Genitourinary system

Question 1

What is the typical liquid intake daily?

Answer 1

1200ml water, 1000ml food, 300ml metabolic=2.5L/day

Question 2

What is the typical liquid output daily?

Answer 2

1500ml urine, 100ml sweat, 200ml faeces, 700ml insensible loss=2.5L/day

Question 3

What is ‘insensible’ water loss?

Answer 3

Water loss due to:
-Transepidermal diffusion: water that passes through the skin and is lost by evaporation, and
-Evaporative water loss from the respiratory tract
It is termed insensible as we are not aware of it.

Question 4

What is the glomerular filtration rate governed by?

Answer 4

The arterial blood pressure arriving at the glomerulus. This pressure is highly regulated by systemic and local control of the diameter of the afferent/efferent arterioles.

Question 5

What is the macula densa?

Answer 5

A unique group of 15-20 cells that are located at the end of the cortical thick ascending limb. The cells sense changes in tubular fluid composition, generating and sending signals to the juxta-glomerular apparatus that controls renal blood flow and GFR through tubuloglomerular feedback and renin release.

Question 6

What is ‘auto regulation?

Answer 6

The process by which the afferent arterioles response to the changes in pressure in the glomerulus by dilating or constricting. This maintains the pressure constant between 60-70mmHg.

Question 7

What does atrial natriuretic peptide do?

Answer 7

When the atria of the heart are distended (increased venous return), they release ANP, which does the following:
-dilation of the afferent arteriole, constriction of the efferent arteriole.
-decreases Na+ reabsorption in the distal tubule.
-inhibits renin release from the macula densa.
Overall the effects of ANP include an increase in the volume of primary urine, reduced Na+ and reduced blood volume.

Question 8

What happens if the afferent arterioles constrict?

Answer 8

The filtration pressure drops and filtration in the glomerulus is reduced.

Question 9

What happens if the efferent arterioles constrict?

Answer 9

The filtration pressure increases and filtration in the glomerulus is increased.

Question 10

Describe capacity and affinity in the proximal tubule

Answer 10

There is high capacity (Vmax) and low affinity. There is bulk reabsorption of solutes and water. Mainly amino acids and glucose are 100% reabsorbed.

Question 11

Describe capacity and affinity in the distal tubule

Answer 11

There is low capacity and high affinity transporters. This is where fine tuning of solutes and water occur, under the influence of aldosterone.

Question 12

What does aldosterone done?

Answer 12

Causes reabsorption of Na+ but not of K+.

Question 13

When is anti-diuretic hormone produced and what does it do?

Answer 13

ADH is produced by the posterior pituitary gland in response to: dehydration, haemorrhage, low blood volume, when extracellular osmolarity of Na+ rises and stress. Increase ADH-increase channels- increased reabsorption of water. Decreased ADH-decreased channels-decreased water reabsorption- water loss.

Question 14

What do diuretics do?

Answer 14

Increase the volume of urine produced. Therefore there is: decreased plasma volume, decreased venous return and decreased arterial and venous blood pressure. Patients with hypertension, congestive heart failure and oedema benefit from diuretics.

Question 15

What does Furosemide do?

Answer 15

It is a loop diuretic that increases the rate of urination. It acts on the thick ascending limb of the Loop of Henle and inhibits Na+/Cl-/K+ symports.

Question 16

What does Hydrochlorothiazide do?

Answer 16

It is a diuretics that acts on the distal ascending limb and proximal distal tubule. It inhibits Na+/Cl- symports.

Question 17

What has happened by the end of the proximal convoluted tubule?

Answer 17

• Complete reabsorption of glucose and amino acids.
• Substantial reabsorption of Na+ and water.
• Volume of filtrate reduced by 2/3.

Question 18

What is the minimum urine production rate?

Answer 18

1ml/minute. Max ADH secretion.

Question 19

What is the maximum urine production rate?

Answer 19

20ml/min. Min ADH secretion.

Question 20

What nerve controls the external sphincter of the bladder?

Answer 20

Somatic fibres in the pudendal nerve.

Question 21

What type of epithelium does the oesophagus have?

Answer 21

Stratified squamous (non- keratinised) epithelium

Question 22

How is reflux prevented?

Answer 22

Lower oesophageal sphincter.

Question 23

What major branch of the abdominal aorta supplied arterial blood to the stomach?

Answer 23

Coeliac trunk.

Question 24

What is unusual about the muscle layers in the stomach wall?

Answer 24

3 layers of smooth muscle:

• Outer-longitudinal
• Inner-circular
• innermost-oblique

Question 25

Anatomically where is the liver?

Answer 25

Right hypochondrium extending to the epigastric region.

Question 26

What are the functions of the liver?

Answer 26

Metabolism, storage of glycogen, release of glucose, inactivation of hormones and drugs, excretion of waste, production of bile, platelet production.

Question 27

Anatomically where is the spleen located?

Answer 27

Left hyponchondrium.

Question 28

What is the function of the spleen?

Answer 28

Identifying, removing and destroying old red blood cells. It can also store RBC and platelets. You can survive without one.

Question 29

What is the arterial supply to the small intestine?

Answer 29

Superior mesenteric artery.

Question 30

How would a surgeon differentiate large from small intestine?

Answer 30

The large intestine has omental appendices (fatty tags), haustra (sacculations of the bowel wall) and taeni coli (longitudinal band of muscle).

Question 31

What is the role of the caecum (large intestine)?

Answer 31

Fluid absorption and the commencement of the fermentation of fibre and lipids, gas production and synthesis of some vitamins.

Question 32

What are the different components to the large intestine called?

Answer 32

Caecum, appendix, ascending, transverse, descending and sigmoid colon, rectum and anal canal.

Question 33

What is the arterial supply to the large intestine?

Answer 33

Up until the first 2/3 of the transverse colon (caecum, appendix, ascending colon), this is supplied by the superior mesenteric artery and from there, the inferior mesenteric artery supplies the rest of the large intestine (descending, sigmoid colons, rectum and anal canal).

Question 34

What type of epithelium is present in the small intestine?

Answer 34

Simple columnar epithelium.

Question 35

What are the two types of epithelium you see at the recto-anal junction?

Answer 35

Simple columnar epithelium (rectal side) and stratified squamous epithelium (anal side).

Question 36

What is the gall bladder and what is its arterial supply?

Answer 36

Stores and concentrates bile. Cystic artery (arises from coeliac trunk).

Question 37

What are gall stones?

Answer 37

Crystallised masses that can contain abundant cholesterol, pigment, or a combination of both.