Key Area 7 - Absorption of Materials Flashcards
When air is breathed in, where does it go?
Passes through the trachea, which branches into the (pl.) bronchi, into the smaller branching bronchioles and finally into the alveoli. The trachea and bronchi have rings of cartilage which keep the airways open.
Why must oxygen and nutrients from food be absorbed into the bloodstream?
To be delivered to cells for respiration.
Waste materials such as carbon dioxide must be removed from cells into the bloodstream
Why must tissues contain capillary networks ?
To allow the exchange of materials at a cellular level
What do surfaces involved in the absorption have in common to increase the efficiency of the absorption?
- Large surface area
- Thin walls
- Extensive blood supply
Give the basic structure of the lungs:
They are sponge-like due to the millions of tiny alveoli(air sacs), providing a large surface area for gas exchange
The lungs can be described as the gas exchange organs
What happens to air when it is breathed in? (What path does it follow)
It passes through the trachea, which branches into the right and left bronchus (pl. bronchi), which branch into smaller bronchioles, and then finally into alveoli.
The trachea and bronchi have rings of cartilage which jeep the airways open
What is the structure of the alveoli?
- Very numerous
- Large surface area for maximum gas exchange
- Thin walls allowing easy diffusion of oxygen into the blood
- Walls are moist to allow oxygen to dissolve before diffusion
- Network of blood capillaries surrounds them to allow an exchange of gases
Give the function of the alveoli:
- Blood arriving in the lungs is deoxygenated, air breathed into the alveolus has a high concentration of oxygen, so the oxygen diffuses from a region of high concentration in the alveolus to a region of low concentration in the blood, therefore the blood becomes oxygenated
- Deoxygenated blood contains higher levels of CO2 than the air in the alveolus, so the CO2 diffuses from a region of high concentration in the blood to a region of low concentration in the alveolus, this CO2 is then exhaled
What is the function of the small intestine?
- First part is where most digestion takes place
- Any remaining starch is broken down into glucose
- Fats are also digested here, breaking down into fatty acids and glycerol
- It is the site of nutrient absorption, where the products of digestion are moved into the bloodstream to be transported around the body
How does the structure of the small intestine increase it’s surface area and therefore increase the rate of absorption?
- It is very long
- The inner surface in folded
- The inner surface has a large number of finger-like projections called villi
What are the epithelial cells?
They provide a very thin lining of the villi (one cell thick) to allow the soluble end products of digestion to pass through easily
What is the lacteal?
The site of absorption on the villi of the products of fat digestion (fatty acids and glycerol)
What is the blood capillary of a villi?
The site of absorption of the products of starch digestion (glucose) and protein digestion (amino acids)
How are substances/nutrients absorbed into the villi in the small intestine?
- Glucose and amino acids are absorbed into the epithelial cells and pass directly onto the blood capillaries.The blood capillaries transport theses soluble food products to the liver
- Fatty acids and glycerol are absorbed into the epithelial cells, then into the lacteal and then pass into the lymphatic system. This system eventually drains into the blood circulatory system
What is the process that moves food through the digestive system?
Peristalsis
