Urinary systems and electrolyte balance Flashcards
(135 cards)
1
Q
What are the two main body fluid compartments?
A
Intracellular fluid and extracellular fluid.
2
Q
What are the two components of extracellular fluid?
A
Interstitial fluid and blood plasma.
3
Q
How do all solutes and water that enter or leave the body do so?
A
Via extra cellular fluid.
4
Q
When does water only move between ICF and ECF and why?
A
Only when an osmotic pressure gradient exists, ICF and ECF at osmotic equilibrium.
5
Q
When does equilibration of ICF and ECF primarily occur?
A
By shifts in water and not shifts in solute.
6
Q
Why can the two compartments osmotic pressure of blood plasma and of interstitial fluid be considered isosmotic?
A
Osmotic pressure of blood plasma only 25mmHg/ 3.3kPa/ 1.5mOsm higher than that of ISF.
7
Q
What are the four major sites of ion and water exchange?
A
Skin, respiratory systems, digestive systems and excretory systems.
8
Q
What is delivered during bulk flow osmoregulation?
A
Gases, salts, nutrients, signalling and other molecules.
9
Q
What is removed during bulk flow osmoregulation?
A
Waste products.
10
Q
Summarise the process of osmoregulation of freshwater fish.
A
Uptake of water and some ions in food, uptake of salt ions by gills, osmotic water gain through gills and other parts of body surface, excretion of large amounts of water in dilute urine from kidneys.
11
Q
What must fish use continually to expel water during osmoregulation?
A
Energy.
12
Q
How much water a day can a 100g goldfish take up via osmosis?
A
30g (one third of body weight).
13
Q
When were aquaporins discovered?
A
In 1992.
14
Q
How many molecular forms of aquaporins are there?
A
12.
15
Q
Where are aquaporins primarily prominent?
A
In brain, RBCs, kidney, and skin/ bladder of amphibians.
16
Q
How is cell volume regulated?
A
By changing the osmotic gradient.
17
Q
Why is water and electrolyte balance very important in cell physiology?
A
Too much water entry means cells swell and burst, too much water loss means cells shrink and die.
18
Q
What does catabolism of food stuffs mean?
A
Produces water, obligates animal to certain losses.
19
Q
What does catabolism of food stuffs not mean?
A
That animals gain water in a net fashion.
20
Q
How can net impact of catabolism on water balance be assessed?
A
Obligatory water losses must be subtracted from gains of metabolic water.
21
Q
Explain the relationship between water loss and respiration.
A
Aerobic catabolism requires O2, water lost by evaporation when breathe to obtain O2, magnitude of loss dependent on physiology of breathing and ambient air humidity.
22
Q
Explain how water is lost through urinary processes?
A
Loss of urine water, protein catabolism usually cause as produces nitrogenous wastes, catabolism of carbs and lipids does not yeild products that need excreting in urine.
23
Q
Why must lost water occur in faeces?
A
For food catabolism to take place.
24
Q
When does faecal water lost occur?
A
Only when ingested foods are catabolised.
25
What do ingested foods usually contain?
Preformed water.
26
Explain faecal water loss.
If animal must loose more water in faeces than it took in as preformed water with ingested foods then it incurs a net water loss that’s required for catabolisation of food.
27
How do desert kangaroo rats survive with no water to drink only air-dried barley grain?
Gain metabolic water in a net fashion by metabolising barley.
28
Why do some animals depend more on metabolic water than others?
Water conservation.
29
What are the three types of blood plasma regulation?
Osmotic, ionic and volume.
30
What do animals that don’t regulate in all 3 ways do?
Conform in certain aspects of their salt-water physiology.
31
What different types of environmental challenges to volume, ionic and osmotic regulation can animals face?
Constant or sporadic.
32
What two ways can ions and water exchanges between an animal and environment be?
Obligatory or regulated.
33
What does obligatory exchange mean?
Responses to factors beyond animal’s physiological control.
34
What does regulated exchange mean?
Physiologically controlled and required for maintaining homeostasis.
35
What do animals often display gradations or mixtures of?
Osmotic regulation and osmotic conformity.
36
What are the differences between osmotic conformity of shrimp, mussels and crab?
Shrimp almost perfect osmoregulator, mussel osmotic conformer, crab imperfect osmotic regulation in dilute water but osmotic conformer in conc water.
37
What do kidneys of fresh water crab regulate only?
Volume of body fluids.
38
What is the hemolymph of fresh water crabs like compared to surrounding water?
Hyperosmotic.
39
What does the amount of water gained by osmosis = in fresh water crabs?
Amount of urine excreted by kidneys.
40
What is the urine of fresh water crabs like compared to hemolymph?
Isosmotic.
41
Despite being integrated in the organism, what are regulation of ion composition, osmotic pressure and volume of body fluids?
Distinct processes.
42
Why are all freshwater animals classified as hyperosmotic regulators?
They regulated their blood osmotic pressures at levels hyperosmotic to freshwater.
43
What challenges does volume regulation pose for freshwater organisms?
Water constantly enter the body from dilute environment due to osmotic gradient.
44
What challenges does osmotic regulation pose for freshwater organisms?
Entering water decreases osmotic pressure of extracellular fluid.
45
What challenges does ionic regulation pose for freshwater organisms?
Ions are moving from the ECF to surrounding water due to conc gradient and entering water dilute ECF.
46
Where does ion exchange occur in marine animals?
In rectal gland of elasmobranchs and gills of teleost fishes.
47
What components of marine fishes are poorly penetrable to water?
Integuments and epithelia.
48
Where do marine fishes absorb drunk water and what aggravates ionic regulation?
Via gut epithelia, co-absorption of monovalent ions.
49
What do kidneys of marine fishes produce small amounts of?
Isosmotic urine.
50
What is the principal role of kidneys in marine fishes?
Excretion of divalent ions while excretion of Na+, Cl- and nitrogenous products of metabolism takes place in gills.
51
What do salt glands in marine eureptilias do?
Secrete sodium and chloride ions.
52
What are the two different types of animals in regards to tolerance to changes in water salinity?
Stenohaline animals tolerate only narrow range of NaCl, euryhaline animals tolerate wide variance of NaCl.
53
What are the three principal functions of the urinary system?
Removal of waste products, regulation of volume and solute conc of blood plasma, elimination of waste products into environment.
54
What process produces waste products?
Cellular metabolism.
55
What are the five principal components of the urinary system?
Kidneys, ureters, bladder, sphincter, urethra.
56
What is the role of the kidneys?
Urine production, excretion and regulation.
57
What is the role of the ureters?
Urine transfer to the bladder.
58
What is the function of the bladder?
Urine storage, elimination.
59
What is the role of the urethra?
Urine release, elimination.
60
61
Where are the kidneys located?
Either side of the midline, on the posterior abdominal wall.
62
What are characteristics of adrenal (suprarenal) glands.
Not part of the urinary systems, located on the superior pole of the kidneys.
63
What role does the cortex have in kidney and adrenal gland function?
Releases corticosteroids and aldosterone, controls sodium and water retention and increases BP and volume.
64
What role does the medulla have in kidney and adrenal gland function?
Releases adrenaline and noradrenaline, produces fight or flight response.
65
What do T and L refer to on the spine?
T = thoracic vertebra, L = lumbar vertebra.
66
What is the vertebraic location of the kidneys?
T12-L3.
67
Which kidney is located slightly higher?
The left.
68
What name is given to the organs that lie behind the parietal peritoneum (including kidneys)
Retroperitoneal organs.
69
What surrounds the retroperitoneal organs?
Adipose fat tissue.
70
What three things primarily protect the kidneys?
Fat, fascia and ribs 11/12.
71
What is the renal capsule rich in?
Collagen.
72
What is the renal fascia?
Collagenous membrane.
73
What other name is given to adipose tissue?
Perinephric fat.
74
What do the renal capsule, renal fascia, perinephric fat and suspensorio fibres provide?
Stability, support, cushioning.
75
What are the four key measurements of the kidneys?
150g, 10cm long, 5cm wide, 2.5cm thick.
76
What does indented ovoid mean?
The kidneys are bean shaped.
77
Where do structures enter and leave the kidneys?
At the hilum.
78
What percentage of cardiac output is supplied to the kidneys?
20-25% - large blood supply.
79
What does the renal lobe contain? Where is it located?
Contains the funcional unit - nephron, is located at the top of the kidney.
80
What are the key components of the nephron?
Bowmans capsule, proximal convoluted tubule, loop of henle, distal convoluted tubule, cortex, collecting duct, pelvis.
81
What are the two types of nephrons in the renal lobe?
Cortical, juxtamedullary.
82
What does the renal cortex include?
Proximal and distal parts of the nephron and collecting ducts (medullary rays).
83
What does the renal medulla (pyramids) include?
Loop of Henle and collecting ducts.
84
Other than the cortex and medulla, what is the third region of the renal lobe?
Renal papilla.
85
What are ureters?
Hollow muscular tubes that propel urine from the kidneys to the bladder.
86
What are characteristics of ureters?
25-30cm in length, located in abdominal and pelvis, retroperitoneal.
87
What congenital anomalies can occur in ureters?
Production of duplex ureters - happens in 1 in 125 people.
88
What word describes the way the ureters enter the bladder?
Obliquely (slanted/ indirect)
89
What happens in regards to ureters when bladder is full?
Backflow of urine into them prevented, compression closes off ureters acting as valves.
90
What are the two areas of the urinary bladder?
Apex and fundus.
91
What are the locations of the apex and fundus?
Apex points toward pubic symphysis and fundus is opposite apex ad formed by posterior wall.
92
What are the components of the unitary bladder?
Trigone (smooth) = funnel, rugae, internal urethral opening, urethra.
93
What are key characteristics of capacity of urinary bladders?
Capacity usually of about 0.75 litres, pathologically this could be very different as obstruction to outflow can cause enlargements of volumes up to 6-7 litres.
94
Why are women more likely to get urinary tract infections?
Urethra 4-5cms long compared to men’s 20cm length.
95
What is the location of the female urethra?
Passes through pelvic floor and opens anterior the vagina.
96
What is the shape and 4 key parts of the male urethra?
S-shaped, pre-prostatic, prostatic, membranous, penile.
97
What are the male urethral sphincters?
Internal, prostate gland, external, external urethral orifice.
98
What is the internal urethral sphincter and what’s it’s role?
Junction between the bladder and urethra - prevents reflux of semen into the bladder.
99
Where is the external urethral sphincter located?
Inferior to the prostate.
100
What does the internal urethral sphincter do in females?
Debated but is junction between bladder and urethra.
101
Where is the external urethral sphincter located?
Immediately inferior to internal urethral sphincter.
102
How is water lost in terrestrial animals?
Low permeability of integument, retention of water in respiratory, production of conc excretory fluids, reduction of amount of solutes excreted, tight regulation of fluid production in changeable conditions.
103
What are the seven main functions of the mammalian kidney function?
Water balance (volume regulation), osmotic balance, ion balance, pH balance, excretion of waste, hormone production, regulation of blood pressure.
104
What are the four principal processes of urine formation in mammalian kidneys?
Filtration, re absorption, secretion, excretion (micturition).
105
Where does urine filtration occur?
The glomerulus.
106
What is the name for the capillary loops used in urine filtration?
Glomerular tuft.
107
What are the main characteristics of the filtration in the glomerulus?
Constant vasoactivity, hydrostatic pressure gradient, 3 layers of filtration barrier, glomerular filtration rate 120mL/min, charge and size selectivity, clearance.
108
What is the starling principal of fluid exchange?
The direction of fluid flow across a capillary wall is the result of net filtration pressure.
109
How much of the CO does the blood flow through kidneys comprise of?
20-25%.
110
What does reduction in the osmolarity of the filtrate cause?
Vasodilation, macula densa cells sense, release of renin, blood pressure returns to normal.
111
What does an increase in osmolarity of the filtrate cause?
Vasoconstriction, blood pressure returns to normal.
112
Overview of regulation of glomerular filtration and tubular reclamation?
Juxtaglomerular apparatus (JGA), macula densa - detect flow in tubule lumen, juxtaglomerular cells line afferent arterials produce renin.
113
What are characteristics of the tubule epithelial cells?
Relatively impermeable, composition of lipid bilayer, tight junctions present paracellular transport, polarity certain proteins directed elsewhere.
114
What happens during reabsorption in PCT?
Reabsorption of ~75% of H2O, Na+ and Cl- from primary urine, at end the tubular fluid is isosmotic to ISF and plasma.
115
What happens in the distal convoluted tubule (DCT)?
Reabsorption and secretion in the DCT.
116
What happens in the collecting duct?
Final stages of urine production.
117
What cells are involved in the control of acid base (pH) balance?
Alpha intercalated cell and beta intercalated cell.
118
What does countercurrent multiplication do?
Concentrates urine in loop of Henle.
119
With what does osmotic pressure increase?
With depth in the medulla of the mammalian kidney.
120
What happens in the descending vasa recta during countercurrent exchange of NaCl?
Blood coming down into medulla from cortex comes into contact with the concentrated medullary ISF, salt diffuses from that ISF into blood increasing the plasma conc.
121
What happens in the ascending vasa recta during countercurrent exchange of NaCl?
Concentrated blood flowing up towards the cortex from the papilla loses salt to the more dilute medullary ISF.
122
What does countercurrent flow of blood in the vasa recta thus lead to of NaCl?
Salt reabsorbed from the loop of Henle is trapped and recycled within the medulla.
123
What happens in the descending vasa recta during countercurrent exchange of H2O?
The dilute blood flowing into the medulla loses water to conc medullary ISF.
124
What happens in the ascending vasa recta during countercurrent exchange of H2O?
The concentrated blood flowing from tip of papilla towards cortex gains water from medullary ISF.
125
What helps preserve the conc of medullary ISF?
Water tends to short-circuit from descending to ascending VR.
126
What happens inside the inner medulla?
Steep osmotic gradient facilitating constant reabsorption of water from descending limb of loop of Henle.
127
Why is the inner medulla’s role important?
For keeping equally high conc inside most distal segment of collecting duct and therefore in urine.
128
What are the key urea transport proteins (uniporters)?
UT-A1, UT-A3, vasopressin (ADH), UT-A2.
129
What do UT-A1 and UT-A3 do when expressed in collecting duct?
Facilitate passive diffusion of urea from intertubular to interstitial fluid (increases osmotic pressure in interstitial of deep layers of renal medulla facilitates reabsorption of water).
130
What does vasopressin (ADH) do?
Upregulates expression of UT-A1 and UT-A3.
131
What does the UT-A2 expressed in the Loop of Henle stimulate?
Urea to pass from interstitial to intertubular fluid.
132
Where is ADH produced and released?
Produced in hypothalamus, released by the pituitary gland.
133
What three key affects does ADH have?
Directly affects water reabsorption in DCT and CD, increases blood pressure, decreases blood osmolarity which down regulates production of ADH.
134
What control of aquaporins does vasopressin have?
Upregulates translocation of channels to apical plasma membrane in DCT and CD to increase water reabsorption = more conc urine.
135
What do juxtaglomerular cells produce?
Renin.
