chpt. 44 Osmoregulation & Excretion

Osmoregulation - Regulating solute concentrations (ions & poisonous N-compounds) in the blood - Balancing the gain and loss of water from the blood

Excretion Getting rid of N-containing waste products (produced via. metabolism)

Metabolic waste… if they accumulated, they would reach toxic concentrations!!! must be dissolved in water when removed from a body.

Types of metabolic waste…

NH3 = high toxicity! NH3 = can only be tolerated at low concentrations Most aquatic animals secrete ammonia immediately in the water where it washes away!

NH2 = lower toxicity compared to ammonia NH3 NH2 = can be stored in the body, therefore, no need to be surrounded by water for instant elimination A disadvantage is that these animals must use ATP to produce Urea from Ammonia

GREAT for animals with little access to water Uric acid = lowest toxicity compared to NH3 Uric acid = insoluble in water, and can be stored in an egg/ excreted as a paste / LESS H2O LOSS! GREAT for animals with little access to water

COST: takes even more ATP to produce than Urea (NH2)

Increasing amount of ATP to produce end product decreasing toxicity & less water needed to excrete

you require 2L of water per day

The excretory system is a system of simple organs, tubes, muscles, and nerves -they work together to create, store, and carry urine

Excretory System excretes waste products regulates water & salt

Excretory System filters blood / produces URINE

Excretory System carries urine to the bladder

Excretory System temporarily stores urine

Excretory System urine exits body via. this tube

Water level in blood, must remain within a certain range of osmolarity, the hypothalmus monitors this

The Excretory System focuses on the KIDNEY Capsule A. Renal Vein B. Renal Artery Renal Medulla Ureter Renal Cortex

The Excretory System focuses on the KIDNEY Blood pressure is higher in the vessels that lead to the kidney… WHY?

Water level in blood, must remain within a certain range… the kidney assists in this

Lets look inside the KIDNEY

NEPHRON- filter element    Proximal Tubule   NEPHRON- filter element

 Fluid forced through the capillaries forming FILTRATE NaCl H2O  Proximal Tubule NH3 H+ Fluid forced through the capillaries forming FILTRATE

NaCl H2O  Proximal Tubule NH3 H+ Secretion to maintain a constant pH & reabsorption of H2O & NaCl into epithelium

NEPHRON- filter element    Proximal Tubule   Descending limb of the Loop of Henle  NEPHRON- filter element

 Reabsorption of water into the interstitial fluid NaCl H2O NH3 H+  Descending limb of the Loop of Henle Reabsorption of water into the interstitial fluid

 Filtrate becomes more concentrated NaCl H2O NH3 H+  Descending limb of the Loop of Henle Filtrate becomes more concentrated

NEPHRON- filter element    Proximal Tubule  Descending limb of the Loop of Henle    Ascending limb of the Loop of Henle NEPHRON- filter element

 Reabsorption of NaCl into interstitial fluid H2O NH3 H+ Ascending limb of the Loop of Henle  Reabsorption of NaCl into interstitial fluid

 Filtrate becomes more dilute! Ascending limb of the Loop of Henle NaCl H2O NH3 H+ Ascending limb of the Loop of Henle  Filtrate becomes more dilute!

NEPHRON- filter element    Proximal Tubule  Descending limb of the Loop of Henle    Ascending limb of the Loop of Henle  Distal Tubule NEPHRON- filter element

 pH regulation secretion of water & salt Distal Tubule H2O NaCl H2O NH3 K+ H+ H+ pH regulation secretion of water & salt

Carries filtrate secretes water & urea NaCl H2O NH3 H+ Carries filtrate secretes water & urea  Collecting Duct

Filtrate becomes more concentrated NaCl H2O NH3 H+ Filtrate becomes more concentrated  Collecting Duct

URINE CONCENTRATION changes throughout the journey!!

hypothalamus detect an increase in the osmolarity Osmoreceptors in hypothalamus Thirst Hypothalamus Drinking reduces blood osmolarity to set point ADH THE NERVOUS SYSTEM AND HORMONES monitor this, and can REGULATE KIDNEY FUMCTIONS Increased permeability Pituitary gland Distal tubule H2O reab- sorption 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 Collecting duct Homeostasis: Blood osmolarity

hypothalamus detect an increase in the osmolarity Osmoreceptors in hypothalamus Hypothalamus ADH Pituitary gland ADH produced in the hypothalmus -> stored in pituitary gland (promotes reabsorption of water into blood) STIMULUS The release of ADH is triggered when osmo- receptor cells in the hypothalamus detect an increase in the osmolarity of the blood

hypothalamus detect an increase in the osmolarity Osmoreceptors in hypothalamus Hypothalamus ADH Increased permeability Pituitary gland Osmoreceptor cells in hypothalmus monitor the osmolarity of blood above 300 =>ADH released Distal tubule STIMULUS The release of ADH is triggered when osmo- receptor cells in the hypothalamus detect an increase in the osmolarity of the blood Collecting duct

hypothalamus detect an increase in the osmolarity Osmoreceptors in hypothalamus Hypothalamus ADH Increased permeability Pituitary gland ADH increases the permeability of interstitial tissue (in the kidney) to water. Increases water reabsorption out of nephron Distal tubule H2O reab- sorption 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 Collecting duct Homeostasis: Blood osmolarity

hypothalamus detect an increase in the osmolarity Osmoreceptors in hypothalamus Hypothalamus ADH Increased permeability Pituitary gland Activity of receptor cells in hypoth. reduced-> NEGATIVE FEEDBACK Distal tubule H2O reab- sorption 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 Collecting duct Homeostasis: Blood osmolarity

hypothalamus detect an increase in the osmolarity Osmoreceptors in hypothalamus Hypothalamus ADH Increased permeability Pituitary gland Activity of receptor cells in hypoth. reduced-> NEGATIVE FEEDBACK Less ADH released! Distal tubule H2O reab- sorption 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 Collecting duct Homeostasis: Blood osmolarity

hypothalamus detect an increase in the osmolarity Osmoreceptors in hypothalamus Thirst Hypothalamus Drinking reduces blood osmolarity to set point ADH Increased permeability Pituitary gland ADH stored in pituitary gland Distal tubule H2O reab- sorption 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 Collecting duct Homeostasis: Blood osmolarity

Osmoreceptor cells in hypothalmus monitor the osmolarity of blood Osmoreceptors in hypothalamus Hypothalamus ADH Increased permeability Pituitary gland Osmoreceptor cells in hypothalmus monitor the osmolarity of blood below 300 => very little ADH released Distal tubule Collecting duct

Decreases permeability of distal tube and collecting duct Osmoreceptors in hypothalamus Thirst Hypothalamus Drinking reduces blood osmolarity to set point ADH Pituitary gland Decreases permeability of distal tube and collecting duct Distal tubule Collecting duct Homeostasis: Blood osmolarity

Vampire bats are unique, they feed on blood…

South American Vampire bats are unique, they feed on blood…

They use their teeth, & make an incision in their prey

They have anticoagulents so the blood does not clot, prey not harmed

They fly for HOURS to search for suitable victims, they need MUCH blood for energy

Problem: they would be too heavy to fly!!!

Their kidneys are specialized to offload MUCH water from the blood - VERY DILUTE URINE, now they can fly back home.

Next Problem: blood has much protein… lots of UREA, little access to drinking water while roosting!!!

Kidneys produce small quantities of highly concentrated urine.

WHAT AN EVOLUTIONARY ADAPTATION!!! GO DARWIN!

Structure and function are related in the various organ systems of animals. Select two of the following four organ systems in vertebrates: * respiratory * digestive * excretory * nervous For each of the two systems you choose, discuss the structure and function of two adaptations that aid in the transport or exchange of molecules (or ions). Be sure to related structure to function in each example.