TOPIC 6 Flashcards
(125 cards)
1
Q
REVIEW URINARY SYSTEM DIAGRAM
A
REVIEW
2
Q
Functions of the kidney
A
- waste removal ( urea, uric acid, creatinine, drugs)
- Preserve valuable substances our body’s cells need ( glucose, amino acids, electrolytes)
- Maintenance of fluid balance, electrolyte concentrations and pH
Regulate blood volume
-Regulation of blood pressure
( less volume = less pressure)
- Production of erythropoietin - responsible for triggering production of red blood cells. Without erythropoietin ppl can become anemic
- Activation of vitamin D by kidneys from the precursor we take up with our diet
3
Q
Which kidney is lower
A
right kidney lower than left
4
Q
Are adrenal glands near the kidney
A
adrenal glands above both kidneys
5
Q
Which side is the vena cava and which side is the renal artery
A
Right Blue inferior vena cava and left red renal artery
6
Q
Are kidneys retro or intraperitoneal
A
Kidneys are retro peritoneal
7
Q
When looking at the kidney cut in halves what does the cortex look like
A
cortex around-> granular appearance as all the renal corpuscles ( do all filtration of blood, contain start and end points of tubules that reach down into our medulla area into pyramids ) located here
8
Q
When looking at the kidney cut in halves what does the medulla look like
A
Middle is medulla-> made up of lobes, pyramids ( renal tubules and capillaries and end in the top called the papillar) plus the columns
9
Q
When looking at the kidney cut in halves what does the renal pelvis look like
A
Renal Pelvis is where the urine starts collecting coming from the minor and major calyx’s
10
Q
What is poiseuilles law
A
How much fluid flows accords a tube at a certain time ( fluid flow) depends on radius and length
Fluid flow higher with a wider tube.
Decreases drastically when the radius decreases
Blood vessels in the kidneys can actually adjust their diameter and therefore adjust the fluid flow
Fluid flow = Pi x pressure difference x radius^4 / length x viscosity
11
Q
What is hydrostatic pressure
A
Hydrostatic pressure ( pressure that a fluid has on surrounding tubes- blood vessels. Also depending on gravity higher something is = more hydrostatic pressure. Hydrostatic pressure also increases with atmospheric pressure Eg, if under water= higher hydrostatic pressure)
The hydrostatic pressure we have in our vessels is partly due to the pumping of the heart.
12
Q
What is osmotic pressure
A
Osmotic pressure ( pressure headed to push a solvent across a semi permeable membrane depending on the amount of solutes present)
13
Q
T or F
Fluid is impaired by resistance
A
fluid is impaired by resistance ( the force you have to use to get fluid along a tube depends on tubing length and diameter)
-blood vessels have resistance as long tubes get smaller and smaller in diameter ( what our heart has to overcome)
- Arteries eventually become arterioles, they then enter tissues giving nutrients and oxygen to the cells in exchange for wastes and carbon dioxide which then travel out the venules and then veins.
- Also as travel from large vessels to small vessels pressure reduces reduces reduces in our Venus system pressure is much lower than in the arteries
14
Q
how much blood in kidneys per day
A
Nearly 200 litres every day but only 1-2 litres per day
15
Q
blood in liver vs blood in kidney
A
Liver Venus blood, kidney arterioles blood
16
Q
apart from being filtered what else does the kidney use blood for
A
Apart from blood that comes in for filtration some of the blood is also used for the kidneys to function. 25% of the oxygen requires at rest goes to the kidneys, 2nd most oxygen hungry organ after our brain
17
Q
what is a nephron
A
Functional unit of the kidney
18
Q
what artery enters the afferent /efferent arterioles
A
cortical artery goes into affertent/ efferent arterioles
19
Q
goal of the nephron
A
Goal is to filter blood and produce urine
20
Q
what is the renal corpuscle like
A
Renal corpuscle has a bunch of bunched up arterioles ( glomerulus)
21
Q
wat is the PCT like
A
Proximal convoluted tubule enters the loop of henle leading to distal convoluted tubule which then leads to collecting ducts. There is ascending and descending loop with thick and thin parts.
Proximal convoluted tubule has cells with a lot of microvilli as they are responsible for reabsorption from filtrate back into blood.
22
Q
cells of the distal convolued tubule
A
the distal convoluted tubule cells have an apical side where micro villi are and a basolateral side.
Collecting ducts have some cells called principle cells responsible for maintaining water sodium balance and intercalated cells play a role in acid base balance.
23
Q
REVIEW cells at different sites of the nephron
A
REVIEW cells at different sites of the nephron
24
Q
where does re absorption happen
A
PCT
25
role of principle cells in the collecting duct of the nephron
Collecting ducts have some cells called principle cells responsible for maintaining water sodium balance and intercalated cells play a role in acid base balance.
26
2 types of nephons
Cortical nephrons
Juxtamedullary nephrons
27
what are cortical nephrons like
Cortical nephrons - short and stay within the cortex not reaching into the medulla of the kidney, bunched up allot more 85%.
28
what are juxtamedullary neprons like
Juxtamedullary nephrons- reach deep into the medulla, whole thing is elongated and blood vessels ( vasa recta) are parallel to defending and ascending look 15%
29
afferent vs efferent arterioles role
afferent arteriole leads into the glomerulus, efferent leads out
30
what type of membrane do tubule vessels in the nephron have
Vessels have filtration membrane
31
what types of cells can you find on the filtration membrane
Podocytes a part of filtration membrane
32
where is the ascending loop located in a real life nephron not looking at a spead out diagram
ascending loop as nephron is actually bunched up is actually close to the afferent and efferent arteriole as there are some cells that are important (macula densa, granular, extra glomerular mesangal)
33
what do mascula densa cells in the ascending limb of the nephron do
Macula desa cells in ascending limb -monitor the salt content of filtrate,
34
what do granular cells on the arteriole do
granular cells on arteriole monitor the blood pressure and release enzyme called renin
35
what do extra glomerular mesangal cells in Between the other two types of cells of the juxtaglomerular complex do?
pass on messages from the other two cell type locations. Keeping the opposition informed of salt levels and pressure
36
The arterioles and ascending tubule and cell’s is called ...
the juxtaglomerular complex
37
what is filtration
kidneys receive blood and everything apart from cells and protein gets put into filtrate
38
what is re absorption
In tubular structures body starts reclaiming what it wants to keep
39
what is secretion
Body Can also throw out things it doesn’t want Eg. Drugs, unwanted electrolytes, ware products
40
Amount that is filtered by kidneys
Of the approx 1200 ml blood that passes through 650ml is plasma and 120-130 will be filtered across
41
What is the filtration membrane like
filtration membrane consists of three layers
( capillary endothelium, basement membrane, foot process of podocyte of glomerular capsule)
The filtration membrane is the wall of the capillary and the interior of the capsule.
Endothelial is fenostrated allowing allowing all the blood components to come through (even protiens - they get blocked by the basement membrane which only allow smaller solutes to get through).
Should anything manage to get through basement membrane as well, then the filtration skits between the extensions/ processes of the podocytes will prevent them from entering the capsular space and the filtarate
42
What is filtrate
The filtrate is basically the precursor of urine
43
Is filtration active or passive
The filtration process is a passive process. It travels passively due to the pressure gradients ( pressure from blood getting pumped, gravity/ standing up of the body causing hydrostatic pressures
44
What is the net filtration pressure
Outward pressure - inward pressure= 10mmhg
55mm Hg millimetres mercury In the afferent arteriole forcing the plasma out INTO the capsular space
Fluid in the glomerular capsule also exerts a hydrostatic pressure of about 15 mm Hg coming OUT
There is also an osmotic pressure. 30mmhg.
No protein can get through the glomerular capsule from the vessel so the concentration of those protiens is much higher in the blood ( water wants to go back butt if we add it all up 1 outward - 2 inward ones = pressure on the whole forces the fluid to go from the arteriole into the glomerular capsule
45
How does diameter impact flow rate
depending on how wide a tube is the flow rate increases. And that’s what the arterioles can do by changing their diameter
46
What happens to BP when exercising
Blood pressure changes when exercising, lying down, sitting up, are hydrated or dehydrated buttt our kidneys would like to maintain that filtration rate as constant as possible ( 125-135 ml per min)
47
How do we regulate filtration rate to keep it constant
It can regulate that by an auto regulation and there’s 2 main intrinsic mechanisms - myogenic and tubule glomerular
48
Explain the myogenic mechanism
If BP drops in arterioles = decreased filtration rate in the glomerular = stretch of muscles in walls of afferent arterioles= vasodilation = increased flow rate and gfr
49
Explain the tubular glomerular mechanism of
if BP drops= decreased filtrate flow and decreased NaCl in ascending limb of nephron loop = masculine dense cells of juxaglomerular complex of kidney = Vado dilation of afferent arterioles = increased gfr
50
What pressure changes can kidneys handle
Kidneys can handle pressure changes between 80-100 ml Mercury but don’t do well with a BP below 80, as means that don’t have enough pressure to get blood back up to brain = autoregulation turns off and autonomic nervous system triggers vasoconstriction and other hormones triggering an increase in blood volume.
51
What happens in the PCT
in PCT most reabsorption happens
Glucose, amino acids, water, electrolytes
2 processes-
trans cellular route - through quite easily through the cell
Para cellular route- in between the cell
52
Tubular reabsorbtion of sodium process
Requires active transport mechanisms ( primary at the basolateral end, secondary at the apical end)
Pump throws out sodium and brings back 2 potassium in exchange decreasing sodium concentration in our tubule cells meaning that sodium will drawn in again via the concentration gradient dragging other things with it particularly glucose, water
Everything ends up in interstitial fluid first then the capillaries
53
How much of filtrate is reabsorbed
tubular reabsorption can see 65% filtrate volume reabsorbed
54
Where is water mainly reabsorbed
Water mainly reabsorbed in descending limb, a lot of aquaporins
In ascending limb usually no water reabsorption ( unless ADH acts );but there is transport of electrolytes, also in this limb urea is secreted
Distal convoluted tubule fine tuning happens,
55
What are nitrogenous wastes
- waste comes from protein metabolism ( degradation of amino acids)
- From bacteria in large intestines
- Ammonia is a product of metabolism and bacteria and it NH3 gets converted into urea in liver and is excreted via kidneys
- Uric acid is the end product of metabolism, also excreted by the kidneys
...
Non toxic NH4 ammonium ion is also extended by the kidneys
56
Aim of filtration, reabsorbtion and secretion
To form uribe
57
Factors affecting using volume and concentration
...hydrogen status/ how much we drink
...elecrolyte concentration in the blood
...Blood volume and pressure
...regulated by hormones
...type of nephron involved
...counter mechanisms
58
Role of anti diuretic hormone
antidiuretic hormone (ADH) = decreases urine output by increasing water reabsorption particularly in collecting duct in those principle cells that cause when acted on by ADH to insert more aqua porins into the apical membrane so more water gets reabsorption
59
Role of aldosterone
also acts on principle cells of collecting ducts increasing Ana+ reabsorption and water follows so increases blood volume/ pressure. Can also be triggered by increased potassium in blood in order to increase sodium reabsorption to chuck out potassium in exchange
60
Role of Atrial natriuretic peptide ( ANP)
Atrial natriuretic peptide ( ANP)= inhibits Na+ reabsorption so decreases blood volume pressure ( counterplayer of aldosterone). Released when heart measures too much blood volume
61
Role of parathyroid gland
Parathyroid hormone (PTH) = increases reabsorption of calcium
62
Triangle region above top of urethra is
Trigone
63
T or F
| Osmolarity/ concentration of solutes in the cortex and medulla increases as we move from the cortex to the medulla
True
Because the Jutamedullay nephrons reach far into the medulla exchange happens not just by pressure gradient of hydrostatic pressure but also by osmotic pressure.
64
What does the fact that urine gets concentrated by counter current mechanisms
urine gets concentrated via counter current mechanisms. Less water and more solutes if dehydrated and contains more water and less solutes if over hydrated
65
How do we test renal function
- urinalysis ( check for protein and blood, uric acid, specific gravity )
- Clearance and glomerular filtration rate (how much blood gets filtrate in the glomerulus)
- Using Creatinine ( byproduct of muscular activity) which gets filtered in the glomerulus- none of it gets reabsorbed. Can use it to determine how much blood or plasma the glomerulus filters. normal 120-125 per min, if below 60 approx half of your kidney function has gone = no good
- Blood urea nitrogen (BUN)- measuring waste product of blood. If increase in kidney failure, less waste products getting into the urine.
66
Where do ureters join bladder
- ureters loop around the back and come in from the bottom so that we don’t get any back flow
- Ureters join the bottom of the bladder
67
Prostate urethra issues
Prostate wraps around urethra which can cause problems in male with prostate enlargement
68
Female urethra issues
Urethra in women is much shorter
Risk of UTIs
69
What are the sphincters on the urethra like
2 sphincters, internal involuntary and external sphincter made up of voluntary skeletal muscle
External and internal sphincter have to relax when urinating
70
Is bladdder a muscle
Whole bladder is a muscle called the detrusor muscle ( 3 layers of muscle 2 longtudinal and one circular that have to contract when urinating- while sphincters relax) regulated by spinal nerves and autonomous nervous systems
Can be problems urinary retention or inconstinence
71
How much water do we consist of
-we consist of about 60% water
-Content depends on body mass, age, gender and content of body fat
Eg. Women have less body fluid about 50% body fluid, males 60%
-Highest water content we ever have is when we are babies, we have about 70% then and as we get older we lose the water content. In older age only about 45% water
72
2 main fluid compartments
- Two main fluid compartments are intracellular (40% of body weight) and extracellular fluid ( 20%)
- Intracellular is fluid inside cells and is about 25 litres
- Extracellular fluid is plasma and interstitial fluid, plasma is about 3 litres
and interstitial fluid between cells and blood vessels is 12 litres
73
Do we have Mechanisms to preserve, conserve and recoup water and also certain triggers to make us drink and increase fluid intake
Yes
But the body can regulate these things using membranes, capillary walls and cell plasma membranes which can determine what gets in and what gets out
Hormones too
Both the osmotic pressure and hydrostatic pressures play a role but also the concentration of the electrolytes
74
Body fluid is composed of
water, non electrolytes ( some protiens, some organic molecules, some waste products).. non electrolytes don’t carry electrical charge and are mainly responsible for osmotic pressure in the blood like the bigger parts proteins cause the oncotic pressure.
75
What are non electrolytes
some protiens, some organic molecules, some waste products)..
non electrolytes don’t carry electrical charge
are mainly responsible for osmotic pressure in the blood like the bigger parts proteins cause the oncotic pressure.
76
The more particles you have in a solution ....
the more water that will draw into it for a certain concentration to be maintained
77
Concentration of ECF vs ICF
The concentration of extracellular and intracellular fluid would be the same because
otherwise we’d have constant fluid loss into one compartment.
But the body can regulate these things using membranes, capillary walls and cell plasma membranes which can determine what gets in and what gets out
78
What are electrolytes
- Electrolytes are everything that has very strong chemical bonds and therefore doesn’t dissociate in water and therefore carries electrical charge.
- Positively charged electrons- cations
- Negatively charged electrons- anions
And mostly very small, often salts
Eg. Sodium, potassium, calcium and magnesium but they can also be small proteins
- Even though mass wise the electrolytes are not as many as the non electrolytes... because there’s more particles of them they have the greatest powers with regards to osmotic pressure.
- as some of them are very small they can cross over the different membranes and draw water with them and are responsible for maintaining a balance between the fluid flow
79
Increase in electrolytes or non electrolytes in the cells INtracellular fluid
Eg. Increase in electrolytes or non electrolytes in the cell that would encourage water to flow into the cells
or
increase of hydrostatic pressure in blood vessel that would encourage water to be pushed out into the interstitial fluid
80
What pressure is more at play when it comes to blood vessels
Hydrostatic pressure perimeter is probably most important one when it comes to the blood vessels because we have a pressure that comes from the pumping of the heart so we do have a certain hydrostatic pressure, where as with the cells it’s often the content of the cells particularly the non electrolytes
81
Is plasma membrane permeable for water
Plasma membranes usually quite permeable for water but other substances have to either get co transported or have facillitated diffusion or active transport mechanisms
82
Output must equal input (water?]
the body keeps losing water all the time BUT water output must equal water input so we are forced to take water into us,
83
Most water we take up is
Most of water we take up is through liquids and food but we also produce water with cellular respiration ( co2 and water are products)
84
Insensible water loss
Water output through skin and lungs is insensible water loss
85
Sensible water loss
Sweating faeces and urination is sensible water loss as that can be regulated by the body much better where as the insensible water loss is just something that happens
86
Body’s reaction to dehydration
- water loss causes leaves higher concentration in ECF so osmotic pressure rises due to more concentration of electrolytes and particles, the increase in osmotic pressure causes water to flow into ECF by osmosis causing cells to shrink
- Thirst center in hypothalamus reacts to certain stimuli eg. Dry mouth or increase in osmotic pressure makes you want to drink
- The moment you start drinking water the thirst reflex immediately stops in order to prevent over hydration so that we take fluid in family measured state.
87
What is is osmolarity
extracellular fluid Concentration
88
What is the body’s reaction too dehydration
Over hydration/ hypotonic hydration= osmotic pressure falls in ECF and water falls into the cells causing the cells to well
Not good for brain, brain swells caused cerebral oedema and leads to confusion, coma, death,...
89
Odema
oedema can happen in interstitial space, often due to increase leakage of blood vessels. Water leaving capillaries and getting into interstitial space. Often impact of kidney or cardiac malfunction
90
Kidneys cN be influenced by what to adjust whether water is absorbed more or less
kidneys are influenced by hormones which determine eater is reabsorbed more of less.
91
Anti diuretic hormone targets
- acts on the collecting ducts and distal convoluted tubules and it basically causes more aquaporins to be inserted into the apical membranes of out cells in the nephron tubules
- Anti- no, diuretic-dieresis means exertion of urine
- Increase in ECF osmolarity/ decrease in BP = osmoreceptors or baroreceptors = trigger posterior pituitary gland= release ADH= targets Collecing ducts = increased water reabsorption= decreased osmolarity / increase plasma volume
- ADH really only acts on water reabsorption
92
What does aldosterone triggered
- acts on sodium content not the aquaporins, it finetunes sodium reabsorption into the blood plasma and triggered by drop in sodium or increase in potassium
- decreased sodium content in juxtaglomerlar complex detected by macular densa cells trigger renin release from granular cells
(part of arteriole walls of afferent/ efferent arterioles )
- renin released goes through 2 steps
- ( triggers angiotensin 1 which then gets triggered into angiotensin 2 which then will act on the adrenal cortext to release aldosterone which then acts on the DCT and CD to increase sodium reabsorption
... increased potassium concentration in ECF can also trigger adrenal cortex to release aldosterone
93
For every sodium ion reabsorbed potassium ion
| ...
gets chucked out ( increased potassium secretion)
94
How can estrogen cause odema
estrogen is very similar to aldosterone and can all have a similar effect on kidney tubules... that’s why before period when estrogen levels rise sometimes you get water retention ( increased sodium reabsorption for no reason= increase in sodium concentration and water follows= more water than needed in ends up in interstitial = odema and bloated)
95
Aldosterone and antidiuretic hormone vs at risk natriuretic peptide
Aldosterone and Antidieuretic increase blood volume
pressure ANP - Atrial natriuretic peptide - acts when there is too much fluid and bp is too high to lower it
96
What is ANP triggered by
- triggered by too much stretch in the atria of the heart due to too much volume or increased blood pressure= releases ANP from atria which
1) blocks release of renin in granular cells of juxtraglomerular complex
2) blocks release of ADH from Posterior pituitary gland and
3) blocks direct release of aldosterone that can be released by the sympathetic nervous system
= no aldosterone, no antidieuretic hormone, no inbetween step of renin to angiotensin to aldosterone
Angiotensin 2 is a very potent vasoconstrictor, no angiotensin 2 means blood vessels will dilate
97
What is the most abundant cation in the extracellular fluid
Sodium
```
Important as
Plasma concentration ( causes resting membrane potential) and body content important( plays a role in fluid balance- how much sodium determines how much water you have
```
98
Regulation of sodium
- Chemoreceptors (macula densa of JGC), baroreceptors (arteries), osmoreceptors (hypothalamus)
- 90% already reabsorbed in PCT and loop (regardless of hormonal influences)
- Aldosterone – ↑ Na+ absorption in DCT and collecting ducts (water follows!)
- ANP – blocks Na+ absorption
- Female sex hormones mimic aldosterone
99
What is the most abundant cation in the intracellular fluid
K+ most abundant cation in ICF
100
Importance of potassium
Vital for resting membrane potential 3 sodium’s out 2 potassium’s in and heart muscle function
101
Body’s regulation of potassium
- 90% reabsorbed in PCT and loop (regardless of need)
- Aldosterone – ↑ K+ secretion in DCT and collecting ducts
- ↑ K+ plasma levels causes principal cells in collecting ducts to secrete (and excrete) more K+, ↓ K+ plasma levels depress secretion
102
What fruit has lots of potassium
Bananas
103
Where is calcium stored
Ca2+ stored in muscle cells (SR) and part of bones
104
Importance of calcium
Vital for neuromuscular function – hypercalcaemia (too much calcium) inhibits neurons and muscle cells, hyocalcaemia ( not enough calcium) causes increased excitability
105
What is hypercalcaemia
too much calcium inhibits neurons and muscle cells,
106
What is hyocalcaemia
( not enough calcium) causes increased excitability
107
Calcium levels regulation in the body
- 98% reabsorbed in PCT
- PTH acts on bones – osteoclasts break down bone matrix, DCT – ↑
- Ca2+ reabsorption in DCT, small intestines – enhanced Ca2+ absorption with help of Vit. D
108
What is a buffer
combination of a weak base and a weak acid
109
What is an acid
Acid- lots of free hydrogen ions
110
What is a weak acid
weak acid- not as many don’t dissociate completely, dissociate depending on what the surrounding solvent is Eg if solution is more alkaline it will dissociate to relealease more hydrogen ions. If more acidic solvent will dissociate to release more alkaline
111
strong acid + weak acid
Strong acid + weak acid= weak acid dissociates according to surroundings and will dissociate to release more basic bits and alkaline
= good for homeostasis and maintaining blood ph
112
Normal blood ph
Normal ph 7.35-7.45
113
What are the bodies 3 buffers
Bicarbonate Buffer System
Phosphate Buffer System
Protein Buffer System
114
What is bicarbonate buffer system
* Mixture of H2CO3(weak acid) and salts of HCO3 (weak base)
| * Main ECF buffer; also operates in ICF
115
What is the phosphate buffer system
* Salts of H2PO4 (weak acid) and HPO42 22 (weak base)
| * Important buffer in urine and ICF
116
What is the protien buffer system
* Some amino acid side chains can act as weak acids (-COOH) or weak bases (e.g.,-NH2)
* Most important buffer in ICF; also in blood plasma
117
Why does the body have to buffer
we have a lot of acidic substances in our blood come form food and metabolic processes Eg. Ketone bodies, lactic acid and carbon dioxide
The 3 buffers act in the ECF particularly in the plasma to react straight away in a fracture of a second to buffer those ph changes when those acidic substances enter the body.
118
Why doesn’t co2 have a massive impact on acidity in day to day life
Co2 is produced all the time and it gets expelled from the lungs so it doesn’t have a big effect on the blood ph because we can get rid of it straight away but it can be used to compensate/ adjust the blood ph quickly by either providing hydrogen ions making blood more acidic or get blown off and therefore remove some acidic substances
Happens within a few minutes and is regulated by the brain stem which measures the blood ph and can help with that
119
Can buffers compensate
The buffers can compensate within the extracellular fluid and within the cells but we still have to get rid of those acidic substances and that is done by the kidneys which produce new bicarbonate and reabsorbing bicarbonate
Cells responsible for doing this are the intercalated cells in the collecting duct
Principle cells- electrolyte eater balance
Intercalated cell- acid base balance
120
What are the cells of the collecting ducts and how do they help regulate acidity
have to get rid of those acidic substances and that is done by the kidneys which produce new bicarbonate and reabsorbing bicarbonate
Cells responsible for doing this are the intercalated cells in the collecting duct
Principle cells- electrolyte eater balance
Intercalated cell- acid base balance
121
What happens if bicarbonate is not reabsorbed
Blood becomes too acidic
122
How is bicarbonate removed
- bicarbonate gets reabsorbed by the type a intercalated cells in the collecting ducts and in exchange for one bicarbonate we chuck out one hydrogen ion
- Hydrogen ion actually end up in the filterate where it comes across bicarbonate as well, gets combined to carbonic acid and then gets split up with the help of an enzyme into water and CO2 which the body can deal with very easily
- Depending on how much co2 travels in or out will determine how much bicarbonate we have in the cell as the reaction can work backwards too
- The more co2 that’s coming in/ the more acidic the blood is = the more we have the reaction happening= we get more bicarbonate which can be reabsorbed whichmeans we get more hydrogen ions that get chucked into the filtrate and produce more co2
- A cycle where the bicarbonate always gets recycled and the hydrogen ion gets kind of neutralised by being tuned into co2 and water
(reabsorbingbicarbonate but we are not making any new bicarbonate... that’s just bicarbonate that’s floating around in the urine.. so it’s not anything new)
123
2 ways to make new bicarbonate
Via phosphate buffer
Or True production of bicarbonate happens via ammonium ion
124
How does phosphate buffer create new bicarbonate
- Water and carbon dioxide in the cell gets tuned into carbonic acid which gets split into hydrogen which gets secreted and bicarbonate which gets reabsorbed
- The hydrogen in the urine combines with phosphate buffer and gets excreted
- Bicarbonate is produced that’s not part of that previous cycle going round p, this time as were losing the hydrogen completely we basically have made sort of a new bicarbonate
125
True production of bicarbonate happens via ammonium ion
substance in cells called glutamine ( an amino acid) goes through catabolic reactions and gets broken into 2 bicarbonate ions and some ammonium ions which get excreted via urine
