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MEDSCI142 > Renal > Flashcards

Renal Flashcards

1
Q

Describe the overall external protective connective tissue shields of the kidney (out to in)

A

Outermost : Renal fascia overlays kidneys and anchors them to surrounding structures

Middle: Adipose capsule :

Maintains the position of the kidneys
provides padding,
Innermost:
Renal Capsule->
-Maintains the shape of the kidneys
-physical barrier against trauma

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2
Q

What is the main role of the kidney (overview)

A

The kidneys collects the fluid from blood through filtration and modifies the composition of that fluid before returning the fluid back to the fluid.

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3
Q

Describe the medulla section of the kidney

A

It is sectioned into medullary pyramids by renal columns which are extensions of the cortical tissue into the medullary tissue.

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4
Q

What makes up a Lobe of kidney and how many lobes are in humans

A

One medullary pyramid, its overlaying cortex and one half of the renal column on both sides. humans have 8-12 lobes per kidney.

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5
Q

What is a lobule

A

A smaller subdivision within a lobe

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6
Q

What is the path of urine drainage in the internal anatomy

A

It goes from out to in.

Many nephrons
Many Collecting duct (filtrate)
Papillary duct (pointy end of medullary pyramid)
Calyx “cups” (minor to major
Pelvis (flattened basin)
Ureter
Stored in Urinary bladder

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7
Q

What is region between lobes

A

interlobar region. (Can extended in the medullary region or cortex region) contains some blood vessels

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8
Q

Describe the path of the arterial blood supply to the kidney up to where it can take 2 paths for gas exchange

A

Firstly from the heart it goes to the
Renal artery
interlobar artery
arcuate artery
interlobular artery
afferent arteriole
Glomerulus/Glomerular capillaries
efferent arteriole where it can take 2 paths

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9
Q

Describe the 2 paths for gas exchange that can be taken after the arterial path

A

Can go through:
8a1: Descending Vasa recta to feed the cells in the medulla
8a2: Gas exchange happens at
Peritubular capillaries of the medulla (gas exchange)
OR
8b1: Peritubular capillaries of the cortex for gas exchange

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10
Q

Describe the path of the venous blood supply from the kidney up to the heart exchange

A

Firstly from place of gas exchange it goes
8a3: Ascending vasa recta
9. Interlobular vein
10. arcuate vein
11. interlobar vein
12. Renal vein
13. Inferior vena cava
to heart

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11
Q

What does parenchyma means and what is the parenchyma of the kidneys and its functional portion

A

Parenchyma: The functional portion containing the functional units
Of the kidneys: renal cortex renal pyramids.
Functional units: nephron

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12
Q

Compare glomerulus vs Glomerular (Bowmans) capsule

A

Glomerulus is endothelium part which forms the network/knot of capillaries. It has afferent and efferent arterioles as input and output.

Conversely, Glomerular capsule is the epithelial layer on top which has visceral podocytes and parietal simple squamous to form outer wall of capsule

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13
Q

What is between the visceral and parietal epithelium of the glomerular capsule

A

Capsular/ Urinary space

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14
Q

What are the 3 elements of the glomerular filter from blood -> urinary space and what do they allow to pass through

A

Fenestrated endothelium of the glomerular capillaries. Allow everything except blood cells to go through
Basal Laminar: Basement membrane (BM) of podocytes + endothelium.
Stops Large proteins from going through
Slit membrane/diaphragm between pedicels (foot processes of podocytes). Only allows small proteins through, stops medium size

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15
Q

Describe the path of the juxtamedullary nephron tubules from the Renal corpuscle

A

Renal corpuscle
Proximal convoluted tubule
Thick descending loop of Henle
Thin descending loop of Henle
Thin ascending loop of Henle
Thick ascending loop of Henle
Distal convoluted tubule
Collecting duct

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16
Q

What parts of the nephron are in the medulla vs cortex

A

In the medulla is the loop of henle, with the convoluted tubules and renal corpuscle in the cortex.
Collecting duct spans both.

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17
Q

List the main functions of the kidney

A

Regulation of water and electrolyte balance.
Regulation of arterial pressure.
+
Regulation of:
-blood pH,
-excretion of metabolic waste products
-RBC production
-hormone production (eg vit D+ Ca2+ regulation)
-blood glucose levels

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18
Q

What body system is kidney part of

A

cardiovascular as it filters the blood, not the food. It helps regulating blood pressure, water and electrolyte balance, pH and waste product removal.

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19
Q

What are the physiological consequences of kidney failure

A

Swelling as kidneys are not filtering any fluid out
Increase blood pressure
Short of breath due to oedema in lungs
Fatigue : heart has to pump harder, less O2 exchange
pH and K+ levels rise and cause nausea

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20
Q

What is osmolarity

A

Assuming that all the osmotic solute cannot permeate the cell membrane, Osmolarity is the number of dissolved particles in a set volume.
therefore = molarity (moles) x dissociation (ie 2 particles per 1 NaCl)

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21
Q

What is osmotic pressure. What osmotic pressure swells the cell vs collapse

A

The pressure required to prevent net water movement
High osmotic pressure : swell
Low osmotic pressure : collapse

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22
Q

What is tonicity

A

Measuring the tone of the cell when put into a solution.It takes into account the concentration of the solute and its ability to cross the semipermeable membrane

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23
Q

what will happen to a cell in an isoosmotic solution of urea (to its cytosol osmolarity)

A

It will swell and burst because there is a concentration gradient for urea to move into the cell and this will make a concentration gradient for water to follow

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24
Q

Compare Hypotonic, Isotonic and Hypertonic solution by their effect on the cell

A

Hypertonic solution causes cells to shrink as water wants to move out of the cell.
Isotonic solution causes no net movement of water in or out of the cell
Hypotonic solution causes cells to swell as water wants to move inside the cell

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25
Q

Compare Isoosmotic, Hyperosmotic and Hypoosmotic solution

A

Iso osmotic solution has same solute concentration.
Hyperosmotic soln has higher solute conc
Hypoosmotic soln has lower solute conc

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26
Q

Compare the osmotic pressure of the extracellular fluid and thus movement of water in cells during dehydration and Hydration

A

In Dehydration water is lost from the ECF, so the ECF osmotic pressure rises. This causes water to move out the of the cells to ECF.
However in Hydration, water is gained in the ECF, so osmotic pressure decrease and water moves into the cells.

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27
Q

How is the body fluid divided between the Intracellular fluid and Extracellular fluid and what are these two divisions

A

ICF have 2/3 of the body’s fluid. It is the fluid inside the cell
ECF have 1/3 of body’s fluid. 20% is blood plasma and 80% is interstitial fluid.

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28
Q

Why is it important to maintain osmolarity

A

The assymetric distribution of ions in the ICF and ECF set up ion gradients which set up membrane potentials. These allow important cell processes such as electrical nerve activity, active transport, intracellular signalling and muscle contraction to take place.

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29
Q

What ions have a higher concentration in the ECF than the ICF

A

Na+ (145: 10), Ca2+ and Cl- (110:4) , HCO3-

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30
Q

What ions have a higher concentration in the ICF than the ECF

A

K+ (140:5),

Mg2+, HPO42-, SO42-, protein anions

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31
Q

How much fluids in the body compared to solids

A

in females 55% and males 60%

32
Q

What are the major sources of water intake and output (from smallest to largest) and how much are they

A

Water gain is through metabolism, food, drinks. Water loss is through GI tract (feces), lungs, skin, and biggest is urine (kidneys). These should equal each other for 1 day at 2500 mL

33
Q

How does filtration, reabsorption and secretion contributes to urine production

A

The formation of urine involves

  1. filtration of blood plasma at the glomerulus
  2. Tubular reabsorption from fluid in the renal tubule into the blood to be kept
  3. Tubular secretion of waste products to be excreted
34
Q

For any substance how to do you find the sum amount excreted in the urine?

A

Excreted: Filtered - reabsorbed + secreted

35
Q

What is totally reabsorbed from initial filtration and what is totally excreted

A

Glucose is totally reabsorbed and creatinine is totally excreted

36
Q

Describe the order of the 5 parts of the nephron tubules that forms the urine and the process happening there

A
  1. Glomerulus for filtration
    Tubular reabsorption in the
    2.proximal tubule,
    3.Loop of Henle (descending and ascending)
    4.Distal tubule
  2. Collecting duct
37
Q

What determines the Net Filtration pressure of glomerular filtration that determines how much water and solutes leave the blood

A

Pressure pushing fluid out is Glomerular Blood hydrostatic pressure (55)

Pressures pushing back in is
-Capsular hydrostatic pressure (exerted from elastic recoil of capsule on plasma) (15)

-Blood colloid osmotic pressure (osmotic force of proteins left in plasma) (30)

Therefore NFP = GBP- (CHP +BCOP)

38
Q

How is glomerular filtration rate regulated by myogenic autoregulation mechanisms to increase GFR
and decrease GFR

A

Myogenic:
If BP drops, there is constriction of efferent arteriole which increases BP in glomerulus-> increase of GFR

If BP increases, increased stretching of smooth muscle in afferent arteriole triggers constriction which makes pressure fall across the glomerulus-> decrease GFR

39
Q

What is the output of urine (Glomerular filtration rate) directly proportional to

A

Renal blood pressure

40
Q

How is increased glomerular filtration rate regulated by Tubuloglomerular feedback

A

higher GFR -> higher flow rate

Macula densa cells in the tubule distal tubule sense increase in Na+ and Cl- due to high flow rate.

Release of NO from Juxtaglomerular apparatus is decreased

Vasoconstriction of afferent arteriole to lower BP->thus GFR

41
Q

What is the normal pressure of the Afferent arteriole, Glomerular and the Efferent arteriole BP

A

60, 55, 50

42
Q

What two factors do regulators of glomerular filtration work on

A

The Glomerular hydrostatic pressure and the Surface area available for filtration

43
Q

How is GFR regulated by Neurons

A

The GFR can be decreased by constriction of afferent arterioles due to norepinephrine from sympathetic nerve activation

44
Q

Compare how GFR regulated by two hormones

A

Angiotensin II (produced by decreased blood vol or BP) decreases GFR by causing vasoconstriction of both efferent and afferent arterioles

whereas ANP (produced in response to stretching of atria)increases GFR by relaxing mesangial cells in glomerulus to increase SA for filtration.

45
Q

Describe the movement of Na+, Cl- and water in the Proximal tubule

A

Na+ is pumped out of the cell into the interstitial space by Na/KATPase to create a conc gradient for

2Na+/Glucose to enter the cell via symporter (down conc gradient) and H+ to be secreted via Na+/H+ antiporter

Cl- follows and water follows by osmosis

46
Q

Q
What is the difference between the cortical nephrons and juxtamedullary nephron

A

Cortical nephrons make dilute urine

and juxtamedullary nephron make concentrated urine

47
Q

What is amount of solute and water reabsorption in Proximal tubule and what is the osmolarity

A

Largest reaborption here
-60% of glomerular filtrate
-60% of NaCl and water
100% Glucose

Osmolarity similar to plasma (300mOsm)

48
Q

What part of the nephron has brush border of microvili and why

A

Proximal convoluted tubule for increased SA for membrane transport processes

49
Q

Describe the movement of Na+, Cl- and water in the Descending loop of Henle

A

There is no movement of ions Na+/K+ as it has low permeability to ions and urea.
However it is highly permeable to water so water moves out obligatory of tubule to interstitial fluid in the renal medulla because it is more concentrated than tubule.

50
Q

What is the osmolarity of the Descending loop of Henle and why

A

1200 mOsmol/L because lots of water left

51
Q

Describe the movement of Na+, Cl- and water in the Ascending loop of Henle

A

Thick cuboidal cells of tubule impermeable to water but Na+, K+ and 2Cl- absorbed through symporter powered by Na+ gradient made by NaKATPase in basolateral membrane.

52
Q

What is the osmolarity of the Ascending loop of Henle and why

A

Very dilute (100 mOsmol/L) as ions are moving out but water can’t

53
Q

What is the counter current mechanism

A

The gradient for water to leave the descending limb is set up by ions leaving the descending limb making the tip of ECF of medulla higher concentrated. This is supported by blood flow of the efferent vasa recta which takes the water away.

54
Q

Describe the movement of Na+, Cl- and water in the distal tubule and collecting duct

A

Additional Na, and Cl- is absorbed through diffusion channels because of gradient set up by NaKATPase. K+ is also secreted by these principal cells.
This section is also impermeable to water in the Absence of ADH, which makes a dilute urine.

55
Q

What is the osmolarity of the distal tubule and collecting duct and why

A

The final osm of the urine is 100mosmol/L - a large volume of dilute volume.

56
Q

What type of urine is made with ADH (vasopressin) and what does this mean for the osmolarity and volume of plasma

A

Increasing the reabsorption of water resulting in a concentrated urine.
As more water was put back into the blood, the plasma osmolarity decreases and the plasma volume increases

57
Q

Describe the path of ADH being made to being released into circulation

A

Osmoreceptors in the hypothalamus detect an increase in osmolarity / increase Na+ concentration in plasma

This triggers the precursor for ADH to be synthesised in the hypothalamus and stored in vesicles in the posterior pituitary.

When osmolarity increases (in dehydration) or there is an increase in Na+ in the ECF, ADH is released from the posterior pituitary to the blood

58
Q

How do osmoreceptors in the hypothalamus detect changes in osmolarity

A

They are shrink activated receptors on neurons. When the osmolarity of ECF increases, the cells shrink and this causes Cation ion channels to open. This allows Na+ to enter the cell which depolarises cell=> triggers APs.
When cells swell (osmolarity of ECF decreases) channels close, APs less frequent.

59
Q

How does ADH act on target tissue and where is this

A

ADH acts on receptors in the last section of nephron (convoluted distal tubule + collecting duct).

It stimulates the insertion of vesicles containing aquaporin-2 into the apical membrane (facing tubule) of collecting duct epithelia.
Water can then move freely from tubule into cell and then to the blood as the basolateral membrane is relatively permeable to water.

60
Q

What effect does alcohol have on ADH

A

It inhibits ADH, thus resulting in water not being reabsorbed so dilute urine and thus possibility of dehydration.

61
Q

What solution is better for dehydration: isotonic or hypotonic + why

A

As water equilibrates throughout ICF and ECF, this decreases osmolarity so is good for dehydration
However isotonic solution is not good because there will be no net movement of water so osmolarity stays the same

62
Q

What is concentration of ADH proportional to in the blood and compare the threshold to thirst

A

[ADH] is proportional to plasma osmolarity. The threshold for it to start being produced is 280 mOsm. Thirst is less sensitive and has a threshold of 295 mOsm

63
Q

What affects the slope of the [ADH] vs Plasma osmolarity curve. Give eg for higher and lower …

A

Blood volume.
Higher blood volume decreases sensitivity: smaller slope, threshold higher

Lower blood volume increases sensitivity: bigger slope, lower threshold.

64
Q

What is a secondary input that triggers the release of ADH. How sensitive

A

Decrease in plasma volume or a decrease in Blood pressure by (10-15%) .
This causes reduced firing of Baroreceptors in atrium and large vessels and this stimulates the posterior pituitary to release ADH.
Less sensitive- requires relatively high changes.`

65
Q

What is the purpose/effect of the Renin-Angiotension- Aldosterone system

A

It maintains balance of sodium.

It increases blood pressure by increasing blood volume by the water that follows sodium

66
Q

What are 3 triggers and production of Renin. Where

A

Trigger;

1a) . If there is decrease of sodium content in the distal tubule, this is sensed by Macula densa cells which increase prostaglandins.
1b) If there is a decrease in blood volume –> this will cause decrease in blood pressure in the afferent arteriole sensed by granular cells.
1c) High sympathetic activity (via baroreflex bc low BP)

Production: This triggers Juxtaglomerular granular cells in the afferent arteriole release Renin

67
Q

What is Renin and its effect

A

Renin is an enzyme which catalyses the rate limiting step of Angiotensin 2 production

68
Q

Describe the pathway of Angiotensinogen to Angiotensin 2 + where they come from

A

Angiotensinogen from liver converted to Angiotensin 1 by Renin.
Angiotensin 1 to Angiotensin 2 by Angiotensin converting enzyme in the lungs.

69
Q

How does Angiotensin 2 affect target tissues

A

It causes vasoconstriction of afferent arterioles to decrease glomerular filtration rate.-> increase Blood pressure.
It has small direct effect on reabsorption in the proximal convoluted tubule by stimulating Na+/H+ antiporters.
It stimulates the release of Aldosterone from the adrenal cortex.
This increases sodium and water reabsoption (+ H+/K+ excretion) in the distal tubule (with presence of ADH)
- This increases blood volume-> increases blood pressure

70
Q

What are the two things that trigger release of Aldosterone from the adrenal cortex

A

Increased Angiotensin 2 levels and increase K+ conc in the plasma

71
Q

What is the response to ingestion of salt

A

Increased salt conc in plasma increases the blood volume because water moves out of cells to plasma

Increased blood volume triggers:
a) Increased atrial stretching=> release of ANP
b) decreased release of renin=> less angiotension 2 which leads to increase GFR bc vasodilation and decreased aldosterone

Reduced reabsorption of NaCl by kidneys
Increased loss of NaCl in urine, and the water following it from plasma

Decreased blood volume

72
Q

How does Aldosterone increase reabsorption of sodium

A

Increases the transcription of Na/KATPase in the basal membrane therefore creating a greater gradient for activity of Na+ channels in apical membrane of principal cells in the collecting duct.

73
Q

What is the response to a haemorrhage

A

1.Haemorrhage decrease blood volume -> thus blood pressure

Sensed by Baroreceptors which trigger
a) Posterior pituitary to release ADH
b) Increase sympathetic nerve activity
-Sensed by Juxtaglomerular cels to secrete Renin-> increased Angiotensin 2 in blood.

From ADH: vasoconstriction, increased water absorption.
From Symp : increased HR and vasoconstriction
From Aldosterone: increased Na+ absorption
Increased blood volume & increased systemic vascular resistance==> Increased BP

74
Q

What is a haemorrhage

A

An isotonic loss of water and salt

75
Q

What is the timescale of the responses to restore blood volume

A
  1. Autoregulation: Feedback (Regulation of filtration of
    glomerulus)
  2. Nerves
  3. Hormones
  4. Thirst
  5. RBC replacement
76
Q

What is difference between ANP and ADH

A

ANP is triggered by stretching of atria (high blood volume)
and works to inhibit all Renin, ADH, Aldosterone release. Therefore increase GFR
-»Reduces Na+ reabsorption + water
Whereas, ADH works to increases water reabsorption

77
Q

What triggers thirst

A

Osmoreceptors in the hypothalamus that sense decreased plasma osmolarity.

MEDSCI142 (9 decks)

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