1.5 Exchanging Materials Flashcards
What do exchange surfaces in organisms need to be?
Thin, moist, and have a large surface area
A rich blood supply is also essential in many animals.
What is the process of diffusion of respiratory gases?
A passive process that does not require additional input of energy.
What materials are taken in by animals?
- Oxygen
- Water
- Carbohydrates
- Lipids
- Proteins
- Vitamins
- Minerals
What materials are removed by animals?
- Excess water
- Salts
- Toxic waste products (e.g., urea, carbon dioxide)
Define unicellular organisms.
Organisms that consist of a single cell (e.g., bacteria, amoeba, protozoa).
Define multicellular organisms.
Organisms that consist of more than one cell (e.g., plants, animals).
What are exchange surfaces?
Sites where nutrients are taken up and waste products are excreted.
List examples of exchange surfaces in the body.
- Blood capillaries
- Nephrons in the kidney
- Alveoli in the lungs
- Villi in the small intestines
What characteristics must exchange surfaces have for efficient material exchange?
- Be thin
- Be moist
- Have a large surface area
- Have a high concentration gradient
How does the thickness of exchange surfaces affect the rate of exchange?
Thinner surfaces increase the rate of exchange.
Why must exchange surfaces be moist?
Substances can only diffuse through the cell membrane as a dissolved substance or solute.
What is the surface-area-to-volume ratio (SA:V)?
It tells how much surface area there is per unit of volume.
What is the importance of a high concentration gradient in exchange surfaces?
It maximizes the rate of exchange through diffusion.
How is a steep concentration gradient maintained in exchange surfaces?
By the flow of blood through capillaries.
What is diffusion?
The random movement of a substance from a high concentrated area to a low concentrated area until equilibrium is established.
Define passive process in the context of diffusion.
A process that does not require energy.
What types of molecules commonly diffuse across the cell membrane?
- Oxygen
- Carbon dioxide
What is the net movement of molecules during diffusion?
From a high concentration to a low concentration area.
What is a concentration gradient?
A difference in concentration of a substance between the inside and outside of the cell.
What are the substances exchanged in the alveoli?
- Carbon dioxide
- Oxygen
- Water
What are the substances exchanged in the villi?
- Water
- Amino acids
- Sugar
- Fatty acids
- Glycerol
What are the substances exchanged in the nephrons? (not reabsorbed)
- Urea
- Water
- Salts
What adaptations do alveoli have for gas exchange?
- Large surface area
- Moist, thin walls (one cell thick)
- Rich network of capillaries
How do villi facilitate nutrient absorption?
- One cell thick
- Rich network of blood capillaries
- Form many finger-like projections called microvilli
What is the structure of the nephron walls?
Made of a single layer of cells.
What is the role of the glomerulus in the nephron?
A cluster of capillaries that helps with absorption.
