urinary system indicators of health and disease

Question 1

explain concentrating urine

Answer 1

Although both cortical and juxtamedullary nephrons regulate theconcentrationsof solutes and water in the blood,countercurrent multiplication (see previous lecture)in the loops of Henle of juxtamedullary nephrons is largely responsible for developing the osmotic gradients that are needed to concentrateurine.

Question 2

absorbed water is returned to the circulatory system by what? and what is it?

Answer 2

the vasa recta

a looping capillary, which surrounds the tips of the loops of Henle in juxtamedullary nephrons.

Question 3

whats the speed of blood flow through the vasa recta, and explain the impact of this

Answer 3

very slow

any solutes that are reabsorbed into the bloodstream have time to diffuse back into the interstitial fluid, which maintains the solute concentration gradient in the medulla.

Question 4

explain the vasa recta in terms of what it lets in and out, what happens as it ascends and what it forms

Answer 4

Solutes in, water out, as blood flows down
(Note blood leaving is approx. iso-osmotic with normal plasma)

Reverses as ascends

Formation of concentrated urine depends on high solute concentration in interstitial fluid

Question 5

Why have a loop of Henle & associated structures?

Answer 5

To set up a concentration gradient in medulla of kidney

To concentrate urine
- i.e., reabsorb water back into the body

The amount of water absorbed out of urine is dependent on the interstitial osmolarity gradient established by the Loop of Henle

Urine becomes concentrated as it equilibrates with interstitium in medullary collecting tubule.

Question 6

Water can move out of duct in the loop of henle and associated structures via what

Answer 6

osmosis, saving energy

Question 7

what do diuretics do and cause

Answer 7

Diuretics slow the renal absorption of water

cause diuresis = elevated urine flow rate

Question 8

name 2 naturally occurring diuretics

Answer 8

Caffeine (inhibits Na+ reabsorption)

Alcohol (inhibits ADH secretion)

Different physiological mechanisms involved

Question 9

what can diuretics be used to treat

Answer 9

to treat hypertension & oedema due to congestive heart failure & cirrhosis of liver

Question 10

what are some complications of diuretics use

Answer 10

dehydration & electrolyte imbalances

Question 11

name 3 forms of clinical evaluations for kidney function

Answer 11

Urinalysis
Blood screening tests
Renal plasma clearance

Question 12

explain urinalysis - the kidney evaluation method

Answer 12

Analysis of volume, chemical & microscopic properties of urine.

Reveals much about the state of the body.

Normally adult eliminates 1-2L/day

Urine volume influenced by fluid intake, blood pressure (BP), blood osmolality, diet, body temp, diuretics, mental state & general health.

Urine normally protein free.

Question 13

name the typical solutes in urine and where theyre from

Answer 13

Urea
- From protein breakdown

Creatinine
- From creatine phosphate breakdown in muscle

Uric acid
- From nucleic acid breakdown

Urobilinogen
- From haemoglobin breakdown

Plus fatty acids, pigments, enzymes & hormones

Question 14

what abnormal constituents can be found in urine

Answer 14

Description of colour & appearance
Specific gravity
pH
Glucose
Ketone Bodies
RBC count
WBC count
Protein
Hormone: hCG for pregnancy.

Question 15

what are some detectable abnormalities

Answer 15

Albuminuria
Glucosuria
Haematuria
Pyuria
Ketonuria
Bilirubinuria

Question 16

what does the detectable abnormalty in urine: albuminuria mean

Answer 16

injury/disease of filtration membranes, increase BP, irritation of kidney cells by bacterial toxins, ether or heavy metals

Question 17

what does the detectable abnormalty in urine: glucosuria mean

Answer 17

diabetes mellitis or stress/epinephrine

Question 18

what does the detectable abnormalty in urine: haematuria mean

Answer 18

RBC in urine; urinary disease or kidney stones, tumours, trauma

Question 19

what does the detectable abnormalty in urine: pyuria mean

Answer 19

WBC in urine; infection in kidney/urinary organs

Question 20

what does the detectable abnormalty in urine: ketonuria mean

Answer 20

diabetes mellitis, anorexia, starvation, too little dietary carbohydrate

Question 21

what does the detectable abnormalty in urine: bilirubinuria mean

Answer 21

RBC destroyed, Hb broken up to form globin + haem;
haem becomes biliverdin which then becomes bilirubin [major bile pigment]

Question 22

what are urines normal values

Answer 22

Yellow – amber
Clear
0.75 - 2L/day
pH 7 (4.5 - 8.0)
0.1mg/ml protein
<130mg/day glucose

Question 23

describe the dip stick test

Answer 23

Quick and simple measurement of chemical composition of urine

glucose: blue coloured = neg
brown coloured = pos

protein: cream coloured = neg
green coloured = pos

blood: orange coloured= neg
brown coloured = trace
black coloured = pos

Question 24

explain what blood screening tests can detect in terms of for evaluating kidney function

Answer 24

blood urea nitrogen (BUN)
plasma creatine

Question 25

why would blood urea nitrogen (BUN) be detected in blood screening

Answer 25

due to catabolism & deamination of amino acids; levels rise steeply if decreased glomerular filtration with renal disease or obstruction of urinary tract.

Strategy: minimise patient’s protein intake

Question 26

why would plasma creatine be detected in blood screening

Answer 26

due to catabolism of creatine phosphate in skeletal muscle; high level if poor renal function.

Question 27

explain renal plasma clearing for evaluating kidney function in terms of what it does

Answer 27

Evaluation of kidney function

Measures how effective kidneys are at removing a given substance from blood plasma

Is a calculated value

Question 28

describe how to calculate renal plasma clearance

Answer 28

plasma clearance (ml/min) = quality of urine (ml/min) x (conc in urine (mg/ml) divided by conc in plasma (mg/ml))

high value = Indicates efficient excretion of substance in urine

Question 29

what is renal plasma clearance

Answer 29

Is the volume of plasma per minute needed to excrete the quantity of solute appearing in the urine per minute.

Question 30

when is the renal plasma clearance of a substance high

Answer 30

if most is cleared to the urine

• therefore., a larger volume of plasma is ‘cleared’ per minute.

Question 31

what would Normal Renal Plasma Clearance

Answer 31

Clearance of glucose normally 0

not excreted in urine at all

filtered glucose returned to blood via tubular resorption

Question 32

what is a renal plasma clearance of high creatinine look like

Answer 32

120-140ml/min

filtered and not reabsorbed

only a very small amount secreted, so is cleared in the urine

Question 33

explain Glucose in nephron

Answer 33

Glucose filtered out of blood in glomerulus into capsule (in corpuscle)

All reabsorbed into blood

None secreted out of blood

None excreted into urine

Renal Plasma Clearance of Glucose is 0

Question 34

explain Creatinine in nephron

Answer 34

Creatinine filtered out of blood in glomerulus into capsule (in corpuscle)

None reabsorbed into blood

None secreted out of blood

All excreted into urine

Renal Plasma Clearance of Creatinine is high (120-140ml/min)

Question 35

what parts of the body are involved in Urine Storage, Transportation & Elimination

Answer 35

ureters
urinary bladder

Question 36

explain Ureters

Answer 36

have no anatomical valve at opening into urinary bladder, but effective physiological one: as bladder fills, pressure within it compresses the oblique openings into ureters & prevents backflow of urine

Question 37

explain the urinary bladders average volume it holds

Answer 37

700-800ml

Question 38

what is micturition

Answer 38

urination = voiding

Occurs via combination of involuntary & voluntary muscle contractions

When bladder volume >200-400ml
- stretch receptors in wall transmit nerve impulses into spinal cord

They propagate to micturition centre in sacral spinal cord segments S2 & S3 to trigger micturition reflex:

Bladder contracts & urinary internal & external sphincter muscles relax

Learn to initiate & stop it voluntarily

Urethra = terminal portion of urinary system

Question 39

explain polycystic kidney disease

Answer 39

Genetic
- Autosomal

Multiple cysts

Form of chronic kidney disease

Reduces kidney function

Question 40

reduced kidney function from Polycystic Kidney Disease causes what

Answer 40

Possible kidney failure

high BP

blood vessel problems

liver cysts

Question 41

how does diabetic nephropathy occur and what can eb detected

Answer 41

Occurs with chronic diabetes
- after 10-15 years onset
- Mostly affects those aged: 50-70

Albuminuria detected

Question 42

what is Pathophysiology

Answer 42

Thickened glomerulus

Abnormal blood vessels

Increasing number of glomeruli destroyed

Question 43

explain Glomerulonephritis

Answer 43

primary or secondary autoimmune disease

Characterised by inflammation of glomeruli

May present different degrees of hyalinization
- Hyalinosclerosis: total replacement of glomeruli and Bowmann’s space with hyaline.
- The hyaline is an amorphous pink, homogenous, material - combination of plasma proteins, increased mesangial matrix and collagen

Such glomeruli are atrophic
- Smaller

Lacking capillaries
- non-functional.

Question 44

Urinary Tract Infection (UTI) can be what types

Answer 44

Urethritis

Cystitis (bladder)

Pyelitis (walls of renal pelvis near hilus)

Pyelonephritis (if also inflame renal cortex & medulla)

If chronic & affects kidney, scar tissue forms in kidney to severely impair function.

Question 45

what happens at the dialysis unit in hospitals

Answer 45

Where blood cleaned artificially through selectively permeable membrane

Question 46

describe dialysis fluids composition

Answer 46

similar to blood except concentration of wastes is very low.

Question 47

what is renal calculi and explain

Answer 47

a.k.a Kidney Stones

Crystal aggregations of dissolved minerals in urine

Size can vary from grain of sand to a grapefruit!

If 2 - 3mm can obstruct ureter
Causes renal colic (pain)

Question 48

kidney stones form due to what

Answer 48

Ingestion of excessive calcium

Scant water intake

Abnormal alkaline or acidic urine

Overactive parathyroid gland

Question 49

its possible to break down kidney stones via what

Answer 49

with shock waves.