Physiology

Question 1

What passes through Fenestrated Capillary Cells?

Answer 1

Non-formed elements I.e. Not cells (less than 100 nm)

Question 2

What drains the Glomerulus?

Answer 2

An efferent arteriole

Question 3

What is the main function of the Kidney?

Answer 3

To maintain a stable internal environment

Question 4

What processes are undergone by the kidney?

Answer 4

Filtration, reabsorption and secretion

Question 5

What is the Glomerulus?

Answer 5

The filtering unit of the kidney

Question 6

What is the Renal Blood Flow?

Answer 6

25% of cardiac output

Question 7

How is blood flow changed in the kidney?

Answer 7

By changing Afferent and/or Efferent arteriolar resistance

Question 8

How is Renal Blood Flow calculated?

Answer 8

Q = ΔP/R

Question 9

What is the renal arterial pressure?

Answer 9

80 - 200 mm Hg

Question 10

What happens if renal arteriole pressure increases?

Answer 10

Renal resistance will increase proportionally

Question 11

What is the Myogenic Theory of autoregulation of RBF?

Answer 11

Increased arterial pressure stretches the blood vessels, causing reflex contraction of smooth muscle in the blood vessel walls and consequently increased resistance to blood flow

Question 12

Where is autoregulation of RBF controlled?

Answer 12

At the level of the Afferent arteriole

Question 13

What happens when blood pressure is increased according to the Myogenic theory of autoregulation of RBF?

Answer 13

Resistance is increased
RBF is kept constant
GFR is increased

Question 14

What happens when blood pressure decreases according to the Myogenic theory of autoregulation of RBF?

Answer 14

Resistance is decreased
RBF is kept constant
GFR is increased

Question 15

What are the effects of the SNS on RBF?

Answer 15

⍺1 receptors (more common on afferent arterioles) stimulate vasoconstriction, decreasing RBF and GFR

Question 16

What are the effects of high levels of Angiotensin II on RBF?

Answer 16

It causes vasoconstriction of both afferent and efferent arterioles (efferent more than afferent), increasing resistance and decreasing RBF

Question 17

What are the effects of low levels of Angiotensin II on RBF?

Answer 17

It produces an increase in GFR by preferentially constricting efferent arterioles

Question 18

What are the effects of Atrial Natriuretic Peptide on RBF?

Answer 18

It causes dilation of afferent arterioles and constriction of efferent arterioles, increasing RBF and GFR

Question 19

What are the effects of Prostoglandins on RBF?

Answer 19

It causes vasodilation of both afferent and efferent arterioles

Question 20

What are the effects of Dopamine on RBF?

Answer 20

Low dosages dilate renal arterioles, increasing RBF

Question 21

What is Ultrafiltrate composed of?

Answer 21

It is composed of Water and all of the small solute of blood (not proteins or blood cells)

Question 22

What is the pathway for ultrafiltration of plasma from the glomerulus to the Bowman space?

Answer 22

Fenestrated capillary endothelium > Capillary basement membrane > Visceral epithelial cell layer (podocytes) of Bowman Capsule

Question 23

What is the Ultrafiltration Coefficient determined by?

Answer 23

The hydraulic conductivity of the glomerular capillary wall and the total capillary surface area available for filtration

Question 24

What determines the GFR?

Answer 24

The Starling Equation
SNGFR = Kf x (∆P-∆𝜋)
SNGFR = Kf x [(Pgc −Pbs)−(𝜋gc −𝜋bs)]

Question 25

How is hydrostatic pressure in glomerular capillaries changed?

Answer 25

It is change by changing the resistance of the afferent and efferent arterioles

Question 26

How is hydrostatic pressure changed in Bowman's space?

Answer 26

it can be changed by obstructing urine flow

Question 27

How is oncotic pressure in glomerular capillaries changed?

Answer 27

It is changed by changing the plasma protein concentration.

Question 28

What happens to oncotic pressure in glomerular capillaries when plasma protein concentration is increased?

Answer 28

It is increased | Net ultrafiltration and GFR is decreased

Question 29

What happens to oncotic pressure in glomerular capillaries when plasma protein concentration is decreased?

Answer 29

It is decreased | Net ultrafiltration pressure and GFR is increased

Question 30

What is the filtration fraction?

Answer 30

It is the fraction of the Renal Plasma Flow that is filtered across the glomerular capillaries It expresses the relationship between the GFR and RPF

Question 31

What is the normal filtration fraction?

Answer 31

20%

Question 32

What happens if the filtration fraction is increased?

Answer 32

It produces increases in the protein concentration and oncotic pressure in glomerular capillaries of peritubular capillary blood

Question 33

What is Renal Clearance?

Answer 33

It is the volume of plasma completely cleared of a substance by the kidney per unit time

Question 34

What does it mean if a substance has high renal clearance?

Answer 34

It is completely removed on a single pass of blood through the kidneys

Question 35

What substances have high renal clearance?

Answer 35

Inulin, Fructose, Polymers, Para-aminhippuric acid

Question 36

What does it mean if a substance has a low renal clearance?

Answer 36

It is not removed well

Question 37

What substances have low renal clearances

Answer 37

Protein, Glucose

Question 38

How is GFR measured?

Answer 38

Using a substance that: 1. Is freely filtered across the glomerular capillaries without size or charge restrictions 2. Cannot be reabsorbed or secreted by the renal tubule 3. cannot alter the GFR when infused

Question 39

What can be used to measure GFR?

Answer 39

Inulin (must be injected intravenously)

Question 40

What are the patterns of reabsorption?

Answer 40

Complete Reabsorption - The filtered substance is completely reabsorbed and is not present in urine Zero Reabsorption - The Filtered substance is not reabsorbed and is present in its entirety (or close to) in the kidney Regulated and Variable reabsorption - Reabsorption is dependant on the circumstances

Question 41

How does tubular transport work?

Answer 41

Through Vectorial transport - the net movement of substance from tubular fluid to blood or vice versa

Question 42

How is the proximal tubule adapted to bulk reabsorption of glomerular filtrate?

Answer 42

The epithelial cells have microvilli on their apical surface to provide large area and the basolateral membrane has folds

Question 43

How is Na+ absorbed in the early proximal tubule?

Answer 43

Na+ is mainly absorbed with HCO3- and organic solutes, i.e. glucose and amino acids

Question 44

How is Na+ in the late proximal tubule?

Answer 44

Na+ is mainly absorbed with Cl-

Question 45

How much Na+ and what else is reabsorbed in the same amount?

Answer 45

67%, water is reabsorbed in the same amount

Question 46

What is isosmotic reabsorption?

Answer 46

The tight coupling between Na+ and water reabsorption

Question 47

What is reabsorbed in the proximal tubule?

Answer 47

65% of water, sodium, potassium and chloride 100% of glucose and amino acids 85%-90% of bicarbonate

Question 48

What is the purpose of secretion in the proximal tubule?

Answer 48

To rapidly clear endogenous solutes and medications from the circulation

Question 49

What is absorbed in the thick ascending limb of the loop of henle and what are the effects?

Answer 49

Sodium, potassium, chloride, bicarbonate and magnesium are reabsorbed. Water is not absorbed. This lowers tubular osmolarity.

Question 50

What are the types of Nephrons?

Answer 50

Cortical (superficial) and Juxtamedullary (deep)

Question 51

What is a nephron?

Answer 51

The functional unit of the kidney

Question 52

What are the nephron segments?

Answer 52

The Bowman's capsule, the Proximal Convoluted Tubule, the Proximal Straight Tubule, the Loop of Henle, the Distal Convoluted Tubule, the Collecting Duct

Question 53

What is Renal Plasma Flow?

Answer 53

The portion of RBF that Is only plasma

Question 54

What is the Paracellular transport pathway?

Answer 54

Passive transport where molecules travel between individual cells

Question 55

What is the Transcellular Transport Pathway?

Answer 55

When molecules travel through cells

Question 56

What does Sodium/Potassium ATPase transport?

Answer 56

It transports 3 Na+ out of the cell and 2 K+ into the cell

Question 57

What is the purpose of Sodium/Potassium ATPase?

Answer 57

It creates a Na+ concentration gradient and a voltage gradient

Question 58

What modes of transport are utilised by Sodium/Potassium ATPase?

Answer 58

Both active and passive transport mechanisms

Question 59

What are the methods of water transport in the tubule?

Answer 59

Paracellular, transcellular and solvent drag/bulk transport

Question 60

What is the renal threshold of reabsorption

Answer 60

The maximum amount of any given substance to be reabsorbed

Question 61

What happens if the renal threshold is exceeded?

Answer 61

The additional substances are lost to the urine

Question 62

What is the difference between Peritubular Capillary absorption and regular capillary absorption?

Answer 62

Peritubular capillaries reabsorb fluid across their entire length whereas regular capillaries filer along their 1st half and reabsorb along their 2nd half

Question 63

What is the primary function of the Proximal Tubule?

Answer 63

To reabsorb as much of those substances the body needs as possible

Question 64

What is the transport mechanism of Cl- reabsorption in the Proximal Tubule?

Answer 64

The Paracellular mechanism

Question 65

How much HCO3- is reabsorbed by the Proximal Tubule?

Answer 65

About 80%

Question 66

What is the function of the parathyroid hormone in the proximal tubule?

Answer 66

It inhibits Phosphate reabsorption