I. Homeostasis Overview

A. Regulator

- use homeostasis to modify internal change

- requires use of energy

B. Conformer

- allows some conditions to change in the body with the environment

II. Thermoregulation

A. 4 Processes for Heat Gain or Loss

1. Conduction – direct transfer of heat between molecules in direct contact

2. Convection – transfer of heat by moving air or liquid over a surface

3. Radiation – emission of electromagnetic waves by objects warmer then absolute zero

4. Evaporation – removal of heat from a surface of a liquid that is losing some of its molecules as gas

B. 4 Categories of Adaptations1. Adjusting Rate of Heat Exchange

a. Insulation – feathers, hair, fatb. Vasodilation / Vasoconstriction c. Countercurrent heat exchange

2. Cooling By Evaporative Heat Lossa. Pantingb. Sweating

3. Behavioral Responsea. Movingb. Baskingc. Hibernationd. Migration

4. Change Rate of Metabolic Heat

C. How Thermoregulation Occurs in Different Organisms

1. Mammals and Birds

a. Moving / shivering

b. Mitochondria make heat instead of ATP / nonshivering thermogenesis

c. Insulation / raise hair or feathers / fat

d. Vasodilation / Vasoconstriction

e. Countercurrent heat exchange

f. Evaporative cooling / sweat, saliva, urine

2. Amphibians and Reptiles

a. Mostly behavioral adaptations

b. “Become” endothermic

3. Fish

a. Most are conformers

b. Countercurrent exchange / cold on surface, warm inside

4. Invertebrates

a. Most are conformers

b. Some are endothermic / shiver, countercurrent exchange, huddle

D. Thermostat

Negative Feedback controlled by the hypothalamus

E. Torpor

• State with low activity and metabolism

1. Hibernation – long term torpor / winter

2. Estivation – summer torpor

3. Daily Torpor

III. Water Balance and Waste Removal

Osmoregulation – management of water and solute composition

A. Transport Epithelium

1. Layer that regulates solute movement

2. Move solutes in specific amounts in a certain direction

3. Joined by tight junctions

B. Nitrogenous Wastes

Ammonia – produced when proteins and nucleic acids are broken down / need ATP to

makeThree Ways to Get Rid of It: Ammonia, Urea,

Uric Acid

1. Ammonia

• Can only be tolerated in low concentrations

• Very toxic

• Need to have access to lots of water to use it

• Occurs across invertebrates entire body

• Lose through gills

2. Urea

• Made from CO2 and Ammonia in the liver

• Low toxicity

• Can be stored and transported in high concentrations

• Needs less water / good for terrestrial organisms

• Mammals, adult amphibians, marine fish, and turtles use it

3. Uric Acid

• Secreted as a semi solid paste

• Lose little water

• Form as a solid in non-permeable eggs

• Insects, birds, and reptiles use it

C. Balancing Water Gain and Loss

1. Osmoconformers – isoosmotic / only marine

2. Osmoregulators – use energy to control internal osmolarity / discharge water if it lives in a hypotonic environment / takes in water if it lives in a hypertonic environment

3. Stenohaline – can’t tolerate large changes

4. Euryhaline – can tolerate large changes

Balancing Water Gain and Loss (cont.)

5. At Sea- dehydration occurs- get water through food- drink sea water and actively transport salt out through gills- very little urine

6. Fresh Water- contractile vacuoles- excrete lots of dilute urine

7. Land- body coverings- nocturnal

IV. Excretory Systems

A. Protonephridia

• Flame - bulb systems

• Flatworms

• Interstitial fluid enters the flame bulb by cilia and filters fluid

B. Metanephridia

• Annelids / 2 per segment

• Brings in coelomic fluid through the nephrostome and exits via nephridiopore

• Filters out using capillaries

C. Malpighian Tubules

• Insects and terrestrial arthropods

• Found in hemolymph and enter into the digestive tract

• Pull out solutes and water and puts them into the digestive system

• Rectum allows for the reabsorption of water and beneficial solutes

D. Kidney

• Kidney, ureters, bladder, urethra

V. Function of the Kidney

A. Parts

• Renal cortex – outer part• Renal medulla – inner part• Renal artery and vein• Renal pelvis – collection tubes lead here• Nephrons – filter of kidney

- cortical – small Loop of Henle- juxtamedullary – large Loop of Henle

• Blood vessels

A. Parts (cont.)

• Bowman’s Capsule – proximal tubule – loop of Henle – distal tubule – collecting duct

• Renal artery - afferent arteriole – glomerulus – efferent arteriole – peritubular capillaries – vasa recta – renal vein

B. Process

1. Filtrate (urea, bicarbonate, salts, glucose, etc) enters the nephron via the glomerulus into the Bowman’s Capsule and moves into the proximal tubule. It can also enter the proximal tubule via the peritubular capillaries.

B. Process

2. In the proximal tubule drugs and poisons stay in the tubule along with the fact that it makes H+ to regulate pH. Bicarbonate, K+, glucose, A.A., Na+, Cl-, and water are all moved back into the interstitial fluid here through active and passive methods. A lot of this will move back into the peritubular capillaries.

B. Process

3. The filtrate then moves down the descending limb of the Loop of Henle. Water moves out passively into the interstitial fluid and the osmolarity of the filtrate increases.

B. Process

4. Then the filtrate moves up the ascending limb of the Loop of Henle. This is not permeable to water but is to salt. Salt moves out the thin section into the interstitial fluid. The medulla has a very high osmolarity as a result. The thick part of the ascending Loop of Henle actively transports out salt.

B. Process

5. The distal tube comes next and, like the proximal tube, it regulates salts, K+, bicarbonate, and H+ (pH).

B. Process

6. The collection duct is the last part and it is permeable to water but not salt. So, water leaves into the hypertonic interstitial fluid. At the end salt is actively transported out and some urea moves out as well which makes the medulla even more hyperosmotic.

C. Hormones Regulating Kidney Function

1. ADH

• Antidiuretic hormone• Produced by the hypothalamus and stored and

released by the pituitarya. When osmoreceptor cells in the hypothalamus

see osmolarity of blood is high more ADH is made and you also become thirsty

b. ADH works on the distal tubules and collecting ducts to amplify water reabsorption

c. If too much water is taken in, little ADH is made

• Alcohol inhibits the release of ADH

2. RAAS

• Renin-angiotensin-aldosterone systema. JGA (juxtaglomerular apparatus) monitors blood

pressure and volume in afferent arterioleb. If it drops renin is made which converts

angiotensinogen to angiotensin IIc. Angiotensin II constricts arterioles and makes the

proximal tubules reabsorb more water and NaCl raising b.p. and volume

d. It also stimulates the adrenal glands to make aldosterone which makes distal tubes absorb Na+ and water increasing b.p. and volume

e. ANF (atrial natriuretic factor) is made to oppose RAAS