Structural and Functional Organization of the Urinary System Flashcards
What does the urinary system consist of?
2 kidneys
2 ureters
1 bladder
1 urethra
What is the scientific study of the kidneys, and of the male and female urinary system?
Nephrology
Urology
What are the five basic functions of the kidneys?
1) Regulation of ion levels in the blood.
2) Regulation of blood volume and blood pressure.
3) Regulation of blood pH.
4) Production of hormones.
5) Excretion of wastes.
What are the most important ions that the kidneys help to regulate in the blood?
(One of the five basic functions)
Sodium (Na+), potassium (K+), calcium (Ca2+), chloride (Cl-), and phosphate (HPO4^2-).
How do kidneys regulate blood volume?
What enzyme is secreted by the kidneys to regulate blood pressure, and what does it activate?
(One of the five basic functions)
1) By returning water to the blood or eliminating it in urine.
2) The enzyme renin is secreted and it activates the renin-angiotensin-aldosterone pathway.
The concentration of what ion is regulated by the kidneys in order to control the pH of blood?
(One of the five basic functions)
H+ (hydrogen)
*Blood bicarbonate ions (HCO3-) are important buffers of H+ and are conserved by the kidneys.
What two hormones are produced by the kidneys?
(One of the five basic functions)
Calcitriol, the active form of vitamin D, which helps regulate calcium homeostasis.
Erythropoietin, which stimulates the production of RBCs.
What are the wastes that are excreted by the kidneys?
(One of the five basic functions)
1) Ammonia and urea from the breakdown of amino acids.
2) Bilirubin from the breakdown of hemoglobin.
3) Creatinine from the breakdown of creatine phosphate in muscle fibers.
4) Uric acid from the breakdown of nucleic acid.
5) Other wastes that are foreign to the body like drugs or environmental toxins.
Describe where the kidneys are located.
On either side of the vertebral canal, between the peritoneum and the back wall of the abdominal cavity (retroperitoneal space) at the level of T12-L3. The 11th and 12th ribs provide some protection for the superior portions of the kidneys.
The right kidney is slightly lower than the left due to the liver.
Describe the pathway of urine drainage.
Collecting duct
Minor calyx
Major calyx
Renal pelvis
Ureter
Urinary bladder
Urethra
The world
This indentation in the kidney is located near the center of the medial border and is the location where the ureter leaves the kidney, and blood vessels, lymphatic vessels, and nerves enter and exit.
The renal hilum.
What is a smooth, transparent collection of connective tissue sheath that surrounds each kidney? What is it for?
The renal capsule.
It helps maintain shape and serves as a barrier against trauma.
What is the purpose of adipose tissue in regards to the kidneys?
It anchors the kidney to the posterior abdominal wall.
What are the two main regions of the kidneys?
Renal cortex
-Outer light red region
Renal medulla
-Inner dark red-brown region
-Several cone-shaped renal pyramids are contained within the medulla.
-Renal columns are between each pyramid - these are extensions of the renal cortex.
What are cup-like structures that urine passes through, and how many does each kidney have?
8-12 minor calyces
2-3 major calyces
*Urine also passes through a single large cavity called the renal pelvis.
About 20-25% of resting cardiac output flows into the kidneys. How many mLs of blood per minute is that?
1,200 mL per minute.
The renal artery in the kidney branches into what four smaller arteries that eventually deliver blood to the afferent arterioles.
Segmental
Interlobar
Arcuate
Interlobular
Afferent and Efferent arterioles divide or reunite into what structures?
Afferent arterioles divide into a tangled capillary network called a glomerulus.
Capillaries of the glomerulus reunite to form an efferent arteriole.
What do efferent arterioles form upon leaving the glomerulus?
Each efferent arteriole divides to form a network of capillaries around the kidney tubules, called peritubular capillaries.
These form peritubular veins, which merge into other veins of the kidneys, and eventually drain into the renal vein.
What are the functional units of the kidneys, and how many does each kidney have?
Nephrons
1 million
What does a nephron consist of?
A renal corpuscule, where blood plasma is filtered
A renal tubule, where the filtered fluid, called glomerular filtrate, is passed
What are the two parts of a renal corpuscle?
Glomerulus and the glomerular capsule (Bowman’s capsule)
What are the three main parts of the renal tubule?
1) Proximal convoluted tubule
-Attached to the glomerular capsule
-Lies within the renal cortex
2) Loop of Henle
-Extends into the renal medulla via the descending and ascending limbs
3) Distal convoluted tubule
-Lies within the renal cortex
-Empties into the common collecting duct, eventually leading into the minor and major calyces, renal pelvis and ureter
What is the first step of urine production?
Glomerular filtration. Blood pressure forces water and most solutes in blood plasma across the wall of glomerular capillaries, forming glomerular filtrate.
What must filtered fluid undergo before it is considered urine?
Tubular reabsorption and tubular secretion.
What cells make up the inner walls of the glomerular capsule, and are adhered closely to the endothelial cells of the glomerulus?
Podocytes
Together with the glomerular endothelium, they form a filtration membrane that permits the passage of water and solutes from blood into the capsular space.
Blood cells and plasma proteins remain in blood because they are too large to pass through this membrane.
What is the pressure that causes filtration?
What are the two additional pressures that oppose glomerular filtration, and what happens if these pressures increase?
Causes: Blood pressure in the glomerular capillaries.
Opposes: Blood colloid osmotic pressure, and glomerular capsule pressure
-If either of these pressures increases, glomerular filtration decreases
What is the net filtration pressure of the kidneys? What is the average volume of filtrated fluid per day in the kidneys for males and females?
10 mmHg
150L for females
180L for males
What is the formula for net filtration pressure?
Blood colloidal osmotic pressure + glomerular capsule pressure - glomerular capillary blood pressure
What does constriction of the afferent arteriole cause?
It decreases blood flow into the glomerulus, which decreases net filtration pressure.
What does constriction of the efferent arteriole cause?
It slows the outflow of blood and increases net filtration pressure.
What is glomerular filtration rate? What are the averages for males and females? What happens with high and low GFRs?
The amount of filtrate that forms in the kidneys every minute. Occurs via net filtration pressure.
-105mL/min for females
-125mL/min for males
If GFR is too high, substances pass so quickly that they cannot be reabsorbed and pass out of the body as part of urine.
If GFR is too low, nearly all filtrate is reabsorbed and waste products are not adequately excreted.