resp anatomy

Question 1

Where is the glomerulus found

Answer 1

The cortex

Question 2

What is the glomerular filtrate

Answer 2

The substance passing through into the renal tubules, which contains no blood cells or platelets and nearly no proteins. It contains organic solutes of a low Mr and inorganic ions.

Question 3

The glomerular filtrate is equal to what

Answer 3

Plasma without the plasma cells

Question 4

What is the surrogate marker for GFR

Answer 4

Renal clearance

Question 5

What does a decrease in GFR indicate

Answer 5

Decline in number of nephrons/ function within each nephron

Question 6

Why might kidney damage be detected late

Answer 6

When kidney function declines slowly individual nephrons may hypertrophy so actual kidney function may not fall much until there’s been significant damage

Question 7

What is renal clearance

Answer 7

The volume of plasma that is cleared of a substance in a unit of time

Question 8

How does GFR vary in babies

Answer 8

Nephron development finishes between week 35 and 36. Foetal excretion relies on the placenta. At birth GFR is approximately 20ml a minute and becomes normal by 18 months

Question 9

How does GFR vary with age

Answer 9

GFR starts declining after 30 by 6-7ml/min per decade and a loss of functioning nephrons. Some compensatory hypertrophy occurs

Question 10

How does GFR vary in pregnancy

Answer 10

It increases to 130-180 ml/min and kidney size increases but nephron number doesn’t. GFR is back to pre-pregnancy levels at 6 months post partum

Question 11

What should be the qualities of a substance used to measure clearance of the kidneys

Answer 11

Be produced at a constant rate, be freely filtered accords the glomerulus, to be reabsorbed into the nephron or secreted into the nephron.

Question 12

What is inulin

Answer 12

A plant polysaccharide that is ingested and freely filtered, not reabsorbed and not secreted.

Question 13

Why do we not use inulin to measure clearance

Answer 13

It requires a continuous IV for a steady state and a catheter with time during collection

Question 14

What is 51 Cr- EDTA

Answer 14

Radioactive labelled marker which is exclusively cleared by renal filtration and timed injection with blood samples every 2,3,4 hours afterwards can be used for clearance. It is used clinically in children or where an indication of renal function is required. Clearance is 10% lower than inulin potentially due to reabsorption and this musta be accounted for

Question 15

How is creatinine used for GFR

Answer 15

Measured urine creatinine over 24 hours and serum creatinine. It can be inaccurate and a bottle of urine must be carried. It overestimates GFR by 10-20% due to creatinine secretion. It is used in pregnancy

Question 16

How do you convert serum creatinine measurements from uk to us

Answer 16

Micro moles per litre in UK P. Divide by 88.4 for mg/dL

Question 17

What can effect creatinine levels

Answer 17

Large muscle mass, lots of meat, supplements, young male.

Question 18

What may serum creatinine reflect on individuals

Answer 18

Widely varied GFR especially for those with muscle mass

Question 19

How do you estimate GFR from serum creatinine

Answer 19

eGFR or CKD-EPI which is recommended by NICE

Question 20

What are the problems with estimating GFR

Answer 20

eGFR is inaccurate in mild kidney disease. Reduced nephron number leads to hypertrophy so no change in GFR. Reduced creatinine filtration results in increased serum creatinine and increased secretion into the tubular in order to maintain a steady state of serum creatinine.

Question 21

Define reabsorption

Answer 21

The movement of a substance from the tubular fluid back into the circulation

Question 22

Define secretion

Answer 22

The movement of a substance from the blood into the tubular fluid via tubular cells of intracellular spaces

Question 23

Define excretion

Answer 23

The removal of waste products from the blood and the net result of filtration, secretion and reabsorption of a substance.

Question 24

When a substance is in the nephron they are considered…

Answer 24

Outside the body

Question 25

What is facilitated diffusion

Answer 25

Diffusion which relies on a carrier

Question 26

How much sodium is reabsorbed?

Answer 26

99.5%

Question 27

What is secondary active transport

Answer 27

the use of the electrochemical gradient set up by NA K ATPase

Question 28

What does the ureter become

Answer 28

The renal pelvis

Question 29

Where do the renal arteries branch

Answer 29

The aorta at L1

Question 30

Principal

Answer 30

Receptors for ADH with few mitochondria

Question 31

What are intercalated cells

Answer 31

They secrete hydrogen ions and have lots of mitochondria

Question 32

What’s the function of renin

Answer 32

Acts on angiotensinogen to produce angiotensin 1. ACE concerts this to angiotensin 2 which causes resorption of Na and aldosterone secretion

Question 33

Describe the function of EPO

Answer 33

Stimulates erythrocyte production

Question 34

Describe endothelial cells of glomerular capillaries

Answer 34

Thin and flat with a large nucleus and perforated by numerous fenestrae which allow plasma to cross but not larger blood components

Question 35

Describe the basement membrane of the glomerulus

Answer 35

Continuous thin layer of connective tissue and glycoprotein

Question 36

Describe the epithelial lining of the bowman’s capsule

Answer 36

A single layer of podocytes which rest on the basement membrane. Large trabeculae extensions which embed in the basement membrane. Pedicels extend from the trabeculae and wrap around the pedicels of adjacent trabeculae which forms split pores which control the movement of substances through the filter. Podocytes have well delevoped Golgi in order to maintain the basement membrane.