lecture 31 - kidney, nephron & urine physiology

Question 1

What are the 7 key fucntions of the kidneys?

Answer 1

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

Question 2

What is the key endocrine function of the kidney?

Answer 2

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

Question 3

What is the endocrine issue created in kidney failure?

Answer 3

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

Question 4

What is the key metabolic function of the kidneys?

Answer 4

Gluconeogenesis

Question 5

How do the kidneys perform gluconeogenesis?

Answer 5

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

Question 6

What is the kidney’s role in pH regulation?

Answer 6

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

Question 7

What is the main buffer in the blood?

Answer 7

Bicarbonate (HCO3-)

Question 8

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

Answer 8

The lungs and the kidneys

Question 9

How does HCO3- act as a buffer?

Answer 9

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

Question 10

How do the lungs regulate [HCO3-]?

Answer 10

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

Question 11

How do the kidneys regulate [HCO3-]?

Answer 11

By reabsorbing bicarbonate or secreting H+

Question 12

What is the resting membrane potential of cells dependent on?

Answer 12

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

Question 13

How do the kidneys balance [K+]?

Answer 13

By secreting potassium to maintain balance

Question 14

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

Answer 14

Hyperkalemia - failure to excrete potassium leads to elevated levels

Question 15

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

Answer 15

Lipophilic and hydrophilic

Question 16

What are lipophilic drugs?

Answer 16

Fat soluble drugs that are metabolised in the liver

Question 17

Where are lipophilic drugs metabolised then excreted?

Answer 17

Metabolised in the liver then excreted by the kidneys

Question 18

What type of drug is lidocaine?

Answer 18

A lipophilic drug used as a painkiller

Question 19

How are hydrophilic drugs and toxins metabolised/excreted?

Answer 19

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

Question 20

What are the 3 basic functions of the nephron?

Answer 20

Filtration, reabsorption, secretion

Question 21

What is the product of filtration in the kidneys?

Answer 21

A plasma-like filtrate of the blood

Question 22

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

Answer 22

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

Question 23

Where does secretion occur in the nephrons?

Answer 23

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

Question 24

Where does filtration occur in the kidneys?

Answer 24

The glomerulus

Question 25

What key substance cannot be filtered at the golmerulus?

Answer 25

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

Question 26

What is secreted in the proximal tubule?

Answer 26

metabolites, medications, and toxins

Question 27

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

Answer 27

[urine] = filtered - absorbed + secreted

Question 28

Where in the nephron is sodium reabsorbed?

Answer 28

Most parts of the tubule

Question 29

What proportion of sodium ions are reabsorbed in the nephron?

Answer 29

Almost all of it

Question 30

Where is glucose reabsorbed in the nephron?

Answer 30

100% of glucose reabsorbed in proximal tubule

Question 31

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

Answer 31

Creatinine

Question 32

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

Answer 32

Urea

Question 33

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

Answer 33

Uric acid

Question 34

Why are H+ ions found in urine?

Answer 34

Excreted to regulate blood pH

Question 35

Why are Na+ and K+ found in urine?

Answer 35

To balance blood and cellular concentrations of these ions

Question 36

What is the condition in which the urine contains glucose?

Answer 36

Glucosuria

Question 37

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

Answer 37

proteinuria

Question 38

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

Answer 38

Haematuria

Question 39

What is the condition in which the urine contains haemoglobin?

Answer 39

haemoglobinuria

Question 40

What is osmolarity?

Answer 40

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

Question 41

What is an isosmotic solution?

Answer 41

Solution with the same osmolarity as the reference solution

Question 42

What is a hypoosmotic solution?

Answer 42

Solution with lower osmolarity than the reference solution

Question 43

What is a hyperosmotic solution?

Answer 43

Solution that has higher osmolarity than the reference solution

Question 44

What is tonicity?

Answer 44

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

Question 45

What occurs if a cell is hypotonic?

Answer 45

Net movement of water into cell - swelling

Question 46

What occurs if a cell is hypertonic?

Answer 46

Net movement of water out of cells - shrinking

Question 47

What occurs if a cell is isotonic?

Answer 47

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