Genitourinary System

Question 1

Name the four sections of the Renal tubule

Answer 1

Proximal Convoluted Tubule
Loop of Henle
Distal Convoluted Tubule
Collecting Duct

Question 2

Explain the function of the PCT

Answer 2

Involved primarily in the reabsorption of nutrients like glucose or amino acids, 2/3 of filtrate is reabsorbed here. it has a brush border too.

Question 3

Explain the occurrences in the Loop of Henle

Answer 3

there is no net reabsorption here. the thicker ascending wall pushes out solutes which diffuse back into the thinner descending wall. this creates a recirculation of solutes which creates high osmolarity at the tip of the loop.

Question 4

What happens in the DCT

Answer 4

The DCT has most of the same function as the PCT, but there is less intense reabsorption and it doesn’t have a brush border.

Question 5

What happens in the collecting tubule

Answer 5

Urine is passed onto to the minor calyx. The concentration of urine can depend on the permeability of luminal membrane. If there is less water in the body, ADH will be secreted, which instructs Aquaporins to insert into the wall, allowing for more permeability. Water can move out due to the high osmolarity from the nearby tip of the Loop of Henle. This concentrates the urine. The opposite can happen and less ADH (anti-diuretic hormone) is released and therefore less water reuptake and more dilute urine.

Question 6

How does the Juxtaglomerular apparatus regulate blood pressure?

Answer 6

The JGA is a mass of cells where the DCT passes up close to the glomerulus of the nephron. if there is low ions moving through the DCT then the JGA will read this as low filtration and therefore low blood pressure. It will secrete Renin, an enzyme that activates the precursor Angiotensinogen which in its active form is Angiotensin 1. this is converted to Angiotensin 2, a powerful vasoconstrictor.

Question 7

How are salt levels controlled?

Answer 7

If concentrations of electrolytes are low e.g. Na+ or Cl- then aldosterone is secreted from the adrenal cortex in higher amounts. This increases reuptake in the renal tubules and from the gut, sweat and tears,

Question 8

Describe the nephron

Answer 8

Functional unit of the kidney. Made of the renal tubules (DCT, PCT and Loop of Henle), and the renal corpuscle (glomerulus and Bowman’s capsule).

Question 9

Blood supply to the kidney?

Answer 9

Blood is supplied via the right and left renal arteries which rise from the abdominal aorta. the renal arteries enter at the hilum and split into the interlobar blood vessels which supply the lobes. these further split into the cortical arteries which supply the cortex. the renal vein exits the hilum and is drained by the inferior vena cava.

Question 10

What are the main principles of early disease detection as per Wilson and Jungner?

Answer 10

1. condition should be a relevant problem for individual and community
2. accepted treatment for patients with disease
3. facilities for diagnosis and treatment need to exist
4. recognisable dormant/early stage
5. suitable test
6. the test should also then be accepted by the general population
7. the history of the condition from development to disease should be known
8. should be policies to agree on who to treat
9. economics should be viable
10. screening must be continuous

Question 11

give an example of how a screening programme like bowel screening works.

Answer 11

Most common cancer in Scotland. men and women between 50-74 invited to take part. A sample of shit is collected in a tube at home, and sent back to a lab. The sample of jobby is tested for haemoglobin as advanced bowel cancers cause bleeding. If a high enough level is detected then patients are referred for colonoscopy.

Question 12

Give a value for the maximum and minimum rate for urine production

Answer 12

Minimum- 1ml/min

Maximum-20ml/min

Question 13

What is the structure of the urinary bladder?

Answer 13

there are four layers to the bladder, the smooth muscle Detrusor, then the submucosa, the lamina propria and then the transitional epithelium. Ureters enter at the ureteral orifice. the internal sphincter at the neck of the bladder is involuntarily controlled whilst the external sphincter on the urethra is voluntarily controlled. the urethra has 3 sections in men, the prostatic, membranous and pendulous. There is a mucosal lining on the transitional epithelium to stop leakage of urine out the bladder and to protect the epithelium lining.

Question 14

Describe the storage phase in peeing.

Answer 14

As the bladder starts to fill there’s still low pressure, bladder wall and external sphincter are relaxed. there’s no flow from the urethra as the pressure is higher in the urethra than the bladder.
First sensations develop, so the sphincter contracts retaining continence. a second sensation follows (UM) the urge to micturate.

Question 15

Describe the voiding phase in peeing

Answer 15

The UM is followed by voluntary voiding
The bladder wall contracts, raising pressure in the bladder above the pressure in the urethra. the sphincters relax leading to a flow from the urethra.
Voiding is then stopped by the sphincter activities, creating a build up of pressure in the bladder.
secondary voiding then follows.

Question 16

Innervation of the sphincters

Answer 16

Internal sphincter and bladder wall innervated by L1,2 nerves (sympathetic)
S2,3,4 innervate bladder wall for parasympathetic
Somatic (voluntary) from S2,3,4 carry fibres to the external sphincters

Question 17

Nerve control of the storage phase

Answer 17

Sympathetic suppress contraction of the detrusor, relaxing the bladder and allowing for filling. Somatic fibres control the external sphincter via the pudendal nerve.
So overall a relaxed bladder but an active external sphincter so urethra pressure still greater than bladder pressure.

Question 18

Nerve control of the Voiding phase

Answer 18

Parasympathetic dominates causing the detrusor muscle to contract. Specifically fibres in the pelvic splanchnic nerve cause the detrusor to contract.

Question 19

what are the sensations in peeing

Answer 19

No sensation –> filling –> fullness (could pee now) –> desire to pee (got to piss now) –> discomfort (not gonna make it to the toilet) –> pain (full on wet the bed)

Question 20

Describe the gross anatomy of the kidneys

Answer 20

There are two kidneys and the right one lies lower down than the left due to the liver pushing down on it. the kidney has an outer cortex and an inner medulla. The medulla consists of medullary pyramids which contain the urine. the minor calyx drain the collecting ducts and join up to form the major calyx, there are around 3-4 in each kidney. the renal pelvis drains the kidney of urine. the hilum is where the renal arteries and veins enter and exit and the renal pelvis exits.

Question 21

Describe the function of the kidneys

Answer 21

The main function of the kidney is to filter blood and produce urine from the waste products.
it regulates blood pressure, pH, plasma osmorality, volume, ions and glucose levels.
It also can secrete calcitriol (active form of Vitamin D), it increases absorption from the gut and secretes it from the bones too.

Question 22

What is BPH and how is it caused?

Answer 22

Benign prostatic hyperplasia is an enlargement of the prostate gland. As the prostate wraps around the urethra this causes discomfort when peeing.
There is no certain cause however it is thought that the steroid hormone testosterone plays a role.
It most commonly affects men over the age of 50, almost half of all men.

Question 23

Symptoms of BPH

Answer 23

difficulty peeing, difficulty fully emptying their bladder, frequently needing to pee as a result of not fully voiding. urinary incontinence (leaking when bladder under pressure e.g. laughing)

Question 24

Treatments for BPH

Answer 24

Alpha blockers- relax the prostate muscles and bladder wall
5-alpha reductase inhibitors- reduce the size of the prostate
Desmopressin- anti-diuretic, concentrates urine so less of an urge to pee at night.
Diuretics- speed urine production, pee more in day less at night

Open prostatectomy- removal of prostate altogether

Transurethral resection of prostate- removal of a section of prostate by shoving resectoscope up urethra