Overview of homeostasis & excretion


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  • Freshwater fish and saltwater fish have simply evolved differently to adapt to their environments over time. Freshwater fish have "physiological mechanisms that permit them to concentrate salts within their bodies" while saltwater fish do not have this mechanism.
  • A large proportion of the creatures traditionally called "warm-blooded", such as mammals and birds, fit all three of these categories. However, over the past 30 years, studies in the field of animal thermophysiology have revealed many species belonging to these two groups that do not fit all these criteria. For example, many bats and small birds are poikilothermic and bradymetabolic when they sleep for the night, or day, as the case may be. For these creatures, the term heterothermy was coined.Further studies on animals that were traditionally assumed to be cold-blooded have shown that most creatures incorporate different variations of the three terms defined above, along with their counterparts (ectothermy, poikilothermy and bradymetabolism), thus creating a broad spectrum of body temperature types (see the section titled "Temperature control in cold-blooded animals", below). Even some fish have warm-blooded characteristics. Swordfish and some sharks have circulatory mechanisms that keep their brains and eyes above ambient temperatures, and thus increase their ability to detect and react to prey.[1][2][3] Tunas and some sharks have similar mechanisms in their muscles, improving their stamina when swimming at high speed.[4]
  • Many birds' and small mammals' (e.g. tenrecs) body temperature drops during daily inactivity, such as at night for diurnal animals or during the day for nocturnal animals thus reducing the energy cost of maintaining body temperature. Human metabolism also slows down slightly during sleep.
  • Removal of metabolic waste products and toxic materials from organs to maintain a constant internal environment
  • Overview of homeostasis & excretion

    1. 1. Homeostasis & Excretion<br />LPK TB Chapter 12 & 11<br />1<br />
    2. 2. Homeostasis is … <br />Excretion is …<br />How are homeostasis and excretion related?<br />2<br />
    3. 3. In the case of these fishes…<br />Homeostasis is somewhat like how Salty Sail maintains the water potential of his cells. <br />Drinking a lot of water and Excreting salt is the way he achieves it. <br />3<br />
    4. 4. Definition<br />Homeostasis is the maintenance of a constant internal environment. <br />e.g. Body temperature, blood glucose concentration & blood water potential<br />Excretion is the process by which metabolic waste products and toxic materials are removed from the body of an organism. <br />4<br />
    5. 5. Principle of Homeostasis<br />Normal/Ideal condition <br />when it becomes<br />Not normal/ideal<br />Sends a <br />Which allows condition to go back to <br />Stimulus<br />to<br />Receptor <br />Activates <br />Corrective Mechanism<br />e.g. Excretion<br />Which causes <br />Response/Changes<br />e.g. negative feedback <br />5<br />
    6. 6. What is homeostasis?<br /><ul><li>Control and maintenance of a constant internal </li></ul> environment around the cells in the body<br />What is negative feedback?<br /><ul><li>A feedback mechanism is called negative if the resulting </li></ul> action opposes the condition that triggers it. <br />6<br />
    7. 7. What are the organs involved in maintaining homeostasis in our body?<br />Lungs <br />Liver <br />Kidney <br />Skin <br />Excretory organs <br />7<br />
    8. 8. 8<br />
    9. 9. THE SKIN <br />9<br />
    10. 10. Learning Objectives for ‘Skin’ <br /><ul><li>Identify and label parts of the skin
    11. 11. Describe the functions of parts of the skin
    12. 12. Describe the maintenance of a constant body temperature in humans</li></ul>10<br />
    13. 13. Structure of the Mammalian Skin<br />7<br />6<br />8<br />6) Sense receptors<br />7) Blood vessels<br />8) Hair<br />5<br />5) Sweat pore<br />9<br />4) Hair follicle<br />9) Sebaceous gland<br />4<br />1<br />1) Epidermis<br />10<br />2<br />10) Erector muscle<br />2) Dermis<br />11) Sweat gland<br />3<br />3) Subcutaneous fat<br />11<br />11<br />
    14. 14. Skin <br />What are the 4 general functions of the mammalian skin? <br /><ul><li>Excretory organ
    15. 15. Removes excess salts, water and urea in the form of sweat
    16. 16. Temperature regulation
    17. 17. to maintain a constant body temperature
    18. 18. Sense organ
    19. 19. Detect pain, pressure changes and temperature
    20. 20. Protective covering</li></ul> Prevents entry of bacteria, protects from mechanical damage and excessive loss of water by evaporation<br />12<br />
    21. 21. outer cornified layer<br />Structure of Epidermis – Protective Layer<br /><ul><li>Outer cornified layer</li></ul> consists of flat, dead cells that continually wear off<br /> preventbacteria from gaining entry into body<br /> prevent mechanical injury to cells deeper inside skin<br />13<br />
    22. 22. outer cornified layer<br />granular layer <br /><ul><li>Granular layer
    23. 23. contains living cells which is gradually pushed up to </li></ul> replace the worn-out cells in the cornified layer<br />14<br />
    24. 24. outer cornified layer<br />granular layer<br />Malpighian layer<br /><ul><li>Malpighian layer
    25. 25. contains actively dividing cells to produce new epidermis
    26. 26. contains melanin pigments that gives skin its colour and </li></ul> absorbs ultraviolet radiation<br />15<br />
    27. 27. Why do some people have freckles?<br /><ul><li>Due to uneven melanin production.
    28. 28. More obvious in fair-skinned people.
    29. 29. Freckles become more prominent when exposed to sunlight because the skin produces extra melanin in sunny conditions.</li></ul>16<br />
    30. 30. Why doesn’t bleeding occur when we lightly scratch ourselves sometimes?<br />17<br /><ul><li>No blood vessels in epidermis</li></li></ul><li>Structure of dermis:<br /><ul><li>Connective tissue with many collagen fibres and elastic</li></ul> fibres<br /><ul><li>Nerve endings
    31. 31. Detect pain, changes in temperature and pressure on skin
    32. 32. Hair follicle and hair
    33. 33. Sebaceous gland</li></ul> secrete sebum to lubricate skin<br /><ul><li>Erector muscles</li></ul> Controls the erection of hair<br />18<br />
    34. 34. Structure of dermis:<br /><ul><li>Sweat gland
    35. 35. Absorbs salts and water from blood capillaries to produce </li></ul>sweat for temperature regulation and excretion<br /><ul><li>Blood vessels
    36. 36. Regulate temperature by vascular constriction or dilation</li></ul>19<br />
    37. 37. Why do we get pimples?<br />20<br /><ul><li>Dead skin cells block hair follicles 
    38. 38. sebum builds up in clogged pores
    39. 39. Sebaceous glands continue to produce sebum but it has no where to go 
    40. 40. Sebum becomes infected with bacteria. Causes clogged pores to become inflamed and swollen. Zits!!!</li></li></ul><li>Why do we get wrinkles and fine lines?<br />21<br />Fine lines and wrinkles arise because of irregular thickening of the dermis and because of a decrease in the amount of water held by the epidermis. This is mainly caused by sun damage and exposure to environmental toxins such as tobacco smoke. <br />
    41. 41. Why are tattoos permanent?<br />22<br />What you see when you look at a tattoo is the ink that's left in the skin after the tattooing. The ink is not in the epidermis, which is the layer of skin that we see and the skin that gets replaced constantly, but instead intermingles with cells in the dermis and shows through the epidermis. The cells of the dermis are remarkably stable, so the tattoo's ink will last, with minor fading and dispersion, for your entire life! <br />
    42. 42. Why is the mammalian skin considered as an excretory organ? <br />The skin produces sweat, which may contain a small amount of metabolic waste product, i.e. urea. <br />Sweat contains:<br /><ul><li>water
    43. 43. dissolved sodium chloride
    44. 44. urea</li></ul>23<br />
    45. 45. Sweat is secreted by the sweat gland.<br />It travels through the sweat duct and out onto the skin via the sweat pore.<br />24<br />
    46. 46. Test Yourself<br />Which part of the skin regulates the following functions? <br />Epidermis<br />Protection from harmful agents of external environment: biological germs, UV light & chemicals <br />Subcutaneous fat <br />Shock absorber <br />Blood vessels & sweat glands <br />Temperature regulation <br />Subcutaneous fat<br />Insulation <br />Nerve endings <br />Sensation <br />Sebaceous glands <br />Lubrication  <br />Subcutaneous fat<br />Calorie reserve <br />Epidermis<br />Vitamin D synthesis <br />Sweat glands<br />Body odour <br />25<br />
    47. 47. Which part of the skin contributes to thermal homeostasis?<br />Epidermis<br />Protection from harmful agents of external environment: biological germs, UV light & chemicals <br />Subcutaneous fat <br />Shock absorber <br />Blood vessels & sweat glands <br />Temperature regulation <br />Subcutaneous fat<br />Insulation <br />Nerve endings <br />Sensation <br />Sebaceous glands <br />Lubrication  <br />Subcutaneous fat<br />Calorie reserve <br />Epidermis<br />Vitamin D synthesis <br />Body odour <br />Sweat glands<br />26<br />
    48. 48. 27<br />Q. What do we call animals which keep their body temperature at a roughly constant level, regardless of the environment’s temperature? <br />Warm-bloodedness generally refers to three separate aspects of thermoregulation.<br />Endothermy (control via internal means strictly - metabolism) <br />Homeothermy (thermoregulation within regardless of external influence; opposite = poikilothermy)<br />Tachymetabolism (high resting metabolism rate)<br />
    49. 49. Reptile <br />Mammals <br />Birds <br />Fish <br />Amphibian <br />Invertebrates<br />Animals <br />“Warm blooded”/<br />Homoiothermic<br />“Cold blooded”/<br />Poikilothermic<br />28<br />
    50. 50. 29<br />
    51. 51. Mechanisms in warm-blooded creatures <br />30<br />
    52. 52. Metabolic rate slows down<br />4<br />3<br />Erector muscle<br />1<br />2<br />Arterioles<br />In hot conditions<br /> Less heat is produced<br />Arterioles in skin dilate<br />Sweat gland active<br /> More blood and more heat send to skin<br />Erector muscles relax<br /> As sweat evaporates, latent heat lost<br /> Hair lie flat, close to skin<br />31<br />
    53. 53. Metabolic rate speeds up<br />5<br />4<br />Erector muscles<br />1<br />2<br />Shivering occurs<br />3<br />In cold conditions<br />Arterioles<br /> More heat is produced<br />Erector muscles contract<br /> Hairs trap a layer of air close to skin. <br />Arterioles in skin constrict<br />Sweat gland inactive<br /> Less blood and less heat send to skin<br />32<br />
    54. 54. Principle of Homeostasis<br />Normal temperature<br />when it becomes<br />Too Hot<br />Too Cold<br />Heat receptors on skin sends<br />Stimulus<br />Which allows condition to go back to <br />Which allows condition to go back to <br />to<br />Hypothalamus<br />causes <br />Arterioles constrict<br />Arterioles dilate<br />Which leads to <br />Increased heat loss<br />Reduced heat loss<br />33<br />
    55. 55. Summary for ‘Skin’<br /><ul><li>Parts of the skin consists of the </li></ul> epidermis; dermis; subcutaneous layer <br />Corn|Granular|Malphigian; connective tissues containing HENSBS<br /><ul><li>Function of parts of the skin for </li></ul>Maintenance of a constant body temperature in humans<br />Excretion of waste products<br />Sense<br />Protection<br />34<br />
    56. 56. Recap - What is excretion?<br />Excretion is the process by which metabolic waste products and toxic materials are removed from the body of an organism. <br />35<br />
    57. 57. Q1. What is metabolism?<br />Excretion is the process by which metabolic waste products and toxic materials are removed from the body of an organism. <br />Chemical activities of the cells which keep the organism alive<br />Anabolic<br />C a t a b ol I c<br />36<br />
    58. 58. 37<br />Metabolic<br />+<br />Anabolic<br />Catabolic<br />=<br />
    59. 59. Metabolic Waste Products<br />substances left over from excretory processes<br />cannot be used (surplus/lethal effect)<br />must be excreted.  <br />E.g.Nitrogen compounds, water, CO2, <br />phosphates, sulfates, medicals, food additives<br />38<br />
    60. 60. Q2. Why must living organisms excrete metabolic waste products?<br />Accumulation of these substances <br />Can interfere with proper functioning of cells<br />Change the concentration of tissue fluid around cells<br />39<br />
    61. 61. Q2.1 What is the difference between excretion and egestion?<br />Excretion ≠ Egestion<br /> (metabolic waste) (undigested waste)<br />40<br />