Kidney Physiology and Function Flashcards

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1
Q

What are the 3 main functions of the urinary system?

A

1) Excretion
2) Elimination
3) Regulation

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2
Q

Explain what excretion means in terms of the kidney.

A

Removal of organic waste products from body fluids.
IE: Ammonia // Uric // Amino acids.
IE: Creatinine.

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3
Q

Explain what elimination means in terms of the kidney.

A

Discharge of waste products from the body.

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4
Q

Explain what regulation means in terms of the kidney.

A

Homeostatic regulation of volume and solute concentration of blood plasma.

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5
Q

What are the 3 main parts of the kidney?

A

Renal Cortex
Renal Medulla
Renal Pelvis

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6
Q

What composed together creates the renal lobes?

A

Renal pyramids + “outer” renal cortex.

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7
Q

What is the renal medulla?

A

This is where the nephrons are located and consists of 6 - 18 structures known as ‘renal pyramids’.

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8
Q

What is the purpose of the renal lobes?

A

This is the site of urine production and the urine drains into the calyx.

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9
Q

In terms of blood supply, how much of the cardiac output does kidneys receive?

A

20 - 25%.

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10
Q

How is blood pressure maintained ini the kidneys?

A

There is a network of capillaries which gets smaller ini size and thus maintains the blood pressure.

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11
Q

Where is blood pressure the highest?

A

In the glomerulus.

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12
Q

Give the journey of blood through the kidney starting at the aorta and ending at the vena cava.

A

From aorta to renal artery to the kidney.
ENTERS THE GLOMERULUS IN THE BOWMANS CAPSULE.
From the kidney to the renal vein to then vena cava.

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13
Q

Which nervous system is associated with the nervous control of the kidneys?

A

Sympathetic Nervous System.

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14
Q

Where are the renal sensory nerves usually found?

A

In the renal pelvic wall.

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15
Q

What does the sympathetic nervous system control?

A

Controls the juxtaglomerular cells alongside the renal tubules and vasculature (known as the vascular system of the body).

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16
Q

What is hypertension?

A

High blood pressure and increased risk of heart disease.

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17
Q

What is the purpose of the adrenal glands?

A

These are important for the production of hormones which can regulate the renal function.

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18
Q

What are the 2 main glands?

A

Adrenal Cortex

Adrenal Medulla

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19
Q

Which gland produces the ESSENTIAL hormones?

A

Adrenal Cortex

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20
Q

What are the essential hormones produced?

A
Cortisol = Regulates metabolism 
Aldosterone = Controls blood pressure
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21
Q

Which gland produces the NON - ESSENTIAL hormones?

A

Adrenal Medulla

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22
Q

What are the non - essential hormones produced?

A

Adrenaline = Reacts to stress levels

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23
Q

What is another name for aldosterone?

A

Mineralocorticoids.

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24
Q

Which types of nephrons are there?

A
85% = Cortical Nephrons
15% = Juxtamedullary Nephrons
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25
Q

What is the difference between cortical and juxtamedullary nephrons?

A

Cortical has the glomerulus near the outer parts of the cortex.
Has a SHORT Loop of Henle.
Juxtamedullary has the glomerulus near the junction of the cortex and the medulla.
Has a LONG Loop of Henle.

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26
Q

What is the purpose of the nephrons?

A

Functional unit of the kidney which regulates water and soluble substances = Filters the blood and reabsorbs what is needed. The rest is excreted as urine.

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27
Q

What is the structure of the nephron?

A

Renal Corpuscle
Renal Tubule
Collecting System

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28
Q

What makes up the renal corpuscle?

A

Bowman’s Capsule
Glomerulus
Glomerular Capillary Network

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29
Q

What makes up the renal tubule?

A

Proximal convoluted tubule.
Loop of Henle
Distal convoluted tubule

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30
Q

What is part of the collecting system?

A

Collecting Duct.

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31
Q

How is blood supplied to the nephron?

A

Blood ARRIVES at the nephron from the AFFERENT arteriole.
Enters the glomerular capillaries.
Blood EXITS the nephron from the EFFERENT arteriole.

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32
Q

What is an arteriole?

A

Single celled vessels which allow efficient gas exchange.

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33
Q

What are the 3 main stages of Nephron function?

A

Ultrafiltration
Selective Reabsorption
Osmoregulation

34
Q

Describe in detail what happens in ultrafiltration.

A

Blood is filtered out of the glomerulus at the Bowman’s capsule to form a filtrate.

35
Q

Describe in detail what happens in selective filtration.

A

Useful materials are reabsorbed in convoluted tubules. (PROXIMAL AND DISTAL.)

36
Q

Describe in detail what happens in osmoregulation.

A

Loop of Henle establishes a salt gradient = Draws water out of the collecting duct.

37
Q

How are plasma proteins prevented from the entering the filtrate?

A

Very small pores are present which prevent the entering of LARGE molecules such as plasma proteins.

38
Q

Where does filtration occur?

A

In the corpuscle :
Bowman’s Capsule
Glomerulus
Glomerular Capillary Network

39
Q

What is the glomerular filtration rate? (GFR)

A

The amount of filtrate produced per minute.

40
Q

Why is the GFR used?

A

It is a test used in order to determine how well the kidney functions.

41
Q

What if the GFR is low?

A

Kidneys are NOT working well and this means the blood pressure is low.

42
Q

Where does reabsorption occur?

A

In the renal tubule :
Proximal convoluted tubule.
Loop of Henle
Distal convoluted tubule

43
Q

Which processes are involved in reabsorption?

A

Diffusion
Osmosis
Carrier mediated transport

44
Q

Which substances are reabsorbed in the PCT?

A

Glucose / Amino Acids / Ions

45
Q

As the PCT is the largest site of water reabsorption, how much is reabsorbed via osmosis?

A

60 - 70%

46
Q

What are the names of the drugs which prevent uptake of glucose?

A

Diuretics

47
Q

How do diuretics work?

A

They make you pee MORE and thus, MORE glucose leaves the body.

48
Q

Where does most of water reabsorption occur?

A

PCT and the descending limb of the Loop of Henle.

49
Q

What are the names of the water channels which aid with reabsorption?

A

Aquaporins.

50
Q

How is osmolality affected when there is INCREASED water reabsorption?

A

There is an increase in osmolality.

51
Q

What are the differences between the descending limb and ascending limb of the Loop of Henle?

A

The descending limb is thin compared to the ascending limb which is thick.
The descending limb is permeable to water and impermeable to solutes whereas the ascending limb is impermeable to water and permeable to solutes.

52
Q

What causes Na+ // K+ // Cl- to be pumped out?

A

The filtrate becomes MORE concentrated and thus, produces a gradient.

53
Q

What happens regarding reabsorption in the DCT?

A

NaCl is ACTIVELY reabsorbed.

NCC transporter is present = Na and 2 Cl out.

54
Q

What is the action mechanism of Thiazide Diuretics?

A

Inhibits reabsorption of Na+ and Cl- ions from the DCT.

BLOCKS the Na+ and Cl- symporter = INCREASES the Ca2+ reabsorption.

55
Q

What happens if reabsorption DOES NOT occur?

A

Leads to Oedema = This is the build - up of fluid due to an ion imbalance.
High blood pressure can lead to oedema too.

56
Q

In terms of secretion, where does it normally occur?

A

Occurs at the proximal and distal convoluted tubules.

57
Q

What normally occurs in secretion?

A

Transport of the solutes into the filtrate for excretion from the body.
H+ and K+ is secreted for reabsorption of Na+.

58
Q

Why is H+ secretion important in the blood?

A

Essential for regulation of plasma potassium concentrations and the pH.

59
Q

Give a summary of Nephron function.

A
  • Filtration at the glomerular capillaries in the renal corpuscle.
  • Active removal of ions / glucose / amino acids at the PCT.
  • Water reabsorption in the PCT and descending limb of Loop of Henle INCREASES the filtrate concentration.
  • Active of transport of Na+ and Cl- from the ascending limb.
  • Reabsorption and secretion in the DCT.
  • Final reabsorption of water in collecting duct.
60
Q

What is the renin - angiotensin - aldosterone system?

A

Signalling pathway responsible for regulating the body’s blood pressure.
CONSTANT HOMEOSTASIS OCCURS.

61
Q

What can be affected by this system?

A

Glomerular Filtration Rate.

62
Q

Why is aldosterone released?

A

This is released for the regulation of kidney function alongside blood vessels too.

63
Q

What is angiotensin known for?

A

Being an ACE inhibitor.

64
Q

Why is renin released?

A

When there is LOW blood pressure.

65
Q

Why is hormonal regulation necessary for the kidneys?

A

Regulates the amount of water excreted by the body.

66
Q

What are antidiuretic hormones used for?

A

These are released from the CNS in response to dehydration.
This increases water reabsorption in DCT and the collecting duct.
CONSTRICTS renal arteries and thus, reduces GFR.

67
Q

What does antidiuretic hormones increase?

A

Increases the number of aquaporins.

68
Q

What are natriuretic peptides?

A

Receptors in the heart which respond to stretch and thus are known as BARORECEPTORS.

69
Q

What are natriuretic peptides used for?

A

Has the opposite effect to ADH
INCREASES diuresis and thus a lot of dilute urine is produced.
RELAXES renal arteries and thus, increases GFR.

70
Q

What does the renal system involve?

A

Involves kidneys // ureters // bladders // urethra.

71
Q

What happens when the volume of blood decreases?

A

Blood pressure decreases.

72
Q

What happens when the volume of blood increases?

A

Blood pressure increases.

73
Q

What are the main electrolytes in the blood?

A

Na+ // K+ // Cl- // HCO3-

74
Q

What happens in patients with kidney failure?

A

There is an imbalance of electrolytes and thus, can lead to hypervolemia / hyperkalemia / hypocalemia.

75
Q

Why is Na+ so important for the body?

A

Controls the plasma levels and helps to regulate blood volume alongside blood pressure.

76
Q

Why is K+ so important for the body?

A

Controls plasma levels important for regulation of excitable cells.

77
Q

Why is pH so important for the body?

A

Kidneys REMOVE H+ and makes HCO3-

Is aided by alkalosis and acidosis.

78
Q

What is the purpose of acidosis and alkalosis?

A

This balances the acid - base constant.

79
Q

In terms of drug excretion, where do drugs CROSS freely?

A

The glomerular membrane

80
Q

In terms of drug secretion, where are drugs secreted into?

A

Renal Tubule

81
Q

What are the 3 main methods of drug excretion?

A

Glomerular Filtration
Tubular Secretion
Passive Reabsorption