Physiological kidney Function

Question 1

Relationship between Na+ and Osmatic pressure

Answer 1

1 mmol Na+ + 1 mmol Cl- = 2 mOsm/L

Question 2

Osmatic pressure def

Answer 2

Pressure applied to solution to prevent extra solvent moving across semi-permeable membrane and entering solution. Units: Osm/L

Question 3

Where in relation to the cell is there a higher Na conc

Answer 3

Outside cell. Need ATPase pumps and energy to move across conc gradient

Question 4

Extracellular Fluid Osmarility at Isotonic with cell

Answer 4

300 mOsm/L

Question 5

Function of Blood Volume Regulation

Answer 5

Maintains blood pressure. Controlled by salt balance (aldosterone)

Question 5

Function of Blood Osmorality Regulation

Answer 5

Maintains cell structure. Controlled by water retention (anti-diuretic hormone)

Question 6

Salt and Water Intake and Excretion

Answer 6

Intake: diet and respiration (water = waste), excretion: faeces, sweat, exhalation (water only) and urine (only 1 regulated)

Question 7

What is Na+ and water balance

Answer 7

When intake of substances = excretion

Question 7

Type of transport Na+ experiences from interstitial fluid across capillary membrane

Answer 7

Diffusion. Down conc gradient

Question 7

Type of transport Na+ experiences across tubule epithelial membrane on basolateral side

Answer 7

Active transport. Na+ and K+ ATPase pumps. UP conc gradient

Question 7

Type of transport Na+ experiences across luminal side tubule (nephron) epithelial membrane

Answer 7

Diffusion (some facilitated, passive and with co-transporters eg glucose and amino acids). Down conc gradient

Question 8

Region of regulated filtered Na+ uptake

Answer 8

Distal tubule and collecting ducts. High blood pressure = little/no uptake = most excreted in urine

Question 9

Relationship between Na+ levels and blood pressure

Answer 9

High Na+ levels = high blood pressure

Question 10

Renin-Angiotensin-Aldosterone System

Answer 10

3 Hormone system. Activated in cases of low blood pressure/volume. Increases filtered Na+ uptake (greater retention). Contain juxtaglomerular complex

Question 11

Juxtaglomerular Complex Outline

Answer 11

Region where distal convoluted tubule connects to afferent and efferent arterioles. Contains mesangial cells that sense Na+ levels in blood

Question 12

Granular Cells Outline

Answer 12

1st part of juxtaglomerular complex. Stimulated by drop in arterial blood pressure (interatrial baroreceptors), drop in plasma Na+ or drop extra cellular fluid volume (sympathetic NS). Excrete renin into blood

Question 13

Macula Densa Outline

Answer 13

Cells in tubule part of juxtaglomerular region. Senses NaCl levels in tubule lumen

Question 14

Effect of Renin in Blood

Answer 14

Converts Angiotensinogen to angiotensin 1

Question 15

Effect of angiotensin converting enzyme (ACE) in blood

Answer 15

Converts angiotensin 1 to angiotensin 2

Question 16

Angiotensin 2 Function

Answer 16

Stimulates adrenal gland to produce aldosterone

Question 17

Aldosterone Function

Answer 17

Increases Na channels on luminal membrane and increases no. of ATPase pumps on basolateral side of distal and collecting tubes cell membranes. This increases the amount of Na out of lumen per unit time and the amount of Na reabsorbed and K+ secreted

Question 18

Association between Na+ and water retention

Answer 18

High Na+ levels = high water retention = high blood volume = low urine volume. More Na+ excreted is more water excreted (by osmosis)

Question 19

Natriuretic Peptides/Hormones

Answer 19

Lowers Blood Pressure by decreasing Na+ reabsorption. Inhibit renin , aldosterone, ADH and vasopressin secretion and sympathetic signalling. Produced in heart and released when muscle cells are stretched more with increased blood volume/pressure

Question 20

2 Types of Natriuretic Hormones

Answer 20

Atrial natriuretic peptide (produced by atrial cardiac muscle cells) and brain natriuretic peptide (produced ventricular cardiac muscle cells)

Question 21

Vasopressin (Anti-diuretic hormone function)

Answer 21

Retention of water

Question 22

Anti-diuretic Hormone Action

Answer 22

enables distill convoluted tubule to be permeable to water by inserting aquaporin 2 on luminal side (aquaporins 3 and 4 are always on basolateral side)

Question 23

Osmatic Gradient Outline

Answer 23

Difference in osmolality surrounding distill convoluted tubule (hypertonic interstitum)(dependent on hydration state, low diff if well hydrated, thus water isn’t reabsorbed this way if well hydrated). Osmality increases moving from outer cortex to medulla. Water moves into medulla as it moves by osmosis into hypertonic (>300 mOsm/L) space

Question 24

Vasopressin Production

Answer 24

Produced in hypothalamus stored in posterior pituitary gland. Released when extracellular fluid is hypertonic (body is dehydrated)

Question 25

Area of most K+ reabsorption

Answer 25

Proximal tubule and ascending loop of Henlee. Most K+ in body is in interstitial fluid due to ATPase Pumps. K+ moves through pumps (active across basolateral , out of cells, against conc gradient) and paracellular uptake (passive into cells, down conc gradient)

Question 26

Aldosterone relation to K+ secretion

Answer 26

Aldosterone increases K+ secretion by adding more ATPase pumps on basolateral membrane increasing Na+ absorption and K+ secretion. When K+ levels are low in plasma aldosterone production reduces

Question 27

Increased plasma membrane K+ levels results in

Answer 27

Depolarization (charge becomes positive). Lower membrane potential

Question 28

Decreased plasma membrane K+ levels result in

Answer 28

Hyperpolarisation (charge becomes negative). Increased membrane potential

Question 29

Blood pH

Answer 29

7.4. Ranges from 7.35 in veins - 7.45 in arteries. (veins have carbonic acid from CO2). Acidosis = below 7.35, akalosis = above 7.45 (enzymes denature)

Question 30

3 ways to maintain ECF pH

Answer 30

Chemical buffers (bind free H+, raise pH), respiration fluxes (CO2 levels), renal (H+ in urine, HCO3- reabsorbed (used as buffer, forming carbonic acid))

Question 31

relationship between HCO3- and Cl-

Answer 31

as one is reabsorbed the other is secreted to maintain cell charge

Question 32

How H+ is secreted into urine

Answer 32

H+ ATPase pump