ALL Human Robotics

B8: RESPIRATION AND GAS EXCHANGE SUMMARY

B8.01 Respiration

Every living cell needs energy:

contracting muscles, for moving
making protein molecules by linking together amino acids into long chains
making new cells
cell division for repairing damaged tissues
producing heat inside the body

All of this energy that we use comes from the food that we eat.

Glucose is the main nutrient that we use to provide energy.

The body makes a lot of metabolic reactions to obtain energy called respiration. This reaction needs the action of the enzymes.

Aerobic respiration

The chemical reaction in cells that use oxygen to break down nutrient molecules to release energy.

glucose + oxygen 一一一一➝ carbon dioxide + water

Anaerobic respiration

The chemical reaction in cells that break down nutrient molecules to release energy without using oxygen.

Yeast: glucose 一一一一➝ alcohol + carbon dioxide

Using yeast to make bread

Bread is made from flour, wheat flour. The flour contains proteins including gluten.

The rest is the explanation of the experiment.

B8.02 Gas exchange in humans

Gas exchange surface

Animals get sugar from the carbohydrates while plants make photosynthesis.

Oxygen is obtained in different ways: animals and plants get oxygen from their surroundings. Humans and some other plants obtain oxygen from air.

We made carbon dioxide as a waste product of aerobic respiration and it must be removed. There are special areas where the oxygen enters and the carbon dioxide leaves, they are called surfaces for gas exchange.

They are thin,
They are close to an efficient transport system,
They have a large surface area,
They have a good supply of oxygen.

The human gas exchange system

There are two lungs that have a lot of tiny air spaces called air sacs or alveoli. It is here that oxygen diffuses into the blood because they are full of space. The lung are supplied with air through the windpipe or trachea.

The pathway to the lungs

The trachea

From the nose or mouth, the air passes into the trachea.

On the top of it there is a piece of cartilage called epiglottis. This closes the trachea and stops the food going down the trachea when you swallow, this is a reflex action.

Below the epiglottis there is the voice box or larynx, this contains the vocal cords.

The bronchi

The trachea divides into two called the left and right bronchi. Each bronchus branches out into smaller tubes called bronchioles.

The alveoli

They are at the end of each bronchiole, this is where gas exchange takes place.

Goblet cells

Cells that line the passages through which air moves towards the alveoli are goblet cells. They have a secrete sticky mucus. There are other cells that have microscopic hair-like extensions called cilia, it causes the swallow.

This protects the lungs from any harmful microorganisms and it also stops too many particles from reaching the lungs.

Gas exchange in the lungs

The walls of the alveoli are the gas exchange surface. Oxygen diffuses across the walls of the alveoli into the blood. Carbon dioxide diffuses in other way. These walls are:

very thin, they are only one cell thick
They have an excellent transport system

Oxygen is obtained in different ways: animals and plants get oxygen from their surroundings. Humans and some other plants obtain oxygen from air.

We made carbon dioxide as a waste product of aerobic respiration and it must be removed. There are special areas where the oxygen enters and the carbon dioxide leaves, they are called surfaces for gas exchange.

They are thin,
They are close to an efficient transport system,
They have a large surface area,
They have a good supply of oxygen.