1. Temperature and the Urinary System
Chapter 50

2. Temperature is determined through multiple factors
Internal Factors
Metabolic Rate
All metabolic reactions produce heat as a by-product
External Factors
Sunlight, Water, Underground
Behavior

3. Body Temps
Low body temperatures do not allow high metabolic rates because of the temperature dependence of enzymes
High metabolic rates may cause excessive heating (which requires cooling)

4. Heat Transfer
4 types
Radiation – transfer of energy by electromagnetic radiation (hot to cold)
Conduction – direct transfer of heat between two objects that are touching (hot to cold)
Convection – transfer of heat by movement of a gas or liquid
Evaporation – energy used to vaporize a liquid
Other factors
Surface area
Small animals lose heat faster than larger ones
Temperature Difference – larger the difference the faster the transfer
Heat conductance
Those with a surface with high conductance will gain or lose heat faster
Fur, Feathers, and Blubber

6. Organisms are classified based on heat source
Homeotherms – regulate their temp around a set point (warm blooded, endotherms)
Poikilotherms – allow their body to conform to their environment (cold blooded, ectotherms)
Heterotherms – fall in between these groups

7. Ectotherms Ectotherms Endotherms Regulate Temp with behavior
Sunbathing, increased movement
Shade, Bathing
Have a generally low metabolic rate
Endotherms
Create internal Metabolic Heat
Warm the organism when cold
Body must be cooled if overheated
Vasoconstriction/dilation
Sweating/Panting

8. Hypothalamus
If the body overheats, then the hypothalamus tells your body to exhibit heat loss reactions
If the body temp falls then the hypothalamus tells the body to create more heat
Fever
Reseting the bodies normal temp to a higher number
Many bacteria can not survive at higher temperatures
Torpor
Reduction of metabolic rate and body temp to produce a state of dormancy (hibernation)

9. The Mammalian Kidney
Blood is delivered to the kidney through the renal artery
It is filtered and urine is produced
Urine drains from each kidney through the ureter to the urinary bladder
Upon filling the bladder urine is passed out of the body through the urethra

12. Functions of the Kidney
Filtration
Blood is filtered into the tubule leaving cells and large proteins in the blood
Reabsorption
Selective movement of important solutes out of the filtrate to be put back into the blood
Secretion
Movement of substances from the blood into the filtrate (toxic substances)

14. The Nephron Filtering Unit of the Kidney
1 million nephrons in each kidney
Afferent arteriole brings blood to the glomerulus blood pressure forces fluid through capillary walls (blood cells and plasma proteins are too large to go through) Glomerulus is surrounded by Bowmans capsule. Capsule has slits so that filtrate can enter the nephron tubules.
Blood components not filtered drain into the efferent arteriole
Next the filtrate enters a portion of the nephron called the proximal convoluted tubule then proceeds into the Loop of Henle and finally through the distal convoluted tubule. Reabsorption and secretion occur in these tubules.
The Distal convoluted tubules drain into a collecting duct that will combine with others to drain urine into the renal pelvis

15. Reabsorption& Secretion
Water
Blood is filtered many times each day to produce 1-2L of urine
Water is reabsorbed from the filtrate by the proximal convoluted tubule, the descending loop of Henle, and the collecting duct
Secretion of water can help to regulate blood volume
Glucose/other Nutrients
Reabsorbed by active transport and cotransport
Secretion of wastes
Done by the same methods as reabsorption but in the opposite direction
Secretion of H+ into the urine maintains the blood at a neutral pH

16. Proximal Convoluted Tubule
Virtually all nutrient molecules present in the filtrate are reabsorbed by the proximal convoluted tubule
2/3 of NaCl and Water is reabsorbed here too
Na+ is actively transported out of the tubule
Cl- follows it by electical attraction
Water follows it by osmosis

17. Loop of Henle Ascending Limb Descending Limb Impermeable to water
Thick Portion has Na+ actively transported out, Cl- follows
Thin portion has NaCl flow out by diffusion
Descending Limb
Permeable to water but not to NaCl
Water moves out by osmosis because of the concentration of NaCl in the fluid that is secreted by the ascending limb

18. Distal Convoluted Tubule and Collecting Duct
The very dilute fluid from the distal convoluted tubule enters the collecting duct.
Water diffuses out due to the higher concentrations of salt outside
This concentrates the urine

20. Hormones Controlling Osmoregulatory functions.
ADH- Stimulates reabsorption of water by the kidneys.
Aldosterone- stimulates distal convoluted tubules and collecting ducts to reabsorb Na+
When blood flow is reduced renin is released, which is then turned into angiotensin1 and then angiotensin 2. This then signals the release of aldosterone
Atrial Natriuretic hormone- promotes the excretion of salt and water

21. Osmoregulation across the phyla
Flatworms- tubules called protonephridia- open only out
Anelids- nephridia- open both in and out
Arthropoda- malpighian tubules which are extensions of the digestive tract. Lets very little water our only waste products and feces.
Vertebrates- kidney filters and reabsorbs important nutrients

22. Types of Nitrogenous Wastes