Homeostasis, Osmosis, and Diffusion

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Homeostasis, Osmosis, and Diffusion
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Homeostasis

• Homeostasis biological balance between a cell
  or organism and its external environment.
• A. In multicellular organisms, you can have
  homeostasis on the cellular level or on the
  organism level.
• B. Homeostasis is maintained by the cell
  controlling what enters and exits

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• C. Good Stuff
• 1. CHO
• 2. Lipids
• 3. Proteins
• 4. Nucleic Acid
• 5. Water
• 6. Various chemicals
• D. Bad Stuff
• 1. Waste
• 2. Extra Water

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• E. Cells can exist in a broad range of
  environment, but there are limits.
• F. Ways a cell maintains homeostasis
• 1. Diffusion
• 2. Osmosis
• 3. Facilitated Diffusion
• 4. Gated Channels
• 5. Active Transport
• 6. Endocytosis
• 7. Exocytosis

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Diffusion

• II. Diffusion movement of molecules from areas
  of HIGH concentration to LOW concentration.

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• A. Equilibrium point where the concentration
  of a substance is equal throughout the solution
• B. In a cell, many small molecules such as water
  will diffuse across the cell membrane through
  protein channels
• 1. Diagram

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• 2. Each protein channel or pore is sepcific to a
  certain type of molecule
• 3. Each cell may have thousands of each type of
  protein channels

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Osmosis

• III. Osmosis the process by which water
  molecules diffuse across a selectively permeable
  membrane
• A. Diagram

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• B. Direction of Osmosis
• 1. Hypotonic Solution solute is less on the
  outside of the cell than the inside water is
  greater on the outside.
• Cell Swells

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• 2. Hypertonic solution solute is more on
  the outside than the inside water is less on the
  outside
• Cell Shrinks

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• 3. Isotonic solution solute is equal on
  the inside and outside of the cell
• a) Cell is in homeostasis

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• C. Examples
• 1. Hypotonic Solution
• a) Jellyfish in Lake Norman

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• 2. Hypertonic Solution
• a) Goldfish in the Atlantic Ocean

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• 3. Isotonic Solution
• a) Jellyfish in the Atlantic Ocean

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• D. Roles of Osmosis
• 1. Kidneys use it to maintain water levels in
  the blood
• 2. Turgor pressure water pressure in plant
  cells
• a) help maintain support
• 3. Plasmolysis occurs when a ell is in a
  hypertonic solution and shrinks due to water
  leaving
• 4. Cytolysis occurs when a cell is in a
  hypotonic solution and it bursts due to water
  rushing into the cell.

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Types of Diffusion
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Facilitated Diffusion

• IV. Facilitated Diffusion diffusion of
  molecules across the cell membrane with the help
  of carrier proteins
• A. Carrier Protein protein which carries
  molecules across the cell membrane
• B. Carries large molecules such as starch,
  sucrose, lipids, and proteins
• C. Each carrier protein is specific to a type
  of molecule

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Facilitated Diffusion continued..
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Active Transport

• V. Active Transport movement of molecules from
  areas of low concentration to areas of high
  concentration with the use of ATP and a carrier
  protein
• A. goes against diffusion
• B. uses ATP to power it

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Gated Channels

• VI. Gated Channels protein that can be opened
  or closed to allow molecules to enter or leave
  the cell wall
• A. works by diffusion
• B. diagram

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Endocytosis

• VII. Endocytosis process where large molecules
  are taken into the cell
• A. Two types
• 1. Phagocytosis takes in solids
• 2. Pinocytosis takes in liquids
• B. diagram

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Exocytosis

• VIII. Exocytosis getting rid of large molecules
• A. diagram

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• B. Ex) Sodium-Potassium Pump
• 1. used to carry nerve signals
• 2. steps

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