Exchange and transport Flashcards
What is diffusiong
Diffusion is the random spreading out of particles from an area of a higher concentration to an area of a lower concentration down a concentration gradient/
Where does diffusion take place?
Gases and Liquids.
How can diffusion go through cell membranes?
It can go through partially permeable cell membranes.
Only small molecules can diffuse through like glucose, water, oxygen, or amino acids.
Starch and proteins can’t go through
Example of Diffusion
In cellular respiration oxygen and glucose diffuse into cells from the blood stream. CO2 then diffuses out of the cell into the bloodstream. Co2 is taken away to keep the concentration low.
What are 3 factors that affect the rate of diffusion?
Concentration gradient
Temperature (Particles have more energy at a higher temp)
Surface area (Lager surface area, more area for the particles to pass)
What is active transport?
the movement of ions or molecules across a cell membrane into a region of a higher concentration, assisted by specialized proteins and requiring energy.
When is active transport used?
When molecules need to move against their concentration gradient.
2 Examples of Active transport
- Root hair cells, root hair cells have a large surface area to absorb nutrients from the soil. Diffusion cant is used, it needs energy from cellular respiration.
- In the intestines, higher concentrations of nutrients are in te intestines after a meal, diffusion can be used here. As moe nutrients are absorbed, the gradient decreases, and active transport must be used.
What are microvilli for?
They provide a large surface area for diffusion
How is active transport different from diffusion?
-Requires Energy
- Goes against concentration gradient
What is osmosis?
The net movement of molecules across a partially permeable membrane from a region of higher water concentration to a region of lower water concnetration.
Example of how ratio of sulte to water works
A higher concentration of solutes leads to a lower concentration of water
What determines the concentration of water?
The ratio of water to solutes.
How does inhalation and exhalation occur?
Inhalation:
The intercostal muscles found between the ribs contract.
This raises the ribs upwards and outward expanding the ribcage
The diaphragm contracts and flattens, pulling downwards.
The result is that the thorax increases in volume, which in turn lowers the pressure and consequently air is sucked into the lungs.
Exhalation
When we exhale:
The intercostal muscles relax.
This lowers the ribs downwards and inwards.
The diaphragm relaxes, moving back upwards.
The result is that the thorax decreases in volume, which in turn increases the pressure inside it and consequently forces air out of the lungs.
What is the purpose of the lungs?
To get the oxygen from the air around us into our bloodstream where it can be transported to the rest of the body
