Genitourinary system and urinalysis

Question 1

When obtaining a urine sample, why is important to get a midstream sample of urine (MSSU)

Answer 1

Some bacteria found on hand, skin and around urethra which can form part of the early urine. Hence not represetiave of real urine from kidney. MSSU is needed

Question 2

How does creatinine change from bowman’s capsule to Collecting duct?

Answer 2

Freely filtered, Not reabsorbed. However, some is secreted so it will increase slightly

Question 3

What could the following found in urine suggest:

1. leukocyte
2. Nitrite
3. Ketones
4. Bilirubin
5. very dilute urine

Answer 3

1. Leukocyte - URINARY TRACT INFECTION
2. Nitrite - Bacteria in significant numbers especially Gram negative rods like E.coli
3. Ketones- Calorei deprivation, starvation, fasting, diabetic ketoacidosis or aspirin poisoning
4. Biirubin- Cirrhosis, gallstones, hepatitis or tumours of the liver or gall bladder
5. Very dilute urine- Diabetes incipitus or Chronic renal disease

Question 4

What could the following substances found in urine suggest:

1. Glucose
2. Protein
3. blood
4. Urobilinogen

Answer 4

Glucose- Diabetes Mellitus (or renal glycosuria if blood glucose conc is normal)

Protein- Glomerular damage. If in large amount, it could suggest nephrotic syndrome

Blood- Glomeruloephritis, kidney stones, tumours, infections

Urobilinogen- Haemolysis, cirrhosis or hepatitis

Question 5

Why should immediately replace the lid on urine dip stick test strips container

Answer 5

Prevent airborne contamination

Question 6

Why does urine appear yellow or white

Answer 6

Urobilin gives urine it’s yellow colour. If urine is concentrated it’ll look mor eye low. If urine is pale/white, there’s a lot mor water in urine

Question 7

What does normal urine look like? What’s the significance

Answer 7

Pale yellow . No strong smell

if it’s red, it could mean blood. If it’s too white, maybe it’s diabetes incipidus or the person takes too much water

if it smells TOO strongly, it could be UTIs/etc

Question 8

What could cause low specific gravity of urine . Normal and abnormal

Answer 8

Abnormal

• Diabetes incipidus
• Pyeloneprhritis

normal

• excessive fluid intake
• use of diuretics

Question 9

How does inulin, water, sodium and glcuose in filtrate change as filtrate moves from bowmans capsule to collecting duct.

start at 100%

Answer 9

Question 10

Look at this test strip

when (time) should you check leukocyte and specific gravity

Answer 10

Leukocyte - 2 min

Specifc gravity- 45s

Question 11

What are the functions of the kidney

Answer 11

Excretion of metabolic products like urea, Uric acid

Excretion of foreign substances

regulation of body fluids, electrolyte and acid base balance

control of blood pressure

secretes hormones like erythropoietin and renin

Question 12

LABEL this structure

Answer 12

Question 13

Descirbe the blood flow in kidneys. What vessels does it flow and in what order

Answer 13

Question 14

Label the following

Answer 14

Question 15

What is the function of the Detrusor muscle and Trigone

Answer 15

Destrusor msucle- Contracts to build pressure in the urinary bladder to support urination

Trigone- this triangular region stretches to limit Brain signals about need to urinate

Question 16

What’s the function of the internal and external sphincter. Contrast them

Answer 16

Internal sphincter- Involuntray control to prevent urination

External sphincter- Voluntary control to prevent urination

Question 17

What’s the fucntion of the Bulbourethral gland?

Answer 17

This produces thick lubricant which is added to watery semen to promote sperm survival

Question 18

LABEL this diagram

Answer 18

Question 19

What are the parts of the loop of Henle

Answer 19

Thin descending limb

Thin ascending limb to

Thick ascending limb

Question 20

What happens in the PCT and what does their epithelial cell contain?

Answer 20

Contains lots of mitochondria - proved energy for Na+/k+ ATPase

majority of water, Na+ and Cl- reabsorbed

solutes reabsorbed

all glucose reabsorbed

Question 21

Contrast the epithelial cell content of the thick ascending limb and thin ascending and descending limb

Answer 21

Thick ascending limb- epithelial cells have lots of mitochondria

Thin ascending and thin descending limb- epithelial cells have low density of mitochondria

Question 22

Why does the cortex look granular and medulla has striated appearance

Answer 22

Medulla has lots of tubules (collecting duct draining and going down into ureter)

cortex has glomeruli

Question 23

What are the 2 different types of nephrons and mention their relative abundance

Answer 23

Surpeficial nephron

Jutamedullary nephrons- inside to inner medulla

Ratio of superficial to juxtamedullary is 10:1

Question 24

What are the constituents of the Juxtaglomerular apparatus and relate to their functions.

draw them in relation to each other

Answer 24

Macula densa cells in DCT- they regulate GFR through tubule-glomerular feedback mechanism

Extraglomerular mesangial cells

Juxtaglomerular cells (Afferent arteriole)- they secrete renin for regulating BP

Question 25

What are 4 renal processes that substances can undergo in the kidney

Answer 25

Glomerular filteration Reabsorption back into the blood Secreted from blood into tubular fluid excreted Different substance undergo different combination of these renal processes

Question 26

Extensively describe the glomerular endothelial. Draw if possible. What substances can pass through which gap.

Answer 26

Question 27

What factors drives glomerular filtration

Answer 27

**Passive process**: fluid pass through semi permeable capillary into bowmans capsule by hydrostatic pressure of the heart **Filteration barrier**: only permeable to fluids and small solutes and impermeable to cells and proteins

Question 28

What are the participating pressures in glomerular filtration. What causes each

Answer 28

**Hydrostatic pressure** in blood AND interstitial fluid: *Fluid* exerts this pressure and **both solute and fluid are pushed out** Oncotic pressure in blood AND interstitial fluid: Solutes (proteins) exert this pressure. Only fluid **drawn in** across semi permeable membrane N:B. Oncotic pressure in tubular fluid is low

Question 29

What is the equation for the Net ultrafiltration pressure (P_uf)

Answer 29

P_uf = HP_gc - HP_bw - π_gc where π= Oncotic pressure in glomerular capillaries

Question 30

What is the equation that links GFR to Net ultrafiltration pressure. Describe what affects any of the variables

Answer 30

GFR= P_uf x K_f K_f is an ultrafiltration coefficient (depending on **membrane permeability** and **surface area** available for filtration ) any changes in P_uf or K will result in GFR imbalances

Question 31

What is the normal range of GFR for a healthy male and female. What does a fall in GFR signify

Answer 31

MALE- 90-140mL/min Females- 80-125mL/min A fall in GFR is the cardinal fetaure of renal disease with a build up of excretory products in the plasma

Question 32

Describe the myogenic mechanism of regulating GFR

Answer 32

Arterial pressures rises Afferent arterioles stretch; this is detected and hence local signals causes Arteriole to contract vessel resistance increases Blood flow decreases GFR stays the same

Question 33

Describe the Tubulo-glomerular feedback mechanism of regulating GFR

Answer 33

Increased GFR leads to Increads NaCl in loop of Henle Macula densa cells detects this change and then increase ATP and adenosine discharge Afferent arteriole constricts and GFR stabilises

Question 34

What is Renal clearance (C) and whats the formulae

Answer 34

The amount of plasma in litres that has been cleared of a particular substance per unit time GFR can be calculated using this concept.

Question 35

What are the conditions for which GFR equals renal clearance of the molecule

Answer 35

If the molecule is freely filtered and neither reabsorbed nor secreted in the nephrons. I.e the amount filtered is the equal to the amount excreted

Question 36

What is the ideal molecule used for measuring GFR (by renal clearance). Give merits and problems

Answer 36

**Inulin-** plant polysaccharide Merits * Not toxic * Meaurable in urine and plasma * freely filtered and neither reabsorbed nor secreted Problems * Not founds in mammals so needs to be infused. Hence not comfortable for patient.

Question 37

What is the commonly used substance used to measure GFR (via renal clearance)

Answer 37

Creaitnine- waste product form creatine in msucle metabolism Merits * amount of creatinine released is fairly constant * if renal function is stable, Creaitnine amount in urine is stable * Low **creatinine** clearance or **high plasma creatine** may indicate renal failure problems * Although freely filtered and not reabsorbed. A tiny amount is secreted into nephron. Not perfect N.B The process of estimations creaitnine in blood and urine can account for that to allow for GFR calculations

Question 38

What substance is used to calculate renal plasma flow? Why

Answer 38

**Para aminohippurate (PAH)** This is because **all PAH** is removed from the plasma passing through the kidney through filtration and secretion

Question 39

What is the equation for filtration fraction. What is the normal range

Answer 39

FF= GFR/ Renal plasma flow Normal range is 0.15-0.20

Question 40

What are the renal tubules transport mechanisms?

Answer 40

Passive transport Active transport

Question 41

Describe PASSIVE transport

Answer 41

Osmosis and diffusion Electrochemical gradient

Question 42

What are the different types of Active transport

Answer 42

Primary active * via Na+/K+ ATPase * Endocytosis secondary acitve/coupled transport * symport * Antiport

Question 43

What are the **different** ways in which substances can move form tubular fluid to blood and vice versa draw it with the best lowest resolution possible

Answer 43

Question 44

Draw out the process of sodium and Bicarobnate reabsorption in PCT. What substance can influence this process and how?

Answer 44

Angiotensin II regulates Na+ reabsorption by increasing Na+ H+ antiporters

Question 45

Draw the process of how glucose is reabsorbed in the PCT

Answer 45

N.B. Most (60-70%) of the substances are reabsorbed in PCT

Question 46

What are the substances reabsorbed and secreted in the PCT. give %

Answer 46

Reabsorbed: * Na+, Cl- and water all 67% * HCO3-, 90% * 100% glucose AND amino acids * 50% UREA Secreted: Drugs, ammonia, bile salts, prostaglandins, vitamins (folate and ascorbate)

Question 47

Summarise the whole of reabsorption in the loop of Henle. DRAW

Answer 47

Substances absorbed : 25% Na+ and Cl-. 15% water. Changes in osmolarity between ascending limb and collecting duct is what causes water conservation

Question 48

Outline the Na+ and Cl- reabsorption in early DCT

Answer 48

Question 49

Outline the process if active Ca2+ reabsorption in early DCT

Answer 49

Question 50

In the distal DCT and collecting duct, what substances move via **principal** cells. Describe it by drawing it out what hormones affect this cells and how

Answer 50

Na+ reabsorption and K+ secretion Water reabsorption Hormones: * ALDOSTERONE: regulates Na+ reabsroption by increasing apical Na+ channels and basolateral Na+ K+ ATPase pumps * ADH: regulates water reabsorption by increasing APICAL aquaporins

Question 51

In distal PCT and collecting duct what is the purpose of the intercalated cells and how do they achieve this?

Answer 51

Maintaining acid base balances alpha intercalated: this carries out HCO3- reabsorption and H+ secretion beta intercalated: this carries out HCO3- secretion and H+ reabsorption

Question 52

What are the 2 cells in collecting duct? Describe their MORPHOLOGICAL differences

Answer 52

Principal cells- low in mitochondria iNTERCALATED- rich in MITOCHONDRIA