Week 1 Lecture 1

Question 1

what does the kidney do?

Answer 1

1. They regulate fluid and electrolyte balance:
   Regulation of :-

• Osmolarity (the concentration of plasma expressed as the total number of solute particles per litre)
• extracellular fluid volume
• blood pressure
• ionic balance ( Na+, K-, Ca2+)

2. pH regulation
3. Excretion of wastes
4. Excretion of xenobiotics (xenos = stranger, foreign) such as alcohol and drugs
5. Production of hormones

Question 2

What percentage of cardiac output (blood that is pumped out of the heart every minute) do you think the kidneys receive?

Answer 2

20%

Question 3

What are nephrons?

Answer 3

Nephrons are the functional unit of the kidney
There are two different types of nephrons

1. 80% are cortical nephrons which are located in the cortex.
2. 20% are juxtamedullary nephrons have long loops that extend down to the medulla region - they allow us to produce urine of different concentrations which enables us to adapt and conserve or lose water.

Question 4

How much renal capacity do you think needs to be lost before potential clinical effects are seen?

Answer 4

70-75%

Question 5

what is the path of blood flow in the kidneys?

Answer 5

Blood enters the kidneys via the renal arteries and arterioles.

In the cortex, blood enters the glomerulus via the afferent arteriole and leaves the glomerular capillaries via the efferent arteriole. Filtration occurs in the glomerulus.

After leaving the efferent arterioles, blood passes into a second capillary bed, the peritubular capillaries. These capillaries surround the tubule and are where reabsorption and secretion occur.

Question 6

what is the path for filtered fluid through the tubular system ?

Answer 6

bowman’s capsule, proximal tubule, LOH, distal tubule

Question 7

how does fluid pass through?

Answer 7

ureter, bladder urethra

Question 8

approximately what percentage of cardiac output do the kidneys receive at rest?

Answer 8

25%