temperature and the urinary system chapter 50. temperatureis determined through multiple factors...
Post on 18-Dec-2015
214 views
TRANSCRIPT
Temperature and the Urinary System
Chapter 50
Temperatureis determined through multiple factors Internal Factors
Metabolic Rate• All metabolic reactions produce heat as a
by-product
External Factors Sunlight, Water, Underground
Behavior
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)
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
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
Ectotherms Ectotherms
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
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)
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
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)
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
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
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
Loop of Henle Ascending 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
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