excretory: disposal & osmoregulation
DESCRIPTION
Excretory: Disposal & Osmoregulation. Excretion: Disposal of nitrogen-containing wastes Osmoregulation: Control of gain and loss of water and solutes Osmoregulation based largely on regulating solutes Water follows the movement of solutes by osmosis. Excretion: Aquatic Animals. - PowerPoint PPT PresentationTRANSCRIPT
Excretory: Disposal & Osmoregulation
Excretion: Disposal of nitrogen-containing wastes
Osmoregulation: Control of gain and loss of water and solutes
Osmoregulation based largely on regulating solutes
Water follows the movement of solutes by osmosis
Excretion: Aquatic Animals
Animals must dispose of nitrogenous waste Metabolism produces nitrogenous wastes from breakdown of proteins and nucleic acids
Most aquatic animals dispose of their nitrogenous wastes as ammonia
Highly soluble in water Diffuses rapidly across cell membranes
Excretory: Saltwater Fish
Excretion: Land Animals
Land animals convert ammonia to less toxic compounds Can be safely stored and transported in the body Released periodically by excretory system Requires energy for conversion Different adaptations and type of reproduction determine excretion as urea or uric acid
Excretory: Disposal & Osmoregulation
Urea Excreted by mammals, most amphibians, sharks, and some bony fishes
Can be stored in concentrated solution but requires water for disposal
Uric acid Excreted by birds, reptiles, insects, some amphibians
Excreted as solid paste for water conservation
Uses more energy for excretion
Excretory
Excretory: Waste Protein and nucleic acid breakdown - nitrogen-containing wastes toxic by-products of Ammonia poisonous but soluble and easily disposed of
Urea less toxic, easy to store and excrete
Some land animals save water by excreting a virtually dry waste
Excretory: Waste in Urine Urea – from amino acid breakdown
Uric Acid – from nucleic acid breakdown
Creatinine – muscle metabolism waste product
Excretory System The excretory system
expels wastes regulates water and salt balance
Two human kidneys each contain ~ million nephrons
Urine leaves kidneys via ureters
Stored in urinary bladder
Excretory Systen
Each nephron: folded tubule and associated blood vessels
Nephrons extract filtrate from blood
Refine filtrate into much smaller amount of urine
Figure 25.9D
Bowman’s capsule
Arteriolefrom renalartery
Arteriolefrom glomerulus
Branch ofrenal vein
Glomerulus
Capillaries
Fromanothernephron
Collectingduct
1 Proximal tubule
2 Loop of Henlewith capillarynetwork
3 Distaltubule
D. DETAILED STRUCTURE OF A NEPHRON
LE 25-11
Blood
Bowman’scapsule
Cortex
Medulla
Proximal tubule
Nutrients H2OHCO3NaCI
HSomedrugsand poisons
Loop ofHenle
H2O
NaCI
NaCI HCO3
H2O
HK
NaCI
Collectingduct
Distal tubule
H2O
Urea
NaCI
Urine (to renal pelvis)
Filtrate compositionH2ONaCI
H
HCO3
Urea
GlucoseAmino acidsSome drugs
Reabsorption
Secretion
– –
–
Excretory: Filtration Filtration (Bowman’s capsule)
Blood pressure forces water and many solutes from blood (glomerulus) into nephron
Excretory: Reabsorption / Secretion Controlled secretion of H+ and reabsorption of bicarbonate ions help regulate blood pH
Secretion also includes active transport of drugs and poisons
Reabsorption of salts and urea allow osmotic reabsorption of water
Excretion: Reabsorption / Secretion PROXIMAL TUBULE – always reabsorb glucose and amino acid- sometimes water, sodium, potassium, calcium depending on need
Secretionurea, creatinine, ions, drugs and toxins
Excretory: Reabsorbing Water LOOP OF HENLE- much water reabsorbed via active transport of salt
- salt concentration in kidney higher in medulla
- Longer loop – more water conservation (desert animals)
Excretory: Reabsorption/Secretion DISTAL TUBULE- specialized “Urine fine tuning”
- Aldosterone hormone – increases amount of sodium reabsorbed into blood (water follows)
Excretory: Water Reabsorption in Collecting Duct Water reabsorbed ADH (antidiuretic hormone) – cause collecting walls to be permeable to water to be reabsorbed
Caffeine interferes with ADH (dehydration)
Excretory: Regulates Blood Pressure Releases RENIN when blood pressure low- enzyme that causes production of chemical (angiotensin II) to constrict blood vessel
- Angiotensin II increase aldosterone production
Excretory: Dialysis
Homeostasis: Liver It assists the kidneys by making urea from ammonia
breaking down toxic chemicals
Liver Blood from intestines flows through the liver before distribution to the rest of the body Allows liver to adjust blood’s chemical content