11. Urinary System Workshop Flashcards

1
Q

List four functions of the urinary system

A
  1. Excretion of waste: Uric acid, urea, toxins
  2. Maintenance of water & electrolyte balance
  3. pH regulation of body fluids (especially blood)
  4. Production of hormones (erythropoietin & calcitriol)
  5. Regulation of red blood cell production.
  6. Regulation of blood glucose levels.
  7. Regulation of blood pressure, volume and osmolarity (concentration of a solution)
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2
Q

Name three metabolic wastes containing nitrogen excreted by the urinary system.

A

Urea
Uric acid
Creatinine

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3
Q

Name one ion excreted by the kidneys

A

Hydrogen

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4
Q

State the minimum daily quantity of urine (ml) required to clear body waste.

A

500ml

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5
Q

What is creatine phosphate?

A

A protein based molecule that stores ATP to be used by muscles.

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6
Q

What is the waste product formed from the metabolism of creatine phosphate in muscles?

A

Creatinine

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7
Q

Name three electrolytes regulated by the kidneys

A

Sodium (Na+)
Potassium (K+)
Hydrogen (H+)

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8
Q

Describe specifically how the kidneys play a role in blood pH balance.

A

The kidneys excrete H+ into urine and produce the buffer HCO3 (bicarbonate) to counter blood acidity.

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9
Q

Describe the main role of the following hormones in relation to the kidney:

a. Calcitriol
b. Erythropoietin

A

a. The kidneys convert inactive Vitamin D into its active form (Calcitriol) which stimulates the uptake of calcium and magnesium from the GIT and reduces the calcium loss from the kidneys.
b. Erythropoietin (EPO) is a hormone that the kidneys produce in response to hypoxia and it stimulates erythropoiesis in the red bone marrow.

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10
Q

Explain why anaemia is common in renal failure

A

The lack of the production of erythropoietin leads to inadequate red blood cell levels and hence results in anaemia.

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11
Q

What range of blood glucose levels is considered as normal?

A

4-7 mmol/L

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12
Q

State the normal renal threshold for glucose in mmol/L

A

9 mmol/L [above this level in the blood, glucose cannot be reabsorbed from the nephrons into the blood when passing through kidney tubules]

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13
Q

Describe specifically how the kidneys compensate for ‘low blood glucose’

A

Through a process known as gluconeogenesis, the kidneys are able to make glucose from the amino acid glutamine, in order to raise blood glucose levels during periods of hypoglycaemia.

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14
Q

What pathology is ‘hyperglycaemia’ indicative of?

A

Diabetes Mellitus

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15
Q

What enzyme is secreted by the kidneys to help regulate blood pressure?

A

Renin

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16
Q

Explain why the right kidney is lower than the left kidney

A

The right kidney is lower than the left because the liver occupies considerable space on the right side of the body, superior to the kidney.

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17
Q

Are the kidneys positioned within or outside the peritoneum?

A

Outside - they are retroperitoneal

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18
Q

What are the three layers of tissue that surround the kidneys?

A
  1. Renal capsule (deep layer) - smooth, transparent connective tissue
  2. Adipose capsule (middle layer) - mass of fatty tissue that protects and supports
  3. Renal fascia (superficial layer) - anchors kidneys to surrounding structures
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19
Q

Name the two distinct regions in the kidney

A

Renal cortex
Renal medulla

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20
Q

What is the functional units of the kidney called?

A

nephrons

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21
Q

Urine formed by the nephrons drain into the ______ and major _______.

A

minor
calyces

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22
Q

Explain what is meant by the ‘hilum’

A

The hilum is the concave medial border of the kidney where blood vessels, lymph vessels, nerves and ureters enter the kidney.

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23
Q

What % of cardiac output is received by the kidneys?

A

20-25%

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24
Q

Name the two parts that make up the nephron

A

The renal corpuscle and the renal tubule.

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25
Q

Where can the peritubular capillaries be found?

A

Surrounding the proximal and distal tubule and loop of henle of the nephron.

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26
Q

State which of the following components are in the ‘renal tubule’ or ‘renal corpuscle’:

a. Loop of Henle
b. Distal convoluted tubule
c. Bowman’s capsule
d. Proximal convoluted tubule
e. Glomerulus

A

a. Tubule
b. Tubule
c. Corpuscle
d. Tubule
e. Corpuscle

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27
Q

Name the specific location in a nephron where anti-diuretic hormone acts.

A

Distal convoluted tubule

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28
Q

Describe the role of the ‘muscularis’ in the ureter

A

The muscularis consists of smooth muscle fibres and is responsible for the peristaltic contractions that propels the urine.

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29
Q

State the volume of urine (ml) which, when exceeded within the bladder, triggers the desire to urinate.

A

200ml

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30
Q

Name the small triangular area located on the posterior floor of the bladder.

A

The trigone

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31
Q

Is the internal urethral sphincter voluntary or involuntary? Which muscle forms this sphincter?

A

Involuntary. The muscularis of the bladder, also known as the ‘detrusor’.

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32
Q

List two differences between the female and male urethras.

A

The female urethra is 4cm long whilst the male urethra is about 20cm long. The male urethra passes through the prostate, where it receives semen during ejaculation.

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33
Q

Name the smooth muscle found in the bladder wall

A

The detrusor muscle

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34
Q

How is urine transported from the renal pelvis to the urinary bladder?

A

Two ureters transport urine from the renal pelvis to the bladder. There is peristaltic contractions of the ureters’ muscular walls that propels the urine forward, aided by gravity and the pressure of the urine.

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35
Q

Where is the ‘detrusor’ muscle specifically located?

A

The middle ‘muscularis’ layer of the urinary bladder wall is known as the detrusor muscle.

36
Q

What is the difference between the internal and external urethral sphincters?

A

The internal urethral sphincter is involuntary and the external urethral sphincter is voluntary.

37
Q

Name three processes involved in urine formation.

A
  1. Glomerular filtration - occurs in the renal corpuscle
  2. Tubular reabsorption - occurs in the renal tubules
  3. Tubular secretion - occurs in the renal tubules
38
Q

Describe specifically how the glomerulus is adapted for filtration

A

Glomerular capillaries present a large surface area for filtration. These capillaries are ~50 times leakier than normal capillaries allowing water and small molecules to pass through. The diameter of the efferent arteriole is less than that of the afferent arteriole, resulting in increased blood pressure, which promotes filtration by forcing substances through the membrane.

39
Q

Name four blood constituents that pass into glomerular filtrate

A
Water
Mineral salts (electrolytes)
Amino acids and glucose
Ketoacids
Hormones
Creatinine
Wastes: Urea; Uric Acid; Toxins
40
Q

Name two blood constituents that remain in glomerular capillaries

A

Erythrocytes; Leukocytes; Thrombocytes; Plasma proteins (e.g. Albumin)

41
Q

Define Glomerular Filtration Rate (GFR)

A

GFR is the amount of filtrate formed in the renal corpuscles of both kidneys each minute.

42
Q

State how GFR is measured

A

A normal GFR is determined to be over 90ml/min and this is calculated through the use of a blood test and a complex calculation.

43
Q

Describe how ‘colloid osmotic pressure’ develops

A
  • Damage to glomerular capillaries can lead to plasma protein loss into urine.
  • Albumin leaks into the filtrate, causing albuminuria. Less albumin in the blood makes it hypotonic and fluid moves from blood to tissues by osmosis.
  • Blood volume decreases and interstitial fluid volume increases, causing oedema.
44
Q

Name three substances/molecules which are:

a. reabsorbed via tubular reabsorption
b. secreted into tubular fluid

A

a. Water; Amino acids & glucose; Electrolytes
b. Waste products: creatinine, urea, ammonium ions
Excess ions such as H+; Drugs such as penicillin

45
Q

In which area of the renal tubule do most reabsorption occur?

A

Proximal Convoluted Tubule

46
Q

Describe how the RAAS works to increase blood pressure

A
  • Baroreceptors in the afferent glomerular arteriole detect a drop in blood pressure below 100mmHg
  • This causes the enzyme renin to be secreted into the blood by the kidneys
  • Renin works on Angiotensinogen in the liver and converts it to angiotensin I (travels in blood)
  • Angiotensin I is converted to angiotensin II by angiotensin-converting enzyme (ACE) in the lungs
  • Angiotensin II in the blood causes the release of aldosterone from the adrenal cortex, which acts on the kidneys to stimulate the reabsorption of salt and water. It also acts directly on the blood vessels, stimulating vasoconstriction and thus leads to increased BP.
  • Angiotensin II also causes the pituitary gland to release ADH, which causes the kidneys to reabsorb more water (by increasing distal convoluted tubule permeability), increasing BP.
47
Q

Describe the role of angiotensin-converting enzyme (ACE)

A

ACE converts angiotensin I to angiotensin II

48
Q

Where is ACE released in the body?

A

In the lungs

49
Q

Describe how angiotensin II acts upon the:

a. Pituitary gland
b. Blood vessels

A

a. Triggers the pituitary gland to secrete ADH
b. Stimulates vasoconstriction

50
Q

Explain how aldosterone affects sodium and water reabsorption

A

Aldosterone increases the reabsorption of sodium in the kidneys and thus increases water retention/absorption into the blood (reducing urine output).

51
Q

List one trigger for ADH (anti-diuretic hormone)

A
  • Angiotensin II in the blood
  • Increased blood osmotic pressure causes the hypothalamus to stimulate the release of ADH from the posterior pituitary
52
Q

Explain how ADH (anti-diuretic hormone) can rebalance osmotic pressure

A

ADH increases the permeability of the distal convoluted tubules in the kidneys, increasing water reabsorption into the blood, thereby aiding the rebalancing of the osmotic pressure.

53
Q

Describe the role of atrial natriuretic peptide (ANP)

A

ANP inhibits the reabsorption of Na+ and water in the renal tubules. It is released from the myocardium in response to atrial stretch and suppresses ADH and aldosterone. The resulting increase in urine output leads to reduced blood volume and hence lowered blood pressure.

54
Q

How does parathyroid hormone impact the kidneys?

A

The role of parathyroid hormone is the elevation of blood calcium levels. One of the ways this is achieved, is in the stimulation of renal reabsorption of calcium and magnesium.
[to this end PTH also increases osteoclast activity and stimulates the release of calcitriol which increases the absorption of calcium from the gut]

55
Q

Define micturition

A

Micturition is the discharge of urine from the bladder

56
Q

Describe the difference in micturition between infants and adults

A

When the fluid volume inside the bladder reaches 200-400ml, the micturition reflex is initiated by the activation of stretch receptors and nerve impulses to the spinal chord at S2 and S3.
In infants, this reflex leads to the contraction of the detrusor muscle and relaxation of both the internal and external urethral sphincters.
In adults, the nervous system has matured adequately to consciously inhibit reflex contraction of the bladder and relaxation of the internal sphincter. Adults can also control the external urethral sphincter and pelvic floor muscles.

57
Q

List four signs/symptoms which may indicate a urinary pathology.

A
  1. Frequent and painful urination with urgency
  2. Red urine
  3. Pain in the loin
  4. High urine volume with great thirst
  5. Low or no urine volume
  6. Nausea and vomiting
  7. Oedema
  8. Exhaustion [anaemia]
58
Q

With regards to ‘signs’ that indicate a possible renal disease, explain why each of the following occur:

a. Pallor
b. Frothy urine
c. Oedema
d. Itchy skin

A

a. Pallor is due to anaemia caused by lack of erythropoietin production in the kidneys
b. Frothy urine indicates the presence of protein in the urine (proteinuria)
c. Oedema occurs due to protein (e.g. albumin) loss from the blood into the urine, disturbing the osmotic pressure and resulting in increased interstitial fluid
d. Itchy skin can develop due to the accumulation of urea in the blood due to inadequate excretion (uraemia)

59
Q

Is urine normally slightly acidic or slightly alkaline?

A

Slightly acidic (average pH of 6)

60
Q

What might glycosuria indicate?

A

Diabetes Mellitus

61
Q

Identify one pathology for each of the following urinalysis parameters:

a. Protein
b. Bacteria
c. Glucose
d. Casts

A

a. Kidney disease
b. UTI
c. Diabetes Mellitus
d. Nephron disease

62
Q

Provide the proper urinary terminology for:

  1. Large quantity of urine
  2. No urine
  3. Painful, burning urination
  4. Protein in urine
  5. Blood in urine
  6. Little urine
  7. Night urination
  8. Bacteria in urine
A
  1. Polyuria
  2. Anuria
  3. Dysuria
  4. Proteinuria
  5. Haematuria
  6. Oliguria
  7. Nocturia
  8. Bateriuria
63
Q

What might elevated nitrites on a dipstick test indicate?

A

Urinary Tract Infection

64
Q

Why is cystitis more common in women than in men?

A

The female urethra is much shorter and closer to the anus, making it more susceptible to bacteria getting into the bladder.

65
Q

Name the main cause of cystitis

A

E. Coli bacteria

66
Q

List three signs/symptoms of cystitis

A

Dysuria, Frequent urination, Nocturia, Cloudy and smelly urine, suprapubic pain, haematuria, nauseau, confusion (late stages)

67
Q

With regards to the positive diagnosis of cystitis, describe what the following tests would reveal:

a. Dipstick test
b. Urine microscopy

A

a. Nitrites, leukocytes and erythrocytes

b. Significant bacteriuria

68
Q

Using definitions, compare pyelonephritis and cystitis.

A

Pyelonephritis is a microbial infection of the renal pelvis and medulla. Cystitis is an infection and inflammation of the bladder.

69
Q

Name two possible causes of pyelonephritis (not infection)

A

Diabetes Mellitus [increased glucose: more bacteria]
Enlarged prostate, Kidney stones [obstructed urine flow]
Gout
Pregnancy
Immunocompromised patients

70
Q

Explain how pyelonephritis can lead to the scarring of renal tissue

A

Repeated episodes of pyelonephritis can lead to a cronic state of infection which can lead to necrosis and the scarring of the dysfunctional renal tissue.

71
Q

With regards to the diagnosis of pyelonephritis, describe what the following tests should reveal:

a. Dipstick test
b. Urine microscopy
c. Blood test

A

a. Dipstick: Nitrites, erythrocytes, leukocytes, protein
b. Microscopy: Bacteria, Urinary casts, Blood cells, protein
c. Blood: Raised inflammatory markers - ESR & WBC

72
Q

List two complications of pyelonephritis

A
  • Septicaemia and renal abscess
  • Kidney disease and renal failure
  • Secondary hypertension [due to increased renin]
73
Q

Describe specifically the pathophysiology of glomerulonephritis

A

Glomerulonephritis develops due to an autoimmune reaction (type III hypersensitivity) whereby antigen-antibody immune complexes are formed in response to infection. These immune complexes are deposited in the glomeruli where they trigger an immune response, which leads to leaky capillaries and leukocyte proliferation, allowing proteins and erythrocytes to escape into urine.

74
Q

List one secondary cause of glomerulonephritis

A

SLE (Systemic Lupus Erythematosus)

75
Q

Name one trigger of an autoimmune reaction in glomerulonephritis

A

Bacterial Upper Respiratory Tract Infection

Streptococcal infection

76
Q

Describe how hypertension can develop in glomerulonephritis

A

The scarring and fibrosis of glomerular capillaries (glomerulosclerosis) reduces renal blood flow and GFR, resulting in an increase in renin and thus elevation of blood pressure.

77
Q

Describe why back pain is present in glomerulonephritis

A

Back pain is due to glomerular inflammation which is present at the level of the lower back

78
Q

Name two urinalysis parameters that you would expect to find in glomerulonephritis

A

Erythrocytes and protein

79
Q

Describe how oedema develops in nephrotic syndrome

A

Glomerular permeability leads to the loss of plasma proteins which leads to low plasma osmotic pressure, so that fluid moves out of capillaries and into tissues.

80
Q

List two infectious causes of nephrotic syndrome.

A

HIV; malaria; hepatitis

81
Q

Name one common medicine that can cause nephrotic syndrome

A

NSAIDS

82
Q

Describe the pathophysiology of diabetic nephropathy

A

Diabetes Mellitus elevates blood pressure, resulting in increased intra-glomerular pressure which leads to glomerulosclerosis. The glomeruli become damaged and proteins leak into the urine (microalbuminuria), which is nephrotic syndrome. The kidneys are often enlarged.

83
Q

Name one mineral that is commonly implicated in renal calculi

A

Calcium oxalate and phosphate

84
Q

Explain how the position of kidney stones affects the signs and symptoms experienced

A

If the stones stay in position, they can obstruct the outflow of urine, or they can migrate down the urinary tract, causing severe loin pain and ureteric colic en route.

85
Q

List two causes of renal calculi

A

Dehydration
Hypercalcaemia (hyperparathyroidism)
Hyperuricaemia (gout)

86
Q

Describe the pain associated with renal calculi

A

Severe loin pain, radiating to the groin (ureteric colic)

87
Q

Describe the key differences between ‘haemodialysis’ and ‘peritoneal dialysis’

A

Haemodialysis is the removal of waste products and water from the blood, which is usually performed in hospital about three times a week and takes 3-4 hours each session.
In peritoneal dialysis a tube is inserted into the abdomen which administers dialysis fluid, into which waste products diffuse. Removal is via a shunt and it is often administered at home and though it takes longer than haemodialysis, it is often more comfortable.