Osmoregulation and Excretion in Humans part 1 Flashcards
Osmoregulation
Regulation of solute concentrations and water balance by a cell or organism
Balances the uptake and loss of water and solutes
Which direction does water move
- Higher to lower free water concentration
- Lower to higher solute concentration
- Down the gradient
Excretion of toxins along with excess salts and water in plants
Plants “excrete” some byproducts into the air and soil but don’t have special excretory organs
Excretion of toxins along with excess salts and water in humans
Humans and other animals have special excretory organs (like kidneys) to get rid of these byproducts
Excretion
-Urinary
Excretion is elimination of wastes that are products of the cell metabolism
Defecation
- Digestive
- The elimination of feces that are waste products of digestive system
urinary system
Interacts with cardiovascular system and respiratory system
Two goals of the kidneys
- Removing metabolic wastes/toxins
- Osmoregulation: Salt and water balance
Functions of the kidneys
- Alter pH by absorbing or secreting protons (H+)
- Alter blood volume by absorbing or secreting water
Where does kidney function occur?
Occurs at the nephron (the functional unit of the kidney)
Nephron
- -A cellular, tube-like structure
- Intimately associated with capillary beds (note blood flow)
Urinary system anatomy
- Nephrons from kidneys connected to ureters (muscular tubes)
- Ureters connect to bladder (muscular sac that holds urine)
- Bladder connects to urethra (tube to external environment)
- 20% of cardiac output goes to the kidney
Filtration
- Nephronic process
- INITIAL movement of molecules from capillary into nephron
Reabsorption
- Nephronic process
- Movement of molecules in nephron back into capillary
Secretion
- Nephron process
- Movement of a molecule from the capillary back into the nephron AFTER filtration
What do kidneys remove?
Metabolic waste, nitrogenous wastes (urea, uric acid, creatinine.
Removed by filtration and secretion and found in urine
Uric acid
DNA metabolism, produced in liver
Creatinine
Protein metabolism, produced in muscles
Two types of nephrons
Juxtamedullary
Cortical
Juxtamedullary nephron location
near the edge of the medulla
Cortical nephron location
mainly in cortex
Five regions of nephron structure
Glomerular capsule, proximal convoluted tubule, nephron loop, distal convoluted tubule, collection duct
Afferent arteriole
Blood flow to glomerulus
Glomerulus
Capillary bed
Efferent arteriole
Blood flow leaving glomerulus
peritubular capillaries
Associated with PCT and DCT
Vasa recta capillaries
Associated with loop of henle
