PBL Topic 4 Case 7 Flashcards
(192 cards)
1
Q
Identify 7 functions of the kidneys
A
- Excretion of waste products
- Water + Electrolyte balance
- Regulation of body fluid osmolality
- Regulation of arterial pressure
- Regulation of acid-base balance
- Secretion, metabolism and excretion of hormones
- Gluconeogenesis
2
Q
Identify four waste products that are excreted by the kidneys
A
- Urea (from amino acid metabolism)
- Creatinine (from muscle creatine)
- Uric acid (nucleic acids)
- Bilirubin (from haemoglobin breakdown)
3
Q
Why must water and electrolyte excretion precisely match intake?
A
- If intake exceeds excretion, the amount of substance in the body will increase
- If intake is less than excretion, the amount of substance in the body will decrease
4
Q
Briefly identify 2 ways that the kidneys regulate arterial pressure
A
- By excreting variable amounts of sodium and water
- By secreting vasoactive factors, e.g. renin, that lead to formation of vasoactive products, e.g. angiotensin II
5
Q
Briefly describe how the kidneys regulate erythrocyte production
A
- Fibroblasts secrete erythropoietin
- Especially during hypoxia
- Which stimulates the production of red blood cells
6
Q
Briefly outline how the kidneys regulate vitamin D.
A
- Hydroxylate vitamin D to calcitriol
7
Q
Identify 3 roles of vitamin D
A
- Calcium deposition in bone
- Calcium reabsorption in GI tract
- Calcium and phosphate regulation
8
Q
Outline the kidneys role in gluconeogenesis
A
- Synthesise glucose from amino acids
9
Q
Outline the physiological anatomy of the kidneys
A
- Surrounded by fibrous capsule
- Contains outer cortex and inner medulla
- Medulla is divided into pyramids by cortex columns
- Base of each pyramid terminates in the papilla
- Papilla projects into renal pelvis
- Urine from papilla is collected by minor calyces which is collected by major calyces
10
Q
Outline the arterial supply of the kidneys
A
- Renal artery enters hilum and gives off lobar arteries
- Which give off interlobar arteries
- Which give off arcuate arteries
- Which give off interlobular arteries
- Which give off afferent arterioles
- Which lead to glomerular capillaries
- Distal end of glomerular capillaries forms efferent arterioles
- Which lead to peritubular capillaries
11
Q
How does hydrostatic pressure differ in the glomerular and peritubular capillaries
A
- High hydrostatic pressure in glomerular capillaries, causing rapid filtration
- Low hydrostatic pressure in peritubular capillaries, causing fluid reabsorption
12
Q
Outline the venous drainage of the kidneys
A
- Peritubular capillaries drain into interlobular veins
- Which drain into arcuate veins
- Which drain into interlobar veins
- Which drain into the renal vein which leaves the kidney through the hilum
13
Q
Identify the two main parts of a nephron
A
- Glomerulus, through which large amounts of fluid are filtered from the blood
- Tubule, where the filtered fluid is converted into urine
14
Q
How many nephrons are there in each kidney? Can the kidney regenerate new nephrons?
A
- 1 million nephrons
- No
15
Q
Describe the hydrostatic pressure in the glomerular capillaries
A
- High (60 mm Hg)
16
Q
What happens to fluid that is filtered from the glomerular capillaries?
A
- Flows into Bowman’s capsule which encases the glomerular capillaries
- Fluid then flows into PCT
17
Q
Is the PCT in the cortex or medulla of the kidney?
A
- Cortex
18
Q
What happens to fluid after it passes through the proximal tubule?
A
- Flows into the loop of Henle
- Which is formed from a descending and ascending loop
19
Q
How does thickness change in the loop of Henle?
A
- Walls of descending limb and lower ascending limb are thin
- The ascending limb thickens as it enters the cortex
20
Q
Is the loop of Henle located in the cortex or medulla of the kidney?
A
- Both
- Dips from cortex to medulla
- Ascending limb thickens as it enters the cortex
21
Q
What happens to fluid after it passes through the ascending limb of the loop of Henle?
A
- Enters the DCT
22
Q
Does the DCT lie in the cortex or medulla?
A
- Cortex
23
Q
What happens to fluid after it passes through the DCT?
A
- Flows into connecting tubules
- Which flows into cortical collecting tubules
- Which leads to cortical collecting duct
- Which runs downward and becomes the medullary collecting duct
24
Q
What happens to fluid after it passes through the collecting ducts?
A
- Passes into the renal pelvis through the tips of the renal papillae
25
Identify two types of nephrons and how they differ from one another in their structure
- Cortical nephrons, located in outer cortex, short loop of Henle
- Juxtamedullary nephrons, located in medulla, long loop of Henle
26
How do the two types of nephrons differ from one another in their vascular supply
- Cortical nephrons, surrounded by peritubular capillaries
| - Juxtamedullary nephrons, surrounded by vasa recta that loop downward like the loop of Henle
27
Express urinary excretion rate mathematically
- Filtration rate - reabsorption rate + secretion rate
28
Identify a substance that is not filtered from the glomerular capillaries into Bowman's capsule
- Protein
| - Since the glomerular capillaries are impermeable to protein
29
Identify 4 substances that are reabsorbed in the tubules
- Water
- Electrolytes
- Amino acids
- Glucose
30
Why are calcium and fatty acids sometimes not freely filtered in the glomerulus?
- They may be bound to plasma proteins
31
Identify two factors that determine glomerular filtration rate
- Balance of hydrostatic and colloid osmotic forces
| - Capillary filtration coefficient (Kf)
32
Identify two factors that determine the capillary filtration coefficient
- Permeability
| - Surface area
33
Identify two reasons that the glomerular capillaries have a much higher rate of filtration that most other capillaries
- High hydrostatic pressure
| - High Kf
34
What is the average GFR in ml/min
- 125 ml/min
35
What is filtration fraction and what is its value in the kidneys?
- The fraction of plasma flow that is filtered
| - 20% (of plasma flowing through kidney is filtered through glomerular capillaries)
36
How is filtration fraction calculated mathematically
- GFR / Renal Plasma Flow
37
Identify the structure of the glomerular capillary membrane and the features of each which increase filtration
- Endothelium (with fenestrations)
- Basement membrane (with proteoglycan fibrillae)
- Epithelial cells (podocytes) (with slit pores)
38
What is the importance of the negative charges in the endothelium, basement membrane and epithelial cells
- Hinders passage of plasma proteins
39
Identify two forces that promote filtration
- Hydrostatic pressure in glomerular capillaries, (glomerular hydrostatic pressure)
- Colloid osmotic pressure of the proteins in Bowman's capsule
40
Identify two forces that opposes filtration
- Hydrostatic pressure in Bowman's capsule outside the capillaries
- Colloid osmotic pressure of the glomerular capillary plasma proteins
41
Why does the plasma protein concentration increase from the afferent to efferent arterioles?
- 20% of fluid is filtered into Bowman's capsule
| - Concentrating the glomerular plasma proteins that are not filtered
42
Identify two factors that influence glomerular capillary colloid osmotic pressure
- Arterial plasma colloid osmotic pressure
| - Filtration fraction
43
Identify two factors that would increase filtration fraction
- Increasing GFR
| - Reducing renal plasma flow
44
Identify three factors that affect glomerular hydrostatic pressure
- Arterial pressure
- Afferent arteriolar resistance
- Efferent arteriolar resistance
45
Outline the biphasic effect of efferent arteriolar resistance on GFR
- Moderate constriction of efferent arterioles increase resistance to outflow
- Which raises GFR
- Severe constriction increases colloid pressure
- Which decreases GFR
46
How is renal blood flow determined?
- Difference between renal artery and vein hydrostatic pressure
- Divided by renal vascular resistance
47
Where does most renal vascular resistance take place? How is this resistance controlled?
- Interlobular arteries
- Afferent arterioles
- Efferent arterioles
- Sympathetic nervous system
48
What is autoregulation?
- Mechanism by which renal blood flow and GFR remains relatively constant
49
Outline the renal blood flow to the medulla
- Blood flow to medulla accounts for 1% of blood flow
| - Supplied by vasa recta from peritubular capillary system
50
Identify hormones that constrict arterioles and reduces GFR
- Noradrenaline
- Adrenaline
- Endothelin
- Angiotensin II
51
Identify an autacoid that decreases vascular resistance and increases GFR
- Nitric oxide
52
Identify autacoids and hormones that cause vasodilation and increases GFR
- Prostaglandins E2 and I2
| - Bradykinin
53
What is glomerulotubular balance?
- Adaptive mechanisms in renal tubules
| - That allow them to increase their reabsorption rate when GFR rises
54
Where are macula densa cells located and what is their role?
- DCT
| - Sense changes in volume delivery to the distal tubule
55
Outline the effect of a reduced GFR on macula densa cells
- Reduced GFR slows the flow rate in the loop of Henle
- Causing increased reabsorption of NaCl in the ascending loop of Henle
- Reducing concentration of NaCl at macula densa cells
- Decreasing resistance to blood flow (increasing GFR)
- And increasing release of renin from juxtaglomerular cells (increasing GFR)
56
Identify the role of renin in raising GFR
- Increases formation of angiotensin I
- Which is converted to angiotensin II
- Which constricts efferent arterioles
- Increasing hydrostatic pressure and returning GFR to normal
57
Outline the purpose myogenic mechanism of renal blood flow
- Ability of blood vessels to resist stretching during increased arterial pressure
- To maintain a constant renal blood flow and GFR
58
Outline the role of calcium ions in the myogenic mechanism of renal blood flow
- Stretch of vascular walls increases movement of calcium ions into cells from extracellular fluid
- Which causes them to contract
- Which prevents over-distension of the vessel
- And increases vascular resistance
- Which helps prevent excessive increases in renal blood flow and GFR
59
Why does a high protein intake increase renal blood flow / GFR?
- Increased release of amino acids into blood
- Which are reabsorbed in proximal tubule
- Which causes reabsorption of sodium in proximal tubule
- Decreased sodium to macula densa
- Which causes a decrease in resistance of the afferent arterioles
- Which raises renal blood flow and GFR
60
Why does a high glucose intake increase renal blood flow / GFR?
- Glucose causes reabsorption of sodium
- Reduced delivery of sodium to macula densa
- Activating tubuloglomerular feedback-mediate dilation of afferent arterioles
- With increase in renal blood flow and GFR
61
Describe the tubular absorption of:
[A] Glucose and amino acids
[B] Ions in plasma
[C] Waste products
- [A] Completely reabsorbed
- [B] Variable absorption
- [C] Poorly reabsorbed
62
Identify two ways in which water and solutes can be reabsorbed
- Transcellular route through the cell membrane
| - Paracellular route, through the tight junctions
63
What is ultra-filtration?
- Reabsorption from interstitial fluid into peritubular capillaries
- Passive process
- Driven by hydrostatic and colloid osmotic pressure gradients
64
What is primary active transport?
- Movement of solutes against an electrochemical gradient
| - Requiring energy from hydrolysis of ATP by ATPase
65
Give an example of the primary activate transport ysstem
- Reabsorption of sodium ions
- Hydrolysis of ATP moves sodium out of cell
- At same time potassium is transported to inside of cell
66
Identify two provisions for moving large amounts of sodium into the cell
- Brush border increases surface area
| - Sodium carrier proteins for facilitated diffusion
67
Identify two mechanisms of secondary active reabsorption
- Co transport, interaction with carrier protein and transport together (e.g. sodium and glucose)
- Counter-transport, diffusion of sodium into cell liberates energy to secrete hydrogen ions into tubule
68
Identify a substance that is reabsorbed by pinocytosis. Outline the process of pinocytosis
- Protein
- Attaches to brush border of luminal membrane
- This portion invaginates to interior of cell and pinched off to form a vesicle
- Once in cell, protein is digested into amino acids
- Which are reabsorbed through basolateral membrane
69
What is meant by transport maximum? Identify an example of this
- Limit to rate at which solute can be actively transported
- Due to saturation of carrier proteins when amount of solute exceeds capacity
- Glucose transport system in uncontrolled diabetes
70
What is gradient time transport
- Limit to rate at which solute can be passively reabsorbed
| - Increased by high diffusion gradient, high permeability increased time that the substance remains in the tubule
71
How does reabsorption of water occur and how does it change throughout the nephron
- Active transport of solutes decreases their concentration
- Which increases osmosis of water
- Reduces throughout nephron as tight junctions become tighter
72
What is solvent drag?
- As water is reabsorbed
| - It carries solvents with it
73
Outline the process of chloride reabsorption
- Sodium reabsorption causes transport of chloride ions due to electrical potentials
- Water reabsorption increases chloride ion concentration which creates a concentration gradient
- Chloride ions can be co-transported with sodium ions
74
Identify three features of the PCT that allow for reabsorption
- Highly metabolic, lots of mitochondria for active transport
- Apical brush border
- Carrier proteins
75
Explain how bicarbonate ions are removed from the PCT
- Secretion of H+ (by counter transport)
- Which combines with bicarbonate ions
- To form carbonic acid
- Which dissociates into water and carbon dioxide
76
Outline substances that are secreted by the PCT
- Bile salts
- Oxalate
- Urate
- Catecholamines
- Harmful drugs and toxins
- PAH
77
What is the function of the descending part of the loop of Henle?
- Simple diffusion of water
| - Ascending part is impermeable to water
78
Which section of the ascending part of the loop of Henle is adapted for reabsorption?
- Thick segment
- ATPase
- Due to high metabolic activity and surface area
79
Which part of the loop of Henle reabsorbs calcium, bicarbonate and magensium?
- Thick ascending part
80
Outline the process of sodium reabsorption in the thick ascending part of the loop of Henle
- ATPase provides energy
- To move sodium through the Na-K-Cl co-transporter across the luminal membrane
- This releases energy which moves chloride and potassium ions into the cell against a concentration gradient
- In a ratio of (1Na:1K:2Cl)
81
Why is the distal tubule referred to as the diluting segment?
- Reabsorption of ions via the Na-K-Cl transporter
| - Impermeable to water and urea
82
Identify the two cell types in the late distal tubule and cortical collecting tubule
- Principal cells: Sodium and water reabsorption, potassium secretion
- Intercalated cells: Potassium reabsorption and hydrogen secretion
83
Describe the process of potassium secretion by principal cells
- Potassium enters cell through sodium potassium ATPase pump
| - Diffuses across luminal membrane into tubular fluid down concentration gradient
84
Describe the process of hydrogen ion secretion by intercalated cells
- Carbonic anhydrase catalyses reaction of H2O and CO2
- To form carbonic acid
- Which dissociated into hydrogen and bicarbonate ions
- Hydrogen ions secreted into lumen by hydrogen-ATPase transport mechanism
85
Outline the special characteristics of the medullary collecting duct
- Its permeability is controlled by ADH
- It is permeable to urea
- Secretes protons against a large concentration gradient
86
What is glomerulotubular balance?
- Rate of reabsorption changes in response to tubular inflow
| - To help prevent overloading of the distal tubular segments
87
How is reabsorption calculated?
- Kf x Net Reabsorptive Force
88
Identify the four osmotic forces that represent the net reabsorptive force
- Hydrostatic pressure in peritubular capillaires
- Hydrostatic pressure in renal interstitium
- Colloid pressure in peritubular capillary
- Colloid pressure in renal interstitium
89
Identify factors that increase the peritubular capillary hydrostatic pressure and the effect on reabsorption
- Increased arterial pressure
- Increase in resistance of afferent and efferent arterioles
- Both of which decrease reabsorption
90
Identify factors that influence the peritubular capillary colloid pressure
- Increase in plasma protein concentration
- Increase in filtration fraction
- Both of which increase reabsorption
91
What is meant by pressure natriuresis and diuresis?
- Increase in arterial pressure
| - Causes marked increase in urinary excretion of sodium and water
92
Where is aldosterone secreted from?
- Zone glomerulosa
| - Of adrenal cortex
93
What is the primary site of aldosterone action?
- Principal cells
| - Cortical collecting tubule
94
What is the action of aldosterone?
- Increased sodium reabsorption
- Increased potassium secretion
- By stimulating sodium-potassium ATPase pump on basolateral side of cortical collecting tubule
95
Outline two clinical conditions in which aldosterone is affected?
- Addison's disease: absence of aldosterone so marked natriuresis and accumulation of potassium
- Conn's syndrome: excess aldosterone so sodium retention and potassium depletion
96
When is angiotensin II secreted?
- Low blood pressure or extracellular fluid volume
97
What is the general action of angiotensin II?
- Helps to increase blood pressure
| - By increasing sodium and water reabsorption from renal tubules
98
Identify three effects of angiotensin II secretion
- Stimulates aldosterone secretion,
- Constricting efferent arterioles
- Stimulates sodium-potassium ATPase pump
99
What is the general action of ADH?
- Increases water permeability of distal tubule, collecting tubule and collecting duct epithelia
- Causing reabsorption of water
- To conserve water e.g. dehydration
100
Outline the cellular action of ADH
- Binds to V2 receptors in distal tubules, collecting tubules and duct
- Which increases cAMP formation and PKA
- Which stimulates movement of aquaporin-2 to luminal side of cell membrane
- Which fuse with the cell membrane by exocytosis
- To form water channels that permit rapid diffusion of water through the cells
101
When is atrial natriuretic peptide released and what is its action?
- Distension of atria
- Reduces reabsorption of sodium and water in collecting ducts
- Which increases urinary excretion
- Helping to return blood volume back to normal
102
Outline the principal action of PTH in the kidneys
- Increases calcium reabsorption in DCT
| - Decreases phosphate and magnesium reabsorption in loop of Henle
103
Outline three effects of the sympathetic nervous system on reabsorption
- Constricts renal arterioles, reducing GFR
- Increased reabsorption in proximal tubule
- Increased renin release and angiotensin II formation
104
Outline the renal mechanism for excreting a dilute urine
- Dilution in ascending limb of loop of Henle
- Due to reabsorption of ions (impermeable to water)
- Absence of ADH so reduces reabsorption in collecting ducts
105
Outline the two basic requirements for forming a concentrated urine
- High level of ADH in collecting ducts (to increase permeability for water absorption)
- High osmolarity of renal medullary interstitial fluid (providing an osmotic gradient)
106
What is the importance of urea recycling?
- Absorption of urea into medullary interstitium from collecting ducts
- Increases osmolarity in renal medulla
- To increase reabsorption of water to produce concentrated urine
107
Outline the countercurrent mechanism
- Blood enters and leaves medulla through vasa recta
- It is concentrated as it descends in due to solute entry and loss of water
- It is diluted as it ascends due to solute loss and gain of water
- Resulting in little net dilution
- Preventing loss of hyperosmolarity in medullary interstitial fluid
108
Outline two mechanisms for controlling extracellular fluid osmolarity and sodium concentration
- Osmoreceptor ADH system
| - Thirst mechanism
109
Where are osmoreceptor cells located and how does their activation cause increase ADH release?
- Anterior hypothalamus near supraoptic nuclei
- They shrink when osmolarity ([Na]) increase above normal
- Which causes them to fire signal down pituitary stalk to posterior pituitary gland
- Causing secretion of granular ADH into bloodstream
110
How is ADH synthesised?
- By magnocellular neurons in the supraoptic and paraventricular nuclei
111
Where is the AV3V region located?
- Anteroventral region of third ventricle
112
Identify the structures of the AV3V region
- Subfornical organ superiorly
- Organum vasculosum inferiorly
- Median preoptic nuclei (which connects to both organs as well as the supraoptic nuclei)
113
Why can the subfornical organ and organum vasculosum respond to changes in osmolarity?
- They lack the typical blood brain barrier
| - Allowing for diffusion of ions from the blood into the brain tissue
114
Outline the two cardiovascular reflexes involving in stimulating ADH release
- Arterial baroreceptor reflexes
- Cardiopulmonary reflexes
- Which originate in high pressure regions (aortic arch and carotid sinus)
- Afferent stimuli are carried by CN9 and CN10 to tractus solitarius
- Which relays signals to hypothalamic nuclei controlling ADH synthesis and secretion
- E.g. increased ADH secretion in haemorrhage
115
Outline 3 additional factors that increase ADH secretion
- Nausea
- Hypoxia
- Drugs: morphine, nicotine, cyclophosphoamide
116
Outline three drugs that decrease ADH secretion
- Alcohol
- Clonidine
- Haloperidol
117
Outline 3 stimuli for thirst
- Extracellular fluid osmolarity
- Angiotensin II
- Dryness of mouth
118
Identify the three determinants of potassium excretion
- Rate of potassium filtration
- Rate of potassium reabsorption
- Rate of potassium secretion
119
Where is the majority of potassium reabsorbed?
- PCT
120
In which part of the loop of Henle does most potassium reabsorption take place?
- Thick ascending part
121
Identify the three main factors that control potassium secretion by the principal cells
- Na+-K+ ATPase activity
- Electrochemical gradient fro potassium secretion
- Permeability of luminal membrane for potassium
122
Which cells reabsorb potassium in severe potassium depletion?
- Intercalated cells
123
What is hypocalcaemic tetany?
- Increased excitability of nerve and muscle cells
- As a result of hypocalcaemia
- Characterised by spastic skeletal muscle contractions
124
How does plasma [H+] affect calcium binding to plasma proteins
- Acidosis: Less calcium is bound to plasma proteins (possible role of denaturation?)
- Alkalosis: More calcium bound to plasma proteins
125
How does calcium excretion differ to other ions?
- Excretion also occurs in faeces
126
Outline the role of the parathyroid glands when extracellular [Ca2+] falls
- Promote secretion of PTH
- Which increases calcium resorption from bone
- And stimulates intestinal resorption of calcium via Vitamin D
- Elevating extracellular [Ca2+]
127
Why is only 50% of plasma calcium filtered at the glomerulus?
- The other 50% is bound to plasma proteins
| - Or forms complex anions with phosphate
128
Identify five factors that increase calcium excretion
- Decreased PTH
- Increased extracellular fluid volume
- Increased blood pressure
- Decrease plasma phosphate
- Metabolic acidosis
129
Identify two ways in which PTH regulates plasma phosphate concentration
- High PTH increases bone resorption, releasing phosphate ions into extracellular fluid
- High PTH decreases transport maximum of phosphate, decreasing tubular absorption and increasing excretion
130
What is the primary site of magnesium reabsorption?
- Loop of Henle
131
Identify 3 factors that cause increased magnesium excretion
- Increased extracellular magnesium concentration
- Extracellular volume expansion
- Increased extracellular fluid calcium concentration
132
What are nonvolatile acids?
- Acids produced from protein metabolism
- That cannot be excreted by the lungs
- So must be removed via the kidneys
133
Outline the process of H+ secretion in the PCT
- Secondary active secretion
- Reabsorption of Na+ into cell
- Provides energy for H+ secretion against a concentration gradient
134
Outline the process of HCO3- reabsoprtion in the PCT
- CO2 diffuses into tubular cells
- Combines with water to form H2CO3 (catalysed by CA)
- Which dissociates into HCO3- and H+
- H+ secretion against a concentration gradient via secondary active secretion with sodium
- HCO3- crosses basolateral membrane into renal interstitium
135
Outline the process of H+ secretion in the DCT
- Primary active transport
| - H+ is transported through ATPase protein in intercalated cells
136
Outline the phosphate buffer system
- Depletion of HCO3-
- So H+ combines with HPo42- to form H2PO4-
- Which is excreted as NaH2PO4 in the urine
137
Outline the ammonia buffer system
- Glutamine enters epithelial cells
- Metabolised to NH4+ and HCO3-
- NH4+ is secreted into lumen by a counter transport mechanism with sodium
- HCO3- is transported across basolateral membrane with sodium
138
How does the ammonia buffer system differ in the collecting tubules?
- Collecting ducts are permeable to NH3
- Which diffuses into tubular lumen
- And combines with secreted H+ to form NH4+
- Which is eliminated in urine
139
When does acidosis occur?
- When ratio of HCO3- to CO2 decreases
| - Decreasing pH
140
What is the difference between metabolic and respiratory acidosis?
- Metabolic: Decrease in HCO3-
| - Respiratory: Increase in PCO2
141
What is the affect of acidosis on the renal tubular fluids?
- Decreased ratio of HCO3- to H+
- Resulting in an excess of H+ in the tubule
- Which combines with urinary buffers
- HCO3- is reabsorbed
142
When does alkalosis occur?
- When ratio of HCO3- to CO2 increases
| - Increasing pH
143
What is the difference between metabolic and respiratory alkalosis?
- Metabolic: Increase in HCO3
| - Respiratory: Decrease in PCO2
144
Outline the renal response to respiratory alkalosis
- Decrease in PCO2 leads to a decrease in H+ secreted by renal tubules
- Not enough H+ to react with HCO3- that is filtered
- HCO3- that cannot react with H+ is excreted in urine
145
Outline the mechanism of action of loop diuretics
- Act on thick ascending limb
- Combine with Cl- binding site on Na+/K+/2Cl-
- Inhibit Na+ reabsorption
- Also have vasodilatory effect
146
Identify two loop diuretics
- Furosemide
| - Bumetanide
147
Loop diuretics increase excretion of [A] and [B] and decrease excretion of [C]
- [A] Ca2+
- [B] Mg2+
- [C] Uric acid
148
Identify unwanted effects of loop diuretics
- Hypovolaemia and hypotension
- Hypokalaemia and metabolic acidosis
- Hypomagnesaemia and hyperuricaemia (gout)
- Hearing loss
- Allergic reactions
149
Outline the mechanism of action of thiazide diuretics
- Act on DCT
- Bind to Cl- site on Na+/Cl- co transport system
- Inhibiting its action
- Resulting in natriuresis with loss of sodium and chloride into urine
- Vasodilatory action (useful in hypertension)
150
Why are thiazide diuretics advantageous over loop diuretics in older patients?
- They reduce Ca2+ excretion
| - So reduced bone resorption in older patients at risk of osteoporosis
151
Identify unwanted effects of thiazide diuretics
- Increased urinary frequency
- Erectile dysfunction
- Impaired glucose tolerance (activation of KATP channels)
- Hyponatraemia
- Hypokalaemia (adverse drug reaction which precipitates encephalopathy)
- Allergic reactions
152
Identify two thiazide diuretics and three related drugs
- Bendroflumethiazide
- Hydrochlorothiazide
- Chlortalidone
- Indapamide
- Metolazone
153
Identify two aldosterone antagonists
- Spironolactone
| - Eplerenone
154
What is the active metabolite of spironolactone
- Canrenone
155
Identify unwanted effects of aldosterone antagonists
- Fatal hyperkalaemia
- GI disturbances
- Gynaecomastia (actions on progesterone/androgen receptors)
156
How is cardiac toxicity of hyperkalaemia counteracted?
- Intravenous calcium gluconate
| - Glucose + Insulin (to shift K+ into cell)
157
Outline the mechanism of action of triamterene and amiloride
- Act on collecting tubules and ducts
- Inhibit Na+ reabsorption by blocking luminal sodium channels
- Decreases K+ excretion
158
Identify the unwanted effects of triamterene and amiloride
- Hyperkalaemia
- GI disturbances
- Kidney stones (triamterene only)
- Skin reactions
159
Identify a carbonic anhydrase inhibitor
- Acetazolamide
160
Identify the mechanism of action of carbonic anhydrase inhibitors
- Acts on PCT
- Increases excretion of bicarbonate
- With accompanying Na+, K+ and water
- Resulting in an increased flow of alkaline urine and metabolic acidosis
161
Identify a use of acetazolamide
- Glaucoma for reduction of aqueous humor formation
162
Identify an osmotic diureitc
- Mannitol
163
Identify the mechanism of action of mannitol
- Reduces passive water reabsorption
164
What is diabetic nephropathy?
- Manifestation of diabetic microvascular disease
| - Involving renal arterioles and glomeruli
165
Outline the pathophysiology of diabetic nephropathy
- Glucose combines with amino acids forming advanced glycosylation end products
- Which accumulate in tissues by cross-linking with collagen molecules
- Stimulation of mesangial cell proliferation and matrix production
- Which produces thicker more permeable glomerular basement membrane
166
What causes glomerular hyperperfusion and hyperfiltration in diabetic nephropathy?
- Defective autoregulation and albumin leakage
167
Identify the clinical features of diabetic nephropathy
- Microalbuminuria (30-300 mg/day)
- Followed by more severe proteinuria
- Commonest cause of end-stage kidney disease
168
Which type of diabetes is most associated with the development of diabetic nephropathy?
- Type 1
| - With a clear relationship between duration of diabetes (15 years) and histological changes
169
Identify the morphological changes in diabetic nephropathy
- Thickening of glomerular basement membrane
- Depletion of podocytes
- Increase in mesangial matrix
- Nodular glomerulosclerosis (Kimmelstiel-Wilson nodules) of collagen and other matrix proteins
170
How is diabetic nephropathy managed?
- Lifestyle changes
- Control of hypertension and poor metabolic regulation
- ACE inhibitors and ARAs following microalbuminuria
- Paricalcitol (vitamin D receptor activator)
171
Identify three clinical findings that suggest acute pyelonephritis
- Fever
- Loin pain
- Tenderness
172
Outline the structural changes in acute pyelonephritis
- Renal cortical abscesses
- Steaks of puss
- Infiltration of leucocytes in tubular lamina
173
What is the treatment for acute pyelonephritis
- Amoxicillin
| - Co-amoxiclav and ciprofloxacin in resistant organisms
174
Outline the basic principles of haemodialysis
- Blood is pumped through semi-permeable membrane (dialyser)
- Blood comes into contact with dialysate
- Causing diffusion of molecules down their concentration gradient
175
What is the blood flow during dialysis and the flow of dialysate?
- Blood: 200-300 ml/min
| - Dialysate: 500 ml/min
176
What is the best way to achieve a blood flow of 200ml for dialysis?
- Arteriovenous fistula
- Usually the radial or brachial artery and the cephalic vein
- Resulting in distension and thickening of the vein
177
What is the frequency and duration of haemodialysis?
- 4-5 hours three times a week
| - Optimal dialysis is adjusted to individual patient needs
178
Why are patients anticoagulated during haemodialysis tretment?
- Contact with foreign surfaces activates the clotting cascade
179
Identify complications of haemodialysis
- Hypotension
- Anaphylactic reactions to ethylene oxide used to sterilise dialysers
- Hard water syndrome (nausea and vomiting)
- Haemolytic reactions
- Air embolism
180
Outline the basic principles of peritoneal dialysis
- A tube is placed in peritoneal cavity through AAW
- Dialysate is run into peritoneal cavity
- Urea, creatine and phosphate pass into dialysate down concentration gradients
- Water is attracted into peritoneal cavity by osmosis
- The fluid is changes regularly to repeat the process
181
What is the role of glucose or polymer (icodextrin) in peritoneal dialysis?
- Determines osmolarity of dialysate
182
Outline the main complication of peritoneal dialysis
- Bacterial peritonitis
- With abdominal pain, guarding, rebound tenderness
- And a cloudy peritoneal effluent (diagnostic)
183
Identify a second complication of peritoneal dialysis
- Constipation
184
Outline the Human Tissue Act 2004
- Permits opt in donation post mortem
- Allows family members to refuse if donor not on ODR
- Permits live organ donation to be target to specific individuals
- Makes paid donations illegal
- Allows 12 years olds and above to make their own decision
185
What does the Amends Organ Donation Bill state?
- Person concerned is deemed to have consented to transplantation
- Unless a person who stands in a qualifying relationship to the person provides information
- That would lead to a reasonable person to conclude that the person concerned would not have consented.
186
Identify factors for assessing allocation policies in organ donation
- Patient benefit
- Transparency
- Equity of access
- Geographical equity
187
What is motivational interviewing?
- Collaborative conversation
- That elicits and strengthens peoples good motivations
- For making lifestyle and behaviour changes
188
Identify four aspects within the spirit of motivational interviewing
- Compassion
- Collaborative
- Evoking
- Supporting autonomy
189
What is sustain talk?
- Patients talk about why they should stay the same
| - Helps to identify obstacles the individual should overcome
190
What is change talk?
- Patients talk about changing
- Including their reasons, motivations and self-efficacy
- Helps an individual move towards change
191
Identify four skills required for motivational interviewing
- Open questions
- Affirmations
- Reflective listening
- Summarising
192
Identify four reasons why motivational interviewing is important
- Understand patient perspective
- Builds relationship with patients
- Helps individuals take more responsibility for their health
- May assist individuals in self-management
