The Urinary System Flashcards

1
Q

Kidneys

A
  • Renal Pelvis where urine is drained
  • Filtration of blood, Reabsorption, secretion,
    Homeostasis
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2
Q

Ureters

A
  • Carry urine to urinary bladder
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3
Q

Urethra

A
  • Tube between bladder
    and external environment
  • Tube for male reproductive system
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4
Q

Nephron

A
  • Functional unit of the kidney
  • Vascular (blood)
  • Tubular (filtered fluid)
  • Component in renal cortex - outer and granular region
  • Component in renal medulla - inner region, made up of triangles
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5
Q

Substances filtered and reabsorbed

A
  • WATER from Glomerular filtrate mostly reabsorbed
  • Nearly all Na+ and Cl- is reabsorbed to maintain internal Osmotic pressure
  • GLUCOSE reabsorbed as long as plasma glucose < 200 mg
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6
Q

Urea

A
  • End product of protein metabolism
  • 2/3 of that filtered is passed out in urine
  • Remainder is reabsorbed
  • Structure of urea H2N - CO - NH2
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7
Q

Contents of urine

A
  • Urea
  • Ureic acie
  • Creatinine
  • K+
  • Other substances that are toxic
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8
Q

Structure of nephron

Interlobular artery

A
  • Afferent arteriole carries the blood to the kidneys
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9
Q

Glomeralus

A
  • A ball of capillaries
    responsible for filtration
  • Splits from the afferent artery
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10
Q

Efferent arteriole

A
  • Rejoin into another bed in the venules
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11
Q

Peritubular capillaries

A
  • Asecond capillary bed to supply renal tissue with blood receives compounds reabsorbed by tubule
    source of compounds secreted by tubule
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12
Q

Bowman’s capsule

A
  • Encloses glomerulusin cortex
    where filtration occurs
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13
Q

Proximal Convoluted Tubule

A
  • In cortexresponsible for most reabsorption/secretion
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14
Q

Loop of Henle

A
  • Cortex/medulla responsible for osmotic gradient in medulla
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15
Q

Distal Convoluted Tubule

A
  • In cortex ‘fine-tuning’ of solute/water reabsorption
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16
Q

Collecting Tubules/Ducts

A
  • In cortex/medulla
    ‘fine-tuning’ of urine concentration
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17
Q

Bowman’s capsule and
Juxta glomerular apparatus

A
  • Juxta glomerular in afferent arteriole
  • Macula densa and distil convoluted tubule
  • JG cells from the MD and from JG apperatus regulate pressure and filteration rate of glomerlus
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18
Q

Podocytes

A

Found in epithelium of Bowmann’s Capsule and surround capillaries

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19
Q

Macula densa

A
  • Densely staining cells of DCT detect low Na+ in DCT and can alter flow through glomerulus and water volume
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20
Q

Juxta glomerular cell

A
  • Responsible for releasing hormones (Renin) that control how much water is reabsorbed
21
Q

Roles of Kidneys

Excretion

A
  • Waste products like urea and foreign compounds (eg drugs)
22
Q

Role of kidney

Blood pressure control

A
  • Long term control of blood pressure
    Via regulation of H2O and electrolytes
23
Q

Kidney and hormones

A
  • Control of RBC number via erythropoietin
  • Production of/conversion to active form of Vit D
24
Q

Importance of regulating water in kidneys

A
  • Volume effects hydrostatic forces 40 L H2O in ‘average’ body
25
Q

Fluid Compartment Barriers

A
  • Cell membrane (ICF ↔ ECF)
  • Very thin
  • Little barrier to H2O movement
  • Barrier to solute movement
26
Q

Fluid Compartment Barriers
(Interstitial fluid ↔ plasma)

A
  • Thin
  • Variable barrier to H2O movement
  • Little barrier to solute movement (except protein)
27
Q

Dynamic equilibrium of fluid movements

A
  • Renal adjustment of plasma composition affects other compartments
  • Renal adjustment of plasma volume affects blood pressure
28
Q

Link between H2O & solutes

A
  • Moved via Na-pump
  • Molecular mechanism
  • Energy-consuming
  • Movement up the concentration gradient
  • H2O only ever moves via osmotic & hydrostatic forces osmotic effects of Na-pump
29
Q

Implications for Renal Function

Maintainance of solute

A
  • Intake is ‘unpredictable’
  • Therefore need both hypertonic and hypotonic urine
30
Q

Filtration into nephrons

A
  • Protein-free plasma
  • Topologically on surface of body
31
Q

Reabsorption back into peritubular capillaries

A
  • Major task to reabsorb most of 180 liters a day
  • H2O only ever moves via osmotic & hydrostatic forces
  • Relies on osmotic forces
32
Q

Basic Renal Processes

Filteration

A
  • Mass movement of water and solutes from plasma to the renal tubule
  • Depends on Glomerular capillary pressure
33
Q

Renal process

Reabsorbtion

A
  • Movement of water and solutes from the tubule back into the plasma
34
Q

Secretion

A

Secretion of additional substances into the tubular fluid

35
Q

Excretion: Components of urine

A

amount excreted = (amount filtered + amount secreted) - amount reabsorbed

36
Q

How is urine formed?

A
  • Filteration is the passive movement at the bowmans capsule
  • Active transport which is the energy driven retrival of valuable substances along nephron
  • Osmosis mainly occours in the loop of henle and the collecting duct
37
Q

Renal corpuscle

A
  • Combination of glomerulus and Bowman’s capsule where filtration occours
  • Epithelium around glomerular capillaries -
    modified into podocytes
38
Q

Filtration

A
  • Movement a balance between
    osmotic pressure while being filtered by pores
  • Glomerular capillary basement
    membrane
  • Basal lamina
  • Bowmans capsule epithelia
39
Q

Filtering membrane

A
  • Contains fenestrated cytoplasm which are flat cells
  • Basement membrane which is muco-polysaccharides filteration
  • Podocytes slit pores filteration
40
Q

Hematuria

A
  • Red blood cells in urine theres signs of damage from outside and inside of kidneys
  • Could be kidney tumour outside or UTI
  • Inside could be the inflammation of glomeruli
  • Necrosis of kidney
41
Q

Proteinuria

A
  • Protien in urine
  • Little protien in healthy humans
  • Haemoglobin is smaller than albumin
  • Due to inability to filter via endothelial fenestrated glomeralus
42
Q

Tubular Re-absorption

A
  • Liters fluid filtered into the tubules must be reabsorbed in the LH
  • Distal segments of nephrons (fine tuning)
  • Re-absorption may be Active or Passive
  • Water regain through solute Na+
43
Q

Reabsorption of Na+

A
  • Carrier molecules for other molecules that co-transported
  • Each of these carrier molecules binds specifically to that substances to be transported and to Na+
  • Move with Na + into tubule cell
  • As solutes are transported out of the lumen, through the proximal convoluted tubule cells, and into the interstitial fluid, water follows by osmosis
  • Reduction of volume
44
Q

Reabsorbtion saturation

A
  • Glucose co-transported with Na+
  • Uses specific transporters
  • Finite number of these
  • Tubular load glucose normally
  • All glucose reabsorbed – not excreted
  • But if excess load then not all glucose reabsorbed and some excreted
45
Q

Secreation

A
  • Transfer of molecules from extracellular fluid into the nephron
  • Metabolites produced in the body
  • Make excretion is even more efficient
  • Depends mostly on membrane transport systems
46
Q

Loop of Henle

Juxtamedullary nephrons

A
  • Hypertonic medulla
47
Q

Vasa recta

A
  • Long peritubular capillaries that dip into the medulla
  • Blood flow in the vasa recta moves in the opposite direction from filtrate flow in the loops of Henle
48
Q

Loop of Henle

A
  • Further resorption of NaCl and H2O by countercurrent muliplier
  • Acending loop actively transports Na+ and Cl- into the intersitial space this is impermeable to water
  • Water leaves the kidney tubule decending loop which is permeable to water taken away by counter current multiplier
  • Increase conc of Na+ down loop
  • Blood in vasa recta removes water leaving loop of henle
49
Q

Urine osmolarity

A
  • Hormone mechanism of Reinin-angeotensis-aldersterone and ANP are sensitive to changes in BP
  • ADH sensitive to blood concentration