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HUBS192 2022 > lecture 31 - kidney, nephron & urine physiology > Flashcards

lecture 31 - kidney, nephron & urine physiology Flashcards

1
Q

What are the 7 key fucntions of the kidneys?

A

Endocrine functions ,metabolic functions, blood filtration, water homeostasis, salt/ion homeostasis, nutrient reabsorption, medicine, toxin & metabolite excretion

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2
Q

What is the key endocrine function of the kidney?

A

Detect low blood oxygen levels and release EPO (erythropoietin) to stimulate the kidneys to produce more red blood cells

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3
Q

What is the endocrine issue created in kidney failure?

A

Kidneys cannot make sufficient EPO leading to anaemia - low blood oxygen levels

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4
Q

What is the key metabolic function of the kidneys?

A

Gluconeogenesis

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5
Q

How do the kidneys perform gluconeogenesis?

A

They can make glucose from lactate during times of fasting or stress

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6
Q

What is the kidney’s role in pH regulation?

A

Ensures the blood pH remains within a small range by controlling the concentration of bicarbonate and hydrogen ions in the blood

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7
Q

What is the main buffer in the blood?

A

Bicarbonate (HCO3-)

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8
Q

What are the 2 organs that control blood [HCO3-]?

A

The lungs and the kidneys

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9
Q

How does HCO3- act as a buffer?

A

Reacts with H+ to form carbonic acid which forms CO2 and water in 2 equilibrium reactions

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10
Q

How do the lungs regulate [HCO3-]?

A

The exhale CO2, which decreases [CO2] driving the equilibrium reaction to form carbonic acid and then bicarbonate

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11
Q

How do the kidneys regulate [HCO3-]?

A

By reabsorbing bicarbonate or secreting H+

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12
Q

What is the resting membrane potential of cells dependent on?

A

Primarily the K+ gradient across the membrane (and Na+concentration)

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13
Q

How do the kidneys balance [K+]?

A

By secreting potassium to maintain balance

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14
Q

What is the resulting condition when the kidneys cannot maintain K+ homeostasis due to kidney failure?

A

Hyperkalemia - failure to excrete potassium leads to elevated levels

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15
Q

What are the 2 types of drugs, classified by their solubility?

A

Lipophilic and hydrophilic

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16
Q

What are lipophilic drugs?

A

Fat soluble drugs that are metabolised in the liver

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17
Q

Where are lipophilic drugs metabolised then excreted?

A

Metabolised in the liver then excreted by the kidneys

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18
Q

What type of drug is lidocaine?

A

A lipophilic drug used as a painkiller

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19
Q

How are hydrophilic drugs and toxins metabolised/excreted?

A

No need to be metabolised as they can be excreted directly by the kidneys due to their high water solubility

20
Q

What are the 3 basic functions of the nephron?

A

Filtration, reabsorption, secretion

21
Q

What is the product of filtration in the kidneys?

A

A plasma-like filtrate of the blood

22
Q

Why is filtrate in the kidneys referred to as ‘plasma-like’?

A

Has similar concentrations of key solutes, has no red blood cells. However, lacks plasma proteins

23
Q

Where does secretion occur in the nephrons?

A

Secretion from peritubular capillary blood into the tubular fluid of the nephrons

24
Q

Where does filtration occur in the kidneys?

A

The glomerulus

25
Q

What key substance cannot be filtered at the golmerulus?

A

Proteins, e.g. albumin, and substances bound to proteins, such as lipid soluble substances

26
Q

What is secreted in the proximal tubule?

A

metabolites, medications, and toxins

27
Q

What is the equation for the amount of a substance in the urine?

A

[urine] = filtered - absorbed + secreted

28
Q

Where in the nephron is sodium reabsorbed?

A

Most parts of the tubule

29
Q

What proportion of sodium ions are reabsorbed in the nephron?

A

Almost all of it

30
Q

Where is glucose reabsorbed in the nephron?

A

100% of glucose reabsorbed in proximal tubule

31
Q

What is the breakdown product of muscle metabolism that is found in urine?

A

Creatinine

32
Q

What is the product of amino acid breakdown that is found in urine?

A

Urea

33
Q

What is the product of purine breakdown that is found in urine?

A

Uric acid

34
Q

Why are H+ ions found in urine?

A

Excreted to regulate blood pH

35
Q

Why are Na+ and K+ found in urine?

A

To balance blood and cellular concentrations of these ions

36
Q

What is the condition in which the urine contains glucose?

A

Glucosuria

37
Q

What is the condition in which the urine contains protein, particularly albumin?

A

proteinuria

38
Q

What is the condition in which the urine contains red blood cells?

A

Haematuria

39
Q

What is the condition in which the urine contains haemoglobin?

A

haemoglobinuria

40
Q

What is osmolarity?

A

A measure of the number of solute molecule in a solution. If a substance is ionic, the sum of all of the ions it dissociates into

41
Q

What is an isosmotic solution?

A

Solution with the same osmolarity as the reference solution

42
Q

What is a hypoosmotic solution?

A

Solution with lower osmolarity than the reference solution

43
Q

What is a hyperosmotic solution?

A

Solution that has higher osmolarity than the reference solution

44
Q

What is tonicity?

A

The effect a solution has on cell volume due to the net/overall movement of water

45
Q

What occurs if a cell is hypotonic?

A

Net movement of water into cell - swelling

46
Q

What occurs if a cell is hypertonic?

A

Net movement of water out of cells - shrinking

47
Q

What occurs if a cell is isotonic?

A

Movement of water into and out of cells is equal so no net movement and cell volume is constant

HUBS192 2022 (38 decks)

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