The Renal System

Question 1

Renal system functions? (5)

Answer 1

1. Regulation of water, inorganic ion balance, acid balance
2. Removes metabolic waste from blood eg urea, creatinine
3. Removes foreign chemicals
4. Gluconeogenesis
5. Production of hormones/enzymes eg EPO, Renin

Question 2

Structure of the Kidney?

Answer 2

Renal Pelvis
Ureter
Renal cortex and medulla
Nephron

Question 2

Structure of Nephron?

Answer 2

Renal corpuscle which contains glomerulus
Renal tubule which forms a cup around the glomerulus called the Bowman’s Capsule

Question 3

What are Juxtaglomerular cells?

Answer 3

Mechanoreceptors - detect blood pressure in the afferent arterioles

Question 4

What are Macula densa cells?

Answer 4

Chemoreceptros - which detect a change in NaCl

Question 5

3 Main renal processes?

Answer 5

Glomerular filtration
Tubular secretion
Tubular reabsorption

Question 6

What is GFR and the factors effecting it?

Answer 6

Amount of blood filtered by glomeruli each minute

1. Capillary permeability
2. Surface area - size of capillary bed
3. Hydrostatic pressure driving fluid out of capillaries
4. Osmotic forces within the capillaries which oppose exit

Question 7

What is Tubular secretion?

Answer 7

Substances such as hydrogen ions, potassium, organic anions moving from peritubular capillaries into tubular lumen

Question 8

What is tubular secretion important for?

Answer 8

1. Disposing of drugs and drugs metabolites
2. Eliminating substances or end products that have been reabsorbed by passive processes eg urea
3. Removing excess K+
4. Controlling blood pH

Question 9

What is Renal clearance ?

Answer 9

The amount of a substance filtered per minute, divided
by its plasma concentration

Question 10

What is filtration fraction?

Answer 10

The proportion of the plasma that enters the
kidneys that is subsequently filtered at the glomerulus and passes into
the renal tubules

Question 11

Process of Sodium reabsorption?

Answer 11

• Active transport out of cells into interstitial fluid.
• Transport achieved by Na+/K+-ATPase pump
• Keeps intracellular conc. of Na+ low to allow
  ‘downhill’ movement of Na+ from lumen
• Mechanism of Na+ movement across luminal
  membrane varies between tubule segments,
  whereas always via Na+/K+-ATPase pump for
  basolateral membrane
• Proximal tubule (a): co-transport / counter-
  transport of organic molecules (glucose, aa)
• Cortical collecting ducts (b): via Na+ channels

Question 12

Three factors determining the rate of tubular Na+ reabsorption?

Answer 12

1) Aldosterone (most major)
2) Atrial Natriuretic Peptide (ANP)
3) Local effect of blood pressure on the tubules

Question 13

Renal function during exercise?

Answer 13

Renal blood flow decreases as soon as exercise starts, as intensity increases blood flow decreases.

Question 14

What is the role of baroreceptors ?

Answer 14

Detect blood pressure

Question 15

Factors affecting steady state exercise?

Answer 15

The delivery of adequate oxygen to the exercising muscles

The ability of the cells to utilise this oxygen in the aerobic process of
energy metabolism

The ability to eliminate heat.

Question 16

Why are humans endotherms?

Answer 16

They generate their own body heat and do not rely on the energy of sunlight etc.

Question 17

How much energy is lost and kept?

Answer 17

75-80% lost through heat and the remainder is kept for external work

Question 18

Why are humans known as homeotherms?

Answer 18

They maintain their body temperature within a narrow limit, eventhough the temperature fluctuates throughout the day

Question 19

What are the mechanisms for heat conservation?

Answer 19

Shivering
Vasoconstriction
Muscular activity
non-shivering thermogenesis

Question 20

What is the mechanisms for heat loss?

Answer 20

Vasodilation
Sweating

Question 21

What is hyperthermia and what are signs?

Answer 21

When core body temperature becomes dangerously high, signs being dizziness, disorientation, dry skin etc

Question 22

Effects of acclimatization?

Answer 22

Sweat more and sooner

Increased blood flow to skin

Have more dilute sweat (conserve electrolytes)

Increased blood volume and stroke volume

Have a lower body core temperature, heart rate, glycogen use and, thus, fatigue

overall improvement of thermoregulation of body temp