Why white blood cells and red blood cells are destroyed?

[Aafia]

Why do white blood cells die and what cause them to destroy within a few (20-30) hours?
I have an other question also that if red blood cells remain within capillaries, veins and arteries then how do they pass onto liver cells for the breakdown or they die within veins, capillaries and arteries?

 

[Simon Bridge]

1. Are you asking about the mechanism of white cell death inmsome context? Have you looked up "apoptosis"?
2. Red cells... and anything else thst needs to be processed out: there isva filter system.

 

[Aafia]

1. Are you asking about the mechanism of white cell death inmsome context? Have you looked up "apoptosis"?
2. Red cells... and anything else thst needs to be processed out: there isva filter system.

Basically I want to know what causes the death of RBC and WBC or what triggers this destruction. Is it necessary for these cells to die. Also, if RBC's and WBC's run within capillaries and arteries then why it is said that they are destroyed in liver and spleen? Does they pass into the liver cells through some opening in capillaries or they dies within these capillaries?

 

[jim mcnamara]

Red blood cells last ~100+ days in the body. Sometimes a lot longer.
https://en.wikipedia.org/wiki/Red_blood_cell

White blood cells are NOT one kind of cell. There are several, and depending on what they do, they last for different times.
On average they last about one year. WB Cells that are created to fight an infection live for short periods of time; the example you gave was 20+ hours and that was probably about them.

On your next question - help us to help you: tell us where you read your information, or give us some context for your question. Thanks

 

[Simon Bridge]

You seem to need more detail on how the liver works. Have you seen:
http://www.ncbi.nlm.nih.gov/pubmedhealth/PMH0072577/ or:
http://www.innerbody.com/image_digeov/card10-new2.html ?
In the last one, scroll down to "kupffer cells".

It would help to have a context though: how does the question come up?

 

[Fervent Freyja]

Why do white blood cells die and what cause them to destroy within a few (20-30) hours?
I have an other question also that if red blood cells remain within capillaries, veins and arteries then how do they pass onto liver cells for the breakdown or they die within veins, capillaries and arteries?

A college microbiology course will help you understand this more in depth (you wouldn't have to ask these questions if you took it). Like Jim posted, your questions aren't specific enough- there are other processes that you need to understand firstly.

Until then, this video might help and addresses your questions; I find visualizing processes like this an important precursor to my own understanding: