Homestasis and Fluid Balance

Question 1

Define homeostasis

Answer 1

Maintenance of the volume and composition of body fluids

Maintenance of a constant internal environment

Question 2

Define negative feedback

Answer 2

Reverse a change in the controlled condition

Question 3

What 4 elements does negative feedback require?

Answer 3

Sensor, ability to compare to reference, sufficient gain, effector mechanism.

Question 4

What is gain?

Answer 4

Correction/Error
E.g Infusion of blood into someone caused SBP to rise from 100 to 175mmHg (no functional baroreceptors) and to 125mmHg in individual with functioning baroreceptors. Gain = -50/25 =-2

Question 5

What would a Gain of -5 suggest?

Answer 5

A gain of -5 would suggest a more sensitive control system compared to a gain of -2.

Question 6

Define positive feedback

Answer 6

Reinforce/amplifies the change in the controlled condition

Question 7

How much of a 70Kg male is water?

Answer 7

60% (42L)

Question 8

How much of a 70kg female is water?

Answer 8

50% (35L)

Question 9

What proportion of the total body water is intracellular fluid?

Answer 9

60%

Question 10

What proportion of the total body water is extracellular fluid?

Answer 10

40%

Question 11

What is the extracellular fluid composed of?

Answer 11

Interstitial fluid
Plasma
Transcellular fluid

Question 12

What proportion of the extracellular fluid is interstitial fluid?

Answer 12

75% of ECF

Question 13

What proportion of the extracellular fluid is plasma fluid?

Answer 13

1/5 or 20%

Question 14

What proportion of the extracellular fluid is transcellular fluid?

Answer 14

5%

Question 15

There is more potassium/sodium within the cell than there is potassium/sodium

Answer 15

There is more potassium within the cell than there is sodium

Question 16

There is more ——– outside the cell than there is ——-

Answer 16

There is more sodium outside the cell than there is potassium

Question 17

what is the osmolarity of the intracellular fluid?

Answer 17

280 mOsm - 300 mOsm

Question 18

what is the osmolarity of the extracellular fluid?

Answer 18

280 mOsm - 300 mOsm

Question 19

Is chloride more extracellular or intracellular?

Answer 19

More extracellular - tends to be with sodium

Question 20

Why is it important to have different concentrations of ions in the ICF and ECF?

Answer 20

Setting the membrane potential

Generating electrical activity

Muscle contraction

Nutrient uptake via secondary active transport

Generation of intracellular signaling cascades

Question 21

How do solutes (ions) move?

Answer 21

Passive transport across a permeable membrane - Electrochemical gradient

Intrinsic membrane proteins
Pores - e.g. Aquaporins

Channels - voltage gated channels like Na/K ATPases for Ca2+

Carriers and Co Transporters - SGLT and GLUTs

Question 22

Na+/K+ ATPase is a form of —— transport. It takes —- sodium ions —- of the cell and —- potassium ions —-. Therefore there is always a —— for —– to move passively —– the cell. These are located in the ———— membrane and are ubiquitous.

Answer 22

Na+/K+ ATPase is a form of active transport. It takes 3 sodium ions out of the cell and 2 potassium ions in. Therefore there is always a gradient for sodium to move passively into the cell. These are located in the basolateral membrane and are ubiquitous.

Question 23

Define osmosis

Answer 23

Osmosis is net diffusion of water (across a semi-permeable membrane) from a region of high water concentration to one that has a lower water concentration

Question 24

What is osmotic pressure?

Answer 24

The amount of pressure required to stop the flow of water through a semipermeable membrane

Question 25

If you put red blood cells into solution that has the same number of osmotically active particles, there will be — net movement of water, there is – change in cell volume, so the solution is ———.

Answer 25

If you put red blood cells into solution that has the same number of osmotically active particles, there will be no net movement of water, there is no change in cell volume, so the solution is isotonic

Question 26

If you put a cell (280mOsm) into a solution that is 180mOsm, water is going to move ——- the cell causing it to —–. This is a ——- solution

Answer 26

f you put a cell (280mOsm) into a solution that is 180mOsm, water is going to move into the cell causing it to burst. This is a hypotonic solution

Question 27

If you put a cell (280mOsm) into a solution that is 400mOsm, water is going to move —– of the cell causing it to ——. This is a ——–solution

Answer 27

If you put a cell (280mOsm) into a solution that is 400mOsm, water is going to move out of the cell causing it to shrink. This is a hypertonic solution

Question 28

If a patient has lost blood, what IV solution would you administer?

Answer 28

Isotonic IV solution because you don’t want to change the structure of the red blood cells

If the red blood cells swell they can’t move through arteries

If the red blood cells shrink can move through fenestrations in the glomerulus

Question 29

What increases the surface area of the small intestine and therefore absorption?

Answer 29

Folds of kerckring
Microvilli
crypts of lieberkuhn
submicroscopic microvilli

Question 30

The absorption of non-electrolyte nutrients (such as proteins, fats and carbohydrate, micronutrients and vitamins) occurs almost exclusively in the —– intestine

Answer 30

small intestine

Question 31

small and large intestine (colon) absorb —– and ——

Answer 31

small and large intestine (colon) absorb water and electrolytes

Question 32

what is the key function of the large intestine?

Answer 32

Absorption through micro villi and crypts

Question 33

The large intestine doesn’t have —– but has __

Answer 33

villi

Semilunar folds
Crypts
Microvilli

Question 34

How many litres of fluid is presented to the large intestine and how much is reabsorbed per day?

Answer 34

2L/day is presented to the large intestine and 1.9L/day is reabsorbed

Question 35

How much fluid is presented and reabosrbed by the small intestine per day?

Answer 35

8.5L/day is presented to the small intestine and 6.5L/day is reabsorbed

Question 36

how much fluid is lost as fecal fluid per day?

Answer 36

100mL

Question 37

How much fluid is secreted by the small intestine?

Answer 37

1L/day

Question 38

Does the small intestine actively absorb sodium?

Answer 38

yes

Question 39

Does the large intestine actively absorb sodium?

Answer 39

yes

Question 40

Does the small intestine actively secrete potassium?

Answer 40

No

Question 41

Does the large intestine actively secrete potassium?

Answer 41

Yes

Question 42

Does the large intestine absorb nutrients?

Answer 42

No

Question 43

Absorption of non-electrolyte nutrients occurs mainly in the —– intestine

Answer 43

Small intestine

Question 44

The —– intestine absorbs water, sodium, chloride and potassium and secretes bicarbonate.

Answer 44

Small intestine

Question 45

The —– intestine absorbs water, sodium and chloride and secretes bicarbonate and potassium.

Answer 45

Large intestine

Question 46

How is water absorbed?

Answer 46

Osmosis

Coupled to solute movement (glucose)

Transcellular or paracellular

Question 47

where does sodium absorption occur (cells)?

Answer 47

In villus epithelial cells of the small intestine and the surface epithelial cells of the large intestine

Question 48

Sodium potassium ATPases

There are Na+/K+ atpases in the ———– membrane pushing – sodium — of the cell and into the —– and bringing – potassium – the cell.

This maintains a high ——– sodium concentration and low —— sodium concentration.

There is always less Na in the —, so there is always a drive for Na —- the cell.

This provides a force for sodium diffusion from the ——- across the —– membrane.

The transport is mediated by sodium ——– transporters.

Answer 48

There are Na+/K+ atpases in the apical membrane pushing 3 sodium out of the cell and into the ECF and bringing 2 potassium into the cell.

This maintains a high extracellular sodium concentration and low intracellular sodium concentration.

There is always less Na in the cell, so there is always a drive for Na into the cell.

This provides a force for sodium diffusion from the lumen across the apical membrane.

The transport is mediated by sodium coupled transporters.

Question 49

Na/glucose or Na/amino acid co transporters

The ———- ——– makes sure there is —— sodium within the cell.

There is a —- for sodium to move — the cell.

When sodium moves —- it co transports glucose via ——-.

The glucose moves out of the cell and into the blood via —–.

Answer 49

The Na/K ATPase makes sure there is low sodium within the cell.

There is a gradient for sodium to move into the cell.

When sodium moves in it co transports glucose via SGLT.

The glucose moves out of the cell and into the blood via GLUT2.

Question 50

Na-H exchanger

The ———- ——– makes sure there is —— sodium within the cell.

There is a —- for sodium to move — the cell.

When sodium moves —- there is an exchange of hydrogen —— of the cell.

Theses exchangers are found on both the apical and basolateral membrane

Answer 50

The Na/K ATPase makes sure there is low sodium within the cell.

There is a gradient for sodium to move into the cell.

When sodium moves in there is an exchange of hydrogen out of the cell.

Theses exchangers are found on both the apical and basolateral membrane

Question 51

Parallel Na-H and Cl-HCO3 exchangers

The ———- ——– makes sure there is —— sodium within the cell.

There is a —- for sodium to move — the cell.

When sodium moves —- there is an exchange of hydrogen —— of the cell.

Sodium is positively charged and chloride is negatively charged so when sodium moves — the cell via Na-H exchangers chloride also moves —- the cell via Cl - HCO3 exchangers.

When hydrogen and bicarbonate move into the —- they form ——– which is unstable and breaks into — and —-.

Answer 51

Parallel Na-H and Cl-HCO3 exchangers

The Na/P ATPase makes sure there is low sodium within the cell.

There is a gradient for sodium to move into the cell.

When sodium moves in there is an exchange of hydrogen out of the cell.

Sodium is positively charged and chloride is negatively charged so when sodium moves into the cell via Na-H exchangers chloride also moves into the cell via Cl - HCO3 exchangers.

When hydrogen and bicarbonate move into the lumen they form H2CO3 which is unstable and breaks into H2O and CO2.

Question 52

Epithelial sodium channels

The ———- ——– makes sure there is —— sodium within the cell.

There is a —- for sodium to move — the cell.

Sodium moves —- the cell via specific sodium channels.

Answer 52

The Na/K ATPase makes sure there is low sodium within the cell.

There is a gradient for sodium to move into the cell.

Sodium moves into the cell via specific sodium channels.

Question 53

How is chloride absorbed?

Answer 53

Linked to Na absorption (Na-H and Cl-HCO3 exchangers)

Paracellular across tight junctions- passive absorption

Cl-HCO3 transporter - active

Question 54

How is potassium absorbed?

Answer 54

Passive paracellular

Active - hydrogen potassium exchangers

Question 55

How is potassium secreted?

Answer 55

Passive - paracellular

Active (large intestine) - Via BK channels

Question 56

What will happen if you have some disease in your large intestine causing active fluid loss?

Answer 56

BK channels will actively secrete potassium.

There is loss of water and potassium ions leading to hypokalemia

Question 57

Chloride secretion

In the ——– membrane —— —— push – sodium —- of the cell and — potassium —- the cell.

Epthelial channels in the —– membrane move the —- —— ions back — of the cell.

The ——- channel in the ——– membrane brings —, — and —- into the cell.

In the —– membrane the —– secretes ——– into the lumen. Sodium and water enters the lumen via ——– transport.

It is driven by —- ions and —— (second messenger)

Results in fluid and ion loss from the —– due to increased activation of —-.

Answer 57

In the basolateral membrane Na/K ATPases push 3 sodium out of the cell and 2 potassium into the cell.

Epthelial channels in the basolateral membrane move the 2 potassium ions back out of the cell.

The NKCC1 channel in the basolateral membrane brings Na, 2Cl and K into the cell.

In the apical membrane the CFTR secretes chloride into the lumen. Sodium and water enters the lumen via paracellular transport.

It is driven by calcium ions and cAMP (second messenger - signals CFTR to be placed into the membrane)

Results in fluid and ion loss from the ECM due to increased activation of CFTR.

Question 58

What happens during cystic fibrosis?

Answer 58

Lack of CFTR = no secretion of chloride and therefore no secretion of sodium

Results in dense secretion and respiratory problems

Question 59

The —– intestine is a net absorber of water, sodium, chloride and potassium but it is a net secretor of bicarbonates

Answer 59

Small intestine

Question 60

The —— intestine carries out net absorption of water, sodium and chloride with few exceptions, but it carries out net secretion of potassium and bicarbonate

Answer 60

Large intestine

Question 61

The dysfunction of fluid absorption in the GI tract leads to ———-

Answer 61

Diarrhoea

Question 62

Would the volume of diarrhoea be larger if a dysfunction in the GI tract occurred in the small or large intestine?

Answer 62

Small intestine

Question 63

—— diarrhoea results from disturbances of absorption.

The amount of —– consumed is not able to be processed by the body.

—— is retained in the —– of the intestine causing an increase in ——- —— so —– is retained in the ———. This is due to ——- intolerance (lack of the enzyme —–).

Increased volume of ——– enters the colon and may overwhelm the ability of the colon to absorb ——- from it. Leads to pronounced diarrhoea.

An ——– reaction to gluten results in the destruction of the —— cells and if severe the —-. This causes nutrient malabsorption. There is an ——- in osmotic pressure in the ——– and water is —— in the lumen. This is due to coeliac disease.

Answer 63

Osmotic diarrhoea results from disturbances of absorption.

The amount of sugar consumed is not able to be processed by the body.

Sugar is retained in the lumen of the intestine causing an increase in osmotic pressure so water is retained in the lumen. This is due to lactose intolerance (lack of the enzyme lactase).

Increased volume of chyme enters the colon and may overwhelm the ability of the colon to absorb water from it. Leads to pronounced diarrhoea.

An autoimmune reaction to gluten results in the destruction of the epithelial cells and if severe the villi. This causes nutrient malabsorption. There is an increase in osmotic pressure in the lumen and water is retained in the lumen. This is due to Coeliac disease.

Question 64

——– diarrhoea results from disturbances in secretion.

Elevation of ———- activity of cells in unidirectional secretory flux may exceed unidirectional ——— flux and net secretion prevails.

Cholera toxin permanently activates —— ——— thereby causing an elevation of ——– which in turn opens the —- channel in the apical membrane of the crypt epithelial cells. This causes a prolonged secretion of —–, —- and —– which can be fatal.

Enterotoxins produced by the bacterial microorganism raise intracellular —–, —– or —– leading to the stimulation of — secretion.

Answer 64

Secretory diarrhoea results from disturbances in secretion.

Elevation of secretory activity of cells in unidirectional secretory flux may exceed unidirectional absorptive flux and net secretion prevails.

Cholera toxin permanently activates adenylate cyclase thereby causing an elevation of cAMP which in turn opens the Cl channel in the apical membrane of the crypt epithelial cells. This causes a prolonged secretion of Cl, Na and water which can be fatal.

Enterotoxins produced by the bacterial microorganism raise intracellular cAMP, cGMP or calcium ions, leading to the stimulation of Cl secretion

Question 65

How can we treat diarrhoea?

Answer 65

Oral rehydration solution

When you have diarrhoea the glucose transporters are not affected so if a solution with sodium and glucose is given, when sodium moves into the cell it takes glucose with it. Chloride follows and bicarbonate (to combat acidosis)

Question 66

Molecules containing hydrogen atoms that can release hydrogen ions in solutions are referred to as —-.

Answer 66

Acids

Question 67

A —- is an ion or a molecule that can accept an H+

Answer 67

Base

Question 68

Proteins in the body also function as ——- because some of the amino acids that make up proteins have a net —— charge that readily accepts H+.

Answer 68

Proteins in the body also function as base because some of the amino acids that make up proteins have a net negative charge that readily accepts H+.

Question 69

What is the normal pH of atrial blood?

Answer 69

7.4

Question 70

Is the pH of venous blood and interstitial fluid above the normal atrial blood pH or below?

Answer 70

Below because of the extra amounts of carbon dioxide released from the tissues to form H2CO3 in these fluids.

Question 71

Is the pH of venous blood and interstitial fluid above the normal atrial blood pH or below?

Answer 71

Below because of the extra amounts of carbon dioxide released from the tissues to form H2CO3 in these fluids.

Question 72

A person is considered to have acidosis when the pH falls below ——- (addition of H+) and to have alkalosis when the pH rises above —– (removal of H+)

Answer 72

A person is considered to have acidosis when the pH falls below 7.4 (addition of H+) and to have alkalosis when the pH rises above 7.4 (removal of H+)

Question 73

Name the mechanisms of pH control from immediate reaction to slow reaction.

Answer 73

Acid-Base buffer system

Respiratory center

Kidneys

Question 74

Acid base buffer system

The chemical acid-base buffer system of the body fluids, immediately combine with —- or —- to prevent excessive changes in —- concentration.

This is the —- line of defense.

When there is a change in — concentration, the buffer systems of the body fluids react within seconds to —— these changes.

Buffer systems do not eliminate —- from or add them to the body but only keep them tied up until balance can be re-established.

Answer 74

The chemical acid-base buffer system of the body fluids, immediately combine with acid or base to prevent excessive changes in H+ concentration.

This is the first line of defence.

When there is a change in H+ concentration, the buffer systems of the body fluids react within seconds to minimise these changes.

Buffer systems do not eliminate H+ from or add them to the body but only keep them tied up until balance can be re-established.

Question 75

Acid base buffer system

The chemical acid-base buffer system of the body fluids, immediately combine with —- or —- to prevent excessive changes in —- concentration.

This is the —- line of defense.

When there is a change in — concentration, the buffer systems of the body fluids react within seconds to —— these changes.

Buffer systems do not eliminate —- from or add them to the body but only keep them tied up until balance can be re-established.

Answer 75

The chemical acid-base buffer system of the body fluids, immediately combine with acid or base to prevent excessive changes in H+ concentration.

This is the first line of defence.

When there is a change in H+ concentration, the buffer systems of the body fluids react within seconds to minimise these changes.

Buffer systems do not eliminate H+ from or add them to the body but only keep them tied up until balance can be re-established.

Question 76

The respiratory center

Regulates the removal of —— and therefore ——–, from the ——— fluid.

This is the ——- line of defence.

Answer 76

Regulates the removal of CO2 and therefore H2CO3, from the extracellular fluid.

This is the second line of defence.

Question 77

The kidneys

Can excrete either —– or —– urine, thereby readjusting the ———- fluid — concentration toward normal during acidosis or alkalosis.
This is the last line of defense

Although the kidneys are relatively slow to respond compared with the other defenses, over a period of hours to several days, they are by far the most powerful of the acid—base regulatory systems.

Answer 77

Can excrete either acidic or basic urine, thereby readjusting the extracellular fluid H+ concentration toward normal during acidosis or alkalosis.

This is the last line of defense

Question 78

The more ——– ions the greater the pH.

Answer 78

The more bicarbonate ions (HCO3-) the greater the pH (pH is directly proportional to HCO3-)

Question 79

Higher ——- the lower the pH

Answer 79

Higher Pco2 the lower the pH (pH is inversely proportional to Pco2)

Question 80

Name the buffer systems.

Answer 80

Bicarbonate buffers
phosphate buffers
Proteins

Question 81

———- buffers are ubiquitous, act fast to sort out pH but are not strong.

Answer 81

Bicarbonate buffers

Question 82

——– buffers are limited to the kidney tubules but are strong buffers

Answer 82

Phosphate buffers

Question 83

Bicarbonate buffer

H2CO3 is an unstable compound so it breaks down into __ and ____

If there is an increase in _, they will combine with ______ to produce ____ which will then dissociate into ____ and ____, catalysed by —– —–. (breathe faster to remove CO2)

For alkalines (NaOH) combines with H2CO3 to form an inert compound (NaHCO3) and water.

Bicarbonate buffer system to be powerful, for two reasons:

First, the pH of the extracellular fluid is about 7.4, whereas the pK of the bicarbonate buffer system is 6.1 (the best pH at which the buffer exists as both a base and acid). This means that there is about 20 times as much of the bicarbonate buffer system in the form of HCO3 (acidic)— as in the form of dissolved CO2 (basic). For this reason, this system operates on the portion of the buffering curve where the slope is low and the buffering power is poor.

Second, the concentrations of the two elements of the bicarbonate system, CO2 and HCO3, are not great.

Answer 83

H2CO3 is an unstable compound so it breaks down into H+ and HCO3-

If there is an increase in H+, they will combine with bicarbonate to produce H2CO3 which will then dissociate into CO2 and H20, catalysed by carbonic anhydrase. (breathe faster to remove CO2)

For alkalines (NaOH) combines with H2CO3 to form an inert compound (NaHCO3) and water.

Bicarbonate buffer system to be powerful, for two reasons:

First, the pH of the extracellular fluid is about 7.4, whereas the pK of the bicarbonate buffer system is 6.1 (the best pH at which the buffer exists as both a base and acid). This means that there is about 20 times as much of the bicarbonate buffer system in the form of HCO3— as in the form of dissolved CO2. For this reason, this system operates on the portion of the buffering curve where the slope is low and the buffering power is poor.

Second, the concentrations of the two elements of the bicarbonate system, CO2 and HCO3, are not great.

Question 84

In our body we are basic at a pH of — so the buffer is operating at that pH, so it exists more as a —– rather than as an —— so it’s not that powerful because it doesn’t exist in equal amounts of acid and base

This is a limiting factor

Answer 84

In our body we are basic at a pH of 7.4 so the buffer is operating at that pH, so it exists more as a base rather than as an acid so it’s not that powerful because it doesn’t exist in equal amounts of acid and base

Question 85

Phosphate buffers

The main elements of the phosphate buffer system are —- and —–.

The buffer system has a pk of —-.

The phosphate buffer is especially important in the —- fluids of the —-.

The phosphate buffer is especially important in the —— fluids of the ——-, for two reasons:

(1) phosphate usually becomes greatly ———- in the tubules, thereby ——- the buffering power of the phosphate system
(2) the tubular fluid usually has a —— pH than the extracellular fluid does, bringing the operating range of the buffer —— to the pK (6.8) of the system.

Answer 85

The main elements of the phosphate buffer system are H2PO4- and HPO4-.

The buffer system has a pk of 6.8.

The phosphate buffer is especially important in the tubular fluids of the kidney.

The phosphate buffer is especially important in the tubular fluids of the kidney, for two reasons:

(1) Phosphate usually becomes greatly concentrated in the tubules, thereby increasing the buffering power of the phosphate system
(2) The tubular fluid usually has a lower pH than the extracellular fluid does, bringing the operating range of the buffer closer to the pK (6.8) of the system.

Question 86

Respiratory regulation of acid-base balance

Acts rapidly and keeps the — concentration from changing too much until the slowly responding —— can eliminate the imbalance

It is one to 2 times greater as the buffering power of all other chemical buffers. So 1 to 2 times as much acid and base can normally be buffered by this mechanism.

Answer 86

Acts rapidly and keeps the H+ concentration from changing too much until the slowly responding kidneys can eliminate the imbalance

Question 87

Respiratory regulation of acid-base balance

increased alveolar ventilation,

——- removal of CO2 so
——– partial pressure of CO2, so ———- CO2 combining with water, ———- carbonic acid, ——— H+ concentration in the extracellular fluid and — back to normal
This is the —– line of defense, which controls extracellular fluid —– concentration by the lungs.

Changes in either ——– ventilation or the rate of —– formation by the tissues can change the extracellular fluid —–.

Answer 87

Respiratory regulation of acid-base balance

increased alveolar ventilation,
increased removal of CO2 so decreased partial pressure of CO2, so decreased CO2 combining with water, decreased carbonic acid, decreased H+ concentration in the extracellular fluid and pH back to normal

This is the second line of defense, which controls extracellular fluid CO2 concentration by the lungs.

Changes in either pulmonary ventilation or the rate of CO2 formation by the tissues can change the extracellular fluid PCO2.

Question 88

Respiratory regulation of acid-base balance

increased alveolar ventilation,

——- removal of CO2 so
——– partial pressure of CO2, so ———- CO2 combining with water, ———- carbonic acid, ——— H+ concentration in the extracellular fluid and — back to normal
This is the —– line of defense, which controls extracellular fluid —– concentration by the lungs.

Changes in either ——– ventilation or the rate of —– formation by the tissues can change the extracellular fluid —–.

Answer 88

Respiratory regulation of acid-base balance

increased alveolar ventilation,
increased removal of CO2 so decreased partial pressure of CO2, so decreased CO2 combining with water, decreased carbonic acid, decreased H+ concentration in the extracellular fluid and pH back to normal

This is the second line of defense, which controls extracellular fluid CO2 concentration by the lungs.

Changes in either pulmonary ventilation or the rate of CO2 formation by the tissues can change the extracellular fluid PCO2.

Question 89

Increase in ventilation ——- pH

Decrease in ventilation ——– pH

The normal rate of alveolar ventilation is —-. At this rate the change in pH of body fluids is —.

The alveolar ventilation rate doesn’t change much during changes in atrial blood pH from 7.4 to 7.2 because of the acting ——-.

Answer 89

Increase in ventilation increases pH

Decrease in ventilation decreases pH

The normal rate of alveolar ventilation is 1. At this rate the change in pH of body fluids is 0.

The alveolar ventilation rate doesn’t change much during changes in atrial blood pH from 7.4 to 7.2 because of the acting buffers.

Question 90

How does the kidney regulate pH?

Answer 90

Secretion of H+

Reabsorption of filtered HCO3-

Production of new HCO3-

Question 91

kidney regulation of pH

Secretion of H+

There are ——- ——- (3 Na out, 2K in), there is always a drive for sodium to move —- the cell

There is a filtrate in the tubular lumen, there is sodium and bicarbonates (phosphate buffers) filtering in.

The sodium is taken — the cell and a — ion is exchanged into the lumen via Na/H+ exchangers, which then goes onto combine with the ————- to form H2CO3, which then dissociates into —— and ——-.

The —— then goes into the cell and combines with —— to produce H2CO3 which dissociates into ——- and —-, with the ——- moving out of the cell and into the blood

It’s complicated because the kidney doesn’t have a system that can actively reabsorb bicarbonates

Answer 91

There are Na/K ATPases (3 Na out, 2K in), there is always a drive for sodium to move into the cell

There is a filtrate in the tubular lumen, there is sodium and bicarbonates (phosphate buffers) filtering in.

The sodium is taken into the cell and a H+ ion is exchanged into the lumen via Na/H+ exchangers, which then goes onto combine with the bicarbonate to form H2CO3, which then dissociates into CO2 and H20.

The CO2 then goes into the cell and combines with H20 to produce H2CO3 which dissociates into HCO3- and H+, with the HCO3- moving out of the cell and into the blood

Question 92

kidney regulation of pH

Active secretion of H+

When there is a lot of acid in the body it actively secretes __ ions

This is done via —-exchangers, which are secondary active transporters turning ATP to ADP when removing the —— into the lumen

The bicarbonate goes back into the cell

Answer 92

When there is a lot of acid in the body it actively secretes H+ ions

This is done via H/Cl exchangers, which are secondary active transporters turning ATP to ADP when removing the H+ into the lumen

The bicarbonate goes back into the cell

Question 93

kidney regulation of pH

Addition of new HCO3-

There are ——— ——-(3 Na out, 2K in), there is always a drive for sodium to move —- the cell

There is a filtrate in the tubular lumen, there is phosphate buffers filtering in, the —- is taken into the cell and a — ion is exchanged into the lumen (sodium hydrogen exchangers), which then goes onto combine with ——- to form NaH2PO4, which is excreted out of the body.

The —- in the blood goes into the cell and combines with —— to produce H2CO3 which dissociates into —- and —-, with the HCO3- moving out of the cell and into the blood.

Answer 93

There are Na/K ATPases (3 Na out, 2K in), there is always a drive for sodium to move into the cell

There is a filtrate in the tubular lumen, there is phosphate buffers filtering in, the sodium is taken into the cell and a H+ ion is exchanged into the lumen (sodium hydrogen exchangers), which then goes onto combine with NaHPO4- to form NaH2PO4, which is excreted out of the body.

The CO2 in the blood goes into the cell and combines with water to produce H2CO3 which dissociates into HCO3- and H+, with the HCO3- moving out of the cell and into the blood.

Question 94

kidney regulation of pH

Addition of new HCO3-

Glutamine dissociates into —- and —– ions which get exchanged into the lumen with sodium ions.

The —- and — gets lost in the urine

The body gains – bicarbonate ions

Answer 94

Glutamine dissociates into HCO3- and NH4+ ions which get exchanged into the lumen with sodium ions.

The NH4+ and Cl gets lost in the urine

The body gains 2 bicarbonate ions

Question 95

Respiratory acidosis (pCO2)

The pH is ——– 7.4

There is ——- H+

There is ——– PCO2

Answer 95

The pH is below 7.4

There is increased H+

There is increased PCO2

Question 96

Respiratory alkalosis (PCO2)

The pH is ——- 7.4.

There is ——- H+.

There is ——- PO2.

Answer 96

The pH is above 7.4

There is decreased H+

There is decreased PCO2

Question 97

Metabolic acidosis (HCO3-)

The pH is ——- 7.4

There is —– H+.

There is ——– HCO3-

Answer 97

The pH is below 7.4

There is increased H+.

There is decreased HCO3-

Question 98

Metabolic alkalosis (HCO3-)

The pH is ——- 7.4

There is —– H+.

There is ——– HCO3-

Answer 98

The pH is above 7.4

There is decreased H+.

There is increased HCO3-

Question 99

What is the function of the kidney?

Answer 99

Maintains homeostasis of hydration. blood volume and pressure

Question 100

If you drink more water than you need the excess volume is excreted as ——.

If you drink less water than you need, you try and —– the fluid ingested to maintain ——.

Answer 100

If you drink more water than you need the excess volume is excreted as urine.

If you drink less water than you need, you try and reabsorb the fluid ingested to maintain homeostasis.

Question 101

What is the normal intake and output of the kidney?

Answer 101

2300ml/day and 900 output respectively

Question 102

What is the outer part of the kidney called?

Answer 102

Cortex

Question 103

What is the inside of the kidney called?

Answer 103

Medulla

Question 104

What is the functional unit of the kidney?

Answer 104

Nephrons

Question 105

The afferent arteriole goes —– the bowman’s capsule.

The efferent arteriole goes —- the bowman’s capsule.

Answer 105

The afferent arteriole goes into the bowman’s capsule.

The efferent arteriole goes out the bowman’s capsule.

Question 106

What are the two types of nephrons?

Whats the difference between them?

Answer 106

Cortical - have small loop of henle’s

Juxtamedullary - long loop of henle’s

Question 107

What is glomerular filtration rate (GFR)?

Answer 107

The rate at which fluid which is virtually free of protein is filtered from the glomerular capillaries into Bowman’s capsule.

Question 108

What is the normal average GFR?

Answer 108

125 ml/min or 144-180L/day

Question 109

Most substances in the plasma are freely filtered so the concentration of the glomerular filtrate in the bowman’s capsule is almost the ——- as the plasma.

As the filtrate passes through the ———, it is modified by both the ———– of water and certain solutes back into the blood as well as by the ——— of substances from the peritubular capillaries into the tubules thereby forming urine

Answer 109

Most substances in the plasma are freely filtered so the concentration of the glomerular filtrate in the bowman’s capsule is almost the same as the plasma.

As the filtrate passes through the nephron, it is modified by both the reabsorption of water and certain solutes back into the blood as well as by the secretion of substances from the peritubular capillaries into the tubules thereby forming urine.

Question 110

Subtle changes in —– can lead to relatively —– changes in renal excretion if the tubular ——- remained constant.

Answer 110

Subtle changes in GFR can lead to relatively large changes in renal excretion if the tubular reabsorption remained constant.

Question 111

If the pressure in the ——- is greater than the pressure in the —— you get filtration

Answer 111

If the pressure in the capillaries is greater than the pressure in the capsule you get filtration

Question 112

What pressures make up the GFR?

Answer 112

Hydrostatic pressure

Osmotic pressure

glomerular capillary filtration coefficient

Question 113

When the efferent arteriole constricts there is an increase ——- in the glomerulus resulting in the GFR ——-.

When the afferent arteriole constricts —– fluid will be filtered

Answer 113

When the efferent arteriole constricts there is an increased pressure in the glomerulus resulting in the GFR increasing.

When the afferent arteriole constricts less fluid will be filtered

Question 114

What mechanism of GFR control is described below?

The concentration of —— and —— in the ——- tubule is sensed by the —– —— cells.

If the GFR is high the concentration of — and —- would be —– causing the —- ——- cells to ——. This is sensed by the ——– arteriole and as a result it ———- to ——- the GFR.

If the GFR is low the concentration of — and —-would be —– causing the — —– cells to ——-. This is sensed by the —— arteriole and as a result it ———- to ——- the GFR.

This is a —— feedback system

This is an ——- mechanism and is called ————- Feedback

Answer 114

The concentration of Na and Cl in the distal tubule is sensed by the macula densa cells.

If the GFR is high the concentration of Na and Cl would be high causing the macula densa cells to swell. This is sensed by the afferent arteriole and as a result it vasoconstricts to decrease the GFR.

If the GFR is low the concentration of Na and Cl would be low causing the Macula densa cells to shrink. This is sensed by the afferent arteriole and as a result it vasodilates to increase the GFR.

This is a negative feedback system

This is an intrinsic mechanism and is called tubuloglomerular Feedback

Question 115

Is the afferent or efferent arteriole more innervated by the sympathetic nerves?

Answer 115

Afferent arteriole

Question 116

Sympathetic nerve innervation and GFR.

There are —- types of sympathetic fibres that innervate the kidney.

Type 1 fibres innervate just the —— arteriole, while type 2 innervates —– and ——– arterioles. As a result the —— arteriole is more innervated than the ——- and therefore will ———– more than the ——–, so more blood passes through and doesn’t get ——.

When you want to retain fluid the sympathetic nerve activity ——— and GFR —–.

If you want to get rid of fluid sympathetic nerve activity —— and GFR ——-.

If you lose blood volume there is an ——– in sympathetic nerve activity causing ————, of the ——- arteriole, ——— GFR, increasing —– —-, therefore not allowing a lot of fluid to be ——–.

Increase in fluid consumption causes a ——— in renal sympathetic nerve activity, causing ———- of the ——– arteriole (efferent doesn’t open up much), ——– GFR and all the fluid is filtered into bowman’s capsule

Answer 116

Sympathetic nerve innervation and GFR.

There are 2 types of sympathetic fibres that innervate the kidney.

Type 1 fibres innervate just the afferent arteriole, while type 2 innervates afferent and efferent arterioles. As a result the afferent arteriole is more innervated than the efferent and therefore will vasoconstrict more than the efferent, so more blood passes through and doesn’t get filtered.

When you want to retain fluid the sympathetic nerve activity increases and GFR decreases.

If you want to get rid of fluid sympathetic nerve activity decreases and GFR increases.

If you lose blood volume there is an increase in sympathetic nerve activity causing vasocontriction, of the afferent arteriole, decreaseing GFR, increasing blood pressure, therefore not allowing a lot of fluid to be filtered.

Increase in fluid consumption causes a decrease in renal sympathetic nerve activity, causing vasodilation of the afferent arteriole (efferent doesn’t open up much), increase GFR and all the fluid is filtered into bowman’s capsule

Question 117

Tubular reabsorption

The —- passes along a tube that has ——– that are impermeable to urea.

——- moves into the cell or intercellular space and gets reabsorbed by the ——– capillary.

——- passes through via osmosis because of the higher —- pressure in the —– than in the —— fluid.

The cell has —- Na and —-K due to the ——– ——- in the basolateral membrane.

The cell has a ——— potential of ——.

Answer 117

The filtrate passes along a tube that has aquaporens that are impermeable to urea.

Na+ moves into the cell or intercellular space and gets reabsorbed by the peritubular capillary.

water passes through via osmosis because of the higher osmotic pressure in the lumen than in the interstitual fluid.

The cell has low Na and high K due to the Na/K ATPase in the basolateral membrane.

The cell has a negative potential of -70mV.

Question 118

Secondary active reabsorption

The —— gradient is maintained by the —- ——–.

The ——- ———– cotransporter, ——–, brings ——- and —– into the cell. The ——- then leaves the cell via ——- and gets absorbed into the capillaries.

Answer 118

The sodium gradient is maintained by the Na/K ATPase.

The sodium glucose cotransporter, SGLT, brings sodium and glucose into the cell. The glucose then leaves the cell via GLUT and gets absorbed into the capillaries.

Question 119

In the first 1/4 of the proximal convoluted tubule most of the —– and ——- acids are reabsorbed.

A lot of —— is reabsorbed but the concentration remains the same because —— is being dragged along with it.

Answer 119

In the first 1/4 of the proximal convoluted tubule most of the glucose and amino acids are reabsorbed.

A lot of sodium is reabsorbed but the concentration remains the same because water is being dragged along with it.

Question 120

Glucose filtration

All the glucose gets ——-.

You are trying to ——– the glucose using the —– —— co transporter, but it can only go so fast.

At some point it cannot ——- at a faster rate so it starts ——– down

Once it starts slowing down glucose starts to show in the ——–, dragging ——with it, ——– urine output

At some point your glucose transporter becomes ———, your plasma glucose levels still ———, so you start —— glucose.

Answer 120

All the glucose gets filtered.

You are trying to reabsorb the glucose using the sodium glucose co transporter, but it can only go so fast.

At some point it cannot reabsorb at a faster rate so it starts slowing down

Once it starts slowing down glucose starts to show in the urine, dragging water with it, increasing urine output

At some point your glucose transporter becomes saturated, your plasma glucose levels still increase, so you start excreting glucose.

Question 121

At the end of the proximal tubule

Around –% of the tubular fluid from the glomerulus has been ———-.

This means a decrease from —L/hr to around — L/hr.

There has been no change in ——- concentration because —– passively follows the —–.

All of the ——– and —— acids have been reabsorbed

The tubular fluid is also ——- with the initial filtrate - missing osmoles (sodium) is replaced by ——

Urea concentration is ~ 2-4x higher than it was in the original glomerular filtrate (and ECF of course) because the proximal convoluted tubule is impermeable to urea

Answer 121

Around 80% of the tubular fluid from the glomerulus has been reabsorbed.

This means a decrease from 6L/hr to around 1.2 L/hr.

There has been no change in sodium concentration because water passively follows the sodium.

All of the glucose and amino acids have been reabsorbed

The tubular fluid is also isoosmoitic with the initial filtrate - missing osmoles (sodium) is replaced by urea.

Iso-osmotic; the missing osmoles are made up by urea (the number of osmoles per unit solution is the same at the end of the proximal convoluted tubule as at the beginning even though the total volume is less by about 80%

Urea concentration is ~ 2-4x higher than it was in the original glomerular filtrate (and ECF of course) because the proximal convoluted tubule is impermeable to urea

Question 122

The thin descending part of the loop of henle is permeable to —— but the thick ascending part is not

Answer 122

The thin descending part of the loop of henle is permeable to water but the thick ascending part is not

Question 123

The thick ascending limb of the loop of Henle

The remaining —– is reabsorbed and the excess —— is reabsorbed via the ——-

Answer 123

The remaining potassium is reabsorbed and the excess Cl is reabsorbed via the sodium, potassium, chloride co transporter.

Question 124

Counter current mechanism

There is no initial ——— gradient in the kidney’s interstitial fluid, the osmolarity is —– mOsm/L throughout the interstitium. This is the —– as the osmolarity of normal body fluids, including the fluid moving inside the —- of ——.
——- is transported out of the ———- limb of the loop of Henle and accumulates in the ——— interstitium. —— exits the —— ascending limb by ——- ——–, and is pumped out of the ——– ascending limb by the ———- cotransporter. The ——— ascending limb is ———- to water, so water stays ——- the loop of henle and the osmolarity of the —— ascending fluid ——-. The —– is added to the interstitial fluid, ———— its osmolarity. This creates a —– mOsm/L difference in the osmolarities of the ——— fluid and the fluid in the —— ascending limb.
——- then diffuses out of the — ——— limb until the fluid there has equilibrated with the ——– fluid at ——- mOsm/L.
Once the ————- limb has equilibrated, —— mOsm/L fluid from the proximal tubule enters the top of the ———– limb. This pushes the ——- osmolarity fluid below it down towards the hairpin curve in the loop of Henle.
The osmolarities of the fluids in the ———– limb and the interstitium are once again mismatched due to —– leaving the —— limb and the movement of fluid in the tube. This causes ——- to leave the ——- limb until the two fluids have re-equilibrated.
You can see a corticopapillary gradient starting to appear. Interstitial fluid in the cortex has an osmolarity of —— mOsm/L, while the papillary interstitial fluid is —— mOsm/L
Steps __-__ are repeated, with each cycle enhancing the ———. At its maximum, the gradient reaches —— mOsm/L between the —— and the inner ——-.

Answer 124

1. There is no initial osmotic gradient in the kidney’s interstitial fluid, the osmolarity is uniform mOsm/L throughout the interstitium. This is the same as the osmolarity of normal body fluids, including the fluid moving inside the tubules of nephrons.
2. Sodium is transported out of the thin descending limb of the loop of Henle and accumulates in the medullary interstitium. Sodium exits the thick ascending limb by active transport, and is pumped out of the thick ascending limb by the sodium-potassium cotransporter. The thick ascending limb is impermeable to water, so water stays in the loop of Henle and the osmolarity of the ascending fluid increases. The sodium is added to the interstitial fluid, increasing its osmolarity. This creates a 200 mOsm/L difference in the osmolarities of the tubular fluid and the fluid in the thick ascending limb.
3. Sodium then diffuses out of the thin descending limb until the fluid there has equilibrated with the interstitial fluid at 300 mOsm/L.
4. Once the thin descending limb has equilibrated, 300 mOsm/L fluid from the proximal tubule enters the top of the thin ascending limb. This pushes the lower osmolarity fluid below it down towards the hairpin curve in the loop of Henle.
5. The osmolarities of the fluids in the thin ascending limb and the interstitium are once again mismatched due to sodium leaving the thin limb and the movement of fluid in the tube. This causes sodium to leave the thin limb until the two fluids have re-equilibrated.
6. You can see a corticopapillary gradient starting to appear. Interstitial fluid in the cortex has an osmolarity of 300 mOsm/L, while the papillary interstitial fluid is 1200 mOsm/L
   Steps 2-5 are repeated, with each cycle enhancing the gradient. At its maximum, the gradient reaches 1200 mOsm/L between the cortex and the inner medulla.

Question 125

The longer the loop of henle you have the greater the —– gradient you will achieve, so the ——- the concentration of the —–.

Answer 125

The longer the loop of henle you have the greater the osmotic gradient you will achieve, so the higher the concentration of the urine.

Question 126

What can you change to allow more fluid to be retained/ less urine?

Answer 126

The longer the loop of henle, the higher the concentration

Change how well or how much the sodium potassium chloride cotransporter there is in the thick ascending limb

Question 127

What are some signs of dehydration?

Answer 127

Thirst
Fatigue
Dry mouth
Concentrated urine

Question 128

Osmoreceptors

Monitor —– deficit

These are specialised cells that sit in the —— —– of the ———, in close contact with ——– that run through the ———. In response to changes in ——– they can —— or ——–, which changes the ——- activity of these cells which signal the supraoptic neurons to release —–.

Answer 128

Monitor water deficit

These are specialised cells that sit in the posterior pituitary of the hypothalamus, in close contact with capillaries that run through the hypothalamus. In response to changes in osmolarity they can expand or shrink, which changes the electrical activity of these cells which signal the supraoptic neurons to release ADH.

Question 129

Antidiuretic hormone (ADH)/Vassopression (AVP)

ADH is manufactured and secreted from the ——- —– of the ——–.

ADH travels down to the —— and binds to — receptors which cause insertions of ——- on the —— —— side, allowing —— to move along its concentration gradient and into the —— interstitial fluid to be absorbed into the ———.

If actions of ADH are impaired (low ADH) it can result in either —— or ——– diabetes insipidus.

——– diabetes insipidus - the pituitary is unable to ——- ADH

———- diabetes insipidus - have the ——– amounts of ADH but the ——— in the kidney do not work.

Answer 129

ADH is manufactured and secreted from the posterior pituitary of the hypothalamus.

ADH travels down to the kidney and binds to V2 receptors which cause insertions of aquaporens on the tubular lumen side, allowing water to move along its concentration gradient and into the interstitial fluid to be absorbed into the capillaries.

If actions of ADH are impaired (low ADH) it can result in either central or nephrogenic diabetes insipidus.

Central diabetes insipidus - the pituitary is unable to secrete ADH

Nephrogenic diabetes insipidus - have the right amounts of ADH but the receptors in the kidney do not work.

Question 130

Why are there high levels of ADH in heart failure?

Answer 130

The heart isn’t beating well, so isn’t perfusing blood to all of its organs, forcing the body to vasoconstrict and keep pressure up and retain as much water as it can.
The high levels of ADH are in response to trying to retain water

Question 131

Does an increase in osmolarity increase ADH levels?

Answer 131

Yes

Question 132

Does a decrease in blood volume increase ADH levels?

Answer 132

Yes

Question 133

Does an increase in ADH levels result in dilute urine?

Answer 133

No

Question 134

ngiotensin and aldosterone

Angiotensinogen gets formed to ———— by the actions of —– which is secreted by the —– cells in the kidneys.

——– is the rate limiting factor - the more —– you have the more ——– you have.

———- gets converted into ——– by the ——– —– enzymes (ACE) in the ——–.

———- can bind to a ——(causes vasoconstriction) or ——- (reabsorption of sodium and water) receptor

Angiotensin 2 activates the —- —— exchanger on the ——- membrane as well as the —– ——— on the —— membrane. Both of these cause ——- to be ———- from the ——- lumen to the ———- space and then into the ——— and the ——– follows

There are about 95% —- receptors and 5% —— receptors, so if ———- binds to both receptors the action of the —– receptor will be expressed almost all the time

So when you inject —– or ——- you get ——— blood pressure

——– can bind to certain cells in the ———- medulla and produce ———-

———- binds to the ——— (MR) receptor and causes insertion of —— channels, which cause reabsorption of ——- into the interstitial fluid

Answer 134

Angiotensinogen gets formed to angiotensin 1 by the actions of renin which is secreted by the granular cells in the kidneys.

renin is the rate limiting factor - the more renin you have the more angiotensin 1 you have.

Angiotensin 1 gets converted into angiotensin 2 by the enzymes (ACE) in the lungs.

Angiotensin 2 can bind to a AT1 (causes vasoconstriction) or AT2 (reabsorption of sodium and water) receptors.

Angiotensin 2 activates the sodium hydrogen exchanger on the apical membrane as well as the sodium potassium ATPase on the basolateral membrane. Both of these cause sodium to be reabsorbed from the tubular lumen to the interstitial space and then into the capillaries and the water follows

There are about 95% AT1 receptors and 5% AT2 receptors, so if angiotensin 2 binds to both receptors the action of the AT1 receptor will be expressed almost all the time

So when you inject renin or angiotensin 2 you get increased blood pressure

Angiotensin 2 can bind to certain cells in the adrenal medulla and produce aldosterone

Aldosterone binds to the mineralocorticoid (MR) receptor and causes insertion of ENac channels, which cause reabsorption of sodium into the interstitial fluid

Question 135

What factors determine renin release from the granular cells in the kidney?

Answer 135

Afferent arteriolar pressure

Macula densa NaCl delivery

Sympathetic nerve activity

Question 136

Renin release

Renin promotes increased ——- —– via ———.

If blood pressure is high, there will be ——– renin release.

If blood pressure is low, there will be ——- renin release.

If there is decreased Na concentration in the —– —- cells, there will be ——- renin release.

If there is increased Na concentration in the —– —- cells, there will be ——- renin release.

If sympathetic nerve activity to the kidney increases, there will be —– renin release along with ——- of the ——- arteriole.

Answer 136

Renin promotes increased blood pressure via angiotensin 2.

If blood pressure is high, there will be decreased renin release.

If blood pressure is low, there will be increased renin release.

If there is decreased Na concentration in the macula densa cells, there will be increased renin release.

If there is increased Na concentration in the macula densa cells, there will be decreased renin release.

If sympathetic nerve activity to the kidney increases, there will be increased renin release along with vasoconstriction of the afferent arteriole.

Question 137

If there is an elevated extracellular ——— concentration you can directly regulate the release of ——– from the adrenal medulla

Answer 137

If there is an elevated extracellular potassium concentration you can directly regulate the release of aldosterone from the adrenal medulla

Question 138

What can block the actions of aldosterone?

Answer 138

Spironolactone which binds to the receptor for aldosterone

Question 139

What can block the actions of aldosterone?

Answer 139

Spironolactone which binds to the receptor for aldosterone

Question 140

What regulates Osmolality?

Answer 140

Renal water handling - ADH

Question 141

What regulates ECF volume?

Answer 141

Renal sodium handling - renin-angiotensin and sympathetic systems.

Question 142

Changes in ECF volume are compensated by changes in —- reabsorption by the kidney.

Decreased EFC volume is compensated by ——- renal reabsorption of ——– via the — —- —- system and the — — system.

Increased ECF volume is compensated by ——- renal reabsorption of ——— via decreased activity of the —— —– —- system and —- ——-

Answer 142

Changes in ECF volume are compensated by changes in sodium reabsorption by the kidney.

Decreased EFC volume is compensated by increased renal reabsorption of sodium via the renin angiotensin aldosterone system and the sympathetic nervous system.

Increased ECF volume is compensated by decreased renal reabsorption of sodium via decreased activity of the renin angiotensin aldosterone system and sympathetic nervous

Also increased secretion of Atrial natriuretic peptide (ANP) by the cardiac muscle cells in the atrial wall in response to increased stretch in the atrial wall due to increased volume, reduces extracellular matrix volume by increasing sodium excretion.

Question 143

What are some Anti-hypertensive medication (high BP)?

Answer 143

irbesartan, candesartan - block AT1 receptors

Prils (ramipril, captoprils) which are the ACE (in the lungs converts angiotensin 1 to 2) inhibitors

Once this medication is consumed the blood pressure is going to be low irrespectively

Question 144

Does an increase in macula densa NaCl concentration lead to a decrease in renin secretion?

Answer 144

yes

Question 145

Does increased production of angiotensin 2 inhibit the sodium hydrogen exchanger?

Answer 145

No

Question 146

Does an increase in angiotensin 2 result in excretion of salt and water in the urine?

Answer 146

No

Question 147

What happens when you eat a lot of salt chips?

There is no change in volume.

As soon as the ——– is reabsorbed the osmolarity will ———-

This increase is sensed by the ———– in the ——— which then secrete ——–.

Increased ——- levels, increases the amount of —– retained through the signalling of ———.

This balances the osmolality

There is now an increased blood ——– which is sensed by the ———- receptors (sense how much the heart stretches). Increased blood volume, increases ——- return to the heart, these receptors fire signals which ——– sympathetic drive to the kidney which allows the excretion of —– and ——-, bringing volume back to its normal (reflex pathway - slow response).

If the increase in blood volume is substantial the ——– is going to increase. If the ——– increased then the carotid and aortic baroreceptors will sense that

Answer 147

As soon as the sodium is reabsorbed the osmolarity will increase

This increase is sensed by the osmoreceptors in the hypothalamus which then secrete ADH.

Increased ADH levels, increases the amount of water retained through the signalling of aquaporins.

This balances the osmolality

There is now an increased blood volume which is sensed by the cardiopulmonary receptors (sense how much the heart stretches). Increased blood volume, increases venous return to the heart, these receptors fire signals which decreases sympathetic drive to the kidney which allows the excretion of sodium and water, bringing volume back to its normal (reflex pathway - slow response).

If the increase in blood volume is substantial the pressure is going to increase. If the pressure increased then the carotid and aortic baroreceptors will sense that

Question 148

Does a high salt pasta meal lead to a decrease in angiotensin 2 levels?

Answer 148

Yes

Question 149

Does dehydration lead to a decrease in ADH levels?

Answer 149

No

Question 150

Is the angiotensin response to haemorrhage decreases if the renal nerves to the kidney are denervated?

Answer 150

yes

Denervated - cut,

Angiotensin 2 response to haemorrhage - decrease in blood volume, so increased renin = increase.

Response is decreased because the renin response also depends on an increase in sympathetic nerve activity to the kidney

Question 151

Does an increase in angiotensin 2 levels result in excretion of salt and water in the urine?

Answer 151

No

Question 152

Is angiotensin released by the juxtaglomerular cells when renal perfusion pressure increases?

Answer 152

No

Angiotensin is not released by the juxtaglomerular cells, renin is.

Question 153

Does stenosis of the renal artery lead to increased sodium and water reabsorption?

Answer 153

A
Yes

Stenosis = narrowing, when you have stenosis there is plaque build up in the artery which decreases the amount of flow to the kidney, there is decreased pressure, which increases renin, angiotensin 2 and therefore sodium and water reabsorption

Question 154

Change in blood volume

Decreased blood volume leads to ——— blood pressure.

The ——– receptors in the —- and —– and —– baroreceptors sense this change.

The cardiovascular system responds by —— cardiac output and ————.

——— intake results in increase ——- and —– fluid volume.

Both these factors ——– blood pressure.

Kidneys act to conserve —– by increased ———– —– activity, ———- of the ——- arteriole and via the —— —– —— system.

Answer 154

Decreased blood volume leads to decreased blood pressure.

The volume receptors in the atria and aortic and carotid baroreceptors sense this change.

The cardiovascular system responds by increasing cardiac output and vasoconstriction.

Water intake results in increase extracellular and intracellular fluid volume.

Both these factors increase blood pressure.

Kidneys act to conserve water by increased sympathetic nerve activity, vasoconstriction of the afferent arteriole and via the renin angiotensin aldosterone system (sodium and water retention).

Question 155

Osmolarity, Blood volume, Blood pressure

Increased osmolarity is sensed by the ———— in the ——- ——- of the ——–.

Decreased blood volume is sensed by the —– —– receptors.

Decreased blood pressure is sensed by the —- and —– baroreceptors.

—— is released which binds to —– receptors causing insertion of ——- on the tubular lumen side. This allows —— to be reabsorbed along its concentration gradient and into the capillaries.

There is increased —— reabsorption, which decreases ——–, increases blood —– and ———.

Answer 155

Increased osmolarity is sensed by the osmoreceptors in the posterior pituitary of the hypothalamus.

Decreased blood volume is sensed by the atrial stretch receptors.

Decreased blood pressure is sensed by the carotid and aortic baroreceptors.

ADH is released which binds to V2 receptors causing insertion of aquaporins on the tubular lumen side. This allows water to be reabsorbed along its concentration gradient and into the capillaries.

There is increased water reabsorption, which decreases osmolarity, increases blood volume and pressure.