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Homeostasis

Homeostasis. Water balance. Temperature. pH. Blood pressure. 60% H 2 O. 60% H 2 O. Keeping an organism’s internal environment stable Examples. Homeostasis. Help the organism respond to stimuli and maintain homeostasis on a large scale (whole body) Negative Feedback Positive Feedback.

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Homeostasis

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  1. Homeostasis

  2. Water balance Temperature pH Blood pressure 60% H2O 60% H2O Keeping an organism’s internal environment stable Examples Homeostasis

  3. Help the organism respond to stimuli and maintain homeostasis on a largescale (whole body) Negative Feedback Positive Feedback Feedback Mechanisms

  4. COLD skin cells detect cold brain gets message response shiver, blood vessels constrict and lower blood flow to the skin • When a situation causes a response that reverses the first condition • Most common in the body Negative Feedback normal body temp

  5. Pancreas secretes insulin Liver coverts glucose to glycogen Blood glucose level falls Soon after a meal Pancreas secretes less insulin Long after a meal Liver converts glycogen to glucose Too Low Blood glucose level rises Too High normal blood glucose level normal blood glucose level

  6. enzymes enzymes enzymes enzymes enzymes enzymes enzymes enzymes enzymes When a situation causes a response that amplifies (increases) the initial (1st) condition Ex. Labor pains, milk production, digestive enzymes Positive Feedback

  7. On a small scale, individual cells maintain homeostasis by controlling what gets into and out of a cell.

  8. Cells move molecules in and out 2 ways: 1. PASSIVE TRANSPORT: does not use energy, moves from high to low concentration. 2. ACTIVE TRANSPORT: uses energy, moves from low to high concentration. Cell transport

  9. PASSIVE TRANSPORT ***Molecules move with the flow, from high to low concentrations. ***No Energy Required! ***3 Types: Diffusion Facilitated Diffusion Osmosis

  10. PASSIVE TRANSPORT • Diffusion: movement of anything from high to low concentration.

  11. PASSIVE TRANSPORT • Facilitated Diffusion: Movement of molecules from high to low concentration. • A protein in the membrane helps make bigger spaces in the membrane.

  12. Facilitated Diffusion outside cell inside cell Movement of larger molecules (ex. glucose) from high concentration to low concentration with the help of a carrier protein

  13. PASSIVE TRANSPORT • Osmosis: movement of water from high to low concentration across a membrane.

  14. Osmosis diffusion with WATER 60% H2O 60% H2O Movement of WATER from high concentration to low concentration * When the cell is at equilibrium with its environment, equal amounts of water move into and out of the cell ISOTONIC SOLUTION

  15. 75% H2O 2% H2O * When there is more water in a cell than outside of a cell, water will leave the cell HYPERTONIC SOLUTION this can cause a cell to shrink

  16. CYTOLYSIS 60% H2O 80% H2O * When there is more water outside a cell than inside of a cell, water will enter the cell HYPOTONIC SOLUTION this can be bad, if too much water enters then the cell may lyse (burst)

  17. 5% H2O 85% H2O Plant cellsrespond differently to osmosis because of their cell wall * When water leaves a plant cell, the cell wall’s shape does not change, but the cell membrane pulls away and creates an air pocket between the two. This causes the plant to WILT. This is called PLASMOLYSIS

  18. 98% H2O 85% H2O * When water enters a plant cell, the cell membrane pushes against the cell wall and creates pressure. This is called TURGOR PRESSURE

  19. Active transport • Move molecules against the flow, from low to high concentration. • Uses ENERGY!

  20. Active transport • For Multicellular Organisms: • Uses a carrier protein, to carry them across the membrane

  21. Active Transport vesicle For Unicellular Organisms VESICLE --> organelle that transports materials through, into, or out of a cell * ENDOCYTOSIS --> into the cell Pinocytosis --> fluids Phagocytosis --> foods

  22. * EXOCYTOSIS --> out of the cell

  23. Cells Review!!!

  24. tissue organ cell organism • Smallest unit of life that can carry on all processes of life • Unicellular or multicellular • Multicellular organization cells  tissues  organs  organ systems The Cell A group of similar cells is called a tissue. A group of similar tissues is called an organ. A group of organs working together form an organ system or organism

  25. All living things are made of one or more cells • Cells are an organisms’ basic unit of structure and function • Cells only come from preexisting cells (mitosis) • The scientist Schwann, Schleiden, and Virchow contributed to what we call today the … CELL THEORY

  26. Prokaryotic • Eukaryotic • YOU ARE EUKARYOTIC! There are two types of cells:

  27. Prokaryotic • DOES NOT have membrane bound nucleus • DOES NOT have organelles with a membrane • Smaller cells • ALWAYS unicellular

  28. A prokaryotic cell 3. Plasma membrane 2. DNA 1. Ribosomes 4. Cell wall

  29. Eukaryotic • HAS a membrane bound nucleus • HAS organelles with a membrane • LARGER cells • Unicellular or multicellular

  30. A eukaryotic cell 1. Nucleus 2. Nucleolus 3. Chromosomes 4. Plasma membrane 5. Organelles Chapter Assessment

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