Question

Describe how filtrate is formed and what substances normally end up in filtrate (and what substances do not). This should include a description of the anatomy and physiology of the glomerus and the glomerular capsule and how they interact with each other.

Answer 1

Answer

• Glomerulus is a cluster of capillaries from afferent arteriole that resides in the Bowman's capsule.
• Glomerulus contains fenetrated capillaries. It means the endothelial layer of capillary wall contains fenestration (pores).
• This wall is attached to underlying basement membrane.
• On the other site of basement membrane, there are foot processes of podocyte cells of glomeular capsule.
• These foot processes are located at a distance forming filtration slits inbetween.
• Collectively,
  - Capillary endothelium
  - Basemment membrane and
  - Foot processes of podocyte cells of glomeular capsule
  forms filtration membrane.
• When blood passes through glomerulus, the hydrostatic pressure in the capillary wall allows small and soluble nitrogenous waste materials to be filtered into capsular space.
• The substances that can pass through filtration membrane are :
  - Water
  - Ions (sodium ion, potassium ion, calcium ion, chloride ion)
  - Glucose
  - Amino acids
  - Urea
  - Uric acid
  - Creatinine
  - Ammonia
• The substances that cannot pass and are not filtered include :
  - Large substances such as protein and blood cells.
• The substances that enters into capsular space is known as filtrate.