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biology > The urinary system > Flashcards

The urinary system Flashcards

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1
Q

The urinary system is

A

one of the human body’s waste disposal units
* It carries out filtration and excretion
* Composed of the kidneys, ureters, bladder and urethra
* Helps to remove potentially harmful waste substances e.g. urea and alcohol

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2
Q

what is The kidneys

A
  • Bean shaped organs about 11cm long
  • Located against the back muscles in the upper abdominal area
  • The right kidney sits a bit lower that the left kidney to
    accommodate the size of the liver
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3
Q

Blood flow through the kidneys

A
  • Blood flows into the kidneys through the renal artery
  • Blood exits the kidneys through the renal vein
  • The kidneys receive 20% to 25% of the cardiac output (about 1.0 to 1.1 litres per minute)
  • Total blood volume is filtered every 40 minutes
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4
Q

what is the Cortex of the kedney

A

Outer granular region

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5
Q

what is the Medulla of the kidney

A

Inner striated region Subdivided into renal pyramids and columns

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6
Q

what is Renal Pelvis

A

-Central collecting cavity
- A funnel shaped cavity which connects the medulla to the ureter

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7
Q

what is Hilum

A

Concave centre of the kidney The point at which blood
vessels, lymphatic vessels, nerves and the ureter enter
the organ

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8
Q

Micturition function

A
  • When 200ml collects in the bladder, the stretching stimulates the autonomic nerve ending in the bladder
  • The walls contract
  • The internal sphincter relaxes when the walls contract
  • Urine empties in the urethra
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9
Q

function of Renal pelvis

A

Collects urine from the tubules in the medulla and
passes it to the ureter

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10
Q

the ureter function

A

Transport urine from the kidneys to the bladder

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11
Q

Bladder function

A
  • Sac like organ in the pelvic cavity
  • A reservoir for urine
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12
Q

Urethra function

A

Has an external sphincter which is voluntarily controlled by the CNS

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13
Q

Each kidney contains about a million very fine tubes
called ———–

A

called nephrons
* Each has its own blood supply

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14
Q

what is the The nephron

A

About 3cm in length composed of five functional regions:
1-The malpighian body
2- Proximal convoluted tubule
3- Descending and ascending limbs of the loop of Henle
4- Distal convoluted tubule
5- Collecting duct

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15
Q

The Malpighian body - ultrafiltration

A
  • Adapted for the process of ultrafiltration
  • The afferent arteriole is wider than the efferent arteriole
    -Blood in the glomerulus is at high pressure
  • Capillary walls are permeable to water (fenestrae) and other substances
  • Pressure pushes the fluid into the Bowman’s capsule
  • Blood cells and most blood proteins are unable to pass through
  • Volume of filtrate produced by both kidneys each minute = 115(W)−125(M) ml
  • Averages 180 L/day males, 150L/day females
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16
Q

The proximal convoluted tubule - reabsorption

A
  • The longest section of the nephron
  • The wall is one cell thick
  • Cells are packed with mitochondria
  • The cell membrane in contact with the filtrate has a ‘brush border’ of microvilli, increasing the surface area
    for uptake.
  • Most (65%) of the filtrate (salt and water) is reabsorbed here
17
Q

Loop of Henle - reabsorption

A
  • Fluid entering loop of Henle is isotonic to extracellular fluids
  • A descending limb
  • permeable to water
  • no active transport
  • An ascending limb
  • impermeable to water
  • Thick segment lined with Na+-K+ pumps
  • Pumping of ions out of thick segment of ascending limb
    creates osmotic gradient in interstitial fluid of the medulla
18
Q

Distal convoluted tubule - reabsorption

A
  • Cells of the distal convoluted tubule walls look identical to those of the proximal convoluted tube
  • Selective reabsorption of ions, typically Ca2+, Mg2+,K+ and especially Na+ , occurs here
  • Aldosterone from the cortex of the adrenal gland maintains a constant level of blood Na+
  • Aldosterone acts directly on the kidney to decrease the rate of Na+ excretion (with accompanying retention of water), and to increase the rate of K + excretion.
19
Q

Collecting duct – water regulation

A
  • The permeability of the walls of the collecting duct to water is variable
  • Impermeable to NaCl
  • The permeability is controlled by antidiuretic hormone (ADH) secreted by the pituitary
20
Q

Collection of fluid in the pelvic calyces

A

1-Each renal pyramid drains into a minor calyx
2-Minor calyces drain into major calyces
3-Major calyces drain into the renal pelvis
4-Urine empties into the ureter

21
Q

Urine composition

A

Only 1% of the liquid filtered into the Bowman’s capsule is actually excreted as urine
* About 1.5l (minimum 0.5l)
* Composed of
- 96% water
- 2% urea
- 2% other substances
- Ammonia, sodium, potassium, phosphates,
chlorides, sulphates, excess vitamins
* Salts are excreted to maintain the correct balance of fluids and electrolytes
* Bilirubin gives the urine its colour
* Normal urine is acidic but may vary with diet

22
Q

Kidney stones (renal lithiasis/nephrolithiasis)

A
  • Hard deposits made of minerals and salts that form inside the kidneys
  • Often form when the urine becomes concentrated allowing minerals to crystallize and stick together
  • May cause a urinary infection if lodged in the urinary tract
  • Symptoms include blood in the urine, severe pain in the groin or side, vomiting and nausea
23
Q

Diabetes insipidus symptoms

A

-Impaired ADH production by the pituitary gland
-Large amounts of dilute urine
-Excessive thirst
-Amount of urine can be nearly 20 litres/day
-Urine does not contain glucose

24
Q

Urinary tract infections

A
  • A bacterial infection that affects any part of the urinary tract
  • Most involve the bladder and urethra
  • Women are at a greater risk of developing a UTI
  • Symptoms may include a burning sensation when urinating, pelvic pain and a strong smelling urine
25
Q

Cystitis

A
  • An inflammation of the bladder
  • Very common in women partly due to a shorter urethra
  • Generally caused by a urinary tract infection
26
Q

Kidney polycystic disease

A
  • An inherited disorder
  • Clusters of cysts develop primarily in the kidneys
  • Kidneys enlarge and lose function over time
  • Cysts may also develop in the liver and elsewhere
  • May cause severe complications e.g. kidney failure
27
Q

Duplicated ureters
(Duplex kidney)

A
  • Two ureters from a single kidney
  • Can drain independently into the bladder or connect and drain as a single ureter
  • Can occur in one or both kidneys
  • Most common renal abnormality
  • Occurs in approximately 1% of the population
  • May result in urine reflux

biology (15 decks)

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