Test info 2010-11 Average: 15 out of 30 Range: 3 – 24

Test info 2011-12 Average: 18.5 out of 30 Range: 11 – 26 Corrections due: Friday Lab notebooks due: Thursday Procedure – 1 sentence for each test Include last 2 tables, conclusion Test Ch. 44-46 next Wednesday Revised syllabus on website

Chapter 44: Osmoregulation and Excretion Osmoregulation regulating solute concentrations balance the gain/loss of water

Excretion Get rid of nitrogenous waste of metabolism Cellular wastes

Osmoregulator vs. an Osmoconformer does not actively adjust its internal osmolarity Marine animals Osmoregulator – actively controls osmolarity

Figure 44.3 Osmoregulation in marine and freshwater bony fishes Gain of water and salt ions from food and by drinking seawater Osmotic water loss through gills and other parts of body surface Excretion of salt ions from gills Excretion of salt ions and small amounts of water in scanty urine from kidneys Uptake of water and some ions in food Osmotic water gain by gills large amounts of water in dilute (a) Osmoregulation in a saltwater fish (b) Osmoregulation in a freshwater fish Hypoosmotic to ocean loses LOTS of water at gills “Drinks like a fish” excretes salt & little urine Hyperosmotic to lake gain LOTS of water at gills LOTS of dilute urine

Problem for land animals: Dehydration adaptations preventing: Shells, exoskeleton, being nocturnal

Nitrogenous waste products animals excrete: fig. 44.8 Amino Groups – -NH2 Ammonia Most aquatic animals, out gills Urea – Mammals, amphibians, sharks Uric acid Reptiles, birds, insects

Figure 44.8 Nitrogenous wastes Ammonia – -NH3 - very sol. in water - VERY toxic - easily passes through membranes Urea - 100,000X <toxic than – NH3 - -NH3 + CO2 in liver - conserves water Uric acid- not very sol. in water - paste-like - little water loss - stored in amniotic egg Proteins Nucleic acids Amino acids Nitrogenous bases –NH2 Amino groups Most aquatic animals, including most bony fishes Mammals, most amphibians, sharks, some bony fishes Many reptiles (including birds), insects, land snails Ammonia Urea Uric acid NH3 NH2 O C N H HN

Filtration Reabsorption Secretion Excretion 4 main functions of excretory systems: fig. 44.9 Filtration Reabsorption Secretion Excretion

Figure 44.9 Key functions of excretory systems: an overview Filtration. The excretory tubule collects a filtrate from the blood. Water and solutes are forced by blood pressure across the selectively permeable membranes of a cluster of capillaries and into the excretory tubule. Reabsorption. The transport epithelium reclaims valuable substances from the filtrate and returns them to the body fluids. Secretion. Other substances, such as toxins and excess ions, are extracted from body fluids and added to the contents of the excretory tubule. Excretion. The filtrate leaves the system and the body. Capillary Excretory tubule Filtrate Urine 1 2 3 4

Evolution of excretory systems

Figure 44.10 Protonephridia: the flame-bulb system of a planarian Nucleus of cap cell Cilia Interstitial fluid filters through membrane where cap cell and tubule cell interdigitate (interlock) Tubule cell Flame bulb Nephridiopore in body wall Tubule Protonephridia (tubules) Protonephridia – Planaria

Figure 44.11 Metanephridia of an earthworm Metanephridia – Earthworm Nephrostome Metanephridia Nephridio- pore Collecting tubule Bladder Capillary network Coelom

Figure 44.12 Malpighian tubules of insects Digestive tract Midgut (stomach) Malpighian tubules Rectum Intestine Hindgut Salt, water, and nitrogenous wastes Feces and urine Anus tubule Reabsorption of H2O, ions, and valuable organic molecules HEMOLYMPH Malpighian tubules – insects

Structure and Function of the kidney fig. 44.13

Kidneys Site of H2O balance/salt regulation Bean shaped – 1 million nephrons Blood supply Renal artery Renal vein (drains)

Structure/function Kidney – 2 distinct regions Renal cortex tubules & Renal medulla blood vessels Nephron – functinal unit of kidney single long tubule ball of capillaries – glomerulus blind end of tubule – Bowman’s capsule

Filtration of Blood BP forces filtrate from glomerulus blood  lumen of Boman’s capsule Capillaries – permeable to water & small solutes Filtrate – salts, glucose, a.a, vit., nitrogenous wastes

Figure 44.13 The mammalian excretory system Posterior vena cava Renal artery and vein Aorta Ureter Urinary bladder Urethra (a) Excretory organs and major associated blood vessels Juxta- medullary nephron Cortical Collecting duct To renal pelvis Renal cortex medulla 20 µm (b) Kidney structure Kidney Section of kidney from a rat Afferent arteriole from renal artery Glomerulus Bowman’s capsule Proximal tubule Peritubular capillaries SEM Efferent arteriole from glomerulus Branch of renal vein Descending limb Ascending Loop of Henle Vasa recta Distal tubule (d) Filtrate and blood flow (c) Nephron

Thursday Turn in lab journals near the window Test corrections due tomorrow Ch. 44 and 45 today

1. Glomerulus/Bowman’s capsule 2. Proximal tubule 3. Loop of Henle Pathway of filtrate thru nephron: Figure 44.14 1. Glomerulus/Bowman’s capsule 2. Proximal tubule 3. Loop of Henle Descending Ascending 4. Distal tubule 5. Collecting duct

Filtrate – fluid extracted from blood stream, contains solutes Figure 44.14 The nephron and collecting duct: regional functions of the transport epithelium Proximal tubule Filtrate H2O Salts (NaCl and others) HCO3– H+ Urea Glucose; amino acids Some drugs Key Active transport Passive transport CORTEX OUTER MEDULLA INNER Descending limb of loop of Henle Thick segment of ascending limb Thin segment limbs Collecting duct NaCl Distal tubule Nutrients HCO3 K+ NH3 1 4 3 2 5 Filtrate – fluid extracted from blood stream, contains solutes

Function of Nephron (Figure 44.14) Proximal and distal tubules pH regulation Descending loop Reabsorpation of water Ascending loop Reabsorption of NaCl Collecting duct Reabsorption of NaCl, scant urea – helps to conserve H2O

Figure 44.15 How the human kidney concentrates urine Nacl 300 100 400 600 900 1200 700 200 Active transport Passive transport OUTER MEDULLA INNER MEDULLA CORTEX Osmolarity of interstitial fluid (mosm/L)

Figure 44.15 How the human kidney concentrates urine Nacl 300 100 400 600 900 1200 700 200 Active transport Passive transport OUTER MEDULLA INNER MEDULLA CORTEX Urea Osmolarity of interstitial fluid (mosm/L)

Urine pathway Kidney (nephron renal pelvis) Ureter Bladder Urethra – out body

Regulation of Kidney Function: Hypothalamus Fig. 44.16 Hypothalamus ADH antidiuretic hormone enhances fluid retention (neg. feedback) RAAS Renin-angiotensin-aldosterone sys.- leads to an increase of blood volume & pressure

Figure 44.16 Hormonal control of the kidney by negative feedback circuits Osmoreceptors in hypothalamus Drinking reduces blood osmolarity to set point Increased Na+ and H2O reab- sorption in distal tubules Homeostasis: Blood pressure, volume STIMULUS: The juxtaglomerular apparatus (JGA) responds to low blood volume or blood pressure (such as due to dehydration or loss of blood) H2O reab- sorption helps prevent further osmolarity increase The release of ADH is triggered when osmo- receptor cells in the hypothalamus detect an increase in the osmolarity of the blood Blood osmolarity Hypothalamus ADH Pituitary gland Increased permeability Thirst Aldosterone Adrenal gland Angiotensin II Angiotensinogen Renin production Collecting duct Distal tubule Arteriole constriction JGA Antidiuretic hormone (ADH) enhances fluid retention by making the kidneys reclaim more water. The renin-angiotensin-aldosterone system (RAAS) leads to an increase in blood volume and pressure. (a) (b)

Explain ADH system RAAS system