The Urinary System Flashcards
(49 cards)
1
Q
Kidneys
A
- Renal Pelvis where urine is drained
- Filtration of blood, Reabsorption, secretion,
Homeostasis
2
Q
Ureters
A
- Carry urine to urinary bladder
3
Q
Urethra
A
- Tube between bladder
and external environment - Tube for male reproductive system
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
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
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
7
Q
Contents of urine
A
- Urea
- Ureic acie
- Creatinine
- K+
- Other substances that are toxic
8
Q
Structure of nephron
Interlobular artery
A
- Afferent arteriole carries the blood to the kidneys
9
Q
Glomeralus
A
- A ball of capillaries
responsible for filtration - Splits from the afferent artery
10
Q
Efferent arteriole
A
- Rejoin into another bed in the venules
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
12
Q
Bowman’s capsule
A
- Encloses glomerulusin cortex
where filtration occurs
13
Q
Proximal Convoluted Tubule
A
- In cortexresponsible for most reabsorption/secretion
14
Q
Loop of Henle
A
- Cortex/medulla responsible for osmotic gradient in medulla
15
Q
Distal Convoluted Tubule
A
- In cortex ‘fine-tuning’ of solute/water reabsorption
16
Q
Collecting Tubules/Ducts
A
- In cortex/medulla
‘fine-tuning’ of urine concentration
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
18
Q
Podocytes
A
Found in epithelium of Bowmann’s Capsule and surround capillaries
19
Q
Macula densa
A
- Densely staining cells of DCT detect low Na+ in DCT and can alter flow through glomerulus and water volume
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
Fluid Compartment Barriers
- Cell membrane (ICF ↔ ECF)
- Very thin
- Little barrier to H2O movement
- Barrier to solute movement
26
Fluid Compartment Barriers
(Interstitial fluid ↔ plasma)
- Thin
- Variable barrier to H2O movement
- Little barrier to solute movement (except protein)
27
Dynamic equilibrium of fluid movements
- Renal adjustment of plasma composition affects other compartments
- Renal adjustment of plasma volume affects blood pressure
28
Link between H2O & solutes
- 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
# Implications for Renal Function
Maintainance of solute
- Intake is ‘unpredictable’
- Therefore need both hypertonic and hypotonic urine
30
Filtration into nephrons
- Protein-free plasma
- Topologically on surface of body
31
Reabsorption back into peritubular capillaries
- Major task to reabsorb most of 180 liters a day
- H2O only ever moves via osmotic & hydrostatic forces
- Relies on osmotic forces
32
# Basic Renal Processes
Filteration
- Mass movement of water and solutes from plasma to the renal tubule
- Depends on Glomerular capillary pressure
33
# Renal process
Reabsorbtion
- Movement of water and solutes from the tubule back into the plasma
34
Secretion
Secretion of additional substances into the tubular fluid
35
Excretion: Components of urine
amount excreted = (amount filtered + amount secreted) - amount reabsorbed
36
How is urine formed?
- 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
Renal corpuscle
- Combination of glomerulus and Bowman’s capsule where filtration occours
- Epithelium around glomerular capillaries -
modified into podocytes
38
Filtration
- Movement a balance between
osmotic pressure while being filtered by pores
- Glomerular capillary basement
membrane
- Basal lamina
- Bowmans capsule epithelia
39
Filtering membrane
- Contains fenestrated cytoplasm which are flat cells
- Basement membrane which is muco-polysaccharides filteration
- Podocytes slit pores filteration
40
Hematuria
- 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
Proteinuria
- Protien in urine
- Little protien in healthy humans
- Haemoglobin is smaller than albumin
- Due to inability to filter via endothelial fenestrated glomeralus
42
Tubular Re-absorption
- 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
Reabsorption of Na+
- 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
Reabsorbtion saturation
- 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
Secreation
- 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
# Loop of Henle
Juxtamedullary nephrons
- Hypertonic medulla
47
Vasa recta
- 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
Loop of Henle
- 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
Urine osmolarity
- Hormone mechanism of Reinin-angeotensis-aldersterone and ANP are sensitive to changes in BP
- ADH sensitive to blood concentration
