Renal Flashcards

1 - Describe the structure of the kidney and define its main roles in the body 2 - Describe the structure and function of the nephron 3- Explain the roles and mechanisms of the kidney in maintaining fluid, electrolyte and acid/base homeostasis 4- Discuss the role of the kidney as an endocrine organ

1
Q

What are the three layers of kidney tissue?

A

Renal capsule – deep layer, maintains kidney shape

Adipose capsule – a mass of fatty tissue that protects the kidney from trauma and holds it in place

Renal fascia – superficial layer – the thin layer of connective tissue that anchors kidney to surrounding structures and abdominal wall

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2
Q

What are the three sections of the internal kidney anatomy?

A

Renal cortex – superficial

Renal medulla – inner region

Renal lobe – renal pyramid

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3
Q

Functions of the kidneys

A

Regulation of water and electrolytes

Regulate pH of blood

Regulate blood volume

Contribute to regulating blood pressure

Control osmolarity of blood

Act as an endocrine organ (produces hormones)

Contribute to regulating blood glucose level (once the renal threshold is exceeded glucose is excreted in the urine)

Excretes waste and foreign substances (ammonia, urea, creatinine, bilirubin, drugs and toxins)

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4
Q

What artery does the kidneys receive blood from?

A

Renal artery

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5
Q

How does blood leave the kidneys?

A

Renal vein

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6
Q

What % of blood goes to the cortex?

A

99%

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7
Q

What % of blood goes to the medulla?

A

1%

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8
Q

How many nephrons in each kidney?

A

Approx 1 million

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9
Q

What are the 2 parts of a nephron? And functions?

A

Renal corpuscle - Filters blood plasma

Renal tubule - Receives filtered plasma

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10
Q

What does the renal corpuscle consist of?

A

Glomerulus - capillary network

Glomerular (Bowmans) capsule - double walled cup surrounding glomerulus

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11
Q

What does the renal tubule consist of?

A

Proximal convoluted tubule

Descending and ascending loop of Henle (nephron loop)

Distal convoluted tubule

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12
Q

What are the 2 types of nephrons?

A

Cortical nephron

Juxtamedullary nephron

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13
Q

What nephrons do we have more of?

A

Cortical nephron - 80-85%

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14
Q

Compare and contrast cortical nephrons and juxtamedullary nephrons

A

Cortical - 80-85% of nephrons in the kidney
Juxtamedullary - 15-20% of nephrons in the kidney

Cortical - short loop of Henle
Juxtamedullary - long loop of Henle

Cortical - loop of Henle penetrate only outer renal medulla
Juxtamedullary - Loop of Henle penetrate deep into the renal medulla

Cortical - Small glomeruli
Juxtamedullary - Large glomeruli

Cortical - Low glomerular filtration rate
Juxtamedullary - High glomerular filtration rate

Cortical - Perform excretory and regulatory function of the kidney
Juxtamedullary - Involved in concentrating or diluting urea

Cortical - no vasa recta network, only peritubular to receive blood
Juxtamedullary - Large network of vasa recta, and peritubular

Cortical - Ascending limb of loop of Henle straight
Juxtamedullary - Ascending limb had thick and thin regions

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15
Q

What does the renal corpuscle consist of?

A

Bowman capsule and a glomerulus (cluster of capillaries)

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16
Q

What % of filtered fluid goes back into the bloodstream?

A

99%

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17
Q

Name the 2 types of capillary beds, under high or low pressure?

A

Glomerular capillaries - Under high pressure for filtering

Peritubular capillaries - Around tubule at low pressure

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18
Q

What does GFR stand for?

A

Glomerular filtration rate

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19
Q

3 Steps of urine formation

A

Simple filtration

Selective and passive reabsorption

Excretion

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20
Q

Describe the glomerular filtration rate

A

It is the amount of filtration formed in all the renal corpuscle of both kidneys each minute

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21
Q

Watch the video about nephrons

A

https://www.youtube.com/watch?v=8UVlXX-9x7Q

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22
Q

What are the 3 mechanisms that regulate GFR?

A

Renal autoregulation

Neural regulation

Hormonal regulation

23
Q

what is renal autoregulation? And the 2 mechanisms?

A

Kidney maintain blood flow and GFR by using:

Myogenic mechanism - Stretching triggers contraction of smooth muscle cells in afferent arterioles - which reduces GFR

Tubuloglomerular mechanism - macula densa provides feedback to glomerulus, inhibits release of NO causing afferent arterioles to constrict and decrease GFR

24
Q

What is neural regulation? And the 2 types of stimulation?

A

Kidney blood vessels supplied by sympathetic ANS fibers that release norepinephrine causing vasoconstriction

Moderate stimulation – both afferent and efferent arterioles constrict to same degree and GFR decreases

Greater stimulation - constricts afferent arterioles more and GFR drops

25
Q

What are the 2 hormones of hormal regulation? And what do the do?

A

Angiotensin II reduces GFR – potent vasoconstrictor of both afferent and efferent arterioles

Atrial natriuretic peptide increases GFR – stretching of atria causes release, increases capillary surface area for filtration

26
Q

What is used to estimate GFR?

A

Creatinine

27
Q

What does the proximal tubule reabsorb and how much?

A
Reabsorbs 
60 % of all solute
100% glucose and amino acids
99% bicarbonate
80-90% inorganic phosphate and water
28
Q

What is the counter current multiplier mechanism?

A

Uses energy to generate an osmotic gradient

Enables you to reabsorb water from the tubular fluid and produce concentrated urine

Prevents you from producing litres and litres of dilute urine every day, and is the reason why you don’t need to be continually drinking in order to stay hydrated.

29
Q

What are the actions of the different parts of the loop of Henle?

A

Descending - impermeable to solutes but permeable to water. The tubular fluid becomes hypertonic because of water moves out

Thin section of ascending - Almost impermeable to water but permeable to solutes (Na & Cl ions). The tubular fluid becomes hypotonic

The thick section and early distal tubule are virtually impermeable to water, however Na and Cl are actively transported out of the tubule making the tubular fluid hypotonic

Distal tubule and collecting duct permeability depends on the amount of antidiuretic hormone secreted by the posterior lobe of the pituitary

30
Q

What cells make up the juxtaglomerular apparatus?

A

Macula densa cells

31
Q

What do the macula densa cells do?

A

Detect chloride concentration and modified smooth muscle cells in the walls of the afferent and efferent arteriole

Produce renin

32
Q

What 3 hormones regulate renal sodium and water reabsorption?

A

Antidiuretic hormone

Renin-angiotensin-aldosterone system

Atrial natriuretic hormone

33
Q

Steps of ADH secretion

A

Increased osmotic pressure due to low water intake

Osmoreceptors in hypothalamus stimulated

Nerve impulses from hypothalamus stimulate posterior pituitary

Posterior pituitary secretes ADH

Water reabsorbed in collecting duct

34
Q

3 factors that stimulate ADH to be secreted

A

Increased osmolarity in ECF

Decreased circulating blood volume (detected by cardiovascular receptors)

Decreased arterial blood pressure (detected by cardiovascular baroreceptors)

35
Q

3 factors that stimulate ADH to be secreted

A

Increased osmolarity in ECF

Decreased circulating blood volume (detected by cardiovascular receptors)

Decreased arterial blood pressure (detected by cardiovascular baroreceptors)

36
Q

Actions of ADH

A

Increases permeability of the collecting duct and distal convoluted tubule

Promotes reabsorption of water so expanding extracellular fluid and reducing the osmolality of the ECF at the same time.

ADH called vassopressin as it also causes a raise in arterial pressure

37
Q

3 reasons why renin is released from the juxtaglomerular apparatus

A

Activated by:

Decrease in afferent arteriolar pressure

Reduced plasma sodium concentration or reduced glomerular filtration

Stimulation of renal sympathetic nerves

38
Q

What is the role of angiotensin II?

A

Promotes the release of the steroid hormone aldosterone

Stimulates arteriolar vasoconstriction

Promotes ADH release

Promotes drinking

39
Q

What is the role of aldosterone?

A

Stimulates reabsorption of sodium from the distal convoluted tubule and collecting ducts

This leads to expansion of ECF and increased blood pressure

Main effect to reduce urine volume

40
Q

Where is atrial natriuretic hormone release from?

A

The atria of the heart

41
Q

What is the role of atrial natriuretic hormone?

A

It promotes glomerular filtration and inhibits tubular reabsorption of sodium

This leads to increased natriuresis (excretion of sodium) and diuresis (increased urine)

This results in a reduction in both extracellular and fluid volumes.

42
Q

Where is in the nephron does potassium get absorbed by active transport?

A

proximal convoluted tubule and the ascending limb of the loop of Henle

43
Q

What role role aldosterone have on potassium?

A

stimulates potassium secretion in the distal convoluted tubule

It is this that regulates plasma potassium

44
Q

What part of the nephron are calcium and phosphate ion reabsorbed and what is the hormone controlling it?

A

Both are actively reabsorbed from the tubular fluid, particularly in the proximal convoluted tubule

Reabsorption is controlled by the hormone parathyroid hormone which promotes calcium reabsorption whilst inhibiting that of phosphate.

45
Q

What gland secretes parathyroid hormone and where is it located?

A

Parathyroid glands located posterior to the thyroid gland

46
Q

What stimulates the secretion of parathyroid hormone?

A

Stimulated by a fall in plasma calcium ion concentration

47
Q

What 3 actions does parathyroid hormone have on the kidney?

A

Increases calcium absorption from renal tubules

Stimulates urinary phosphate excretion

Stimulates conversion of Vit D to active form so increasing gut absorption of calcium and phosphate

48
Q

Name 3 ways acid/base balance is achieved?

A

Chemical buffers

Respiratory regulation

Renal regulation of bicarbonate ion

49
Q

3 chamical buffer systems in the body?

A

Systems in body are

Bicarbonate
Phosphate
Protein

50
Q

What system does respiratory regulation utilise? And what effect does acidosis and alkalosis have on respiritory regulation?

A

Utilises bicarbonate system

Acidosis activates respiratory system to increase respiratory rate and depth. This eliminates more carbon dioxide causing blood pH to rise.

Alkalosis depresses the respiratory centre causing carbon dioxide to build up and a fall in blood pH

51
Q

How does the renal regulation of bicarbonate ions counteract acidosis and alkalosis?

A

To counteract acidosis, more bicarbonate ions are generated and the resulting secreted hydrogen and ammonia ions are excreted in the urine.

To counteract alkalosis, bicarbonate ions are secreted into the filtrate and hydrogen ions are reabsorbed.

52
Q

Steps of tubular secretion of acid (H+)

A

The buffer sodium bicarbonate is filtered by the glomerulus and then reabsorbed in the proximal tubule

The sodium is absorbed by a sodium/hydrogen ion pump which exchanges sodium ions for hydrogen ions on the luminal proximal border of the tubular cell

A sodium/potassium pump forces sodium through the cell from the tubular fluid in exchange for potassium.

53
Q

Where is most of the filtered bicarbonate reabsorbed and what %?

A

About 90% is reabsorbed in the proximal tubule