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Test info Average: 15 out of 30 Range: 3 – 24
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Test info 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 next Wednesday Revised syllabus on website
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Chapter 44: Osmoregulation and Excretion Osmoregulation regulating solute concentrations balance the gain/loss of water
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Excretion Get rid of nitrogenous waste of metabolism Cellular wastes
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Osmoregulator vs. an Osmoconformer
does not actively adjust its internal osmolarity Marine animals Osmoregulator – actively controls osmolarity
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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
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Problem for land animals:
Dehydration adaptations preventing: Shells, exoskeleton, being nocturnal
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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
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Figure 44.8 Nitrogenous wastes
Ammonia – -NH3 - very sol. in water - VERY toxic - easily passes through membranes Urea ,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
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Filtration Reabsorption Secretion Excretion
4 main functions of excretory systems: fig. 44.9 Filtration Reabsorption Secretion Excretion
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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
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Evolution of excretory systems
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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
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Figure 44.11 Metanephridia of an earthworm
Metanephridia – Earthworm Nephrostome Metanephridia Nephridio- pore Collecting tubule Bladder Capillary network Coelom
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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
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Structure and Function
of the kidney fig
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Kidneys Site of H2O balance/salt regulation
Bean shaped – 1 million nephrons Blood supply Renal artery Renal vein (drains)
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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
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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
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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
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Thursday Turn in lab journals near the window
Test corrections due tomorrow Ch. 44 and 45 today
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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
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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
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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
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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)
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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)
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Urine pathway Kidney (nephron renal pelvis) Ureter Bladder Urethra – out body
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Regulation of Kidney Function: Hypothalamus
Fig Hypothalamus ADH antidiuretic hormone enhances fluid retention (neg. feedback) RAAS Renin-angiotensin-aldosterone sys.- leads to an increase of blood volume & pressure
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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)
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Explain ADH system RAAS system
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