1 – Physiological Anatomy of Kidney and Urine Formation

Question 1

What are the main components of our body?

Answer 1

-water and solutes=body fluids
>we don’t have pure water in our body=cells would burst

Question 2

What are the main stores of fluid in our body?

Answer 2

1. Intracellular fluid (65%)
2. Extracellular fluid (28%)
3. Blood/plasma (7%)
   *changes in one affects other stores
   >tight regulation is needed

Question 3

What do the kidneys regulate in order to regulate body fluids?

Answer 3

-plasma volume
-inorganic solutes
-osmotic balance
-acid-base balance (pH)
-removing waste products

Question 4

Kidney locations:

Answer 4

-retroperitoneal
-dorsal aspect of animals
-posterior aspect of humans
-hilum

Question 5

Hilum of kidney:

Answer 5

-gateway for entry and exit of blood vessels, ureters and nerves

Question 6

Outermost part of kidney:

Answer 6

-tough, fibrous layer=renal capsule
-protection

Question 7

Medulla contains:

Answer 7

-cone shape structures that open into the centre of the kidney (renal pelvis)

Question 8

Renal pelvis:

Answer 8

-dilated area of ureter

Question 9

What is the functional unit of the kidney?

Answer 9

-nephron
>around 1 million in each kidney

Question 10

Nephrons:

Answer 10

-each can produce urine by itself INDEPENDTLY of other nephrons
-no re-generable (but highly adaptable)

Question 11

What are the 2 structural components of each nephron?

Answer 11

1. Tubular component
2. Vascular component

Question 12

Tubular component of nephron contains:

Answer 12

-Bowman’s capsule
-proximal tubule
-Loop of Henle
-distal tubule (goes close to Bowman’s capsule)
-connecting tubule
-collecting tubule (cortical and medullary)
-collecting duct

Question 13

Loop of Henle:

Answer 13

-descending limb: toward medulla
-ascending limb: 2 segments
>thin and thick

Question 14

How much of cardiac output is renal blood flow?

Answer 14

-22%

Question 15

Vascular component of each nephron:

Answer 15

*2 capillary networks associated with each nephron
>glomerulus
>peritubular

Question 16

Glomerulus:

Answer 16

-network of glomerular capillaries
-afferent arterioles brings blood in
-efferent arterioles bring blood out

Question 17

What supplies blood to the glomerulus capillaries?

Answer 17

-afferent arterioles

Question 18

What supplies blood to the peritubular capillaries?

Answer 18

What supplies blood to the peritubular capillaries?

Question 19

Glomerular capillaries are important for

Answer 19

-important for the FILTRATION process
>leaky

Question 20

Peritubular capillaries are important for:

Answer 20

-REABSORPTION process

Question 21

What are the 2 types of nephrons?

Answer 21

1. Cortical nephron
2. Juxtamedullary nephron

Question 22

Cortical nephron:

Answer 22

-70-80% of all nephrons
-glomeruli in outer cortex
-short loop of Henle (not into medulla)
-extensive network of peritubular capillaries

Question 23

Juxtamedullary nephron:

Answer 23

-20-30% of all nephrons
-glomeruli closer to medulla
-long loop of Henle (deep into medulla)
-peritubular capillaries are side by side to Loop of Henle
>vasa recta (not extensive)

Question 24

Vasa recta:

Answer 24

-specialized peritubular capillaries seen in juxtamedullary nephrons

Question 25

What is the product of renal function?

Answer 25

-urine

Question 26

What are the 3 processes important for renal function and formation of urine?

Answer 26

1. Filtration (glomeruli)
2. Reabsorption (tubules)
3. Secretion (tubules)
   *all occur in each nephron

Question 27

Secretion:

Answer 27

-removal of substances from peritubular capillaries and release it into the tubule
Ex. drugs, acids, or bases

Question 28

Excretion of different substances in urine varies based on how they are:

Answer 28

-filtered
-reabsorbed
-secreted

Question 29

What is the urinary excretion rate? (equation)

Answer 29

Excretion=filtration – reabsorption + secretion
*filtration and reabsorption are significantly higher than excretion (for most solutes)

Question 30

What happens if filtration rate increases by 10% but reabsorption stays the same?

Answer 30

-excretion of 19.5L/day
>vs. 1.5L/day

Question 31

Why is the amount of filtration and reabsorption so high?

Answer 31

-very high permeability of glomerular capillaries
-everything is filtered except cells and proteins
-concentration of most solutes in plasma and within Bowman’s capsule is almost the SAME

Question 32

What is the benefit of high filtration and reabsorption?

Answer 32

-entire plasma is filtered many times a day
-waste products are removed faster

Question 33

How are different substances excreted? (4 most common scenarios)

Answer 33

-filtration only
-filtration and partial reabsorption
-filtration and complete reabsorption
-filtration and secretion

Question 34

Filtration only: example

Answer 34

-most of waste products
Ex. creatinine, uric acid

Question 35

Filtration and partial reabsorption: example

Answer 35

-most of electrolytes
Ex. sodium, chloride ions

Question 36

Filtration and complete reabsorption: example

Answer 36

-nutritional substances
Ex. glucose, AA

Question 37

Filtration and secretion: example

Answer 37

-when rapid clearance is needed
Ex. organic acids