BIOL 22000 Lecture Notes - Lecture 18: Calcitriol, Red Blood Cell, Urination
2 Aug 2018
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Lecture 18
• Kidney receives a rich blood supply
o About 20 to 25 percent of the cardiac output go to the kidney for filtering
• Functions of Mammalian Kidney
o Regulation of H2O and inorganic ion balance (such as Na+, K+, H+, Ca+)
o Elimination of metabolic waste products (such as urea, uric acid, creatine)
o Removal of foreign chemicals (pesticides, drugs, food additives…)
o Gluconeogenesis (during periods of prolonged fasting)
o Secretion of hormones and an enzyme
▪ Erythropoietin (stimulates red blood cells production)
▪ 1,25 dihydroxyvitamin D3 (important for CA+ homeostasis)
▪ Renin (an enzyme; controls formation of angiotensin II which influences
blood pressure and NA+ and K+ homeostasis)
o Kidney is an endocrine organ
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• Micturition
o
o The bladder itself is a smooth muscle
o External sphincter is a striated somatic muscle
▪ You have conscious control over this muscle
o When the bladder contracts the sphincter must relax, so urine can go out
o This is a coordinated effort
▪ Integrating increase activity in parasympathetic in the bladder to cause a
bladder contraction, and a decrease in the somatic intervation of the
urethra sphincter allowing sphincter to be opened
▪ Any type of nervous degeneration is associated with a problem with the
micturition
•
o We tend to find filtration component the nephrons in the medulla
o Nephron is tubule and it dives down into the medulla of the kidney
o Nephrons does the filtering and the absorption
