Module 5 - The Urinary System Flashcards
What are the 4 key urinary system organs?
- kidneys
- ureters
- urinary bladder
- urethra
What are the 6 functions of the urinary system?
- regulates ion levels in the blood (Na+, Ca2+, K+, Cl-)
- regulates pH of the blood
- secretes erythropoietin (RBC synthesis)
- regulates blood volume and blood pressure
- activates vitamin D (calcium homeostasis)
- Excretes wastes and foreign substances
Where are the kidneys located?
located between the peritoneum and the posterior abdominal wall at the level of T12-L3
Why is the right kidney located lower than the left kidney?
The liver is in the way
What part is the renal hilum of the kidney?
It is part of the external kidney
It is an indentation on the medial surface of the kidney
it is where the ureter, blood vessels, lymphatic vessels and nerves enter and exit
What are the two main regions of the kidney?
- renal cortex (outer)
- renal medulla (inner)
- renal pyraminds (~8-14 cone shaped structures containing kidney tubules)
- renal columns (region between renal pyramids containing blood vessels)
What is the path of urine drainage?
- collecting duct
- minor calyx
- major calyx
- renal pelvis
- ureter
What supplies blood to and from the kidney?
- renal artery
2. renal vein
What is the nephron? What is it comprised of?
the nephron is the basic functional unit of the kidney
comprised of
- the renal corpuscle
- filters blood - renal tubule
- transport filtered fluid
What is the renal corpuscle comprised of and where is it located?
it is located in the kidney cortex
consists of:
- glomerulus
- capillary network - bowman’s capsule
- double walled structure receiving filtered fluid
What is the renal tubule and what are the 3 main sections?
the filtrate passes into the renal tubule
three main sections:
- the proximal convoluted tubule (cortex)
- loop of henle (medulla)
- distal convoluted tubule (cortex)
How does urine formation happen?
Nephrons form urine by 3 processes
- glomerular filtration
- tubular reabsorption
- tubular secretion
What is glomerular filtration?
blood pressure forces water (95%) and solutes through the filtration membrane
glomerular filtration rate: 105-125mL/min
MUST BE KEPT CONSTANT
if too high –> needed substances pass through the tubule system too quickly to be reabsorbed
if too low –> too many filtrate components are reabsorbed, including wastes
Filtered substances: water and all solutes present in blood (except proteins) including ions, glucose, amino acids, creatinine
What gets through the filtration membrane and what does not?
turned back: erythrocytes, white blood cells, platelets, plasma proteins e.g. albumin clotting factors, antibodies, lipoproteins
passed through filter: water, electrolytes, glucose, amino acids, fatty acids, vitamins, urea, uric acid, creatinine
How is GFR used to assess kidney function?
GFR decreases with:
kidney disease, toxic damage to tubules
low blood pressure (e.g due to hemorrhage, severe dehydration, heart failure)
urinary tract obstructions: kidney stones (renal calculi), severe prostatitis (men), tumours, etc
What is tubular reabsorption?
-tubular reabsorption returns most of the filtered water and many solutes back into the blood, about 99%
substances needed by the body (i.e glucose, water, ions) are retained
Water reabsorption is primarily driven by Na+ transport
-Na+ is reabsorbed and water follows by osmosis (to an area of higher Na+ concentration)
Hormones regulate water reabsorption in response to changes in blood pressure or the concentration of blood solutes
- antidiuretic hormone (ADH) makes kidney tubules more permeable to water
- aldosterone increases Na+ reabsorption (and water)