Lecture 30

Question 1

What are the major functions of the kidney?

Answer 1

Endocrine, metabolic, pH, water, salt/ion, reabsorption and excretion

Question 2

What are the endocrine functions?

Answer 2

EPO, VD → Calcitriol, Renin secretion

Question 3

What is EPO?

Answer 3

Erythropoietin, a hormone secreted by the kidney to stimulate the bone marrow to produce RBCs

Question 4

What is chronic kidney/renal failure?

Answer 4

Kidneys cannot make enough EPO leading to reduced RBC production and potential for anaemia (low blood O2 levels)

Question 5

What is the metabolic function?

Answer 5

Gluconeogenesis - synthesis of new glucose from lactate

Question 6

When does glucogenesis occur?

Answer 6

While fasting or when the body is under stress

Question 7

What is pH?

Answer 7

A measure of how acidic or alkaline a solution is
pH = - log [H+]

Question 8

More H+ means…?

Answer 8

lower pH, more acidic

Question 9

Fewer H+ means…?

Answer 9

Higher pH, more basic

Question 10

What is the normal pH range for the blood?

Answer 10

7.35-7.45

Question 11

What is the normal pH range for the urine?

Answer 11

4.6-8

Question 12

What are the main sources of acid in the body?

Answer 12

Acids coming from metabolism, food and drink as a direct source of H+ and carbon dioxide from metabolism

Question 13

What is the pH of the blood controlled by?

Answer 13

The lungs and kidneys

Question 14

Why are there two systems controlling blood pH?

Answer 14

If one fails, the other can compensate

Question 15

How do the lungs control blood pH?

Answer 15

Exhalation of carbon dioxide

Question 16

How do the kidneys control blood pH?

Answer 16

Through reabsorption and secretion of bicarbonate and H+

Question 17

Why is water homeostasis important?

Answer 17

ECF osmolarity and blood pressure

Question 18

What can be adjusted to maintain water balance within the body?

Answer 18

Urine output

Question 19

Why is salt/ion homeostasis important?

Answer 19

[Na+], [K+] and blood pressure

Question 20

Why is [K+] so important?

Answer 20

All cells resting membrane potential is based on the K+ gradient and neurons & cardiomyocytes rely on K+ for action potentials, rhythm generation in pacemaker cells, contractility and signalling

Question 21

What happens if you suffer from a kidney disease or failure?

Answer 21

Kidneys cannot secrete enough K+ leading to a build-up in the blood (hyperkalemia) which can cause arrhythmias and death

Question 22

What nutrients are reabsorbed?

Answer 22

Amino acids and glucose

Question 23

What medication are excreted?

Answer 23

All e.g. asprin and lignocaine

Question 24

What toxin is excreted?

Answer 24

All e.g. urea

Question 25

What metabolite is excreted?

Answer 25

Uric acid

Question 26

What is lidocaine?

Answer 26

A lipophilic medicine used for local anaesthetic

Question 27

How are lipophilic medicines excreted?

Answer 27

Via the kidneys AFTER metabolism in the liver

Question 28

What is asprin?

Answer 28

A hydrophilic medicine used as a pain killer

Question 29

How are hydrophilic medicines excreted?

Answer 29

Directly via the kidneys

Question 30

How much of TBW is extracellular fluid?

Answer 30

1/3

Question 31

How much of TBW is intracellular fluid?

Answer 31

2/3

Question 32

How much of ECF is plamsa?

Answer 32

1/5

Question 33

How much of ECF is interstitial fluid?

Answer 33

4/5

Question 34

How can the volume of fluid in the body water compartments change?

Answer 34

Based on how much water there is in the body and the osmolarity of the body water compartments

Question 35

What does a change in plasma water content cause?

Answer 35

A proportional change in blood pressure

Question 36

What does an increase in ICF water content cause?

Answer 36

Swelling of cells

Question 37

What does a decrease in ICF water content cause?

Answer 37

Shrinking of cells

Question 38

What is osmolatiry?

Answer 38

The total number of solute molecules in a solution

Question 39

What is isosmotic?

Answer 39

The same amount of solute molecules, same osmolarity

Question 40

What is hyposmotic?

Answer 40

Increase water, less solute molecules, decrease in ECF osmolarity

Question 41

What is hyperosmotic?

Answer 41

Decrease in water, more solute molecules, increase in ECF osmolarity

Question 42

Where do ingested fluids travel first?

Answer 42

To the extracellular fluid

Question 43

What does the addition of isosmotic fluid in the body cause?

Answer 43

A change in ONLY the ECF

Question 44

What are the basic functions of the nephron?

Answer 44

Filtration, secretion and reabsorption

Question 45

Where does filtration occur?

Answer 45

In the renal corpuscle

Question 46

What does filtration do?

Answer 46

Creates a plasma-like filtrate of the blood

Question 47

What movement occurs during filtration?

Answer 47

Plasma from glomerular capillaries to glomerular capsule Blood → Nephron

Question 48

What can be filtered?

Answer 48

Most substances are free filtered except large proteins and RBCs

Question 49

Where does secretion occur?

Answer 49

In the proximal convoluted tubule

Question 50

What does secretion do?

Answer 50

Removes additional substances from the blood and adds them to the tubular fluid Blood → nephron

Question 51

What additional substances are added to the tubular fluid?

Answer 51

Metabolites, mediations and toxins

Question 52

Where does reabsorption occur?

Answer 52

The PCT, nephron loop and DCT

Question 53

What does reabsorption do?

Answer 53

Returns useful substances to the blood by removing them from the peritubular fluid Nephron → blood

Question 54

What major function occurs in the glomerulus?

Answer 54

Filtration

Question 55

What major functions occur in the PCT?

Answer 55

Secretion, bulk reabsorption (ions, H2O & glucose)

Question 56

What major function occurs in the nephron loop?

Answer 56

Bulk reabsorption (ions & H2O)

Question 57

What major function occurs in the DCT and collecting duct?

Answer 57

Fine-tuning reabsorption (ions and H2O)

Question 58

How do you determine the amount of a substance excreted in the urine?

Answer 58

Amount filtered + amount secreted - amount reabsorbed

Question 59

What happens to glucose in the nephron?

Answer 59

Freely filtered, not secreted and fully reabsorbed in PCT (none in urine)

Question 59

What happens to sodium in the nephron?

Answer 59

Freely filtered, not secreted and almost fully reabsorbed (small amount in urine)

Question 60

What happens to mediation and toxins in the nephron?

Answer 60

Free filtered, rest entirely secreted, none reabsorbed so ALL in urine

Question 61

What happens to creatinine and insulin in the nephron?

Answer 61

Freely filtered, not secreted or absorbed so all filtered is in urine, rest remains in blood