Urinary System Flashcards
7.4 THE URINARY SYSTEM 7.5 FORMATION OF URINE 7.6 WATER BALANCE 7.7 KIDNEY DISEASE
The urinary system consists of:
Kidneys
Cortex - outer layer of the kidney
Medulla - area inside of the cortex
Renal pelvis - area where the kidney joins the ureter
Ureters
Tubes that conduct urine from the kidneys to the bladder
Bladder
Urethra
Tube that carries urine from the bladder to the exterior of the body
Kidneys
Cortex - outer layer of the kidney
Medulla - area inside of the cortex
Renal pelvis - area where the kidney joins the ureter
Ureters
Tubes that conduct urine from the kidneys to the bladder
Urethra
Tube that carries urine from the bladder to the exterior of the body
The kidneys play a crucial role in
Waste removal/production of urine
Maintaining water balance
Balancing blood pH
Balancing blood pressure
The Nephron
It is the functional unit of the kidney
There are about 1 million contained within the kidneys
The Nephron
Afferent arterioles -
small branches that carry blood to the glomerulus
The Nephron
Glomerulus -
high-pressure capillary bed that is the site of filtration
The Nephron
Efferent arterioles -
small branches that carry blood away from the glomerulus to a capillary net
The Nephron
Peritubular capillaries -
network of small blood vessels that surround the nephron
Reabsorbs solute from the nephron into the blood and secretes solute from the blood into the nephron
The Nephron
Bowman’s capsule -
Cuplike structure that surrounds the glomerulus
The Nephron
Proximal tubule -
section of the nephron joining the Bowman’s capsule with the loop of Henle
The Nephron
Loop of Henle -
carries filtrate from the proximal tubule to the distal tubule
The Nephron
Distal tubule -
conducts urine from the loop of Henle to the collecting duct
The Nephron
Collecting duct -
tube that carries urine from nephrons to the pelvis of a kidney
Filtration
movement of fluids from the blood into the Bowman’s capsule (not selective) *ask
Reabsorption
the transfer of essential solutes and water from the nephron back into the blood (active transport/selective)
Secretion
the movement of materials from the blood back into the nephron (active transport/selective)
Steps in formation of urine
Filtration - movement of fluids from the blood into the Bowman’s capsule (not selective)
Reabsorption - the transfer of essential solutes and water from the nephron back into the blood (active transport/selective)
Secretion - the movement of materials from the blood back into the nephron (active transport/selective)
Filtration
As blood moves from the afferent arteriole into the glomerulus (capillary bed), dissolved solutes move from the walls of the glomerulus into the Bowman’s capsule due to high pressure
Not all materials leave the blood and enter the capsule
Plasma protein, blood cells, and platelets are too large to move through the walls of the glomerulus.
Smaller molecules pass through the cell membrane and enter the nephron
Reabsorption
Why filter out materials, only to reabsorb them again
120 ml of filtrate enters the nephron per min and only forms about 1 ml of urine bc the remaining fluids are reabsorbed
If reabsorption did not occur, you would be peeing 120 ml of urine every minute
- Glomerulus and Bowman’s capsule
Description of Process
Filtration of water and dissolved solutes occurs as blood is forced through walls of glomerulus into Bowman’s capsule by fluid pressure in capillaries