Exchange Surfaces and Breathing

Question 1

What is SA:V?

Answer 1

This is an important concept- the surface area of an organism divided by its volume, expressed as a ration.

Question 2

Why do multicellular organisms need a specialised exchange system?

Answer 2

Multicellular organisms are so large so have a small SA:Vol.
Active, so metabolic rate means a higher demand for oxygen. Cells and tissues are too deep in the body.
Diffusion alone is too slow to supply enough oxygen and remove carbon dioxide.

Question 3

What are features of a good exchange system?

Answer 3

Large surface area- to provide more spaces for molecules to diffuse through
Thin barrier- to reduce diffusion distance
Good blood supply- maintains a steep concentration gradient.

Question 4

How are the alveoli adapted?

Answer 4

Large numbers of alveoli provide a large surface area.
Alveoli are small in size to provide a small surface area to volume ration.
Alveolar cells secrete surfactant to maintain surface area and prevent collapse.
Squamous epithelial cells are one cell thick so provide a short diffusion distance.
Elastic fibres recoil to help ventilation.
Ventilation maintains a steep concentration gradient.

Question 5

What is inspiration?

Answer 5

The diaphragm contracts, flattens and moves down.
External intercostals contacts and the ribs rise.
Volume of the thorax increases.
Pressure in thorax drops below atmospheric pressure.
Air moves into lungs down a pressure gradient.

Question 6

What is expiration?

Answer 6

The diaphragm relaxes, curves up and moves into the chest cavity.
External intercostal muscles relax and ribs fall.
Volume of the thorax decreases.
Pressure in thorax rises above atmospheric pressure.
Air moves out of the lungs down a pressure gradient

Question 7

Alveoli:

Answer 7

Squamous epithelium

Elastic fibres that stretch during inspiration and recoil to expel air during expiration

Question 8

What is the trachea composed of?

Answer 8

Large C-shaped pieces of cartilage 
Smooth muscle
Elastic fibres
Goblet cells
Ciliated Epithelium

Question 9

What is the bronchi composed of?

Answer 9

Small pieces of cartilage 
Smooth muscle
Elastic fibres
Goblet cells
Ciliated Epithelium

Question 10

What are the Bronchioles composed of?

Answer 10

No cartilage 
Elastic fibres 
Smooth muscle
Goblet cells
Ciliated Epithelium

Question 11

What is Smooth muscle?

Answer 11

Involuntary muscle that contracts without the need for conscious thought. E.g. in an allergic reaction

Question 12

What is a method for a spirometer?

Answer 12

1. Subject wears nose clip to not breathe through the nose
2. Subject breathes regularly
3. During inspiration, air is drawn from the chamber and the lid moves down.
4. The movement of the lid is recorded by a data logger
5. CO2 rich air is passed through a chamber of soda lime, absorbing the CO2, allowing the measurement of O2 consumption.

Question 13

What precautions need to be taken before using a spirometer?

Answer 13

Check the health of the volunteer e.g. asthma
Soda lime should be fresh and functioning
No leaks in the apparatus
Mouthpiece should be sterilised
Water levels is not too high
Medical grade oxygen used

Question 14

What is the equation for total lung volume?

Answer 14

Total Lung Volume= Vital Capacity+Residual Volume

Question 15

What does vital capacity depend on?

Answer 15

Age
Gender
Level of regular exercise
Height of a person

Question 16

What is vital capacity?

Answer 16

The maximum volume of air inhaled and exhaled in one breath

Question 17

What is residual volume?

Answer 17

The volume of air that remains in the lungs even after forced expiration.

Question 18

Why is there residual volume?

Answer 18

Thorax can not be completely compressed. Trachea and bronchi are held open by cartilage. Bronchioles and alveoli are held by elastic fibres.

Question 19

What is tidal volume?

Answer 19

The volume of air inhaled or exhales in one breath at rest.

Question 20

Gaseous Exchange in bony fish

Answer 20

Gills are the exchange surface
Each fill consists of two rows of primary lamellar attached to a fill arch so large surface area. Primary lamellae folded into secondary lamellae so larger surface area. Primary lamellae are thin so shorter diffusion distance.

Question 21

What is countercurrent flow?

Answer 21

Where two fluids flow in opposite directions.

Question 22

What is ventilation of a bony fish?

Answer 22

Mouth opens, floor of buccal cavity lowers. Volume of the buccaneers cavity increases, pressure drops and water moves in.
Mouth closes, floor of buffalo cavity raises.
Volume of the buccal cavity decreases, pressure increases.
Opercular valves open.
Water is pushed through the gills.

Question 23

Gaseous exchange in insects:

Answer 23

Open circulatory system- oxygen is not transported in the blood
Air-filled tracheal system supplies air directly to all respiring tissues. Air enters via a spiracle, is transported through trachea, then tracheole.
Ends of tracheoles are open and filled with fluid called tracheal fluid.
It occurs between the air in the tracheoles and the tracheal fluid.

Question 24

Gilbert cells and Ciliated epithelium:

Answer 24

Goblet cells secrete mucus to trap dust, bacteria, pollen. Cilia waft mucus away from the lungs, up the airways to be swallowed.

Question 25

Cartilage

Answer 25

Allows flexibility and holds airways open to prevent collapse

Question 26

Elastic fibres

Answer 26

Recoil to help expel air during ventilation

Question 27

Which two types of epithelial tissue found in lungs are?

Answer 27

Squamous and Ciliated