Renal system Flashcards

1
Q

Functions of the kidney

A

Waste removal and to regulate blood pressure

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2
Q

Filtration in the glomerulus

A

Substances in the blood filter from the glomerulus into the Bowman’s capsule because the hydrostatic pressure in the glomerulus is higher than the glomerular oncotic pressure and capusular hydrostatic pressure

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3
Q

Oncotic pressure

A

Pressure keeping things in the blood vessel because of proteins (e.g. albumin) which draw water

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4
Q

Hydrostatic pressure

A

Pressure exerted by blood pushing against the walls of the capillaries, pushing things out

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5
Q

Filtrate contains (9):

A
Water
Sodium
Chloride
Potassium
Bicarbonate
Glucose
Amino acids
Creatinine
Urea
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6
Q

Reabsorption in the proximal convoluted tubule

A

Active reabsorption of glucose, sodium, potassium, phosphate, and sulphate
Passive reabsorption of urea, water, and chloride

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7
Q

Secretion in the proximal convoluted tubule

A

Uric acid
Creatinine
Drugs

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8
Q

Function of the loop of Henle

A

To create a hyperosmolar medulla (a counter current multiplier) - lots of water lost by bottom of loop - to help with fluid reabsorption

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9
Q

Reabsorption in the descending loop of Henle

A

Passive removal of water, sodium and chloride

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10
Q

Reabsorption in the ascending loop of Henle

A

Active removal of chloride

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11
Q

Urine formation process

A
  1. ADH released from posterior pituitary
  2. Creates aquaporins (water channels) in collecting duct wall
  3. Medulla is hyperosmolar so water is pulled out of filtrate back into blood vessels
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12
Q

Osmolarity

A

The number of solute particles dissolved in one litre of water, measured using specific gravity.
High osmolarity = high pull of water

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13
Q

Renin-Angiotensin-Aldosterone System

A
  1. Low fluid volume in nephron causes kidney to produce enzyme renin
  2. Renin acts on angiotensinogen from liver to create angiotensin I
  3. Angiotensin I converted to angiotensin II by ACE in the lungs
  4. Angiotensin II causes adrenal gland to secrete aldosterone (steroid hormone)
  5. Aldosterone creates more sodium channels in the distal convoluted tubule and increases activity of the sodium-potassium pump in the blood vessel, thus increasing sodium reabsorption
  6. Change in osmolarity increases water reabsorption
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14
Q

The Juxtaglomerular Apparatus consists of…

A

Justaglomerular (granular) cells in the afferent arteriole and macula densa cells in the distal convoluted tubule

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15
Q

In response to high sodium chloride levels, macula densa cells…

A

Cause the afferent arteriole to constrict, leading to a lower glomerular filtration rate and less sodium chloride entering the filtrate

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16
Q

In response to low sodium chloride levels, macula densa cells…

A

Cause the afferent arteriole to dilate, and stimulates renin release to increase blood pressure

17
Q

Juxtaglomerular cells release renin in response to (3):

A
  1. Stimulation of the beta-1 adrenergic receptor
  2. Stretch receptors detecting a decreased blood pressure
  3. Signal from the macula densa due to low sodium chloride levels
18
Q

Positive feedback loop of urination

A

Urine into bladder ->
Bladder increases in size ->
Stretch causes increased nerve impulse to brain ->
Cholinergic nerves fire on detrusor muscle via M3 receptors ->
Detrusor muscle contracts, urethral smooth muscle relaxes

19
Q

2 sphincters of the bladder

A

Inner - involuntary

Outer - voluntary, nicotinic

20
Q

Young and old people urinate more frequently because…

A

Parasympathetic nerve tone is increased at the extremities of age

21
Q

Older people can faint when they urinate because…

A

The parasympathetic system slows heart rate and drops BP

22
Q

Larger prostate causes frequent urination because…

A

The prostate squeezes on the urethra, meaning more pressure is needed in the bladder for fluid to pass into the urethra, thus fluid is left in the bladder even after passing urine

23
Q

The aim of diuretics is to…

A

Lose sodium

24
Q

Loop of Henle diuretics

A
  1. Prevent passive transport pump from transporting sodium ions into the blood
  2. Sodium ions build up in ultrafiltrate
  3. Ultrafiltrate has a high osmolarity so retains water
25
Q

Main issue with loop of Henle diuretics

A

Potassium isn’t reclaimed into the blood, as this usually is transported with sodium ions.
Destabilises excitable tissues (e.g. the heart)

26
Q

Distil tubule diuretics

A
  1. Prevent passive transport pump transporting sodium from ultrafiltrate
  2. Sodium moves from blood stream into tubule cell
  3. Co-transporter swaps sodium for calcium, and calcium enters blood from filtrate
  4. Potassium removed from blood stream