Chapter 44

 Living in the world organisms had a choice:  regulate their internal environment ▪ maintain relatively constant internal conditions  conform to the external environment ▪ allow internal conditions to fluctuate along with external changes mammals internally regulatereptiles fluctuate with external conditions

 Control of solute concentrations and balancing water gain and loss.  Based upon osmosis.  Osmolarity = total solute concentration expressed as molarity.  -Hyperosmotic  -Isoosmotic  -Hypoosmotic  * Water moves from a hypoosmotic solution to a hyperosmotic solution- H to L!

 Osmoconformer- isoosmotic with surrounding. – All are marine animals.  Osmoregulator- controls internal environment independent of external.  Stenohaline- can be either of above- can’t tolerate substantial changes in external osmolarity.  Euryhaline- can be either of above- can survive large external changes in osmolarity.

 Keeping the balance  animal body needs to coordinate many systems all at once ▪ temperature ▪ blood sugar levels ▪ energy production ▪ water balance & waste disposal ▪ nutrients ▪ ion balance ▪ cell growth  maintaining a “steady state” condition

 Osmoregulation  solute balance & gain or loss of water  Excretion  elimination of nitrogenous wastes  Thermoregulation  maintain temperature within tolerable range

 Most invertebrates are osmoconformers  Must move solutes to keep homeostasis  Most marine vertebrates are osmoregulators  Ocean strongly dehydrating  Fish balance by drinking seawater  Use gills and kidneys to get rid of salt  Chloride cells in gills  Retain water in kidneys

 Sharks are not hypoosmotic because tissue:  High amounts of urea- a N waste  TMAO- organic molecule protects from urea damage  Together these maintain an osmolarity close to seawater  Sharks are often considered osmoconformers  Body actually hyperosmotic water enters body  Sharks don’t drink water  Excess water removed in kidneys

 Opposite problems of marine animals  Bodies must be hyperosmotic  Problem of gaining water by osmosis and losing salts by diffusion  Balance by drinking no water and excreting large amounts of dilute urine  Salt replenished by eating and uptake across gills  Chloride cells in gills move salts in

Why do all land animals have to conserve water? always need water for life always lose water (breathing & waste) may lose life while searching for water  Water balance  freshwater = hypotonic ▪ manage water moving into cells ▪ salt loss  saltwater = hypertonic ▪ manage water loss from cells ▪ salt accumulation  land ▪ manage water loss ▪ need to conserve water

 Threat of dehydration  Humans die if lose 12% of body water  Body covering  Nocturnal  Lose water in urine, feces, across skin, gas exchange etc.  Balance by eating and drinking  Produce water by metabolism

 Energy Cost  Cost depends on how large difference is between internal and external environments  Diffusion will try to equalize and so osmoregulators must expend energy to keep osmotic balance  Active Transport- to manipulate solute concentration

 1 or more layers of specialized epithelial cells that regulate solute movement  Specific solutes in specific directions

 Salt secreting glands of marine birds remove salt from blood allowing them to drink sea water during months at sea  secrete a fluid much more salty than ocean water How does structure of epithelial cells govern water regulation?  different proteins in membranes  sea birds pump salt out of blood  freshwater fish pump salts into blood from water

|  What waste products?  what do we breakdown? ▪ carbohydrates = CHO  CO 2 + H 2 O ▪ lipids = CHO  CO 2 + H 2 O ▪ proteins = CHON  CO 2 + H 2 O + N ▪ nucleic acids = CHOPN  CO 2 + H 2 O + P + N ▪ relatively small amount in cell H H N –C– R | H C–OH || OH CO 2 + H 2 O NH 2 = ammonia Animals can’t store proteins

 Ammonia (NH 3 )  very toxic ▪ carcinogenic  very soluble ▪ easily crosses membranes  must dilute it & get rid of it… fast!  How you get rid of N-wastes depends on  who you are (evolutionary relationship)  where you live (habitat)

 Ammonia  most toxic  freshwater organisms  Urea  less toxic  terrestrial  Uric acid  least toxic  egg layers  most water conservative N waste

 Nitrogen waste disposal in water  if you have a lot of water you can dilute ammonia then excrete ▪ freshwater fish pass ammonia continuously through gills ▪ need to excrete a lot of water anyway so excrete very dilute urine ▪ freshwater invertebrates pass ammonia through their whole body surface

 Nitrogen waste disposal on land  evolved less toxic waste product ▪ need to conserve water ▪ urea = less soluble = less toxic  kidney ▪ filter wastes out of blood ▪ reabsorb H 2 O ▪ excrete waste ▪ urine = urea, salts, excess sugar & H 2 O  urine is very concentrated  concentrated NH 3 would be too toxic

 2NH 2 + CO 2 = urea  combined in liver  Requires energy to produce  worth the investment of energy  Carried to kidneys by circulatory system H H N H H N CO

 Nitrogen waste disposal in egg  no place to get rid of waste in egg  need even less soluble molecule ▪ uric acid = less soluble = less toxic  birds, reptiles, insects

 Polymerized urea  large molecule  precipitates out of solution ▪ doesn’t harm embryo in egg ▪ white dust in egg ▪ adults excrete white paste ▪ no liquid waste ▪ white bird poop! And that folks… is why a male bird doesn’t have… a you know what!

 Protonephridia- flatworms  Network of dead end tubes external opening  Tubes branch through body  Cell units called “flame bulbs” cap branches of each protonephridium  Covered with cilia draws water and solutes from interstitial fluid through bulb releasing to outside  Urine has low solute concentration

 Annelids- earthworms  Excretory organ that open internally to coelom  Each segment of worm has a pair of metanephridia  Pass dilute urine

 Insects and terrestrial arthropods  Remove wastes and osmoregulate  Come out from dead end tubes in hemolymph to digestive tract

 Key functions  filtration ▪ body fluids (blood) collected ▪ water & soluble material removed  reabsorption ▪ reabsorb needed substances back to blood  secretion ▪ pump out unwanted substances to urine  excretion ▪ remove excess substances & toxins from body

 Urinary system filters blood & helps maintain water balance (osmoregulation)  pair of bean-shaped kidneys  supplied with blood ▪ renal artery ▪ renal vein

nephron

that’s called a “counter current exchange system”  Functional units of kidney  1 million nephrons per kidney  Function  remove urea & other solutes (salt, sugar…)  Process  liquid of blood (plasma) filtered into nephron  selective recovery of valuable solutes

 Interaction of circulatory & excretory systems  Circulatory system  glomerulus = ball of capillaries  Excretory system  nephron  Bowman’s capsule  loop of Henle ▪ descending limb ▪ ascending limb  collecting duct

 Filtered out  H 2 O  glucose  salts / ions  urea  Not filtered out  cells  proteins

Descending limb Ascending limb  Proximal tubule  reabsorbed ▪ NaCl ▪ active transport Na + ▪ Cl - follows by diffusion ▪ H 2 O ▪ glucose ▪ HCO 3 - ▪ bicarbonate ▪ buffer for blood pH

Descending limb Ascending limb  Loop of Henle  descending limb  many aquaporins in cell membranes  high permeability to H 2 O  low permeability to salt  reabsorbed  H 2 O structure fits function!

Descending limb Ascending limb structure fits function!  Loop of Henle  ascending limb  low permeability to H 2 O  Cl - pump  Na + follows by diffusion  reabsorbed  salts  maintains osmotic gradient

 Distal tubule  reabsorbed  salts  H 2 O  HCO 3 -  bicarbonate

Nephron: Reabsorption & Excretion  Collecting duct  reabsorbed  H 2 O  excretion  urea passed through to bladder

 How is all this re-absorption achieved?  tight osmotic control to reduce the energy cost of excretion  as much as possible, use diffusion instead of active transport

 Not filtered out (remain in blood)  cells u proteins  Reabsorbed: active transport  Na + u amino acids  Cl - u glucose  Reabsorbed: diffusion  Na + u Cl -  Reabsorbed: osmosis  H 2 O  Excreted  urea u H 2 O  any excess solutes

 Monitor blood osmolarity  amount of dissolved material in blood in brain ADH = anti-diuretic hormone High solutes

 High blood osmolarity level  too many solutes in blood ▪ dehydration, salty foods  release ADH (anti-diuretic hormone) made in hypothalamus and stored in posterior pituitary (in brain)- also called vasopressin  increases permeability of collecting duct & reabsorption of water in kidneys ▪ increase water absorption back into blood ▪ decrease urination  also stimulates thirst = drink more Get more water into blood fast Alcohol inhibits ADH… makes you urinate a lot!

 Low blood osmolarity level or low blood pressure Low solutes renin activates angiotensinogen angiotensin triggers aldosterone aldosterone increases absorption of NaCl & H 2 O in kidney

 Low blood osmolarity level or low blood pressure  JGA releases renin in kidney  renin converts angiotensinogen to angiotensin  angiotensin causes arterioles to constrict ▪ increase blood pressure  angiotensin triggers release of aldosterone from adrenal gland  increases reabsorption of NaCl & H 2 O in kidneys ▪ puts more water & salts back in blood Get more water & salt into blood fast Why such a rapid response system?

Kidney disease is one of the costliest illnesses in the U.S. today. Each year, more than 50,000 Americans die because of Kidney Disease. More than 260,000 Americans suffer from chronic renal failure and need dialysis or kidney transplantation to stay alive. More than 35,000 patients are waiting for kidney transplants, but only about 11,000 will receive transplants because of a shortage of suitable organ donors. The Facts About Kidney Disease

Review: how do your kidneys function? Your kidneys do some important jobs to keep your body healthy:  Balance your body fluids. Excess fluid is filtered out as urine.  Remove waste products from your blood.  Remove drugs and toxins from your body.  Release hormones into your blood to : - Control blood pressure - Make red blood cells - Keep your bones healthy.

Kidney diseases are diseases of the kidney substance that alter the structure and function of the kidney. There are many diseases of the kidneys such as glomerulonephritis, pyelonephritis & polycystic kidney.The treatment and potential for recovery depends on the type of disease. Kidney diseases can lead to kidney failure. Normal Kidneys Polycystic kidneys Healthy kidneys eliminate waste from the blood & maintain the body’s normal chemical balance. Fluid filled sacs, called cysts, characterize autosomal Dominant polycystic kidney disease. What are kidney diseases?

 Kidney failure is a condition where the kidneys are incapable of performing its normal function. Certain toxic substances which should have been excreted such as urea and creatinine are accumulated in the body.  The two main causes of kidney failure are Diabetes & High Blood Pressure. Many other conditions can harm the kidneys. These include :  Glomerulonephritis, a disease that causes inflammation in the kidneys.  Inherited diseases like polycystic kidney disease, which causes many cysts to form in the kidneys.  IgA nephropathy or other nephropathy. Essentially an autoimmune problem. Exact trigger not well known.  Very large, long standing kidney stone.  NSAID or pain killer like ponstan, voltaren can cause kidney failure. What is kidney failure ?

Who is at Risk ? Risk factors for chronic kidney disease include :  Diabetes  High blood pressure  A family history of chronic kidney disease  Older age  Drug overdose, excessive use of alcohol  Long term use of pain medications such as aspirin, panadol, ibuprofen and treatment with antibiotic.

1.Blood in urine. Most often not visible. But sometimes may appear tea color urine. 2.Protein in urine, low urine output. 3.Swelling of face and legs 4.Tiredness, fatigue 5.Pale and sallow complexion 6.Have dry and itchy skin 7.Poor appetite, sometimes accompanied with nausea and vomiting 8.High blood pressure. Especially when it is hard to bring it to good control. How to early detect kidney ailments?

Dialysis is a type of treatment that removes wastes and excess fluid from your blood. 3 forms of dialysis can be done – hemodialysis, peritoneal dialysis and continuous ambulatory peritoneal dialysis ( CAPD ). A kidney transplant is an operation to place a new kidney in your body to take over the work of your failed kidneys. The kidney may come from someone who has died or from a living donor who may be a close relatives, friend or possibly a stranger who wished to donate a kidney to anyone in need of a transplant. You need dialysis when you develop End stage renal disease – usually by the time you lose about 85 – 90% of your Kidney function. Dialysis and Kidney Transplant – what are they ?

 Kidney transplantation is the most effective therapy for end-stage renal disease.  The transplanted organ can come from either a live donor or deceased donor.  Most deceased donor organs come from brain dead donors.  Non-standard criteria donors:  Expanded criteria donors (ECD).  Donation after cardiac death (DCD).