Lecture 1 -- Blood Supply to the Kidney and Filtration

What are the two main regions of the kidney's internal anatomy?

The outer cortex and inner medulla.

What is the primary function of the kidney's cortex?

Filtration to form filtrate.

What is the primary function of the kidney's medulla?

To collect and excrete urine.

What are the main functions of the kidney?

1. Regulation of fluid volume

2. Electrolyte balance

3. Excretion of waste

4. Production of hormones (Activation of vitamin D/ Erythropoietin synthesis and RBC production)

What does GFR stand for in renal physiology?

Glomerular Filtration Rate = How many milliliters of blood are filtered from glomerulus to Bowmen’s capsule per minute

What is the anatomical structure that conveys urine from the kidneys to the bladder?

Ureters.

Name a waste product that the kidneys excrete.

Urea.

Where is the renal corpuscle located?

In the cortex of the kidney.

Describe the capillary portal system of kidney

Renal artery → Segmental artery → Interlobar artery → Arcuate artery → Interlobular artery → Afferent arterioles → Glomerulus (Capillaries) → Efferent arterioles → Peritubular capillaries
Capillary portal system = One capillary sits between two arterioles; another sits between a arterioles and veins

What is ultrafiltration?

→ Happen in renal corpuscle (Glomerulus + Bowman’s capsules) → Hydrostatic pressure can NEVER be balanced out through protein osmotic pressure → Except protein because of its large size, other substances e.g. Na+/ K+/ Cl- (50% bind with albumin; 50% freely filtrate)/ H2O/ Amino acid/ Ca+/ Phosphorus/ Glucose/ Urea/ Creatinine/ HCO3-) can be passed through from the glomerulus to Bowman’s capsule

What anatomical feature increases the filtration rate in the glomerular capillaries?

1. 20 -25% of cardiac output → High blood volume

2. Low resistance → Blood passes through 3 leaky membranes (Gaps between endothelial capillaries cells of glomerulus→ Basement membrane → Podocytes has finger-like projection, which creates holes)

3. Pressure in afferent arterioles > efferent arterioles

Explain the role of osmotic pressure in the kidney.

It helps draw fluid back into the blood vessels due to the presence of proteins.

What is the glomerular filtration rate (GFR) approximate for a dog?

Approximately 3 ml/kg/min.

What is a renal pyramid?

A structure in the medulla that collects and excretes urine.

What happens if the blood supply to the kidney is cut off?

The renal pyramids will become necrotic.

Where does urine accumulate before excretion?

In the bladder.

What does the afferent arteriole do?

It supplies blood to the glomerulus.

What are the two types of nephrons mentioned?

Cortical nephrons and medullary nephrons.