Absorption of materials

Question 1

What must be absorbed into the bloodstream to be delivered to cells for aerobic respiration?

Answer 1

Oxygen and nutrients from food must be absorbed into the blood stream to be delivered to cells for aerobic respiration.

Question 2

What must be removed from cells into the blood stream?

Answer 2

Waste materials such as carbon dioxide must be removed from cells into the blood stream to be removed from the body.

Question 3

What do tissues contain to allow the exchange of materials at cellular level?

Answer 3

Tissues contain capillary networks to allow the exchange of materials at cells.

Question 4

What are the common features included in surfaces involved in the absorption of materials and why?

Answer 4

Surfaces involved in the absorption of materials have certain features in common, these include:
A large surface area
thin walls
Extensive blood supply
All these features increases the efficiency of absorption.
These features can be found in gas exchange system in the lungs and in the digestive system.

Question 5

What is the body’s organ for gas exchange?

Answer 5

The lungs are the body’s organs of gas exchange.

Question 6

Describe the pathway of gases to the alveoli.

Answer 6

When we breathe in, air moves down the windpipe (trachea). This then branches off into right and left bronchus which further branch into narrower tubes called bronchioles. The windpipe and bronchus are supported and held open by rings of cartilage. At the end of the bronchioles are the air sacs (alveoli) and this is where gases are exchanged with the blood.

Question 7

What is the main function of the alveoli?

Answer 7

The main function of the alveoli is the exchange of gases (i.e. oxygen into the body then blood and carbon dioxide out of blood then body).

Question 8

What are the features the alveoli possess which make them very efficient at gas exchange?

Answer 8

The alveoli possess the following features which make them very efficient at gas exchange:
There are thousands of alveoli in each lung which provides a large surface area for diffusion of gases.
The walls of the alveoli are very thin.
The walls of the alveoli are very close to the blood cappillaries.
They are surrounded by a network of blood capillaries so that gases can be easily transported to and from the lungs.

Question 9

What is one alveoli called?

Answer 9

Alveolus

Question 10

Why do the alveoli have a large surface area?

Answer 10

For diffusion of gases.

Question 11

Why do the alveoli have thin walls?

Answer 11

Allows fast diffusion of oxygen into the blood and carbon dioxide into the alveoli.

Question 12

Why are the alveoli surrounded by a large capillary network?

Answer 12

So gases can be easily exchanged to and from the lungs.

Question 13

Describe the pathway of blood that arrives in the lungs to respiring cells.

Answer 13

Blood which arrives in the lungs is deoxygenated (low in oxygen). The air breathed into the alveoli in the lungs has a high oxygen concentration . The oxygen diffuses from the lung alveoli (high oxygen concentration) to the blood and its red blood cells (low oxygen concentration). The blood then becomes oxygenated and is pumped to respiring cells.

Question 14

Describe the pathway of deoxygenated blood that arrives at the lung alveoli.

Answer 14

Deoxygenated blood arriving at the lung alveoli will have a high concentration of carbon dioxide than the air which is breathed into the lungs. This means that carbon dioxide will diffuse from the blood into the alveoli in the lungs and will then be breathed out of the lungs.

Question 15

What are nutrients carried to the cell in?

Answer 15

Nutrients are carried to the cell in the blood

Question 16

What is digestion?

Answer 16

Digestion involves the breakdown of large insoluble molecules of food into smaller soluble molecules, which can then diffuse into the bloodstream.

Question 17

What is the main function of the very long small intestine?

Answer 17

The very long small intestine’s main function is the absorption (by diffusion) of the small food molecules.

Question 18

How is the very long small intestine ideally suited to its main function?

Answer 18

The very long small intestine is ideally suited to its main function which is the absorption (by diffusion) of the small food molecules in several ways:
The inner surface has a large number of finger-like projections called villi.
These provide a large surface area.

Question 19

Describe the structure of each villus.

Answer 19

The lining/wall of each villus is only one cell thick.

The villi also contain a dense network of blood capillaries.

Question 20

What is one villi called?

Answer 20

villus

Question 21

Why is the lining/wall of each villus only one cell thick?

Answer 21

The lining/wall of each villus is only one cell thick, allowing the soluble end products of digestion through easily.

Question 22

Why do the villi contain a dense network of blood capillaries?

Answer 22

The villi also contain a dense network of blood capillaries for the absorption of glucose and amino acids.

Question 23

What are the products of fat digestion absorbed by?

Answer 23

The products of fat digestion i.e. fatty acids and glycerol are absorbed by the lacteal found in each villus.

Question 24

What happens to the small food molecules/nutrients after being absorbed by the villi?

Answer 24

These small food molecules/ nutrients will then be transported to and diffuse into the body cells. Glucose will be used by the body cells during the process of aerobic respiration, to make energy. The liver will build up any extra glucose into the compound glycogen to be stored until it is needed. The amino acids will be used by the body to make proteins.

Question 25

What system are the lacteals part of?

Answer 25

Lacteals are part of the lymphatic system.

Question 26

What happens to the products of fat digestion after being absorbed by the lacteal?

Answer 26

Lacteals are part of the lymphatic system. The lymphatic system will eventually empty its contents into the bloodstream via two large ducts found in the upper chest region. The fatty acids and glycerol are transported to and diffuse into cells and are used as energy sources and any extra is stored under the skin or around organs as fatty tissue.