Chapter 24 Flashcards
functions of the urinary system
the kidneys work to:
- dispose of waste (e.g. urea, uric acid, and creatinine) and excess ions
- regulate the volume and chemical makeup of blood by maintaining the proper balance of water and salts, and acids and bases
organs of the urinary system
kidneys
ureters
urinary bladder
urethra
gross anatomy of the kidneys
Renal hilus:
-area on the medial side where vessels, kidneys and nerves enter and leave the kidney
Renal capsule:
-tough layer of dense CT that surrounds each kidney
Adipose capsule
- just external to the renal capsule - consists of adipose tissue
Renal fascia:
-external to the adipose capsule
Pararenal fat
-external to the renal fascia
Internal gross anatomy of the kidneys
2 distinct regions:
- cortex (superficial) - medulla (deep) - consists of masses called medullary pyramids (renal pyramids) which contain bundles of tiny-collecting tubules
Lobes:
-single medullary pyramids and the tissue that surrounds them
Renal Pelvis:
-a tube formed from the superior part of a ureter
Calices:
-branches leading to the renal pelvis that collect urine and empty into the renal pelvis
Blood supply of the kidneys
the kidneys have rich blood supply
- blood is brought to the kidneys via the renal arteries
- the blood leaves the kidneys via the renal veins
microscopic anatomy of the kidneys
Uriniferous tubule:
-the main structural and functional unit of the kidney
each uriniferous tubule consist of 2 major parts:
1. nephron: urine-forming structure
2. Collecting duct (collecting tubule)
-involved in concentrating urine by removing water
urine production
the uriniferous tubule produces urine through three mechanisms:
1. Filtration:
- a filtrate of the blood leaves the kidney capillaries and enters the nephron
2. Reabsorption:
- most of the nutrients, water, and essential ions are recovered from the filtrate and returned to the blood
- remaining wastes are added to urine
3. Secretion:
- active process in which additional undesired molecules move into the tubule from the blood of capillaries
the nephron
Renal corpuscle: “little body”
-the 1st part of the nephron
-where filtration occurs
consists of a glomerulus (a collection of capillaries) surrounded by a glomerular capsule
-the glomerulus vessels secrete the filtrate that becomes urine
Tubular section:
-receives the filtrate from the renal corpuscle
-composed of:
~proximal convoluted tubule
~loop of Henle
~distal convoluted tubule
-involved with reabsorption and secretion
classes of nephrons
Cortical nephrons:
- 85% of all nephrons
- located almost entirely in the cortex
Juxtamedullary nephrons:
- renal corpuscles lie near the cortex-medulla junction - have loops of Henle that deeply invade the medulla
collecting tubules
- receive urine from the nephrons
- adjacent collecting tubules unite to form papillary ducts which empty into calices
- cells participate in the reabsorption and secretion of ions
- have an important role in conserving body fluids (water)
microscopic blood vessels associated with uriniferous tubules
Glomeruli:
-produce the filtrate that becomes urine
Peritubular capillaries
- cling closely to the convoluted tubules - adapted for absorption of solutes and water from the filtrate - secretes molecules into the urine
ureters
slender tubes that carry urine from the kidneys to the bladder
-lined with transitional ET mucosa
urinary bladder
muscular sac that stores and expels urine
three layers:
-transitional ET mucosa
-thick muscular layer (smooth muscle)
-fibrous adventitia
urethra
thin-walled tube that allows urine to drain from the bladder out of the body
-expulsion of urine (micturition/passage of urine) is controlled by the internal urethral sphincter (smooth muscle) external anal sphincter (skeletal muscle)
