Lecture 31: Urine composition, functions of the kidney, and basic nephron processes

Question 1

How much normal urine is produced a day?

Answer 1

1.5 L/day

Question 2

What % of urine is water?

Answer 2

95% - 98%

Question 3

What is excreted in normal urine?

5

Answer 3

• Urea/uric acid
• H+/NH3 (hydronium ions/ammonia)
• Potassium/sodium
• Drugs
• Toxins

Question 4

What is found in pathological urine?

6

Answer 4

• Glucose
• Protein
• Blood
• Haemoglobin
• Leucocytes
• Bacteria

Question 5

How should normal urine look?

Answer 5

Clear, light or dark amber

Question 6

How should normal urine taste?

Answer 6

Acidic (pH 5-6)

Question 7

How should normal urine not taste?

Answer 7

Sweet

Question 8

What is the pH of our urine dependent on?

Answer 8

Diet

Question 9

What can the pH of vegetarians urine be up to?

Answer 9

7.2

Question 10

What is the pH of meat eaters (high protein)?

Answer 10

4.8

Question 11

what is the smell of normal urine?

Answer 11

Unremarkable

Question 12

What does pathological urine look like?

Answer 12

golden, red, brown or blue

Question 13

What does pathological urine taste like?

Answer 13

Sweet

Question 14

What does pathological urine smell like?

Answer 14

Fruits or rotten

Question 15

What are low oxygen levels detected by?

Answer 15

The kidneys

Question 16

What does the kidney release?

Answer 16

Erythropoietin (EPO)

Question 17

What does EPO do?

Answer 17

Stimulates the bone marrow to produce more red blood cells

Question 18

What can chronic renal failure lead to?

Answer 18

Anaemia

Question 19

What does anaemia lead to?

Answer 19

Low levels of red blood cells/haemoglobin

Question 20

What does low levels of red blood cells/haemoglobin lead to?

Answer 20

Low blood oxygen levels

Question 21

What can happen to substances in the kidneys?

Answer 21

They can be metabolised

Question 22

What is meant by the kidneys being able to preform gluconeogenesis?

Answer 22

They can produce glucose in a fasted state

Question 23

What is potassium ion concentration important for?

Answer 23

Many processes

Question 24

What is the resting membrane potential of all cells based on?

Answer 24

The potassium gradient (inside/outside) of cells

Question 25

How much potassium is in a banana?

Answer 25

0.5g

Question 26

How much potassium is needed dietarily daily?

Answer 26

5g

Question 27

How much potassium is needed to kill a 165lb person?

Answer 27

190g

Question 28

What do the kidneys do to potassium?

Answer 28

They secrete it

Question 29

What does kidney disease/failure lead to?

Answer 29

Hyperkalemia (death)

Question 30

What is lidocaine?

Answer 30

A commonly used local anaesthetic

Question 31

When is lidocaine excreted by the kidneys?

Answer 31

After metabolism in the liver

Question 32

Why is lidocaine excreted by the kidneys, after metabolism in the liver?

Answer 32

Due to its fat soluble (lipophilic) nature

Question 33

How is aspirin excreted?

Answer 33

Directly by the kidneys

Question 34

Why is aspirin excreted directly from the kidneys?

Answer 34

Because it is highly water soluble (hydrophilic)

Question 35

What is pH?

Answer 35

-log[H+]

Question 36

What does pH indicate?

Answer 36

Degree of acidity or alkalinity

Question 37

What is the range of pH?

Answer 37

0-14

Question 38

What does a pH of 7 mean?

Answer 38

Neutral

Question 39

What does a pH of <7 mean?

Answer 39

Acid (excess H+)

Question 40

What does a pH of >7 mean?

Answer 40

alkaline/basic (excess base)

Question 41

What is a blood pH of > 7.4 called?

Answer 41

Alkalosis

Question 42

What is a blood pH of < 7.4 called?

Answer 42

Acidosis

Question 43

What is the main buffer of the blood stream?

Answer 43

Bicarbonate

Question 44

How does bicarbonate act as a buffer?

Answer 44

By neutralising so called non-volatile acids coming from metabolism, food and drinks, maintaining a pH of 7.4

Question 45

What is bicarbonate concentration in the blood controlled by?

Answer 45

The lungs and kidneys

Question 46

How is bicarbonate concentration in the blood controlled by the lungs and kidneys?

Answer 46

By exhalation of carbon dioxide from the lungs or reabsorption of bicarbonate by the kidneys/secretion of hydrogen ions

Question 47

What are the 3 basic functions of a nephron?

Answer 47

- Filtration - Secretion - Reabsorption

Question 48

What does filtration in the nephron do?

Answer 48

Creates a plasma-like filtrate of the blood

Question 49

What does reabsorption in the nephron do?

Answer 49

Removes useful solutes from the filtrate and returns them to the blood

Question 50

What does secretion in the nephron do?

Answer 50

Adds additional wastes from the blood to the filtrate

Question 51

What does the balance of filtration/reabsorption/secretion determine?

Answer 51

The way a particular substance is handled in the kidneys

Question 52

Many substances are filtered with a constant what? at the renal corpuscle

Answer 52

Rate

Question 53

What is the exception to substances being filtered at a constant rate?

Answer 53

Substances bound to proteins

Question 54

What are examples of substances that need to be partly/entirely re-absorbed respectively? (2)

Answer 54

- Na,K | - Glucose

Question 55

What process occur at the glomerulus?

Answer 55

Filtration

Question 56

What process occurs at the proximal tubule? | 2

Answer 56

- Bulk reabsorption of electrolytes (sodium, potassium) | - Secretion of metabolites, drugs and toxins

Question 57

What process occurs at the distal tubule?

Answer 57

Fine tuning of electrolytes/water reabsorption

Question 58

What process occurs at the collecting duct?

Answer 58

Fine tuning of electrolytes/water reabsorption

Question 59

What only happens to glucose and where does this only happen?

Answer 59

It is only reabsorbed and it only occurs in the proximal tubule

Question 60

What does potassium reabsorption/secretion depend on?

Answer 60

Diet

Question 61

Where is water reabsorbed?

Answer 61

In most parts of the nephron

Question 62

How are drugs/toxins e.g. penicillin mostly excreted?

Answer 62

By active secretion or non-filtration

Question 63

What happens to big molecules such as albumin?

Answer 63

It is not filtered

Question 64

``` What disease(s) are indicated by blood being present in the urine? (3) ```

Answer 64

- Haematuria - Urinary tract infection - Damage to filtration barrier

Question 65

``` What disease(s) does a urine sample with a specific gravity not between 50-1335 mOsmol/L indicate? (3) ```

Answer 65

- Polyuria - Diabetes mellitus - Diabetes insipidus

Question 66

``` What disease(s) are indicated by glucose being present in the urine? (2) ```

Answer 66

- Glucosuria | - Diabetes mellitus

Question 67

``` What disease(s) are indicated by protein being present in the urine? (3) ```

Answer 67

- Proteinuria - Glomerulonephritis - damage to filtration barrier