1
Q
what are the functions of the urinary system?
A
- storage of urine (nitrogenous waste)
- excretion of urine
- regulate blood volume
- regulate ion balance/acid-base balance
2
Q
what are the major organs of the urinary system?
A
- kidneys
- ureter
- urinary bladder
- urethra
3
Q
describe the anatomy of the kidneys
A
- kidneys are bean-shaped organs
- located in retroperitoneal position (posterior abdomen) and protected by floating ribs
4
Q
how are the kids stabilized and protected?
A
- in addition to the ribs, the kidneys are protected by adipose tissue and a tough fibrous capsule
- two layers of adipose: perinephric fat (deep, near fibrous capsule), paranephric fat (more superficial)
- fibrous capsule (or renal capsule) is outer surface of the kidney. maintains shape and protects from trauma and pathogens
5
Q
describe the basic structure of the kidney
A
- renal cortex is the outer layer (deep to fibrous capsule). deep to that is the renal medulla
- the concave medial surface is the hilum. ureter and renal artery/vein enter and exit kidney here
- extensions of renal cortex between renal medulla are renal columns and divide medulla into renal pyramids
- each pyramid ends in a renal papilla, or rounded tip. each papila empties into a mino calyx. two or three minor calices empty into the major calyx
6
Q
how does the kidney receive its blood supply?
A
- renal arteries branch several times, travel through renal columns to afferent arterioles
- the afferent arterioles form a capillary network called the glomerulus
- once some blood plasma is filtered, exits via efferent arterioles
7
Q
what is a nephron?
A
- smallest functional unit of the kidney
- produces urine through: filtration, resorption, and secretion
- millions of nephrons in each renal pyramid
8
Q
what are the two kinds of nephrons?
A
- cortical: 85%
- juxtamedullary: 15%
- juxtamedullary nephrons: very long loops; contribute to ability to concentrate urine
9
Q
what are the two main parts of the nephron?
A
- glomerulus + glomerular capsule = renal corpuscle
- renal tubules : contains proximal convoluted tubule, nephron loop (loop of henle), distal convoluted tubule, collecting duct
10
Q
what is the renal corpuscle?
A
- designed for filtration of blood
- glomerulus is a capillary bed
- afferent arterioles bring blood in
- glomerular capsule captures filtrate pushed out of capillaries
- blood exits out efferent arterioles
- filtrate (water, salts, waste) travels through renal tubule
- bowman’s capsule is also called the glomerular capsule*
11
Q
describe the structure of renal tubules?
A
filtrate enters tubules from the renal corpuscle. travels through tubule:
- proximal convulated tubule: reabsorption and secretion
- loop of henle: reabsorption and secretion
- distal convulated tubule: secrete ions mostyl but some reabsorption of water
- collecting ducts: extends to papilla. once filtrate exits collecting duct, it is urine
12
Q
describe the flow of urine out of the kidney
A
- urine is made in the pyramids
- the remaining structures just transport the urine to the ureter
- travels through papilla to minor calyx, major calyx, renal pelvis and to ureter
13
Q
what is the urinary tract?
A
- transports urine to outside of body. the kidney is not part of the urinary tract
- includes: ureters, bladder, urethra
14
Q
what are the ureters?
A
- urine exits kidneys via ureters, which are fibromuscular tubes
- they are retroperitoneal (behind the parietal peritoneum
- ureters go from kidney to bladder, located in pelvis
- urine is transported from the kidney to the bladder by both gravity AND peristaltic waves (smooth muscle in ureter wall)
15
Q
what are kidney stones?
A
- aka renal calculus
- mineral filtering through the kidneys accumulate to form crystals
- identified by location (kidney, ureter, or bladder) or by type. more common in men
- extremely painful
- related to dehydration, abnormal pH of urine, oversaturation of calcium, uric acid or oxalate, blockage of urine flow, bacteria infection
16
Q
what is the urinary bladder?
A
- the bladder is a expandable muscular sac that stores and expels urine
- lies on pelvic floor posterior to pubic symphysis
- trigone, a stationary region that directs urine to urethra is located posteriorly between openings for ureters
- wall is composed of mucosa internally and detrusor muscle (smooth muscle). detrusor muscle contracts to expel urine
17
Q
what is the urethra?
A
- fibromuscular tube lined with smooth muscle/mucosa – drains urine from bladder
- thickening of detrusor muscle forms internal urethral sphincter at bladder-urethra junction (involuntary)
- external urethral sphincter surrounds urethra with skeletal muscle sheet, inhibits urine (voluntary)
- male urethra longer than female, also carries semen
18
Q
what is micturition (urination)?
A
- expulsion of urine from bladder
- controlled by the pons
- when bladder is distended (full), stretch receptors send signals to pons
- detrusor muscle is stimulated to contract, squeeze out urine to urethra
- internal sphincter relaxation is involuntary
- external sphincter relaxation voluntary
