HOMEOSTASIS

Discussion Questions 1. What is homeostasis? 2. What does a living thing need to perform homeostasis? 3. What are some examples of things that the body will regulate?

4. What are some examples of how the body regulates these things? 5. How does the body do homeostasis?

Homeostasis in the Human Body homeostasis

An example of homeostasis within the human body: DIALYSIS  It’s a process that separates solvents from blood. Such as removing glucose or fats with out removing the important molecules that our blood needs.  The tubing used in semi-permeable. Meaning some material can pass through and others cannot.

The Cell Membrane

Label your cell membrane!

 A membrane is a device that selectively permits the separation of one or more materials from a liquid or gas. What is a membrane? ?

Diffusion Demonstration Model  Molecules are always in motion  In a closed system the molecules evenly try to distribute  Which results in a the initial movement of molecules from high to low concentrations  Once an equilibrium is reached there is no net movement of molecule.

 What is separating the two different types of beads?  How do the two volumes compare in this model?  Which side of the model has a higher concentration of beads?  How is diffusion going to take place?  What happens with continued shaking?  Is equilibrium reached? (Has homeostasis been reached?)

Passive Transport  The transport of substances through the cell membrane without using energy.

Diffusion  The process of moving from areas of high concentration to areas of low concentration

Osmosis

Osmosis  The diffusion of water from areas of high concentration to areas of low concentration through a semi- permeable membrane.

Osmosis Cont.  The concentration (amount) of all substances affects the movement of materials in and out of the cell.

Explain to your lab partner why water is moving into the cell…

SUMMARY: Water moves from a high concentration of water (less salt or sugar dissolved in it) to a low concentration of water (more salt or sugar dissolved in it). This means that water would cross a selectively permeable membrane from a dilute solution (less dissolved in it) to a concentrated solution (more dissolved in it).

 Water can cross the cell membrane through the lipid bi-layer and with special proteins. If enough water enters the cell by osmosis, the cell can swell enough to burst open and die. This is demonstrated in the picture.

Hypotonic Solute concentration: contains a low concentration of solute Water concentration: contains a high concentration of water Water movement: water diffuses into the cell Effect on the cell: causing the cell to swell and possible explode

Exploding RBC Exploding RBC

Cells in hypotonic solution

Draw a picture

Isotonic  Solute concentration: is equal to the water concentration  Water concentration: is equal to the solute concentration  Water movement: equal diffusion (water diffuses into and out of the cell at equal rate)  Effect on cell: none

Normal cells in isotonic solution

Draw a picture of an isotonic solution next to the definition

Hypertonic Solute concentration: contains a high concentration of solute Water concentration: contains a low concentration of water Water movement: water diffuses out of the cell Effect on the cell: causing the cell to shrivel

Cells in hypertonic solution RBC's shrinking! RBC's shrinking!

Draw a picture next to the definition

Quiz yourself

Watch video after you conduct the potato lab! Egg Experiment Egg Experiment

Active transport

 The transport of molecules from areas of high to low concentration with the use of energy.  The cells energy is the ATP made in the mitochondria.

Bulk movement of substances across the membrane Endocytosis:  Phagocytosis  Pinocytosis Exocytosis

Endocytosis  A process by which a cell surrounds and takes in materials from its environment by engulfing them.

Phagocytosis  “CELL EATING”. Process in which phagocytes engulf and digest microorganisms and cellular debris "phagocyte" or eating cell "phagocyte" or eating cell (phago = "eating", cyte = "cell"). An important defense against infection

phagocytosis

Pinocytosis “CELL DRINKING”. Process by which certain cells can engulf and incorporate droplets of fluid

Examples on Endocytosis Is it phago or pino… Is it phago or pino…

Exocytosis  when materials and wastes are transported out of the cell.

Label where endo and exo take place

Diffusion Quiz Diffusion Quiz

Bookwork Facilitated Diffusion: