Structure and Functions

Question 1

How many kidneys do we have

Answer 1

2

Question 2

Where are the kidneys found

Answer 2

lie extraperitoneally on either side of the vertebral column

Question 3

What are the kidneys surrounded by

Answer 3

Fat in the retroperitoneal space

Question 4

What is the kidney made up of

Answer 4

1. Outer correct that contains glomeruli, tubules and vessels,
2. Inner medulla, containing the loop of Henle and medullary collecting tubules.

Question 5

What is found in kidneys

Answer 5

Nephrons

Question 6

What are nephrons

Answer 6

A functional filtering unit of the kidney comprising a glomerulus and the renal tubule

Question 7

What happens at the glomerulus

Answer 7

The afferent arteriole divides into several golmerilar capillaries to form a loop of capillaries that make up the glomerular

Question 8

What are the glomerulus enclosed in

Answer 8

An epithelial cell capsule called Bowmans capsule

Question 9

What is Bowmans capsule connected with

Answer 9

It is continuous with the basement membrane of the glomerulus and also with the start of the tubule

Question 10

What does the tubule consist of

Answer 10

1. First proximal tubule
2. Loop of Henle
3. Distal tubule that drains into the collecting ducts

Question 11

What happens to uri found int eh collecting ducts

Answer 11

It drains into the pelvis of the kidney
Then travels to the bladder via the ureters

Question 12

What does teh structure of the glomerulus allow for

Answer 12

Permits the production of an ultra filtrate of plasma consisting of water containing only small solutes

Question 13

Where does the ultra filtrate of plasma go in the glomerulus

Answer 13

Passes across the glomerular filtration barrier into the urinary space and then into the tubule

Question 14

What is found next to the glomerulus

Answer 14

The juxtaglomerular apparatus (JGA)

Question 15

What is the juxtaglomerular apparatus

Answer 15

Where the afferent arteriole arrives and the efferent arteriole leaves the glomerulus

Question 16

What are the cells of the juxtaglomerular apparatus a rich source of

Answer 16

Renin

Question 17

What is renin

Answer 17

A hormone

Question 18

What does renin do and how

Answer 18

Contributes to the control of blood pressure, salt and water homeostasis via the renin-angiotensin-aldosterone system
Also maintains vascular tone

Question 19

What happens to the ultra filtrate of plasma as it passes through the tubules

Answer 19

It is modified
ie some substances may be reabsorbed into the capillaries
and some may be actively transported out the capillaries secreted to the tubular lumen

Question 20

Where does most of the absorption of the ultra filtrate of plasma occur

Answer 20

At the proximal tubule

Question 21

What is reabsorbed at the proximal tubule

Answer 21

60% of filtered water, sodium, chloride and potassium
100% of glucose
95% of amino acids

Question 22

When is 100% of glucose not reabsorbed at the proximal tubule

Answer 22

If the filtered load of glucose exceeds reabsorption capacity when the plasma glucose level is very high

Question 23

What can incomplete reabsorption of glucose lead to and in whom

Answer 23

glycosuria in diabetes

Question 24

Other than absorption and secretion what else does the kidney do

Answer 24

It can vary the volume and concentration of urine depending on water intake and body fluid status

Question 25

What happens when the water intake is high

Answer 25

Water is excreted in excess of solute in a dilute urine that is hypo osmolar compared to plasma

Question 26

What happens when water intake is low

Answer 26

Water is retained by the kidney and a concentrated urine that is hyperosmolar compared with plasma is excreted

Question 27

Where does the formation of dilute vs concentrated urine occur

Answer 27

depends on the countercurrent multiplier mechanism in the loop of Henle

Question 28

What is special about the loop of Henly

Answer 28

There is a different permeability of the ascending and descending limbs of the loop of henly

Question 29

Where is teh medullary osmotic gradient highest in the loop of henly

Answer 29

Highest at the tip of the loop in the inner medullar and papilla

Question 30

How is renal function described

Answer 30

As the glomerular filtration rate (GFR)

Question 31

What is the glomerular filtration rate equal to

Answer 31

The sum of all the filtering nephrons

Question 32

How do we assess the glomerular filtration rate

Answer 32

1. Insulin clearance 2. Plasma creatine concentrations

Question 33

How does insulin clearance give an assessment of glomerular filtration rate

Answer 33

As insulin can only be cleated by filtration at the glomerulus it provides a very accurate estimate of the GFR

Question 34

What is the problem with using insulin clearance to measure GFR

Answer 34

Insulin as to be infused intravenously so this method is more of a research tool

Question 35

What is creatine produced by

Answer 35

Muscle turnover

Question 36

What happens to creatine in teh kidneys

Answer 36

As it is small it is freely filtered at teh glomerulus and NOT reabsorbed or metabolised to any significant extent

Question 37

Why can we use plasma creating concentration to assess GFR

Answer 37

As creating is not reabsorbed in the kidneys it can be used as a rough guide to GFR

Question 38

What is the drawback of using plasma creatine concentration to assess GFR

Answer 38

Creatine is secreted by the renal tubules so may be higher concentration than expected

Question 39

What does metabolism produce

Answer 39

Hydrogen ions (proteins)

Question 40

What is the problem with hydrogen ions

Answer 40

They are acidic so lower pH so myst be buffered to maintain body pH

Question 41

Name the most widespread buffer system in THE body

Answer 41

Bicarbonate (HCO3)

Question 42

State the chemical formula of how bicarbonate buffers hydrogen ions

Answer 42

H+ +HCO3− => H2CO3 => CO2 +H2O

Question 43

Can the bicarbonate buffering system go on forever

Answer 43

no as there is limited bicarbonate in teh body

Question 44

What happens when the buffering system needs to be regenerated

Answer 44

Protons need to be excreted from the body

Question 45

How is bicarbonate regenerated

Answer 45

By the kidneys Where it is remade and also reabsorbed from the urine

Question 46

How do the kidneys achieve net secretion of protons

Answer 46

by generating and excreting ammonium (NH4+) in urine Also by excreting protons bound to other buffer

Question 47

Describe the ultra filtrate of plasma found at teh glomerulus

Answer 47

Consists of water and very small solutes only

Question 48

Talk through the journey the ultra filtrate of plasma goes through from the glomerulus

Answer 48

1. Passes into the Bowmans capsule 2. Passes into proximal tubule 3. Travels down the nephron where it is modified via active and passive ion transport 4. Reaches collecting duct

Question 49

Name the main determinants of extracellular volume

Answer 49

Sodium (Na+) and chloride (Cl-) The amount of these 2 ions controls body extracellular volume

Question 50

List the main functions of the kidney

Answer 50

1. Control of acid base balance 2. Regulation of body fluid volume and composition 3. Excretion 4. Endocrine activity 5. Blood pressure control

Question 51

What do ten kidneys need to excrete

Answer 51

Waste products of metabolism, urea, creatine, potassium and hydrogen ions (protons) Also excretes many drugs and their metabolites

Question 52

What do we need to consider if kidney function is reduced

Answer 52

The dose of water soluble drugs needs to be reviewed and reduced as they are excreted via kidneys

Question 53

Which vitamin does the kidney have a role in synthesising

Answer 53

Synthesises the vitamin D metabolite

Question 54

Name the vitamin D active metabolite

Answer 54

1,25 dihydroxyvitamin D3 or calcitriol

Question 55

What is the significance of calcitriol

Answer 55

Acts on the gut to increase calcium and phosphate uptake Also feeds back to suppress the parathyroid hormone Reduces osteoclast activity

Question 56

Where is the parathyroid hormone released from

Answer 56

Parathyroid glands

Question 57

Which hormone does the kidney produce

Answer 57

erythropoietin

Question 58

What is the significance of erythropoietin

Answer 58

Acts on the bone marrow to maintain red cell production and thus haemoglobin concentration

Question 59

Name the system that controls blood pressure via the kidneys

Answer 59

renin–angiotensin– aldosterone system

Question 60

How are the kidneys involved in controlling arterial blood pressure

Answer 60

Through the regulation of salt, water balance and vasoconstriction

Question 61

What is renin synthesised by

Answer 61

The juxtaglomerular apparatus (JGA) in response to carious stimulus

Question 62

What does renin do

Answer 62

It cleaved to angiotensin to form angiotensin I

Question 63

Where is angiotensin synthesised

Answer 63

The liver

Question 64

What happens to angiotensin 1

Answer 64

If is converted into angiotensin II By angiotensin converting enzyme (ACE)

Question 65

Where are angiotensin converting enzymes (ACE) found

Answer 65

In the lungs and endothelial cells

Question 66

What does angiotensin II do

Answer 66

Binds to at least 2 receptors: 1. AT1 2. AT2

Question 67

What effect does the binding to AT1 by angiotensin II have

Answer 67

1. Vasoconstriction 2. Aldosterone and vasopressin release 3. Water and salt retention in kidneys 4. Sympathetic nervous system activation

Question 68

What effect does the binding to AT2 by angiotensin II have

Answer 68

Anti proliferative and remodelling effects