Exchange surfaces

Question 1

What are the features that make the lungs an efficient exchange surface?

Answer 1

Increased surface area due to many alveoli.

The walls of the alveoli and the capillaries are thin (only 1 cell thick) , decreasing the distance needed for the diffusion of gases.

A good blood supply. There is a capillary close to each alveolus, rapidly taking the oxygenated blood away and bringing in deoxygenated blood. This ensures that a steep concentration gradient for oxygen and carbon dioxide is maintained.

Question 2

Where is cartilage found?

Answer 2

Trachea and bronchi

Question 3

Where are goblet cells found?

Answer 3

Trachea and bronchi

Question 4

Where is smooth muscle found?

Answer 4

Trachea, bronchi, bronchioles

Question 5

Where is ciliated epithelium found?

Answer 5

Trachea, bronchi, bronchioles

Question 6

Where are elastic fibres found?

Answer 6

Trachea, bronchi, bronchioles, alveoli

Question 7

What is the function of cartilage?

Answer 7

Holds the airways open

Question 8

What is the function of goblet cells?

Answer 8

Secrete mucus in order to trap pathogens and particles in the lungs.

Question 9

What is the function of smooth muscle?

Answer 9

Constricts airways to prevent harmful gases from entering the lungs.

Question 10

What is the function of ciliated epithelium?

Answer 10

Surface is covered in cilia that move mucus out of the lungs.

Question 11

What is the function of elastic fibres?

Answer 11

Allow recoil of the smooth muscle or the alveoli back to their original size.

Question 12

What is inspiration?

Answer 12

Breathing in

Question 13

What is expiration?

Answer 13

Breathing out

Question 14

What is the mechanism of inspiration?

Answer 14

Intercostal muscles contract. The ribcage moves upwards and outwards.

Diaphragm contracts and becomes flatter.

Thoracic cavity expands and volume increases. This deccreases the pressure to below atmospheric pressure.

Air moves into the lungs from high pressure to low pressure.

Question 15

What is the mechanism for expiration?

Answer 15

Intercostal muscles relax. The ribcage moves downwards and inwards.

Diaphragm relaxes and becomes dome-shaped.

Thoracic cavity reduces and volume decreases. THis increases the pressure above at atmospheric pressure.

Air moves out of the lungs from high pressure to low pressure. The recoil of the elastic fibres in the alveoli helps to expel this air.

Question 16

What is a spirometer?

Answer 16

The air chamber is filled with air or oxygen. When a person exhales into the spirometer, the air chamber rises. When a person inhales, air is removed from spirometer and the air chamber moves down. Thismovement drwas the graph. The soda lime absorbs any carbon dioxide in the exhaled air.

Question 17

What can a spirometer trace be used for?

Answer 17

A spirometer trace can also be used to work out a person’s breathing rate and rate of oxygen uptake.

Question 18

What is the tidal volume?

Answer 18

The volume of air breathed in and out of the lungs in one breath, when the person is at rest.

Question 19

How do you measure tidal volume on a graph?

Answer 19

Measure the distance from the top to the bottom of a small peak.

Question 20

What is the vital capacity?

Answer 20

The maximum volume of air that can be inhaled or exhaled in one breath.

Question 21

How do you measure the vital capacity on a graph?

Answer 21

Measure the distance from the top to the bottom of the largest peak.

Question 22

How do you calculate breathing rate?

Answer 22

Divide the number of breaths by a given time (s), and multiply by 60 to get breaths per minute.

Question 23

How do you calculate rate of oxygen uptake?

Answer 23

Divide the amount of oxygen used by a given time and multiply by 60 to get oxygen uptake per minute.

Question 24

How do fish ventilate?

Answer 24

Water enters the fish’s mouth, or buccal cavity, when the mouth opens, lowering the pressure inside the buccal cavity compared to the surrounding water. When the fish closes its mouth, the pressure in the buccal cavity increases and water flows over the gills and out of the fish, behind a flap called the operculum.

Question 25

What is the countercurrent mechanism?

Answer 25

As the water flows over the deoxygentated blood, oxygen diffuses into the blood. The blood flows in the opposite direction to the water.

Question 26

Why is the countercurrent exchange system important?

Answer 26

It allows the maximum amount of oxygen to diffuse into the blood.

Question 27

What do insects use to take oxygen in?

Answer 27

Insects use spiracles to take in oxygen from the air through the sides of their bodies.

Question 28

What circulatory system do insects have?

Answer 28

Open

Question 29

What is an open circulatory system?

Answer 29

The blood flows out of the blood vessels and into the body cavity.

Question 30

How do insects ventilate?

Answer 30

Oxygen from the air diffuses into the insect’s body cavity through the spiracles, and into long thin tubes called tracheae. The tracheae branch into smaller tubes called tracheoles that have an open ending inside the insect cell, filled with tracheal fluid. Oxygen diffuses into this fluid,and into the insect’s cells.

Question 31

How can insects increase the rate of diffusion?

Answer 31

The rate of diffusion can be increased in active insects by withdrawing the tracheal fluid into the cells. This increases the surface area of the tracheole wall that is exposed to air, and more oxygen can be absorbed.

Question 32

How can very active insects further enhance their ventilation system?

Answer 32

By increasing and decreasing the volume of the thorax by moving their wings.