Lecture 10 - Urinary system

Question 1

What do arterial baroreceptors do

Answer 1

respond to changes in arterial pressure
Nerve ending highly sensitive to stretch or distortion
The degree of stretching is directly proportional to blood pressure

Question 2

How do you treat hypertension (high blood pressure)

Answer 2

Diuretics: increase excretion of sodium and
water, decreasing cardiac output with no
change in peripheral resistance
Beta-adrenergic receptor blockers: Reduce
cardiac output
Calcium channel blockers: Reduce entry of
calcium in vascular smooth muscle cells =
weaker contractions = lowers peripheral
resistance
Angiotensin-converting enzyme (ACE)
inhibitors: Final step in formation of
Angiotensin II (a vasoconstrictor) is mediated
by an ACE. Blocking this enzyme causes
vasodilation lowering peripheral resistance

Question 3

What does aldosterone do

Answer 3

slow-acting steroid hormone that stimulates
sodium reabsorption by kidney tubules

Question 4

What does Vasopressin do (anti-diuretic hormone)

Answer 4

rapid-acting
peptide produced by the pituitary gland which stimulates
water reabsorption

Question 5

What do Angiotensin-converting enzymes (ACEs) do

Answer 5

Found on endothelial cells

Question 6

How to kidneys regulate blood pressure

Answer 6

intra-renal
baroreceptors detect changes in stretching with changes in blood
volume which stimulates a change in the production of renin

Question 7

How does the heart interact with the kindeys

Answer 7

Produce ANP - Atrial natriuretic peptide which
1. Inhibits sodium reabsorption by kidney tubular cells
2. Acts on renal blood vessels to increase filtration rate causing
sodium excretion
3. Inhibits the action of aldosterone

Question 8

What happens if there is a blood loss

Answer 8

Compensatory movement of interstitial fluid
into the capillaries to increase plasma volume
But this is a redistribution of fluid and not a
replacement of fluid
Other slower effects include:
- an increase in thirst
- a decrease in salt and water excretion
Mediated by hormones and kidney function:
- renin, angiotensin and aldosterone

Question 9

What are the ratios for heat lost at rest in ambient environmental conditions

Answer 9

60% via radiation
* 12% via convective air currents
* 3% via conduction (e.g. feet to floor)
* 25% via evaporation (lungs and skin)

Question 10

How does heat loss during exercise differ from rest

Answer 10

Up to 80% via evaporation of sweat from
the skin (dependent on humidity)

Question 11

How does the kidney help during a water deficit

Answer 11

Help to conserve body water
and electrolytes during period
of increased loss

Question 12

What does renal mean

Answer 12

“pertaining to the kidneys”.
The kidneys process the plasma portion of blood by
removing substances from it and, in some cases, by
adding substances to it”

Question 13

What do the kidneys do

Answer 13

Remove waste products (e.g. urea) and foreign chemicals (e.g.
drugs) from the blood
* Regulate total body water, salts and acid base balance – kidneys
excrete just enough water and salts to maintain homeostasis
* Involved in gluconeogenesis (e.g. during fasting, the kidneys
produce glucose from amino acids that is released into the blood)
* Release hormones that regulate blood pressure (e.g. renin) and
EPO (increases number of red cells)
* Produce an active from of Vitamin D that influences calcium
balance and promotes strong, healthy bones

Question 14

What are the sections of the urinary system

Answer 14

Kidney, uteter, bladder, urethra

Question 15

What is the parts of a kidney

Answer 15

Renal pelvis, nephron, renal medulla, renal cortex, ureter

Question 16

What does the renal corpuscle do

Answer 16

Forms a filtrate from blood
free from cells and proteins
- Filtrate leaves the corpuscle
and enters the tubule
- As it flows through the
tubule, substances are
added/removed
- Remaining fluid combines in
collecting ducts and exits the
kidneys as urine

Question 17

What are the 2 types of nephron

Answer 17

Juxtamedullary and cortical

Question 18

What are the components of the renal corpuslce

Answer 18

Bowmans capsule - containing podocytes

Glomerulus - contains afferent and efferent arterioles

Question 19

What are fenestrae

Answer 19

small pores found in this instance on a podocyte

Question 20

What are the 3 layers of filtration in the Bowmans capsule

Answer 20

Single cell lining of the capillary endothelium

Non-cellular protein-rich layer of basement membrane

Single cell lining of the Bowman’s capsule

Question 21

What are the glomerular capillaries specialized for

Answer 21

Filtering

Question 22

What do the peritubular capilaries do

Answer 22

Supply the nephron/tubules with their own blood supply
They then form the veins
where blood leaves the kidney

Question 23

What are juxtamedullary nephrons (slide 29)

Answer 23

15% of all kidney nephrons
* Renal corpuscle close to cortical-medullary junction
* Henle’s loops plunge deep into the medullar
* Generate osmotic gradient for water reabsorption

Question 24

What are cortical nephrons (slide 29)

Answer 24

These represent the majority of the kidney nephrons
* Corpuscle located in outer cortex
* Henle’s loops do not plunge deep into the medullar

Question 25

What are the sections of the juxtaglomerular apparatus

Answer 25

Juxtaglomerular cells
Macula Densa

Question 26

What does the Macula Densa do

Answer 26

Contains sensors that detect changes in blood composition

Question 27

What do juxtaglomerular cells do

Answer 27

• Secrete RENIN
• Influence the formation of
  ANGIOTENSIN 2
• Controls blood pressure
  (vasoconstriction and
  sodium/water retention)
  Distal tubule
  (not connected to
  Bowman’s
  capsule directly)
  Macula
  Densa
  Contain sensors that de

Question 28

What are the 3 distinct inputs to juxtaglomerular cells that increase renin secretion

Answer 28

1) Renal sympathetic nerves
2) Intrarenal baroreceptors
3) Macula densa

Question 29

What does isotonic mean

Answer 29

he same
concentration of nonpenetrating
solutes as normal extracellular fluid.

Question 30

What is a hypotonic solution

Answer 30

have a lower
concentration of nonpenetrating solutes
compared to normal extracellular fluid.
- water rushes in to the cell to dilute
intracellular solutes

Question 31

What is a hypertonic solution

Answer 31

have a higher
concentration of nonpenetrating
solutes compared to normal
extracellular fluid.
- water rushes out of the cell to
dilute extracellular solutes

Question 32

What is glomerular filtration

Answer 32

Urine formation begins with the filtration of
plasma from glomerular capillaries into the
Bowman’s space

Question 33

What ultra-filtrate

Answer 33

The filtrate is cell free and, except for
large proteins, contains all the substance
in virtually the same concentrations as in
plasma

Question 34

What is favouring filtration (slide 38)

Answer 34

P-GC = Glomerular capillary blood pressure

Question 35

What is opposing filtration (slide 38)

Answer 35

P-BS = Fluid pressure in Bowman’s space
‘pi’-GC = osmotic force due to protein in
plasma

Question 36

What doess Glomerular filtration rate (GFR) show

Answer 36

How well the kidneys are functioning

Question 37

What are the features of tubular reabsorption (slide 40)

Answer 37

1) The filtered loads are very high (e.g. water)
2) Reabsorption of waste products is incomplete (e.g. urea)
3) Reabsorption of useful components is complete (e.g. water and salts)

Question 38

What is the mechanism for sodium and water reabsorption

Answer 38

1) 2) Sodium reabsorption is an active process
occurring in all tubular lumen (except the
descending limb of loop of Henle)
Water reabsorption is by osmosis and is
dependent on sodium reabsorption

Question 39

Slide 43 - Aquaporin role

Answer 39

Directed reading - * Primary active sodium reabsorption
* Coupling of water reabsorption to Sodium reabsorption
* Urine concentration: The countercurrent multiplier system
* The medullary circulation