Notes on Homeostasis

1. Notes on Homeostasis

2. Homeostasis – “biological balance” cell(s) keeping a steady state with orin spite of the environment • homeo - same • stat - steady

3. Homeostasis Regulation of the internal environment to maintain constant, favorable conditions Every cell, tissue & organ in the human body contributes toward total body homeostasis

4. Ex: Body is cold (low temp), you begin to shiver to raise body temperature • Ex: Your blood oxygen level is low**, your respiratory rate increases to meet this O2 need • (raise blood O2) **generalization

5. Ex: Blood collects & carries wastes from all tissues toward kidneys, which then filter blood & send waste materials toward excretory system

6. Ex: Enzymes used in producing sperm function best at 2-3° lower than regular body temperature.

7. What determines a cell’s set of homeostatic conditions? The metabolicneeds of the cell.

8. Homeostasis • In the human body, these are the conditions of homeostasis: • pH of human blood is: 7.4 • Normal body temp is: 98.6 ºF (or 37 ºC) • Saline concentration in blood is: 9g salt per liter • Regular blood glucose level is: 100-150 mg/dL • Clearly, homeostasis does NOT mean conditions are equal to the conditions of the environment

9. Write down the key ideas from the following video clip dealing with metabolism and homeostasis; use these for your Frayer Model in comp book!.

10. The BIG idea: Because the cell membrane is the interface between the cell and the external environment, the cell membrane plays a MAJOR role in governing homeostasis for the cell.

11. Review…. Solute: Any substance that is dissolved in water is a solute. Example: salt Solvent: The liquid in which a solute is dissolved Example: water (of the saltwater ) Solution: A liquid that contains one or more solutes Example: Water with sugar and/or salt Concentration: The mass of solute in a given volume ofsolution. Concentration, then, just means how “salty” the water is. What are two methods for changing a solution’s concentration?

12. New idea: Concentration Gradient • A concentration gradient is a difference between two solutions that are separated by space or a barrier. Notice these two “salt” solutions: One solution is saltier than the other. What do you think will happen to the salt particles over time?

13. K Definition A separation of two different concentrations of a solution. K K K K Outside the cell K K K Inside the cell K K K K K K K K K K K K K K concentration gradient K K K Na Na Na Na Na Na Na Na Na Na Na Na Na Na Na Na Na Outside the cell Na Na Equilibrium / Equal on both sides Na Inside the cell Na Na Na Na Na

14. In cells, concentration gradients occur at the cell membrane—between the intracellular and extracellular environments. Interacting with the concentration gradient is how the cell membrane helps to maintain homeostasis.

15. Cell membrane – regulates what enters and leaves the cell Semipermeable membrane – keeps out some molecules but allows others to enter

16. Structure of the Cell membrane • composed of a bilayer of phospholipids and proteins

17. Structure of Non-polar

20. regulates what enters and leaves the cell – selectively permeable (semipermeable) • Keeps out some molecules but allows others to enter

21. Movement across the cell membrane: 2 types: 1. passive transport 2. active transport

22. 1. Passive transport – does not require cellular energy A. Diffusion – movement of molecules from areas of greater concentration to areas of lesser concentration Particles move WITH the concentration gradient.

23. Diffusion across a membrane: Diffusion with no membrane:

24. Once the concentration of the molecules is the same, dynamic equilibrium has been reached… There is no NET change of concentration Molecule of dye Membrane Equilibrium

25. Human body examples of Diffusion: • Oxygen diffusing from lungs to blood • Carbon dioxide diffusing from blood to lungs • Nitrogenous waste diffusing from blood in the kidneys into urine • Food particles absorbed in the small intestine from the digestive tract. What is the homeostatic role of the cell membrane in processes of diffusion?

26. B. Facilitated diffusion – molecules that can not cross the cell membrane’s lipid bilayer directly are guided through the protein channels • example: glucose

27. Solute Cell Membrane Protein Channel What is the homeostatic role of the cell membrane in processes of facilitated diffusion?

28. C. Osmosis – diffusion of water across a membrane In osmosis, solute isn’t moving, but the solute is the reason for water movement Hypotonic – concentration of solute molecules in the environment is lower than in the cell HYPO could make a cell POP

29. “hypo” means lower • water comes in and the cell swells

30. Hypertonic – concentration of solute molecules in the environment is greater than in the cell • “hyper” means higher • water leaves and the cell shrinks HYPER will make a cell SHRINK

32. Isotonic – concentration of solute molecules in the environment is equal to the inside of the cell • “iso” means equal • cells neither gain nor lose water

34. Examples: Salty water will be hypertonic to a cell Distilled water will be hypotonic to a cell

35. Plant cells swell until they are restricted by the cell wall • this sets up turgor pressure and result in the cell becoming rigid

36. Water leaves (loss of turgor pressure) the plant cell wilts • This condition is known as plasmolysis

37. If too much water enters an animal cell, the cell will burst - this is called cytolysis What is the homeostatic role of the cell membrane in processes of osmosis?

38. ISOTONIC SOLUTION HYPOTONIC SOLUTION HYPERTONIC SOLUTION ANIMALCELL (1) Normal (2) Lysing (3) Shriveled Plasmamembrane PLANTCELL (4) Flaccid (5) Turgid (6) Shriveled

39. Animal Type of cell - ___________ 8.5% NaCl hypertonic Type of solution - _____________ 91.5% H2O out How will water move? _____ 45% NaCl osmosis 55% H2O By what process? ______________ in How will salt move? ______ diffusion By what process? _______________ shrink in size What will happen to the cell? _____________ plasmolysis Biological term - __________________

40. Plant Type of cell - ___________ 8.5% NaCl hypotonic Type of solution - _____________ 91.5% H2O in How will water move? _____ 0% NaCl Distilled water osmosis By what process? ______________ 100% H2O out How will salt move? ______ diffusion By what process? _______________ swell and become rigid What will happen to the cell? _____________ turgor pressure Biological term - __________________

41. Passive Transport high low

42. 2. Active transport – requires cellular energy • materials move from an area of lesser concentration to an area of greater concentration

43. In active transport, materials are moved against the concentration gradient. • Types of active transport are found in: • protein pumps • endocytosis • exocytosis

44. Types of Active Transport A. A Protein Pump pushes substances against their concentration gradient in order to keep the amounts that the cell prefers. Example: Nerve cells use a sodium-potassium pump to keep desirable concentrations inside the cell. During a nerve impulse, protein channels OPEN, all solutes diffusewiththe concentration gradients, but away from the desired levels…oh no!!! That’s where the sodium-potassium pump comes in…see next slide…--pumping things back so that there IS the desired concentration gradient.

45. example: the sodium-potassium pump • sodium (out) and potassium (in)

46. Proton Pump Link to online video

47. ActiveTransport Endocytosis vs. Exocytosis Online link to video clip

48. B. Endocytosis – passage of large molecules into the cell through the cell membrane

49. The material is enclosed in a vesicle which pinches off from the cell membrane

50. 2. Phagocytosis is the process of large particles being taken into the cell by means of extensions of cytoplasm that go out and engulf the large particles. • This is a leukocyte (white blood cell) in • your blood that is shooting out extensions • to get the large particles that you see.