K2 - Kidney Structures and Function

Question 1

what are the functions of the kidneys?

Answer 1

• water balance
• salt balance
• maintenance of plasma volume
• maintenance of plasma osmolarity
• acid-base balance
• excretion of metabolic waste products
• excretion of exogenous foreign compounds
• secretion of renin and erythropoietin
• conversion of vitamin D into active form

Question 2

what organ in the body regulars volume, composition and osmolarity of body fluids by the controlled excretion of substances?

Answer 2

kidneys

Question 3

what part of the kidney has a granulated appearance and lines the outside?

Answer 3

renal cortex

Question 4

what is the region of the kidney that is made up of individual renal pyramids and has a stripped appearance?

Answer 4

renal medulla

Question 5

where does the urine drain into in the kidneys before entering the ureter?

Answer 5

renal pelvis

Question 6

what is the functional unit of the kidneys?

Answer 6

nephron

Question 7

what makes up the wall of the nephron?

Answer 7

single layer of epithelial cells

Question 8

describe the vascular component of the kidney?

Answer 8

renal artery > afferent arteriole > glomerulus > efferent arteriole > peritubular capillaries> venule > renal vein

Question 9

what part of the nephron drains into the loop of Henle?

Answer 9

proximal tubule

Question 10

where is the loop of Henle located?

Answer 10

starts off in the cortex and then loops down into the medulla before returning to the cortex

Question 11

what drains tubular fluid into the collecting duct?

Answer 11

distal tubule

Question 12

what is the importance of the juxtaglomerular apparatus?

Answer 12

contains specialised cells where fluid from the distal tubule passes between the afferent and efferent arterioles

Question 13

what are the two types of nephrons?

Answer 13

juxtamedullary and cortica

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Question 14

what are the differences between the two types of nephrons?

Answer 14

• length of the loop of Henle is longer in the Juxtamedullary than in the cortical
• juxtamedullary has a single capillary structure called the vasa recta instead of peritubular capillaries

Question 15

what type of nephron produces more concentrated urine?

Answer 15

juxtamedullary

Question 16

what is the single layer of endothelial cells which contain pores. the afferent arteriole drains into and is important in filtration?

Answer 16

glomerulus

Question 17

what is in close proximity of the glomerulus and is made up of single layer of epithelial cells where the inner layer contains specialised cells called podocytes?

Answer 17

bowman’s capsule

Question 18

what specialsed vascular cells of the juxtaglomerular apparatus produces and secretes renin ?

Answer 18

granular cells

Question 19

what are the salt sensitive cells that sense the amount of salt in the tubular fluid?

Answer 19

macula densa

Question 20

what is urine?

Answer 20

modified filtrate of the blood

Question 21

what importance do the kidneys have in the production of urine (3)?

Answer 21

• filtration system
• rich blood supply
• mechanisms for urine modification

Question 22

what is glomerular filtration?

Answer 22

• 20% of the plasma that enters the glomerulus is filtered

- 80% of the plasma that enters the glomerulus is not filtered and returned back to the blood

Question 23

what is tubular reabsorption?

Answer 23

tubular fluid is reabsorbed back into the blood stream via the peritubular capillaries

Question 24

what is tubular secretion?

Answer 24

fluid from the blood stream is secreted into the tubular fluid

Question 25

how do you calculate rate of filtration of a substance?

Answer 25

mass of X filtered into the Bowman’s capsule per unit time.

Rate of filtration of X = [X]plasma GFR

Question 26

what is the constant value for GFR - glomerular filtration rate?

Answer 26

125ml/min

Question 27

how do you calculate the Rate of excretion of a substance?

Answer 27

Rate of excretion of X = mass of X excreted per unit time.

Rate of excretion of X = [X]urine Vu

Question 28

how do you calculate rate of reabsorption of a substance?

Answer 28

If rate of filtration > rate of excretion, net reabsorption of that substance has occured.

Rate of reabsorption of X = rate of filtration of X – rate of excretion of X

Question 29

how do you calculate the rate of secretion of a substance?

Answer 29

If rate of filtration < rate of excretion, net secretion of that substance has occured.

Rate of secretion of X = rate of excretion of X – rate of filtration of X

Question 30

describe the filtration component of the kidney?

Answer 30

glomerulus > bowman’s capsule > proximal tubule > loop of henle > distal tubule > collecting duct > renal pelvis > ureter > urinary bladder > uretha