Urinary System (Ch. 27) Flashcards
What does the urinary system include?
Kidneys
Ureters
Bladder
Urethra
What are the fxns of the urinary system?
Elimination of nitrogenous wastes and excess ions (storage and excretion of urine)
Maintain ion balance, acid-base (pH balance), regulates blood volume
Where are the kidneys located?
Retroperitoneal position (behind vertebrae T12-L 1, 2, or 3)
*Remember, the kidneys are not parallel to each other.
What protects the kidneys?
The floating ribs
Kidney anatomy
Study kidney drawings. Familiarize yourself with these structures and their locations: Hilum Major calyx Renal cortex Papilla of pyramid Renal medulla Renal pyramid [in renal medulla] Renal pelvis Minor calyx Renal column Fibrous capsule Ureter
Starting from the outer region, the kidney is surrounded by a ____ ____.
Fibrous capsule
In this saggital section, the outer part of the kidney is the ____ and the inner part is the ____.
Cortex; Medulla
Beyond the medulla is the ____ ____, which is really just an expansion of the ureter.
Renal Pelvis
The ureter will carry the ____ to the bladder.
Filtrate
Looking more closely, the medulla has a series of segments called the ____ ____.
Renal Pyramids
Each pyramid is separated by a ____ ____ (extension of the cortex).
Renal Column
The papilla of the pyramid contain many ____ ____, which drain urine into the ____ ____ located in the renal pelvis.
Urine Tubules; Minor Calices
Minor calices drain into larger, ____ ____, which then drain into the ____.
Major Calices; Ureter
The ____ is the region where blood vessels and the ureter enter/exit.
Hilum
Kidney Blood Supply
Renal arteries branch several times, travel through renal columns to afferent arterioles. The afferent arterioles form a capillary network called the glomerulus. Once blood is filtered, it exits via efferent arterioles.
Efferent arterioles branch into peritubular capillaries surrounding nephron structures.
–termed peritubular capillaries if they surround tubules in cortex
Peritubular capillaries around Loop of Henle are the vasa recta
Drain into interlobar vessels eventually
The Nephron
A nephron is the smallest functional unit of the kidney. It’s the actual site of filtration of all of the blood passing through the body. Each renal pyramid contains millions of nephrons.
How many quarts blood can a healthy kidney process per hour?
about 8-9 quarts of blood/hour
Glomerulus
Capillary bed fed by the afferent arteriole. The walls of the glomerular capillaries are fenestrated - they have slits or pores - and small molecules and water (not RBCs!) are pushed out of the capillaries and into Bowman’s capsule. The fluid is termed filtrate and will be the urine
Filtrate vs Blood
Always keep track of whether you’re talking about filtrate or blood. The filtrate is in the tubules. The blood is in vessels.
What are the 2 types of nephrons?
Cortical and Juxtamedullary
Cortical Nephrons
~85%; found in cortex
Juxtamedullary Nephrons
~15%
Very long loops, contribute to ability to concentrate urine and also help conserve water
What are the 2 major parts of the nephron?
Renal Corpuscle and Renal Tubules
Renal Corpuscle
Glomerulus + Glomerular capsule* = Renal Corpuscle
*Bowman’s capsule aka Glomerular capsule
Renal Tubules
Proximal convoluted tubule (closest to renal corpuscle)
Loop of Henle (nephron loop): extends down into medulla
Distal convoluted tubule
Collecting duct (multiple tubules feed into here)
Loop of Henle
Has a descending and an ascending limb. These play different roles in the secretion and absorption of ions and fluids
Renal Corpuscle: Filtration
Renal corpuscle is designed for filtration:
- -glomerulus is a capillary bed
- -afferent arterioles bring blood into corpuscle and high pressure pushes the filtrate out through the capillaries and into glomerular capsule. From there it moves into the tubules
Corpuscle: Filtration
Blood exits via efferent arteriole
Filtrate exits via proximal convoluted tubule
Filtrate: water, waste, salt, glucose
What comprises the filtrate?
Water, waste, salt, glucose
Structure of Renal Tubules
Filtrate enters tubules from renal corpuscle
Proximal convoluted tubule: secretory/absorptive (cuboidal epithelial cells)
Loop of Henle:
–descending limb permeable, simple squamous epithelium
–ascending limb impermeable to water
Distal convoluted tubule: selectively secretory/absorptive (cuboidal epithelial cells)
Exits into collecting ducts
Urine Formation: Glomerular Filtration
Movement of substances w/in the glomerulus into the capsular space
Occurs in Glomerulus
Urine Formation: Tubular Reabsorption
Movement of substances from the tubular fluid back into the blood
Occurs in Posterior Convoluted Tubule (PCT) and Nephron Loop
Urine Formation: Tubular Secretion
Movement of substances from blood into tubular fluid
Occurs in Distal Convoluted Tubule (DCT)
One the fluid is in the ____ ____, it is ____.
Collecting Duct; Urine
Urinary Tract
Transports urine to outside of body
What does the Urinary TRACT include?
Ureters, bladder, urethra
Ureter
Urine exits kidneys via ureters
Ureters go from kidney to bladder
Urine is transported from kidney to bladder by both gravity and peristaltic waves (smooth muscle in ureter wall)
Kidney Stones
aka renal calculus
Mineral filtering through the kidneys accumulate to form crystals
ID’d by location (kidney, ureter, or bladder) or by type (calcium, struvite, uric acid, or other)
80% afflicted are men
Extremely painful
Related to dehydration, abnormal pH of urine, overstated w/ calcium, uric acid, or oxalate, blockage of urine flow, bacterial infection
____% of people afflicted with kidney stones are ____.
80%; Men
Urinary Bladder
Muscular sac that stores and expels urine
Lies on pelvic floor posterior to pubic symphysis
Mucosa (lining) = transitional epithelium + lamina propria
Stretches as bladder fills
Detrusor muscle (smooth muscle) - contractions squeeze urine from bladder
Urethra
Tube lined with smooth muscle/mucosa - drains urine from bladder
Thickening of detrusor muscle forms internal urethral sphincter at bladder - urethral junction (involuntary)
External urethral sphincter surrounds urethra w/ skeletal muscle sheet, inhibits urine (voluntary)
Male urethra longer than female, also carries semen
Micturition (urination)
Controlled by brain (pons)
When bladder distended (full), stretch receptors send signals to pons
Detrusor muscle is stimulated to contract, squeeze out urine.
Internal sphincter relaxation involuntary
External sphincter relaxation voluntary
The urinary bladder can expand to hold up to ____L (liter) of urine.
1 liter
Follow a sodium ion from the renal artery to the outside of the body.
- Renal artery
- Afferent arteriole (in renal cortex) –> carries blood
- Glomerulus –> filters blood
- -some blood will exit via Efferent Arteriole - Nephron
- -Proximal Convoluted Tubule (PCT) –> reabsorbs about 65% of nutrients
- -Loop of Henle (or Nephron Loop) –> reabsorption of water
- -Distal Convoluted Tubule (DCT) –> secretion of potassium and hydrogen - Collecting Duct (goes through Medulla)
- -water exits out of Collecting Duct - Renal Papilla (now urine)
- Minor Calyx
- Major Calyx
- Renal Pelvis
- Ureter
The Proximal Convoluted Tubule reabsorbs about ____% of nutrients.
65%
Water exits out of the ____ ____.
Collecting Duct
In the Loop of Henle, ____ is reabsorbed.
Water
In the Distal Convoluted Tubule, ____ and ____ are secreted.
Potassium; Hydrogen
