Urinary System Flashcards
Which organs are part of the urinary system?
- kidneys
- ureters
- urinary bladder
- urethra
Describe the shape and location of the kidneys.
- small fist-sized organs located within the abdominal cavity on either side of the midline between the levels of ~T12-L3
Why are the kidneys surrounded by connective and adipose tissue?
- to protect and anchor them in place
What percentage of cardiac output do the kidneys receive?
- normally receive 20-25% of the resting cardiac output
What are the names of the areas of the kidney?
- renal cortex (outside)
- renal medulla (inside - renal pyramids)
- renal hilum
What is the renal hilum and entry or exit point for?
- ureter
- renal blood vessels
- nerves and lymphatic vessels
How many nephrons extend through the renal cortex and renal pyramids of each kidney?
- 1,000,000
What is a nephron?
- the functional units of the kidney
Describe the composition of a nephron.
- each nephron is composed of a renal corpuscle and renal tubule
What does the renal corpuscle do?
- glomerulus (capillary network) that is surrounded by a glomerular (Bowman’s) capsule
- filters the blood in the glomerulus and deposits the filtered fluid (“filtrate”) into the renal tubule
Describe the function of the renal tubule.
- divided into a proximal convoluted tubule, loop of Henle, and distal convoluted tubule
- each section (as well as the adjoining collecting duct) adjusts the concentration and composition of the filtrate
- the end product is called urine
What are afferent arterioles?
- each gives rise to a glomerulus that enters a nephron’s glomerular capsule
What are efferent arterioles?
- exit the glomerular capsule and branch into peritubular capillaries that surround the tubular portion of the nephron
Describe glomerular filtration.
- the movement of water and solutes from the glomerular capillary into the glomerular capsule
- the amount of filtrate that is formed (“glomerular filtration rate”) is regulated by neural
and hormonal mechanisms as well as by the kidney itself (“renal autoregulation”)
Describe tubular reabsorption.
- the movement of water and solutes from the tubule back into the peritubular capillaries
- most tubular reabsorption occurs in the proximal convoluted tubule, which reabsorbs all of the filtered nutrients (e.g., glucose, amino acids) and most of the filtered water and ions
Describe tubular secretion.
- the movement of certain substances (e.g., H+, wastes, drugs) from the peritubular
capillaries into the tubule and collecting duct - most tubular secretion occurs in the proximal convoluted tubule
What are some hormones that regulate tubular
reabsorption and secretion?
- Antidiuretic Hormone
- Parathyroid Hormone
- Aldosterone
What does the Antidiuretic Hormone do?
- increases H20 reabsorption
What does the Parathyroid Hormone do?
- increases Ca++ reabsorption
What does Aldosterone do?
- increases Na+/H20 reabsorption (🡩BP)
- increases H+ secretion (acid-base balance)
What are diuretics?
- substances that lead to decreased reabsorption of H2O and therefore increased urine production
From the collecting ducts, urine drains into a series of progressively larger ducts. What are they called?
- papillary duct
- minor calyx
- major calyx
How long are ureters?
- 25-30 cm long
What is the function of the ureters?
- transport urine from the kidneys to the urinary bladder
- transport urine from the kidneys to the urinary bladder
