Bio 224.3 – animal body systems – lecture 9 – the kidney
the kidneys serve several essential regulatory roles.
§ Remove excess of organic molecules
o Reabsorb glucose, amino acids, and other small molecules
§ Waste products of metabolism
o Urea – 90% reabsorbed, ammonium
o Clearance of toxins
§ Regulation of fluids and electrolytes,
o Sodium, potassium, and other electrolytes,
o Maintain of acid-base balance
o Regulate blood pressure
o Water balance
§ Endocrine organ
o Production of hormones, such as renin, erythropoietin; and activation of Vitamin D.
§ Erythropoietin: produce of red blood cells.
Formation of Urine
§ Depends on the three fundamental functions:
o Filtration
o Reabsorption
o Secretion, called renal clearance or renal excretion
§ Urinary excretion rate = filtration rate – reabsorption rate + secretion
rate
The nephron is the smallest functional unit of the kidney.
§ Each nephron begins with a filtration component that filters the blood entering the
kidney:
o The renal corpuscle
§ This filtrate flows along a tubular structure lined by a single layer of specialized cells
surrounded by capillaries
, o The major functions of these limiting cells are the reabsorption of water and small molecules
from the filtrate into the blood
o The secretion of wastes from the blood into the urine
Renal Corpuscle, also called Malpighian body
§ has high permeability
filtration is driven by the starling Principle
§ the movement of fluids between blood and tissues are determined by differences in:
o hydrostatic pressure
o the colloid osmotic concolic pressure between plasma and the pressure of the Bowman’s
capsule
forces involved in Glomerular Filtration
force effect Magnitude (mm Hg)
Glomerular Favors filtration
Capillary Blood
Pressure
plasma-colloid Opposes filtration
osmotic pressure
the kidneys serve several essential regulatory roles.
§ Remove excess of organic molecules
o Reabsorb glucose, amino acids, and other small molecules
§ Waste products of metabolism
o Urea – 90% reabsorbed, ammonium
o Clearance of toxins
§ Regulation of fluids and electrolytes,
o Sodium, potassium, and other electrolytes,
o Maintain of acid-base balance
o Regulate blood pressure
o Water balance
§ Endocrine organ
o Production of hormones, such as renin, erythropoietin; and activation of Vitamin D.
§ Erythropoietin: produce of red blood cells.
Formation of Urine
§ Depends on the three fundamental functions:
o Filtration
o Reabsorption
o Secretion, called renal clearance or renal excretion
§ Urinary excretion rate = filtration rate – reabsorption rate + secretion
rate
The nephron is the smallest functional unit of the kidney.
§ Each nephron begins with a filtration component that filters the blood entering the
kidney:
o The renal corpuscle
§ This filtrate flows along a tubular structure lined by a single layer of specialized cells
surrounded by capillaries
, o The major functions of these limiting cells are the reabsorption of water and small molecules
from the filtrate into the blood
o The secretion of wastes from the blood into the urine
Renal Corpuscle, also called Malpighian body
§ has high permeability
filtration is driven by the starling Principle
§ the movement of fluids between blood and tissues are determined by differences in:
o hydrostatic pressure
o the colloid osmotic concolic pressure between plasma and the pressure of the Bowman’s
capsule
forces involved in Glomerular Filtration
force effect Magnitude (mm Hg)
Glomerular Favors filtration
Capillary Blood
Pressure
plasma-colloid Opposes filtration
osmotic pressure
