 11

When does ventilation occur?

Answer 11

When active muscle force is applied to the relaxed respiratory system

Question 12

Is inspiration active or passive?

Answer 12

Active process

Question 13

In inspiration, what changes?

Answer 13

Volume of thorax increases
Diaphragm contracts
External intercostal muscles contract

Question 14

As the volume of the thorax increases, the intrapleural pressure … ?

Answer 14

Falls

Question 15

What is Boyle’s law?

Answer 15

P1 x V1 = P2 x V2

pressure x volume is constant

Question 16

As the volume of the thorax increases, what happens to alveoli and alveolar pressure?

Answer 16

Alveoli expand
Air flows into lungs until alveolar pressure equals atmospheric pressure (before it was negative wrt atmospheric pressure)

Question 17

Is expiration largely passive or active?

Answer 17

Passive

Question 18

What happens in expiration?

Answer 18

Elastic recoil of lungs and chest wall reduces volume of thorax (passive mechanism)
Intrapleural pressure rises
Alveoli recoil
Alveolar pressure > atmospheric pressure
Air expelled from lungs

Question 19

Air moves … from a region of … to … pressure

Answer 19

Air moves passively from a region of high to low pressure

Question 20

Pressure-volume graph:

Why does the curve deviate to the right in inspiration?

Answer 20

Because of resistive forces which oppose airflow

Question 21

Pressure-volume graph:

Why does the curve deviate to the left in expiration?

Answer 21

Resistive forces assist airflow

Question 22

Describe ventilation in birds.

Answer 22

Birds lung volume changes less than in mammals
Air moves through lungs from interconnected air sacs
Sacs do not participate in gas exchange

Question 23

Describe ventilation in frogs.

Answer 23

Air forced into lungs

Lungs emptied by abdominal contraction

Question 24

Describe air movement in insects.

Answer 24

Airways penetrate each body segment, allowing diffusion

Abdominal muscles pump air through tracheae

Question 25

Describe water movement across gills.

Answer 25

Energy is required to pump water across gills
Water pulled across gills when opercular cavity expands and opercular flaps open
Water pulled across gills when opercular cavity expands and opercular flaps open
Water pushed over gills when fish closes mouth

Question 26

Describe laminar flow.

Answer 26

Slow flow rate

Parallel stream lines

Question 27

Describe turbulent flow.

Answer 27

High flow rate

Disorganised strwam lines

Question 28

Describe transitional flow.

Answer 28

intermediate flow rate

eddy currents

Question 29

What is radial traction?

Answer 29

As lung expands, connective tissue pulls on bronchioles, so their diameter expands and the airway resistance falls
As lung volume is reduced, airway resistance rises rapidly because radial traction is relieved

Question 30

What is dynamic compression?

Answer 30

Occurs at low lung volume, or when intrathoracic pressure > alveolar pressure (forced expiration)
Airways are compressed and may close

Question 31

What is bronchioconstriction?

Answer 31

Irritants cause reflex constriction: trachea, large bronchi
Parasympathetic stimulation
Fall in PCO2
Asthma

Question 32

What is bronchiodilation?

Answer 32

Autonomic stimulation

Sympathomimetic agents

Question 33

How does infection impact airway resistance?

Answer 33

Infection can significantly increase
Inflammation of the tissues lining the upper airways
Overproduction/ accumulation of mucus

Question 34

What is elastic recoil determined by?

Answer 34

Elastic properties of the lung tissue

Surface tension in the alveoli

Question 35

What elastic tissues are in the lung and where?

Answer 35

Elastin and collagen fibres in alveolar wall and around vessels and bronchi

Question 36

What does the network of fibres in the lungs do?

Answer 36

Allows distension but recovers geometry the pressure is released

Question 37

What are alveoli lined with?

Answer 37

Fluid

Question 38

Why does the presence of an air-fluid interface create potential problems? How can these problems by minimised?

Answer 38

Attractive forces in liquid (surface tension) oppose expansion by inspired air
Promotes collapse of smaller alveoli
Causes transudation of fluid form capillaries
These problems are minimised by surfactant

Question 39

What is surfactant?

Answer 39

Substance that reduces surface tension between two liquids; a gas and a liquid or a solid and a liquid