Homeostasis and Homeostasis and Cell TransportCell TransportPassive and Active TransportPassive and Active Transport

What is Homeostasis?What is Homeostasis?

Homeostasis is the process by which an Homeostasis is the process by which an organism tries to stay in equilibriumorganism tries to stay in equilibrium

Examples:Examples: Body TemperatureBody Temperature Water ContentWater Content Salt ContentSalt Content

How does Diffusion Help How does Diffusion Help Maintain Homeostasis?Maintain Homeostasis?

Diffusion - the process by which Diffusion - the process by which molecules spread from areas of high molecules spread from areas of high concentration, to areas of low concentration, to areas of low concentration. concentration.

When the molecules are even throughout When the molecules are even throughout a space - it is called a space - it is called EQUILIBRIUMEQUILIBRIUM

Concentration gradient - a difference Concentration gradient - a difference between concentrations in a space. between concentrations in a space.

What does Diffusion Look What does Diffusion Look Like?Like?

OSMOSIS OSMOSIS

Osmosis is the Osmosis is the diffusion of water diffusion of water across a membrane.across a membrane.

Water will move in Water will move in the direction where the direction where there is a high there is a high concentration of concentration of solute (and hence a solute (and hence a lower concentration lower concentration of water. of water.

A simple rule to remember A simple rule to remember is:is: Salt Sucks Salt Sucks

Salt is a solute, when it is concentrated Salt is a solute, when it is concentrated inside or outside the cell, it will draw the inside or outside the cell, it will draw the water in its direction. This is also why you water in its direction. This is also why you get thirsty after eating something salty. get thirsty after eating something salty.

A simple rule to remember A simple rule to remember is:is: Salt Sucks Salt Sucks

Types of SolutionTypes of Solution

IsotonicIsotonic Hypotonic Hypotonic HypertonicHypertonic

Type of Solutions Type of Solutions

If the concentration of If the concentration of solute (salt) is equal on solute (salt) is equal on both sides, the water will both sides, the water will move back in forth but it move back in forth but it won't have any result on won't have any result on the overall amount of the overall amount of water on either side.water on either side.

""ISOISO" means the same" means the same

Types of SolutionTypes of Solution

The word "The word "HYPOHYPO" means " means less, in this case there are less, in this case there are less solute (salt) molecules less solute (salt) molecules outside the cell, since salt outside the cell, since salt sucks, water will move into sucks, water will move into the cell.the cell.

The cell will gain water and The cell will gain water and grow larger. In plant cells, the grow larger. In plant cells, the central vacuoles will fill and central vacuoles will fill and the plant becomes stiff and the plant becomes stiff and rigid, the cell wall keeps the rigid, the cell wall keeps the plant from burstingplant from bursting

Types of SolutionTypes of Solution

In animal cells, the In animal cells, the cell may be in danger cell may be in danger of bursting, of bursting, organelles called organelles called CONTRACTILE CONTRACTILE VACUOLESVACUOLES will will pump water out of pump water out of the cell to prevent the cell to prevent this.this.

Types of SolutionTypes of Solution

The word "The word "HYPERHYPER" means " means more, in this case there are more, in this case there are more solute (salt) molecules more solute (salt) molecules outside the cell, which causes outside the cell, which causes the water to be sucked in that the water to be sucked in that direction.direction.

In plant cells, the central In plant cells, the central vacuole loses water and the vacuole loses water and the cells shrink, causing wilting.cells shrink, causing wilting.

In animal cells, the cells also In animal cells, the cells also shrink.shrink.

In both cases, the cell may In both cases, the cell may die.die.

Types of SolutionTypes of Solution

This is why it is dangerous to This is why it is dangerous to drink sea water - its a myth drink sea water - its a myth that drinking sea water will that drinking sea water will cause you to go insane, but cause you to go insane, but people marooned at sea will people marooned at sea will speed up dehydration (and speed up dehydration (and death) by drinking sea water. death) by drinking sea water.

This is also why "salting This is also why "salting fields" was a common tactic fields" was a common tactic during war, it would kill the during war, it would kill the crops in the field, thus crops in the field, thus causing food shortages.causing food shortages.

Warm-UPWarm-UP

What is a Concentration Gradient?What is a Concentration Gradient? How is diffusion different from osmosis?How is diffusion different from osmosis? Explain with scientific terms what Explain with scientific terms what

happens in a beaker of water when food happens in a beaker of water when food coloring is added. A illustrated diagram coloring is added. A illustrated diagram may help you answer this question.may help you answer this question.

Types of Solution Types of Solution ReviewedReviewed

Passive Facilitated Passive Facilitated DiffusionDiffusion

Sometimes, large molecules cannot Sometimes, large molecules cannot cross the plasma membrane, and are cross the plasma membrane, and are "helped" across by "helped" across by carrier proteinscarrier proteins - this - this process is called process is called facilitated diffusionfacilitated diffusion..

Passive Facilitated Passive Facilitated DiffusionDiffusion

Diffusion and Osmosis Diffusion and Osmosis

Diffusion and Osmosis are both types of Diffusion and Osmosis are both types of Passive TransportPassive Transport that is, no energy is required for the that is, no energy is required for the

molecules to move into or out of the cell. molecules to move into or out of the cell.

Active TransportActive Transport

Active Transport - this type of transport Active Transport - this type of transport requires that the cell use energy, requires that the cell use energy, because substances are moving against because substances are moving against the concentration gradient. the concentration gradient.

Sodium-Potassium PumpSodium-Potassium Pump

Sodium-Potassium PumpSodium-Potassium Pump The The sodium-potassium pumpsodium-potassium pump moves three moves three

NaNa++ ions into the cell’s external environment ions into the cell’s external environment for every two Kfor every two K++ ions it moves into the ions it moves into the cytosol. cytosol.

ATP supplies the energy that drives the ATP supplies the energy that drives the pump.pump.

Sodium Potassium PumpsSodium Potassium Pumps

Endocytosis and Endocytosis and ExocytosisExocytosis

Some substances (macromolecules and Some substances (macromolecules and nutrients) are large to pass through the nutrients) are large to pass through the cells membranecells membrane

EndocytosisEndocytosis

In endocytosis, cells ingest external In endocytosis, cells ingest external materials by folding around them and materials by folding around them and forming a pouch. forming a pouch.

The pouch then pinches off and becomes The pouch then pinches off and becomes a membrane-bound organelle called a a membrane-bound organelle called a vesicle.vesicle.

EndocytosisEndocytosis

Endocytosis includes pinocytosis, in Endocytosis includes pinocytosis, in which the vesicle contains solutes or which the vesicle contains solutes or fluids fluids

Phagocytosis, in which the vesicle Phagocytosis, in which the vesicle contains large particles or cells.contains large particles or cells.

ExocytosisExocytosis

In In exocytosisexocytosis, vesicles made by the cell , vesicles made by the cell fuse with the cell membrane, releasing fuse with the cell membrane, releasing their contents into the external their contents into the external environment.environment.

Endocytosis and Endocytosis and ExocytosisExocytosis