Slide Set 7 - The Urinary System - Kidney

Question 1

How does each system react to decreased blood pressure?

1. Cardiovascular:
2. Behavioral:
3. Kidneys:

Answer 1

1. increase cardiac output and vasoconstriction to increase blood pressure
2. increase thirst - increase water intake which will increase extracellular and intracellular fluid volume to increase blood pressure
3. kidneys conserve water to minimize further volume loss - so urine turns out more concentrated and smaller in volume

Question 2

How does the cardiovascular system react to an increase in blood pressure? The kidney?

Answer 2

1. decrease cardiac output and decreases vasodilation to decrease blood pressure
2. The kidney excretes salts and water in urine - this decrease extracellular and intracellular volume of body, decreasing blood pressure

Question 3

What are the 3 structures that carry urine from the kidneys to the outside for elimination from the body?

Answer 3

1. uterers
2. urinary bladder
3. urethra

Question 4

What are nephrons?

Answer 4

functional units of the kidney

Question 5

Where does the urine travel to after the nephron?

Answer 5

calyx (which can be thought of as the start of the urinary plumbing) then to the ureter

Question 6

What is the tube that leads urine from the kidney to the bladder?

Answer 6

ureter

Question 7

What is the tube that leads the urine from the bladder to the exterior for excretion?

Answer 7

urethra

Question 8

Size of urethra or women relative to men?

Answer 8

Men have a much longer urethra

Question 9

What does the urethra of men pass through?

Answer 9

The prostate gland (site of passage of seminal fluid/semen)

Question 10

How many nephrons can be found in a kidney?

Answer 10

~ 1 million

Question 11

What are the two components of each nephron?

Answer 11

Tubular and vascular

Question 12

The arrangement of the nephrons within the kidney gives rise to what two distinct regions?

Answer 12

renal cortex and renal medulla

Question 13

Does the vascular or tubular component dominate the glomerulus?

Answer 13

vascular

Question 14

What passes through the glomerulus?

Answer 14

water and solutes - kind of like plasma which is then transformed into urine

Question 15

Discuss the vascular route of the kidney step by step

Answer 15

1. The renal artery brings blood into the afferent arteriole which delivers blood to the glomerulus
2. the blood that does not get filtered through the glomerulus leaves via the efferent arteriole
3. efferent arteriole breaks down into peritubular capillaries which surround the tubular part of the nephron and supply the blood for exchange with the fluid in the tubular lumen
4. Peritubular capillaries join into venules which transport blood into the renal vein which is the way by which blood leaves the kidney

Question 16

What is filtered through the glomerulus?

Answer 16

all constituents within the blood except blood cells and proteins – non-discriminant

Question 17

What is tubular reabsorption?

Answer 17

highly selective movement of filtered substances from the tubular lumen into the peritubular capillaries

Question 18

What is tubular secretion? What does this provide?

Answer 18

selective movement of non-filtered substances from the peritubular capillaries into the tubular lumen for excretion. This provides a second chance for substances to enter the tubules for excretion after glomerulus filtration already occurred

Question 19

How much of our blood passes through the glomerulus?

Answer 19

20%

Question 20

What 3 things must substances pass through in order to be filtered and enter the lumen of bowman’s capsule?

Answer 20

1. the pores between the endothelial cells of the glomerular capillary
2. basement membrane
3. Inner later of bowman’s capsule: the filtration slits between the foot processes of the podocytes of the inner layer of bowman’s capsule

Question 21

What two forces are involved in filtration at the glomerulus? Which force favours and which force opposes filtration?

Answer 21

1. Glomerular Capillary Blood Pressure (favours filtration)
2. Plasma-colloid Osmotic Pressure (opposes filtration)
3. Bowman’s capsule hydrostatic pressure (opposes filtration)

Question 22

What is the magnitude of the Glomerular Capillary Blood Pressure, Plasma colloid osmotic pressure, and Bowman’s capsule hydrostatic pressure?

Answer 22

1. 55 mm Hg out of glomerulus
2. 30 mm Hg into glomerulus
3. 15 mm Hg into glomerulus

Question 23

What exerts the plasma-colloid osmotic pressure?

Answer 23

the unfiltered proteins on the filtered fluid that is in the bowman’s capsule

Question 24

Under what circumstance can the Bowman’s Capsule Hydrostatic pressure increase?

Answer 24

in the case of a blockage

Question 25

What happens at the proximal and distal tubules?

Answer 25

solutes are actively transported back into blood

Question 26

What 3 things trigger vasopressin release?

Answer 26

1. osmolarity of plasma > 280 mOsM (detected by hypothalamic osmoreceptors in the plasma - then in 2. Decrease in atrial stretch due to low blood volume 3. Decrease in blood pressure

Question 27

What synthesizes vasopressin and what releases it?

Answer 27

Neurons that detect osmolarity, atrial stretch, and carotid/aortic baroreceptors send signals to the hypothalamus. Hypothalamic neurons then synthesize vasopressin. The posterior pituitary releases vasopressin

Question 28

As plasma osmolarity ________, secretion of plasma vasopressin by the posterior pituitary _______. A graph representing this relationship is _______.

Answer 28

increases, increases linear

Question 29

What is myogenic regulation?

Answer 29

When arteriole pressure increases the renal afferent arterial is stretched. The vascular smooth muscle responds by contracting thus increasing resistance.

Question 30

Where does tubuloglomerular feedback occur?

Answer 30

Juxtaglomerular apparatus

Question 31

What is the juxtaglomerular apparatus?

Answer 31

The fork made by the afferent and efferent arteriole that surround the distal tubule

Question 32

There are specialized __________ cells in the wall of the afferent arteriole which are called __________ cells. There are also specialized ________ cells in this region called ________.

Answer 32

smooth muscle granular tubular macula densa

Question 33

What happens when more fluid passes through the distal tubule at the juxtaglomerular apparatus?

Answer 33

More fluid means a higher salt level. Macula densa cells act to detect changes in salt levels in the distal tubule. In turn, they release adenosine which acts as a paracrine regulator and causes vasoconstriction at adjacent granular cells.

Question 34

What are the 4 kidney functions?

Answer 34

1. Filtration: blood to lumen 2. Reabsorption: lumen to blood 3. Secretion: blood to lumen 4. Excretion: lumen to external environment

Question 35

Adenosine acts as what type of regulator? What does it cause?

Answer 35

Acts as a paracrine regulator and causes vasoconstriction at adjacent granular cells

Question 36

Once the glomerulus filtration rate increases, what auto regulatory process occurs to decrease the GFR back to normal levels?

Answer 36

GFR increase --> flow through tubule increases --> NaCl flow past macula densa increases 1. Macula densa cells release adenosine (acts as a paracrine regulator and causes vasoconstriction) 2. Afferent arteriole constricts 3. resistance in afferent arteriole increases 4. hydrostatic pressure in glomerulus decreases 5. GFR decreases

Question 37

How does counter current exchange occur in the medulla of the kidney?

Answer 37

The filtrate passing through the distal tubule is flowing the opposite direction as the blood in the vasa recta

Question 38

How does the presence of ADH affect the urine?

Answer 38

small volume of concentrated urine

Question 39

What happens when the body needs salt? (5 steps)

Answer 39

1. aldosterone combines with a cytoplasmic receptor 2. hormone-receptor complex initiates transcription in the nucleus 3. new protein channels and pumps are made & there is also an increase in Na and K channel open times 4. Na ATPase pump speeds up 5. Increased Na absorption into vasa recta and K secretion into the lumen of the distal tubule

Question 40

When is the renin-angiotensin-aldosterone system initiated?

Answer 40

when there is low blood pressure

Question 41

RAAS: 1. What does the liver normally constantly produce for the plasma? 2. How does a decrease in blood pressure affect this molecule? 3. How does the production of ANG-2 affect the arterioles, the cardiovascular control centre in medulla oblongata, the hypothalamus, and the adrenal cortex in order to increase blood pressure back to normal?

Answer 41

1. angiotensin 2. Causes granular cells to produce renin. Renin converts angiotensin to ANG-1 in plasma. ACE enzyme converts ANG-1 to ANG-2 in plasma 3. Arterioles vasoconstrict. There is an increased cardiovascular response. The hypothalamus increases vasopressin and increases thirst meanwhile the adrenal cortex increases aldosterone which increases Na absorption -- both these things together increase volume and maintain osmolarity. All of this together works to increase blood pressure

Question 42

What is produced in the case of high blood pressure? It is secreted as a response to what 3 things?

Answer 42

Atrial Natriuretic Peptide (ANP) Secreted by atria in response to: 1. being stretched by Na+ retention 2. expansion of ECF volume 3. increase in arterial pressure

Question 43

What does the release of Atrial Natriuretic Peptide inhibit? What 3 things does this result in?

Answer 43

Na reabsorption in the distal tubule which increases Na output in urine 1. increases Na output in uine 2. increase GFR - more water loss 3. Inhibits renin secretion by the kidneys these are all hypotensive effects to help correct the original stimulus that brought about release of ANP

Question 44

What are 5 causes of Renal Failure?

Answer 44

1. infectious organism 2. Toxic agents 3. Inappropriate immune response 4. obstruction of urine flow 5. insufficient renal blood supply

Question 45

What are 10 of the kidneys functions?

Answer 45

1. Mantain H2O balance in the body 2. Maintain proper osmolarity of body fluids, primarily through regulating H2O balance 3. Regulate the quantity and concentration of most ECF ions 4. Maintain proper plasma volume 5. Help maintain proper acid-base balance in the body 6. Excreting the wastes of bodily metabolism 7. Excreting many foreign compounds 8. Producing erythropoietin 9. Producing renin 10. Converting vitamin D into its active form