Renal physiology and function Flashcards

1
Q

what is the function of the kidneys

A

produces urine

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2
Q

what is the function of the ureter

A

transports urine towards the urinary bladder

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3
Q

what is the function of the urinary bladder

A

temporarily stores urine prior to elimination

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4
Q

what is the function of the urethra

A

conducts urine to exterior

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5
Q

what are the 2 main functions of the urinary system

A
  1. excretion- the removal of organic waste products from body fluids
  2. elimination- the discharge of waste products into the environment
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6
Q

what are the main essential renal functions

A
  1. excretion- excretion of endogenous waste products, excretion of drugs and their metabolites
  2. homeostasis- water and electrolyte balance, acid base balance
  3. regulation- production of hormones (eg. renin)
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7
Q

what occurs during renal dysfunction

A
  1. reduction in renal excretory function (uraemia, drug toxicity)
  2. inability to maintain salt and water balance and acid base balance
  3. compromised hormone function (anaemia, hypertension)
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8
Q

what names are given to renal failure that occurs rapidly and that which may take years to develop

A
  1. acute kidney failure

2. chronic kidney failure

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9
Q

what must happen when renal dysfunction occurs

A

renal function must be supplemented artificially, either by dialysis or by transplanted kidney

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10
Q

where are the kidneys located and describe their approximate size

A

paired organs situated: on posterior wall of abdomen, behind the peritoneum, and on either side of the vertebral column

  • each kidney= 120-170g and approx 11cm long, 6cm wide and 3cm thick
  • joined at medial side to renal artery and vein, nerves and ureter
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11
Q

name the 2 major layers of the kidney

A

cortex (outer layer) and the medulla (inner layer)

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12
Q

what does the cortex comprise of

A

composed of 1.25million nephrons

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13
Q

what is a nephron

A

the functional unit of the kidney responsible for urine formation and composition

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14
Q

what is the medulla

A

pyramids drain into pelvis which drain into ureters

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15
Q

what are the 5 distinct sections of the nephron

A
  1. glomerulus
  2. proximal tubule
  3. loop of henle
  4. distal tubule
  5. collecting duct
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16
Q

what are the 2 types of nephrons that exist

A
  1. cortical nephrons- 70-80% of all nephrons in kidneys
    - located in cortex
    - short loop of hence into medulla
  2. juxtamedullary nephrons- 20-30% of all nephrons in kidneys
    - situated closer to medulla
    - loop of hence extends deep into renal pyramids
17
Q

describe the process of nerves supplying the kidneys

A

the kidneys have a rich nerve supply:

  1. sympathetic postganglionic fibres from sympathetic chain and fibres from coeliac ganglion
    - supplies arteries, afferent and efferent arterioles and granular cells
    - reduces blood supply to kidney during stress (fight or flight)
  2. parasympathetic efferent supply from vagus nerve- ganglion in hilium
    - may control tone of efferent arterioles
    - may modify glomerular filtration rate and renal blood flow
18
Q

what are the 3 major functions of the nephron

A
  1. filtration of blood to produce a filtrate
  2. reabsorption of water, ions and organic nutrients from filtrate
  3. secretion of waste products into tubular fluid
19
Q

what is transcellular transport?

A

movement through the cells

20
Q

what is paracellular transport

A

movement between cells

21
Q

describe the process of glomerular filtration

A
  1. filtration occurs at the glomerulus and is the initial step in urine formation
  2. all small molecules are filtered- electrolytes, amino acids, glucose, metabolic waste, and some drugs and metabolites
  3. cells and large molecules remain in the blood- red blood cells, lipids, proteins, large size or protein bound drugs
22
Q

describe the process of tubular reabsorption

A
  1. more than 99% of filtered water, electrolytes and nutrients are reabsorbed back into blood
  2. some solutes are reabsorbed down conc/electrochemical gradients
  3. other molecules can undergo co transport
  4. water follows passively along the osmotic gradient created by solute reuptake via aquaporins
  5. reabsorption of solutes requires energy in the form of ATP which drives Na+ reabsorption via the Na+K+ATPase transporter
23
Q

describe the process of tubular secretion

A
  1. some endogenous substances and drugs can’t be filtered at the glomerulus due to their size or their protein binding
  2. specialised pumps in the proximal tubule can transport compounds from the plasma into the nephron for excretion
  3. there are 2 kinds of pumps:
    - for organic acids or drugs (uric acid, diuretics, antibiotics)
    - for organic bases or drugs (creatinine)