Urinary System Flashcards
1
Q
What are the functions of the kidney?
A
Regulation of fluid and volume, electrolyte balance, excretion of waste, production of hormones
2
Q
Where does filtration and collection occur in the kidneys?
A
Filtration- cortex
Collection- medulla
3
Q
Order these organs from start to finish: Ureter, urethra, kidney, bladder
A
Kidney, ureter, bladder, urethra
4
Q
Outline blood flow in kidneys
A
Renal artery, segmental arteries, interlobar arteries, arcuate arteries, interlobular arteries, afferent arteriole, glomerulus, efferent arteriole, peritubular capillaries, interlobular vein, arcuate vein, interlobar vain, renal vein
Really, Small, Indians, Aim, Inside
5
Q
After filtration in the glomerulus describe the route of the filtrate to the collecting duct?
A
Proximal convoluted tubule, descending loop of henle, ascending loop of henle, distal convoluted tubule, collecting duct
6
Q
Where does the nephron enter the medulla?
A
At the bottom of the loop of henle
7
Q
What force is responsible for filtration?
A
The difference in hydrostatic pressure and protein-osmotic pressure
8
Q
Why is the glomerular filtration rate high?
A
To remove toxic substances quickly
9
Q
How is the GFR high?
A
Large SA across filtration and size difference between afferent and efferent arterioles and low resistance of thin porus membrane
10
Q
What is tubular reabsorption?
A
The process of returning substances from filtrate back to renal interstitial then renal blood vessels
11
Q
What are the mechanisms of tubular reabsorption?
A
active transporters, osmosis, solvent drag, co-trasporters
12
Q
What three barriers filter the blood?
A
Capillary endothelium, basement membrane, podocytes
13
Q
What does the endothelial cells filtrate?
A
Prevents blood cells allows components to pass
14
Q
What does the basal lamina filter?
A
Prevents large proteins
15
Q
What do podocytes prevent filtration of?
A
Medium sized proteins
16
Q
What is the definition of the GFR?
A
Volume of fluid filtered from the glomerular capillaries into bowmans space per min
17
Q
What is the difference between paracellular and transcellular reabsorption?
A
Paracellular- between cells
Transcellular- through cells
18
Q
How does tubular reabsorption occur in the proximal tubule?
A
Na+ is diffuses from lumen into tubular cell is pumped into interstitial fluid and diffuses into capillaries, water follows by osmosis, causing solvent drag, this increases conc gradients of all other ions, chloride moves down electrochemical gradient, therefore K, Ca, Mg diffuse
19
Q
How does the proximal tubule increase surface area?
A
Tubular luminal side has villi like structures
20
Q
How is glucose reabsorbed in the proximal tubule?
A
Secondary active transport using Na, glucose symporter then diffusion into the capillaries
21
Q
What causes glucose to reach the urine?
A
Filtration of glucose can saturate, reabsorption can be saturated and no where else can absorb the glucose
22
Q
How is phosphate reabsorbed and regulated?
A
Reabsorbed same as glucose, regulated by parathyroid hormone
23
Q
How does Na/H exchanger allow reabsorption of Bicarbonate?
A
Binds to bicarbonate producing H2O and CO2 which can pass through into the proximal tubule cells and bicarbonate is reproduced using carbonic anhydrase and diffuses into blood
24
Q
Why is not all H+ effective for reabsorbing bicarbonate?
A
Some binds to HPO4 and is excreted
25
How are the small proteins returned to blood?
Endocytosis in the PCT, degradation in tubular cells to amino acids diffuses into capillaries
26
Why is a high filtration rate needed to prevent high concentration of Urea being reabsorbed?
Urea is slightly lipid soluble so can move down concentration gradient into blood therefore high rate needed to prevent more of this
27
Why does water leave the descending limb by osmosis?
The solute from the ascending limb increases ISF concentration water follows by osmosis
28
How does the osmolarity change down the medulla?
Increases
29
How does the LOH and vase recta cause a counter current?
Vassa recta runs parallel and in opposite direction of LOH
30
Why does the osmolarity of the vassa recta increase down the medulla
As it runs down the ions of ascending limb diffuse in increasing osmolarity as it runs up by descending limb water moves in by osmosis
31
How does the LOH create concentrated urine whilst reabsorbing most water?
The ascending limb pumps out solute causing water to leave descending causing an increase in concentration from water loss then when solute pumped out reducing concentration
32
How does the LOH cause less concentrated fluid whilst reabsorbing most water?
The ascending limb pumps out solute causing water to leave descending causing an increase in concentration from water loss then when solute pumped out reducing concentration
33
Which of the limbs of the LOH are permeable and non permeable to water?
Ascending non-permeable
| Descending permeable
34
Where is ADH produced?
Hypothalamus
35
Where is ADH secreted?
Posterior pituitary
36
What does ADH cause?
Insets aqua porins into apical membrane of collecting duct
37
Why is urea recycled?
To contribute to the medulla osmotic gradient
38
Where is urea released from for recycling?
Collecting duct
39
Why does water leave the collecting duct along the whole tube?
Countercurrent system from osmotic gradient in medulla
40
Where does selective reabsorption of Ca occur?
Distal convoluted tubule and collecting duct
41
What controls reabsorption of Ca?
Parathyroid hormone- increases ca/decreases Phosphate reabsorption
42
Is Phosphorus reabsorbed in DCT and CD?
No
43
What ions does the ascending limb of the LOH pump out?
Na
K
Cl
44
What are the cells lining the DCT called?
Principal cell
45
How does the DCT increase K in the urine?
Sodium potassium ATPase from peritubular capillaries into principal cell which causes Na to diffuse in and K to diffuse out
46
What controls the NaK ATPase in DCT?
Aldosterone
47
How is H+ changed in the urine in DCT?
H+ATPase
| H+K+ATPase
48
What cells pump H+ into urine in DCT?
Intercalated
49
What are the two types of intercalated cells?
Type A- works during acidosis (produces H+/HCO3- from CO2 and water)
Type B- work during alkalosis do the opposite
50
What does type b intercalated cell do during alkalosis?
Produces bicarbonate/H+ from H2O and CO2, bicarbonate exchanged for Cl-, H+ pumped or exchanged for K+ into blood
51
What is the problem with the GFR being too high or too low?
Too high- too much filtrate produced and lost in urine
| Too low- certain waste substances may not be excreted
52
How is the GFR auto regulated?
The resistance of the afferent arteriole, GFR decreases when afferent constricts and increases when arteriole dilates
53
What are the two mechanisms of auto regulation?
Tubuloglomerular feedback
| Myogenic response
54
What makes up the juxtamedullary apparatus?
Juxtaglomerular cells and macula densa cells
55
Where is the juxtamedullar apparatus located?
Between the ascending loop of Henley and the arteriole walls
56
How do the macula densa cells of the juxtameduallry apparatus decrease and increase GFR?
The detect increase or decrease in GFR and send paracrine signal to either constrict or relax arterioles
57
How does the kidney respond to the efferent arteriole being contracted due to the ANS system?
Contracts more to maintain GFR and prevent kidney failure
58
How much of K+ is filtered?
100%
59
What regulates the Na/K pumps in the distal convoluted tubule?
Aldosterone
60
What detects the amount of K+ in the ECF?
Adrenal cortex
61
What does aldosterone stimulate in the DCT?
Stimulates pumps in the DCT and collecting ducts to secrete more K+
62
Where is aldosterone in the adrenal gland released from?
Zona glomerulosa
63
Where is adrenaline and noradrenaline released form in the adrenal gland?
Medulla
64
Where is angiotensin synthesised?
The liver
65
Where is renin produced?
Juxtaglomerular cell
66
What does renin convert angiotensin to?
angiotensin I
67
What converts angiotensin I to II?
ACE in the lungs (angiotensin converting enzyme)
68
What does angiotensin II cause the adrenal cortex to do?
Release aldosterone
69
What does aldosterone do?
Stimulates principal cells in the collecting ducts to secrete more K+ and reabsorb more Na/Cl, therefore more water is reabsorbed increasing blood volume/pressure
70
What are the 4 effects of angiotensin in response to decreased blood pressure?
Arterioles vasoconstrict
Adrenal cortex secretes aldosterone
Hypothalamus secretes ADH and increases thirst
Medulla oblongata reflex increases blood pressure
71
What are the effects of natriuretic peptides?
Afferent arterioles dilate
Adrenal cortex decreases aldosterone secretion
Nephron decreases water and Na reabsorption
Hypothalamus decreases ADH secretion
72
Describe the generic histological structure of the urinary tract
Mucosa- sheet of epithelium, mostly transitional, lamina propria
Sub-mucosa- merged with lamina propria
Muscularis- 2-3 layers of smooth muscle
Adventia- lose FECT
73
What are the three layers of muscle in the bladder?
longitudinal
circular
Longitudinal
74
How does the mucosa of the urethrae start and finish?
Starts as transitional and ends as stratified squamous
75
What muscle controls outflow of urine?
Detrusor muscle (bladder wall)
Internal urethral sphincter (smooth)
External urethral sphincter (skeletal)
76
Describe the nerve supply to the muscles of the bladder
Parasympathetic- contracts detrusor
Sympathetic- relaxes detrusor, contracts internal sphincter
Somatic- controls external sphincter
77
What causes contraction of the sympathetic muscles of the bladder?
Noradrenaline on Beta 2 receptors on detrusor muscle and alpha 1 on internal sphincter muscle
78
What happens when the bladder is full?
When filling is sufficient to stretch smooth muscle there is a myogenic reflex
79
What are the two reflexes caused by the myogenic reflex?
Activation of the parasympathetic motor nerves to the bladder (contraction of detrusor, relaxation of internal sphincter)
Inhibition of the somatic motor drive to the external sphincter
80
What two changes allows the bladder to empty?
Contraction of detrusor
| Inhibition of continuous excitation
81
How is voluntary control of the bladder learned?
CNS overides reflexes
82
What does the hypogastric nerve supply to the bladder?
Sympathetic and motor to internal sphincter and detrusor
83
What kind of nerve supply does the pelvic nerve supply to the bladder?
Parasympathetic and motor to the detrusor
84
What part of the bladder does the pudenal nerve supply?
Somatic motor
85
What % of body weight is water?
60%
86
What fraction of the body water is ECF and ICF?
ECF- 1/3
| ICF- 2/3
87
What is the normal rate of fluid intake?
2ml/kg/hr
88
What is the normal rate of fluid loss?
1ml/kg/hr
89
What are the two categories of fluid loss?
Sensible and insensible
90
What are some examples of sensible fluid loss?
Kidneys
91
What are some examples of insensible fluid loss?
Skin, breathing, faeces
92
What monitors osmolarity of blood and where are they?
Osmoreceptors in the hypothalamus
93
What does the hypothalamus do in response tho and increase in osmolarity?
Increases production and release of ADH
94
What causes the thirst centre to be stimulated?
Increase in plasma osmolarity by 3%
95
How does the response to increased osmolarity result in decreased osmolarity?
Increased ADH, decreases excretion of water and therefore decreases osmolarity, also increases sense of thirst, ingestion of water decreases osmolarity
96
What does ADH do?
Increased permeability of collecting ducts to water by promoting insertion of aqua porins into principal cells
97
When might ADH be released in very large quantitates?
If an animal haemorrhages, to minimise sensible loss
98
How much of ingested Na+ is absorbed?
All of it, not regulated
99
How is blood volume and pressure monitored?
Blood pressure- baroreceptors
| Blood volume- stretch receptors
100
What three hormones regulate Na+?
Angiotensin II, aldosterone, natriuritic peptides
101
What do angiotensin II and aldosterone do?
Promote NA/CL reabsorption when dehydrated
102
What do natriuritic peptides do?
Promote excretion of NA/CL to decrease blood volume
103
What are the homoeostatic mechanisms to a reduce in blood volume?
Decreased venous return to the heart, decreases atrial pressure, decreases stroke volume, decreases atrial blood pressure, decreases GFR, blood volume normalises
104
How does angiotensin II help a reduction in blood volume?
Reduced atrial pressure, increases sympathetic action to the kidneys, increased angeotensin, decreases GFR
105
What is the effects of renin on blood volume?
Renin causes the release of angeotensin II causing increased aldosterone release therefore increased Na reabsorption, water follows, therefore increases blood volume
106
What is the range of pH for normal ECF?
7.35- 7.45
107
What are the byproducts of metabolise reactions that result in an increase in pH?
H+ and CO2
108
What are the three ways the body corrects pH?
Buffer systems- act quickly to temporarily bind excess H+ or OH-
Changing the rate and depth of breathing CO2 us exhaled or retained
Kidney excretion/reabsorption of acidic or basic ions
109
What is the first line of defence against change in pH?
buffers
110
What are the 5 buffers the body uses and where are they found?
HCO3- in ECF
Proteins and haemoglobin in cells
Phosphates and ammonia in urine
111
How does the body breathing rate respond to an increase or in plasma ph?
An increase in plasma ph is detected in the carotid and aortic chemoreceptors, this send impulses to the respiratory centre in the hypothalamus, increases rate and depth of breathing, lowers plasma CO2, decreasing plasma Ph
112
What are the limitations of controlling of using the respiratory system for correction of acid-base balances?
Only functions when respiratory and control centres are working normally
Limited by the availability of bicarbonate ions
Cannot protect the ECF from pH changes due to increased or depressed CO2 levels
113
How much bicarbonate is filtered and reabsorbed in the kidneys?
100% filtered and absorbed
| 80-90% in the PCT, 10-20% in LOH
114
Why are some protons not reabsorbed in the PCT and LOH?
Some protons bind to non-bicarbonate buffers e/g phosphate and therefore are lost in the urine
115
What are the two types of intercalated cells found in the distal nephron?
Type A- during acidosis
| Type B- during alkalosis
116
How do type A intercalated cells help prevent acidosis?
Carbonic anhydrase produces H+ and bicarbonate
H+ ATPase pumps H+ into the collecting duct
H+K+ATPase exchanges H+ for K+
Bicarbonate exchanged for Cl-
Therefore H+ is produced from the plasma and pumped out into the collecting duct and bicarbonate is pumped back into the plasma to further act as a buffer
117
Where are intercalated cells found?
Distal nephron
118
How do type B intercalated cells help prevent acidosis?
H+ATPase and H+K+ATPase both pump H+ into the blood
Carbonic anhydrase produces H+ and bicarbonate
Bicarbonate in pumped into the collecting duct
119
What is respiratory acidosis?
When CO2 accumulates because of hypoventilation
120
What causes metabolic acidosis?
Occurs when non-respiratory acids accumulate or the acid load is normal but bicarbonate is deficient
121
What can cause decreased bicarbonate?
Chronic diarrhoea
| Loss of kidney function therefore reduces reabsorption
122
What is the normal range of urine specific gravity?
1.025- 1.045
123
What are some abnormal constituents of urine?
```
Glucose
Blood
Protein
Ketones
Cells
```
124
If GFR is reduced or stopes what would be the main changes to the composition of blood?
Increase in concentration of urea and creatinine
Increase in concentration of K+ in blood
Increase in concentration of inorganic phosphate in blood
Decrease in concentration of bicarbonate
125
What is azotaemia?
Increased nitrogenous waste products in blood
126
What is the difference between prerenal and renal azotaemia?
In prerenal the pathology is occurring before the kidney and animal is able to concentrate urine
If renal there is specific problem with the kidneys and the animal is not able to concentrate urine
127
How might hyperkalameia occur?
If the animal is eating and taking in potassium with reduced kidney function
Acidosis- K+ exchanged for H+
128
Why might hypokalaemia occur?
If animals stop eating and taking in potassium with kidney disease, so continue to lose K+
129
What are the clinical signs of hypo/hyperkalaemia?
Hyper- nerve cells iniatially more excitable but depolarised cells cannot repolarise properly- bradycardia and cardiac arrhythmiaa
Hypo= nerve and muscle cells hyper polarised and less exitable- muscle weakness
130
What is Addisons disease in dogs?
Hypoadrenocorticism- dogs cannot produce enough hormone from the cortex, too little aldosterone
