Today: Hormones and the Endocrine System cont’d Hormones and the Endocrine System cont’d Case...

Today:Today: Hormones and the Hormones and the

Endocrine System Endocrine System cont’dcont’d

Case StudyCase Study Into to Into to

Homeostasis?Homeostasis?Reminder: Next week’s

group quiz moved to Thursday!

Vertebrate Coordination of Vertebrate Coordination of Endocrine and Nervous Endocrine and Nervous

SystemsSystems Hypothalmus: Hypothalmus:

endocrine endocrine gland in the gland in the brain of brain of vertebratesvertebrates


SystemsSystems Oxytocin: Oxytocin:

Positive-feedback Positive-feedback mechanism mechanism involved in involved in release of milk release of milk from mammary from mammary glands and glands and uterine uterine contractioncontraction

Vertebrate Vertebrate Coordination Coordination of Endocrine of Endocrine and Nervous and Nervous

Systems: Systems: ADHADH

What would an Anti-Diuretic

Hormone (ADH) do?

When would I produce it?

Vertebrate Vertebrate Coordination Coordination of Endocrine of Endocrine and Nervous and Nervous

Systems: Systems: ADHADH


SystemsSystems Anterior pituitary Anterior pituitary

produces a variety of produces a variety of tropic and nontropic tropic and nontropic hormoneshormones

Tropic hormones Tropic hormones regulate the function of regulate the function of endocrine cells or glands. endocrine cells or glands. Example: Example: TSHTSH

Nontropic hormones Nontropic hormones target nonendocrine target nonendocrine tissues. Example: tissues. Example: MSHMSH


SystemsSystems


SystemsSystems A few hormones, A few hormones,

like Growth like Growth Hormone (GH) Hormone (GH) have both tropic have both tropic and nontropic and nontropic effectseffects

These impacts make GH tempting for adult athletes to abuse!

Rugby player makes history with Rugby player makes history with growth hormone bangrowth hormone ban

By ROBERT MILLWARD, AP Sports Writer Robert Millward, Ap Sports By ROBERT MILLWARD, AP Sports Writer Robert Millward, Ap Sports Writer Writer – Mon Feb 22, 2010 2:48 pm ET– Mon Feb 22, 2010 2:48 pm ET

LONDON – In a major breakthrough in the fight against doping, a British rugby league player has become the first athlete to be suspended for using human growth hormone.Terry Newton admitted taking the substance in a statement released by his attorneys on Friday. The United Kingdom Anti-Doping authority announced a two-year ban on Monday after Newton was fired by his club, Wakefield."It's the first time and very significant," WADA director general David Howman said. "It shows the people who say that HGH cannot be detected that it can. The sports people who said it can't be detected are fooling themselves."

Example: Example: TSHTSH, a tropic , a tropic

hormone, acts hormone, acts in a in a hormone hormone

cascadecascade

Functions of the Thyroid HormoneFunctions of the Thyroid Hormone

Involved in both homeostasis Involved in both homeostasis (blood pressure, heart rate, (blood pressure, heart rate, etc.) and developmentetc.) and development

Excessive secretion = Excessive secretion = hyperthyroidism (high temp, hyperthyroidism (high temp, high blood pressure, weight high blood pressure, weight loss)loss)

Insufficient production = Insufficient production = hypothyroidism (weight gain, hypothyroidism (weight gain, lethargy, intolerance to cold)lethargy, intolerance to cold)

Iodine was added to salt Iodine was added to salt in 1924 when up to a in 1924 when up to a third of US adults third of US adults suffered from goiter!suffered from goiter!

Controlling Calcium (CaControlling Calcium (Ca2+)2+)

Stress and the Adrenal GlandStress and the Adrenal Gland

Moving on to ApplicationsMoving on to Applications

Next in Homeostasis Survey:Next in Homeostasis Survey:OSMOREGULATIONOSMOREGULATION

OsmoregulatioOsmoregulation:n:

management of management of body’s water body’s water and solute and solute

contentcontent

www.pbs.org

Transport EpitheliaTransport EpitheliaMost animals use layers of specialized Most animals use layers of specialized

epithelial cells to regulate solute epithelial cells to regulate solute movements. (Remember our tight movements. (Remember our tight

junctions??)junctions??)

Transport Transport EpitheliumEpithelium

Example: Salt Example: Salt excretion in excretion in marine birdsmarine birds

Osmoregulation: Metabolic Osmoregulation: Metabolic WastesWastes

Most wastes (except Most wastes (except COCO22) must be dissolved ) must be dissolved

in water to be in water to be eliminated, including eliminated, including nitrogenous wastes.nitrogenous wastes.

Breakdown of proteins Breakdown of proteins produces ammonia produces ammonia

(soluble but very toxic)(soluble but very toxic)

To secrete ammonia To secrete ammonia directly, must have directly, must have

access to lots of water!access to lots of water!

So what kinds of animals would you expect to secrete

ammonia directly?



Not an efficient strategy Not an efficient strategy for land animals!for land animals!Most mammals, Most mammals,

amphibians, marine amphibians, marine fish, turtles, etc., fish, turtles, etc.,

excrete mainly excrete mainly ureaurea

Urea is much less toxic, Urea is much less toxic, but but requires energyrequires energy

to produceto produce


Option #3: Option #3: Uric AcidUric Acid

Land snails, insects, birds, Land snails, insects, birds, and some reptiles use and some reptiles use uric acid to eliminate uric acid to eliminate

nitrogenous wastenitrogenous waste

Uric Acid is also relatively Uric Acid is also relatively nontoxic, but insoluble nontoxic, but insoluble in water! (And even in water! (And even more expensive to more expensive to

produce!)produce!) So why bother??

Water BalanceWater Balance

All animals must balance the rate of All animals must balance the rate of water uptake and water losswater uptake and water loss

Two solutions: Two solutions: osmoconformersosmoconformers and and osmoregulators!osmoregulators!

Where do you expect to find each of these?

Measuring OsmolarityMeasuring Osmolarity

Osmolarity = total solute Osmolarity = total solute concentration expressed as moles of concentration expressed as moles of

solute per litersolute per liter

Common unit in biology = milliosmoles Common unit in biology = milliosmoles per liter (mosm/L)per liter (mosm/L)

Osmoregulation has Energetic Osmoregulation has Energetic CostsCosts

““Expense” depends on:Expense” depends on:

Concentration gradient between Concentration gradient between animal and environmentanimal and environment

Permeability of surface to water and Permeability of surface to water and solutessolutes

Energetic cost of membrane-Energetic cost of membrane-transport worktransport work

General Strategies: Saltwater General Strategies: Saltwater AnimalsAnimals

Invertebrates: Invertebrates: Most have Most have body fluids body fluids

that are that are isoosmotic to isoosmotic to

the the surrounding surrounding environmentenvironment

Nudibranch, Photo: Robbie Wong, MSU

Note: This is not as easy as it

seems!


Vertebrates: Most Vertebrates: Most have body fluids that have body fluids that

are hypoosmotic are hypoosmotic compared to the compared to the

surrounding surrounding environmentenvironment..

So which way does water

move?

HabitatOsm

(mOsm/litre)

Na K Ca Mg Cl Urea

Seawater 1000 459 10 10 53 538 -

Hagfish Seawater 1002 454 7 9 23 532 3

Lamprey Freshwater 248 120 3 2 2 96 0.4

Dogfish Seawater 1075 269 4 3 1 258 376

Stingray Freshwater 308 150 6 7 4 149 1

Flounder Sea water 337 180 4 3 1 160

Goldfish Freshwater 293 142 2 6 3 107Data courtesy of Professor Balment,

University of Manchester

Exceptions to the “Rule”: Exceptions to the “Rule”: Marine Sharks Marine Sharks

(Chondrichthyes)(Chondrichthyes) Internal salt Internal salt

concentration lowconcentration low Kidneys remove Kidneys remove

some of this salt; some of this salt; rest is excreted by rest is excreted by the rectal gland or the rectal gland or in fecesin feces

However, net However, net diffusion of water is diffusion of water is inward!!inward!!

Photo: Pisces Conservation LTD


Marine reptiles and Marine reptiles and birds drink seawater birds drink seawater to replace lost to replace lost water.water.

Kidneys cannot Kidneys cannot produce produce concentrated urine concentrated urine and excess salts are and excess salts are excreted using excreted using special glandsspecial glands..

Photo: BBC News

General Strategies: Freshwater General Strategies: Freshwater AnimalsAnimals

Net movement of water?

Salt issues?

General Strategies: Freshwater AnimalsGeneral Strategies: Freshwater Animals

Opposite problem! Opposite problem! Water is constantly Water is constantly diffusing in as salts are diffusing in as salts are lostlost

Many freshwater Many freshwater animals cope by animals cope by excreting large amounts excreting large amounts of very dilute urine, of very dilute urine, replacing salts through replacing salts through food and active food and active transport from the transport from the environmentenvironment

General Strategies: Freshwater AnimalsGeneral Strategies: Freshwater Animals

What about the What about the salmon??salmon??

Ocean-going salmon drink seawater and

excrete excess salt from the gills

After migrating to freshwater, they stop drinking and

produce lots of dilute urine

Also Problematic: Temporary Also Problematic: Temporary WatersWaters

Animals inhabiting Animals inhabiting temporary waters temporary waters

must have must have mechanisms for mechanisms for preventing the preventing the

effects of effects of desiccation desiccation

(anhydrobiosis)(anhydrobiosis) Ditylenchus larvae in anhydrobiosis(photo M.McClure)

General Strategies: Terrestrial General Strategies: Terrestrial AnimalsAnimals

Desiccation is a Desiccation is a serious serious regulatory regulatory challenge!challenge!

Many adaptations:Many adaptations: waxy coveringswaxy coverings nocturnal lifestylenocturnal lifestyle kidneys!kidneys!

A Kangaroo (desert) Rat

Example: This Kangaroo Rat doesn’t drink!

Potential sources of water??

ExcretionExcretion

Most systems share a Most systems share a two-step process:two-step process:

1. Fluid collection1. Fluid collection

2. Content adjusted 2. Content adjusted by selective by selective

reabsorption or reabsorption or secretionsecretion

ExcretionExcretion

Step 1: Fluid CollectionStep 1: Fluid Collection

Typically involves filtration Typically involves filtration through membranes of through membranes of

transport epitheliatransport epithelia

Membranes retain cells Membranes retain cells and large molecules and large molecules

(proteins); water and (proteins); water and small solutes end up in small solutes end up in

the filtratethe filtrate

This process is non-selective!

ExcretionExcretion

Step 2: Selective Step 2: Selective Reabsorption or Reabsorption or

SecretionSecretion

Useful solutes (glucose, Useful solutes (glucose, some salts, amino acids) some salts, amino acids)

are reabsorbed; are reabsorbed; nonessential solutes and nonessential solutes and

wastes are left or wastes are left or actively transported into actively transported into

the filtratethe filtrate

Excretion: A Excretion: A Simple Simple ModelModel

Animal Survey Stop 1: Animal Survey Stop 1: FlatwormsFlatworms

Planaria utilize simple Planaria utilize simple excretory systems excretory systems

called called protonephridiaprotonephridia

This system is a network This system is a network of dead-end tubules of dead-end tubules

branching through the branching through the body; cilia draw fluid in body; cilia draw fluid in through the flame bulb through the flame bulb into the tubule systeminto the tubule system

Animal Animal Survey Survey Stop 1: Stop 1: FlatworFlatwor

msms

Animal Survey Stop 2: Animal Survey Stop 2: AnnelidsAnnelids

Most annelids utilize Most annelids utilize metanephridiummetanephridium

Each segment has a pair Each segment has a pair of metanephridia of metanephridia

immersed in coelomic immersed in coelomic fluid; fluid is collected in fluid; fluid is collected in

a ciliated funnel and a ciliated funnel and then passed through the then passed through the

collecting tubule and collecting tubule and out the nephridiopore out the nephridiopore

Photo: Dr. Frederic Janzen, ISU

Animal Survey Stop 2: Animal Survey Stop 2: AnnelidsAnnelids

Animal Survey Stop 3: Animal Survey Stop 3: InsectsInsects

Insects and terrestrial Insects and terrestrial arthropods utilize arthropods utilize

malpighian tubules malpighian tubules to to remove nitrogenous remove nitrogenous

wastes (and wastes (and osmoregulation)osmoregulation)

Outfoldings of the digestive Outfoldings of the digestive tract secrete wastes and tract secrete wastes and

salts from the hemolymph salts from the hemolymph into the lumen into the lumen

Survey Stop 4: Mammalian Survey Stop 4: Mammalian KidneysKidneys

Mammals have two Mammals have two kidneys, each supplied kidneys, each supplied

with LOTS of blood with LOTS of blood flow via the renal flow via the renal

artery; as a result, all artery; as a result, all blood is filtered blood is filtered

~every 30 minutes~every 30 minutes

Our kidneys can excrete Our kidneys can excrete urine 4X as urine 4X as

concentrated (1,200 concentrated (1,200 mosm/L) as our blood!mosm/L) as our blood!

Image: The Biology Project

Survey Stop 4: Mammalian Survey Stop 4: Mammalian KidneysKidneys

Functional Unit = the Functional Unit = the NephronNephron (single (single

long tubule with a long tubule with a ball of capillaries)ball of capillaries)

Kidneys are Kidneys are compacted bundles compacted bundles of nephrons (~1.3 of nephrons (~1.3

million) all draining, million) all draining, eventually, into the eventually, into the

ureterureterImage: The Biology Project

Kidney Kidney FunctioFunctio

nn1.Blood Pressure

forces fluid from the

blood (glomerulus)

into the lumen of

Bowman’s capsule

Non-selective!! (~180 L of

filtrate/day)


nn

2. In the proximal tubule,

salt, water and

nutrients are

reabsorbed

TEM of the TEM of the Proximal Proximal TubuleTubule

EM: Loyola University Chicago Stritch School of Medicine

Note all folding on the inner

surface of these cells.

Form and function!


nn In the

descending loop,

membranes are highly

permeable to water. Water diffuses out passively!

(Note that this means the

interstitial fluid must be

increasingly concentrated!)


nnIn the ascending

loop, the transport

epithelium is permeable to salt but not water. Salt

initially diffuses out, and is later

actively transported

out.

(Lots of energy expended here!)


nn The collecting

duct actively reabsorbs

salt. This, in turn,

increases the rate of diffusion of water out of the filtrate.


nn

Remember: Kidney Function is Remember: Kidney Function is Well-Regulated!Well-Regulated!

Kidney Function is Well-Kidney Function is Well-Regulated!Regulated!

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