Presentation 12 - Osmoregulation And Excretion

Key Concepts ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

Key Words ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

Types of metabolic waste produced by living systems ,[object Object],[object Object],[object Object],[object Object]

Osmoregulation ,[object Object],[object Object],[object Object],[object Object],[object Object]

Types of nitrogenous wastes ,[object Object],[object Object],[object Object],[object Object],[object Object],300 – 500 mL/gN 1 step rxn 50 mL/gN 4 step rxn 10 mL/gN 15 step rxn

Type of Organism Structure Product of excretion Other features Plants Stomata, lenticels Insoluble crystals Crystals are kept inside plant cells Cnidarians and echinoderms No excretory organ - Osmoconformers, isoosmotic with environment Freshwater protists and sponges Contractile vacuole

Excretory Systems ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

Flatworms Flame cells Unsegmented roundworms Protonephridia, closed network of dead-end tubes lacking openings Annelids Metanephridia, open-ended network of tubes with internal openings that collect body fluids Type of Organism Structure Product of excretion Other features

Molluscs Nephridia or metaphridia Crustaceans Antennal/green gland Insects Malpighian tubules and digestive tract Uric acid Type of Organism Structure Product of excretion Other features

Marine fishes Gills Ammonia Elasmobranchs (sharks, skates, rays) Kidneys Urea Rectal glands – excrete excess NaCl Freshwater fishes Gills Ammonia or urea Amphibians and mammals Kidneys Urea Liver converts ammonia to urea Reptiles and birds Kidneys Uric acid Salt glands Type of Organism Structure Product of excretion Other features

From Blood Filtrate to Urine: A Closer Look Proximal tubule – secretion and reabsorption Filtrate H 2 O Salts (NaCl and others) HCO 3 – H + Urea Glucose; amino acids Some drugs >> Same concentration of substances in blood plasma Key Active transport Passive transport CORTEX OUTER MEDULLA INNER MEDULLA ,[object Object],[object Object],[object Object],[object Object],Thick segment of ascending limb – reabsorption - Impermeable to water but permeable to salt Thin segment of ascending limb Collecting Duct – permeable to water but not to salt, bottom portion is permeable to urea NaCl NaCl NaCl Distal tubule – secretion and reabsorption NaCl Nutrients Urea H 2 O NaCl H 2 O H 2 O HCO 3  K + H + NH 3 HCO 3  K + H + H 2 O 1 4 3 2 3 5

[object Object],[object Object],H 2 O H 2 O H 2 O H 2 O H 2 O H 2 O H 2 O NaCl NaCl NaCl NaCl NaCl NaCl NaCl 300 300 100 400 600 900 1200 700 400 200 100 Active transport Passive transport OUTER MEDULLA INNER MEDULLA CORTEX H 2 O Urea H 2 O Urea H 2 O Urea H 2 O H 2 O H 2 O H 2 O 1200 1200 900 600 400 300 600 400 300 Osmolarity of interstitial fluid (mosm/L) 300

Nervous system and hormones regulate kidney functions ,[object Object],[object Object],[object Object],[object Object],Osmoreceptors in hypothalamus Drinking reduces blood osmolarity to set point H 2 O reabsorption helps prevent further osmolarity increase STIMULUS: The release of ADH is triggered when osmo- receptor cells in the hypothalamus detect an increase in the osmolarity of the blood Homeostasis: Blood osmolarity Hypothalamus ADH Pituitary gland Increased permeability Thirst Collecting duct Distal tubule

[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],Increased Na + and H 2 O reabsorption 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) Aldosterone Adrenal gland Angiotensin II Angiotensinogen Renin production Renin Arteriole constriction Distal tubule JGA

Some medical aspects concerning the excretory system ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

Presentation 12 - Osmoregulation And Excretion

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Presentation 12 - Osmoregulation And Excretion