Chapter 7- Mammalian Gas Exchange

Question 1

Why do organisms need ti exchange substances with their environment ?

Answer 1

1) cells need to take in things like oxygen and glucose for aerobic respiration and other metabolic reactions.

2) they also need to excrete waste products from these reactions , like carbon dioxide and urea.

Question 2

How does sa:v ratio affect exchange of substances?

Answer 2

The larger the sa:v ratio, the faster the rate of exchange/diffusion.

Question 3

Why do unicellular organism not need exchange surfaces?

Answer 3

In single cells organisms, these substances can diffuse directly into or out of the cell across the cell surface membrane. The diffusion rate of quick because of the small distances the substances have to travel.

Question 4

Why do multicellular organisms need exchange systems?

Answer 4

1) some cells are deep within the body, there’s a big distance between them and the outside environment

2) larger animals have a smaller surface area to volume ratio so it’s more difficult ti exchange enough substances ti supply a large volume of animal through a relatively small outer surface.

3) multicellular organisms have a higher metabolic rate than single-celled organisms, so they use up oxygen and glucose faster.

Question 5

What are the features that specialised exchange surfaces have?

Answer 5

1) large surface area
2) thin layers
3) good blood supply
4) good ventilation

Question 6

How do root hair cells have large surface area?

Answer 6

1) the cells on plant roots grow into long “hairs” which stick out into the soil. Each branch of a root will be covered in millions of these microscopic hairs.

2) these gives the roots a large surface area, which helps to increase rate of absorption of water and mineral ions from the soil.

Question 7

How do thin layers improve efficiency of alveoli?

Answer 7

1) the alveoli are the gas exchange surface in the lungs and each alveolus is made from a single layer of thin, flat cells called the alveolar epithelium.

2) O2 diffuses out of alveolar space into blood and CO2 diffuses in opposite direction. Thin alveolar epithelium allow for shorter diffusion distance for O2 and CO2 which increases diffusion rate.

Question 8

How does good blood supply improve efficiency in alveoli?

Answer 8

The alveoli are surround by a large capillary network, giving each alveolus its own blood supply. The blood constantly takes oxygen away from the alveoli, and brings more carbon dioxide. This helps maintain concentration gradients of O2 and CO2

Question 9

How does ventilation improve efficiency of alveoli?

Answer 9

The lungs are also ventilated so the air in each alveolus is constantly replaced. This maintains concentration gradients of O2 and CO2

Question 10

How does good blood supply improve efficiency of fish gills?

Answer 10

The hills are the gas exchange surface for fishing. In the gills, O2 and CO2 are exchanged between the fish’s blood and the surrounding water. They contain a large number of capillaries to keep them well supplied with blood to maintain a concentration gradient of O2

Question 11

How does ventilation improve efficiency of fish gills?

Answer 11

Gills are well ventilated because fresh waste constantly passes over them. This helps maintain a concentration gradient of O2 increasing the rate at which O2 diffuses into the blood.

Question 12

How does air reach the lungs?

Answer 12

1) as you breathe in, air enters the trachea.

2) the trachea splits into two bronchi, one bronchus going to each lung

3) each bronchus then branches off into smaller tubes called bronchioles

4) the bronchioles end in alveoli where gases are exchanged.

Question 13

What is the function of goblet cells in the gas exchange system?

Answer 13

Goblet cells line the airways and secret mucus. The mucus traps microorganism and dust particles in the inhaled air, stopping them from reaching the alveoli.

Question 14

What is the function of cilia in the gas exchange system?

Answer 14

Cilia on the surface of cells lining the airways best the mucus. This moves the mucus that has trapped microorganisms and dust upward away from the alveoli towards the throat, where it’s swallowed. This helps prevent lung infections.

Question 15

What is the function of elastic fibres in the gas exchange system?

Answer 15

Elastic fibres in the walls of vessels help the process of breathing out. On breathing in, the lungs inflate and the elastic fibres are stretched. Then, the fibres recoil to help push the air out when exhaling.

Question 16

What is the function of smooth muscle in the gas exchange system?

Answer 16

Smooth muscle allows the diameter of parts of the lung to be controlled. During exercise smooth muscle relaxes, making tubes wider. This means there is less resistance to airflow and air can move in and out of the lungs easier.

Question 17

What is the function of cartilage in the gas exchange system?

Answer 17

Rings of cartilage in the walls of the trachea and bronchi provide supports. its strong and flexible to stop trachea and bronchi collapsing when you breathe in and pressure drops.

Question 18

What is the structure of the trachea?

Answer 18

Incomplete rings of cartilage
Has smooth muscle, elastic fibres and goblet cells
Contains ciliated epithelium.

Question 19

What is the structure of bronchi?

Answer 19

It has small pieces of cartilage
Contains smooth muscle, elastic fibres and goblet cells
Contains ciliated epithelium

Question 20

What is the structure of bronchioles?

Answer 20

No bronchioles have cartilage.

Larger bronchioles have smooth muscle, elastic fibres, goblet cells and ciliated epithelium
Smaller bronchiole has smooth muscle, elastic fibres and ciliated epithelium
Smallest bronchiole has elastic fibres and no cilia .

Question 21

What is the structure of the alveoli?

Answer 21

They contain no cartilage. They have elastic fibres and no cilia.

Question 22

How does inspiration occur?

Answer 22

1) the external intercostal and diaphragm muscles contract

2) this causes the rib cage to move upwards and outwards and the diaphragm to flatten, increasing the volume of the thorax

3) as the volume of the thorax increases the lung pressure decreases below atmospheric pressure.

4) this causes air to flow into the lungs. Inspiration is an active process and require energy.

Question 23

How does expiration occur?

Answer 23

1) the external intercostal and diaphragm muscles relax.

2) the rib cage moves downwards and inwards and the diaphragm becomes curved again.

3) the thorax volume decreases causing air pressure to increase above atmospheric pressure

4) air is forced out of lungs. normal expiration is a passive process

Expiration can be forced. During forces expiration the internal intercostal muscles contract, to pull the rib cage down and in.

Question 24

What are the terms you need to know about breathing?

Answer 24

Tidal volume (TV) - the volume of air in each breath (usually 0.4 dm3)
Vital capacity - the maximum volume of air that can be breathed in or out
Breathing rate- how many breaths taken in a minute
Oxygen consumption- rate at which an organism uses up oxygen

Question 25

How do spirometers work?

Answer 25

1) a spirometer has an oxygen-filled chamber with a moveable lid

2) the person breathes through a tube connected to an oxygen chamber

3) as the person breathes in and out, the lid of the chamber moves up and down

4) these movements can be recorded by a pen attached to the lip of the chamber. This writes on the rotating drum, creating a spirometer trace.

5) the spirometer can also be hooked up to a motion sensor, so movements produce electronic signals picked up by a data logger

6) soda lime in the tube the subject breathes inti absorbs carbon dioxide.

Question 26

How to analyse data from a spirometer graph?

Answer 26

1) tidal volume is the regular traces going up and down.
2) vital capacity is the length from the bottom to the top of the largest wave
3) breathing rate is the number of peaks in the first minute
4) oxygen consumption is the gradient of the graph.