1. Homeostasis Physiological state of the body Internal physical and chemical conditions are maintained within a tolerable range (balance) – Internal temperature, hormone levels, pH, pressure, concentrations of glucose and other solutes in the blood, water balance (osmoregulation)

2. Extracellular Fluid Interstitial fluid – Surrounds fills the spaces between cells and tissues – Approx 10L – Consists of water, sugars, salts, FA, AA, coenzymes, hormones, neurotransmitters, waste products – Regulates flow of chemicals and allows cells to function properly Blood plasma – Helps movement of water and electrolytes throughout the body – Approx 3L

3. Internal Environments Changes in Extracellular Fluid has negative effects on cellular function Body uses organ systems to regulate internal conditions – Nervous system – Endocrine system – Muscular system – Integumentary system – Excretory system – Reproductive system

4. Nervous System (Communication) Brain, spinal cord, peripheral nerves, sensory organs Receives sensory data from the environment Informs body of external conditions Transmits signals throughout the body

5. Endocrine System (Communication) Pituitary, thyroid, pancreas, adrenal (glands) Regulates levels of hormones and other chemicals

6. Excretory System (Protect the Body) Kidneys, bladder, urethra, ureters Rids the body of waste Maintains clean internal environment

7. Integumentary System (Protect the Body) Skin, sweat glands, hair, nails Maintains a constant body temperature

8. Immune System (Protect the Body) White blood cells Protects/fights infection

9. Digestive System (Acquire Energy) Liver Breaks down amino acids Detoxifies harmful chemicals (alcohol) Manufactures important proteins Stores glucose

10. Circulatory System (Acquire Energy) Transports important substances, including food molecules, oxygen, carbon dioxide, hormones throughout the body

11. Respiratory System (Acquire Energy) Exchanges oxygen and carbon dioxide between the lungs and the atmosphere. Oxygen is needed to release energy from food molecules Carbon dioxide is a waste gas

12. Skeletal System (Support and Move Body) Includes bones, ligaments, cartilage Bones protect organs and are points of attachment for muscles

13. Muscular System (Support and Move Body) Provide movement for the body 3 types – Skeletal muscle – move skeleton – Smooth muscle – organs – Cardiac muscle – heart

14. Reproductive System (Produces Next Generation) Includes organs that produce and transport sperm and eggs Enables female to give birth

15. Mechanisms used in Homeostasis Respond to internal and external conditions Feedback systems – Positive/Negative Help bring the body back into balance Breathing rate, heart rate, internal temperature, blood glucose levels

16. Negative Feedback Reduces the output or activity of an organ or system back to its normal range Include 3 elements 1. Sensor – tissues or organs - detects change 2. Integrator - hypothalamus – control centre – compares conditions from environment with to optimal conditions in the body – Set points – ranges of values which need to be maintained 3. Effector – returns measured condition back to set point – response – Antagnositc effectors – produce opposite effect of change detected

17. Positive Feedback Mechanisms Increases change in environmental condition Does not result in homeostasis Cause system to become unstable “fight or flight” response reproduction fever Positive feedback mechanisms operate within negative feedback mechanisms Allows body to be brought back into balance

18. Thermoregulation Internal temperature regulation Negative feedback mechanism Thermoreceptors – compare external temp with internal set point – Found throughout integumentary system Trigger responses (2) – Rate of exothermic reactions in body (metabolism) – Rate of thermal energy exchange through surface of body

19. Hypothalamus Body’s thermostat Maintains body temperature Optimal body temperature – 35⁰ - 37.8⁰ Signals from hypothalamus make us aware of our own temperature

20. Body temp rises above hypothalamus set point → blood vessels dilate/induce vasodilation/sweating → increase blood flow→ increase thermal energy loss to environment (radiation)→ sweat glands activated → body temp decreases Body temp falls below hypothalamus set point → vasoconstriction in skin/ skeletal muscles start shivering→ reduced blood flow→ less thermal energy lost to environment → body temp increases Mechanism

22. Mechanisms of Thermal Energy Exchange Occurs at the surface where body comes into contact with the external environment Exchange of thermal energy occurs through 1 of 4 mechanisms – Conduction – Convection – Radiation – Evaporation All of these mechanisms act simultaneously

23. Thermal Energy Conduction – Flow of thermal energy between molecules that are in direct contact Convection – Transfer of thermal energy within a fluid (liquid or gas) Radiation – Thermal energy is transferred electromagnetically Evaporation – Absorbs thermal energy from skin via water/sweat

24. Homeotherms Animals that maintain a stable internal temperature regardless of external conditions Includes – Poikilotherms – Endotherms – Ectotherms

25. Poikilotherms Fish, amphibians, reptiles, and most invertebrates Body temperature varies with and often matches the temperature of the external environment

26. Endotherms Warm blooded animals (mammals, birds) Homeotherms that use internal physiological mechanisms (metabolism) to generate thermal energy and maintain body temp Remain fully active over a wide range of temperatures Need a constant supply of energy

27. Ectotherms Cold blooded animals (reptiles, amphibians, fish) Homeotherms that use external sources of energy to absorb thermal energy and regulate body temperature Temperature fluctuates with environmental temperature Inactive when temp are too low Undergo thermal acclimatization – Gradual adjustment to seasonal temp

28. Torphor, Hibernation, Estivation Adaptations to survive extreme climates by conserving energy Torphor – Sleeplike state – Metabolic rate and body temperature drop in response to daily temp (nocturnal animals, hummingbird) Hibernation – State of inactivity over an extended period of time Estivation – Seasonal torphor – environment is hot and water is scarce

29. Water Balance Extracellular fluid needs to maintain a constant volume (~15L) of water and balance of solute within the body Mechanism – Osmosis

30. Osmosis Water molecules move from a high concentration to a region of lower concentration across a selectively permeable membrane Osmotic pressure – Results from a difference in water concentration gradient between the two sides of the selectively permeable membrane Hyperosmotic Hypoosmotic Isoosmotic

31. Hyperosmotic – Solution with higher concentration of solute molecules than water molecules – Water tends to move to this side Hypoosmotic – Solution with lower concentration of solute molecules than water molecules – Water tends to move from this solution Isoosmotic – Solution with equal solute and water concentrations on both sides of cellular membrane Osmotic Environments (Cell)

32. Osmoregulation Process of actively regulating the osmotic pressure of bodily fluids Osmole (osmol) – Contributes to osmotic pressure of solution Extracellular fluid = intracellular fluid (isoosmotic) – [solute] remains the same across cellular membrane – [water] remains the same across cellular membrane

33. The Excretory System Main functions (with the help of osmoregulation) – Concentrate wastes and expel them from the body – Regulate fluids and water within the body Organs included – Kidney – Adrenal gland – Ureter – Urinary bladder – Urethra

34. Removal of Metabolic Waste WasteOrigin of WasteOrgan of Excretion AmmoniaBreakdown of amino acids in the liverkidneys UreaConversion of ammonia in the liverkidneys, skin Uric AcidBreakdown of purines in food and drinkkidneys Carbon DioxideCellular respiration (breakdown of glucose)lungs, intestines, skin Bile PigmentsBreakdown of porphyrin ring (hemoglobin)intestines Lactic AcidCellular respiration (breakdown of glucose)kidney Solid WasteBreakdown of foodintestine

35. Mechanism Thirst – Physiological sensation to drink water Stimuli to Thrist – Hypertonicity – cellular dehydration is monitored by the hypothalamus via osmoreceptors Mechanism – Hypothalamus sends a signal to pituaitry gland to release ADH (anti-diuretic hormone/vasopressin) – ADH acts on collecting tubules in nephrons making them more permeable to water – >1% of filtered water is excreted – Reabsorption of water reduces [Na⁺] – Osmoreceptors send signal to hypothalamus stopping release of ADH

36. Kidneys Removes waste Balances blood pH Maintain body’s water balance Blood is supplied to kidney via renal artery Re-enters circulatory system via renal vein

37. Nephrons Functional unit of the kidney (1 000 000 per kidney) Regulate water balance Conduct excretion Different sections of the nephron have specialized functions in formation of urine and conservation of water

38. Urinary Bladder Renal pelvis connects the kidney to the ureter which fills the bladder Holds ~300mL-400mL of urine before exiting the urethra

39. Deamination Occurs in the liver – breakdown of protein Removal of amino group from amino acid Creates ammonia NH₃ (toxic to body) Urea Cycle – Ammonia reacts with bicarbonate and 2 ATP molecules to form urea – Transported to kidneys where excretion occurs via blood

40. Bicarbonate Buffer System (Kidneys) Maintains pH of blood (acid-base homeostasis) Regulates the excretion of H⁺ ions in the urine and reabsorption of bicarbonate into bloodstream – TOO ACIDIC – hydrogen ions are excreted – TOO BASIC – less hydrogen ions are excreted CO₂ dissolved in blood reacts with water to form carbonic acid (H₂CO₃)

41. Formation of Urine Ultimate goal – conserve water, balance salts, concentrate wastes Urine – hypoosmotic to surrounding body fluids – water tends to move from urine into the body fluids 3 Feature of nephron interact to achieve ultimate goal – Arrangement of loop of Henle – Difference in permeability – Concentration gradient of molecules and ions 3 processes interact to achieve formation of urine – Filtration – Reabsorption – Secretion

42. Formation of Urine: Overall Process

43. Filtration Begins at Bowman’s capsule (selectively permeable membrane) Receives water, ions, glucose, AA and urea from glomerulus Difference of pressure allows for transfer of molecules and ions into capsule 1400L of blood pass through kidneys every day Bowman’s capsule filters ~180L from blood ~1.5L is excreted as urine daily

44. Reabsorption Occurs as fluid from Bowman’s capsule enters proximal convoluted tubule, Loop of Henle and distal convoluted tubule Water, ions and nutrients are transferred back into interstitial fluid and peritubular capillaries via passive and active transport Microvilli inside tubules increase surface area Difference in solute concentration allows water to move across the membrane and back into interstitial fluid via osmosis (aquaporins)

45. Secretion Removal of waste products from the blood and interstitial fluid and secreted into the nephron Include – detoxified poisons, water soluble drugs, metabolites, H⁺ Secretion of H⁺ ions balances acidity in body Reabsorption of HCO₃⁻ occurs simultaneously Buffer system controls pH levels of blood – Increased acidity – H⁺ excreted as urine Urine reaches bottom of collecting ducts, flows into renal pelvis, through ureters, into urinary bladder and exits through urethra

46. Kidneys Regulate Blood Oxygen Levels Kidneys monitor blood oxygen levels (RBC’s) If too low – kidneys release erythropoetin (EPO) into the blood stream which stimulates the production of red blood cells

47. Kidney Diseases Renal Failure 2 types 1.Acute – rapid progressive loss of renal function – Injuries, accidents, complications from surgery 2. Chronic – slow progressive with long term consequences – Diabetes mellitus, uncontrolled hypertension, polycystic kidney diseases Treatments – Dialysis – Kidney transplant