Urinary System

Question 1

What are the main functions of the kidneys?

Answer 1

+ Urine excretion
+ Endocrine organ
+ Homeostatic role controlling blood pressure, tissue osmolality, electrolyte & water balance, pH

Question 2

What are the functions of the kidneys in regards to maintaining/maintenance?

Answer 2

Maintain: Blood/water homeostasis by production of urine

• i.e removal from circulating blood of excess water and electrolytes and toxic, metabolic waste products such as urea and creatinine

Question 3

What are the functions of the kidneys in regards to monitoring/affecting?

Answer 3

Monitor/affect: acid/base balance by excreting hydrogen ions during acidosis or bicarbonate ions during alkalosis

Question 4

What are the functions of the kidneys in regards to secretion?

Answer 4

Secrete:

Renin
- indirectly raises blood pressure

Erythropoietin
- accelerates red blood cell production

Question 5

What is the function of ureters?

Answer 5

Conduct urine to the bladder, where it is stored

Question 6

What is the function of the urethra?

Answer 6

For passage of urine out of the body

Question 7

What is the anatomical position of the kidneys?

Answer 7

+ Lie one on each side on the posterior abdominal wall, high up under the diaphragm

+ Retroperitoneal

+ Encapsulated and protected by layers of fascia and fairly firm renal fat

Question 8

What are the major structures within the kidneys?

Answer 8

\+ Papilla (opening into a Minor Calyx)
\+ Pyramid in Medulla
\+ Cortex, extending between medullary pyramids as a renal colum
\+ Minor Calyx
\+ Major Calyx
\+ Renal Sinus
\+ Ureter
\+ Pelvis

Question 9

What is the role of the pelvis in the kidneys?

Answer 9

The pelvis becomes the ureter that transports urine to the bladder

Question 10

What is the relationship betwen the minor calyces and the major calyces?

Answer 10

The minor calyces converge on major calyces, which themelves form the renal pelvis at the hilum of the kidney

Question 11

What does the nephron consist of?

Answer 11

\+ Renal corpuscule (glomerulus and Bowman's capsule)
\+ Proximal convoluted tubule (PCT)
\+ Loop of Henlé
\+ Distal convoluted tubule (DCT)
\+ Collecting duct

Question 12

What are the two different types of nephron?

Answer 12

+ Juxtamedullary

+ Superficial cortical

Question 13

What are functions/features of juxtamedullary nephrons?

Answer 13

+ Receive ~10% renal supply
+ Designed to concentrate urine
+ Glomeruli in inner corical regions; long nephron loops
+ Associated with vasa recta

Question 14

What are the functions/features of superficial cortical nephrons?

Answer 14

+ Receive ~90% renal supply
+ Reabsorb large % of fluid that filters from vasculature
+ Glomeruli in outer cortical regions; short nephron loops

Question 15

Where does the ureter in females pass in relation to surrounding structures?

Answer 15

+ Passes posteriotl to ovary

+ Passes lateral to cervix and vagina

Question 16

What are features of the male urethra

Answer 16

+ Passes through the prostate into the penis
+ Longer than female urethra
+ Dual purpose; conduit for urine and semen ejaculation

Question 17

What are the features of the walls of the ureters and bladder?

Answer 17

+ Essentially muscular

• peristaltic waves propel urine down the ureter
• bladder fills by relaxation of its muscular wall (known as DETRUSOR muscle)

Question 18

How does emptying of the bladder occur?

Answer 18

By muscular (detrusor) contraction, aided by raised intra-abdominal pressure

Question 19

Describe the epithelial lining of the ureter and bladder

Answer 19

Transitional epithelium or urothelium, which is “urine-proof” and allows distension:
- the cells are rounded and piled on top of each other, but flatten and spread out to cope with distension

Question 20

Where does the ureterin males pass in relation to surrounding structures?

Answer 20

Passes posteriorly to bladder

Question 21

The bladder and ureter contain what type of muscle?

Answer 21

Smooth and involuntary

• controlled autonomic (particularly PSNS)
• but external sphincter around urethra is striated and under voluntary control

Question 22

What percentage of cardiac output does the kidney recieve?

Answer 22

20%

Question 23

How effective is the proximal tubule (PT) in reabsorption?

Answer 23

Recovers ~2/3 of the fluid and up to 100% of some solutees filtered into renal tube by glomerulus

Question 24

What are the features of the PT cells that allow it be effective in reabsorption ?

Answer 24

PT epithelial cells have apical microvilli that increase surface area and junctions between cells that are leaky to maximize free flow of water and dissolved solutes

Question 25

What are the underlying mechanisms involved in reabsorption and sectretion?

Answer 25

+ Na reabsorption by PT is driven by the basolateral Na-K ATPase through co-transport with organic solutes in exchange for H+ + Cl- absorption occurs principally in the later PT by the paracellular route or by a Cl- base exchanger + Water reabsorption occurs by osmosis, driven by influx of Na, Cl and solutes

Question 26

Via what structure is reabsorbed fluid returned to the vasculature?

Answer 26

Via the peritubular network

Question 27

What is micturition?

Answer 27

It is the ejection if urine frm the urinary bladder through the urethra to outside of the body

Question 28

Where/when is there no modification of urine?

Answer 28

En route to or in bladder

Question 29

What happens to formed urine?

Answer 29

Channeled by renal calyces and the renal sinus into ureters and conveyed to the urinary bladder, where it is stored until micturiton

Question 30

What is the bladder?

Answer 30

+ Bladder is a hollow muscular organ that stores urine until micturition is convenient + Valves prevent urinary reflux into the ureters, whereas inner and outer sphincters control the outflow via the urethra

Question 31

What are the functions of valves and sphincter in the urinary system?

Answer 31

Valves prevent urinary reflux into the ureters, whereas inner and outer sphincters control the outflow via the urethra

Question 32

How are the outer and inner sphincters controlled?

Answer 32

+ Outer sphincter is under voluntary control + Inner sphincter and bladder contraction is controlled by spinal relfexes and the CNS

Question 33

What is the capacity of the bladder?

Answer 33

~500ml

Question 34

What does the filling of the bladder do?

Answer 34

+ Stretches its muscular wall and initates a spinal micturition reflex, which causes PS motor efferents to stimulate bladder contraction

Question 35

How is micturition prevented?

Answer 35

Prevented by the CNS until the outer sphincter is relaxed voluntarily

Question 36

Where is the bladder in males located in relation to surrounding structures?

Answer 36

+ Superior to the prostate + Anterior to the rectum + Extends upward from pelvis into lower abdomen + Just above and behind pubic bone

Question 37

Where is the bladder in females located in relation to surrounding structures?

Answer 37

+ Inferior and anterior to the cervix and uterus | + Anterior to the vagina

Question 38

What are features of the female urethra?

Answer 38

+ Situated between the clitoris and the vagina + Shorter than male urethra + More prone to infections due to shorter length