Question

Does blood usually enter the nephron tubules of the kidney?

How does the decreased glomerular filtration rate relate to feling puffy and swollen?

How does the decreased glomerular filtration rate related to the decreased urine volume?

Answer 1

No, blood doesn't usually enter the nephron tubules of kidney. Blood from afferent arteriole gets filtered from glomerular capillaries into nephron tubules. This glomerular filtrate contains only ions, glucose, urea,etc and no plasma proteins, RBCs, WBCs. So after filtration, this fluid (Blood plasma - glomerular filtrate) goes to efferent arteriole, which is basically blood itself deprived of some molecules.

If glomerular filtration rate is decreased, it means less volume of urine is being formed. It further means that there is accumulation of blood volume. Now since blood maintains it's osmolarity, therefore, excess water in the blood would diffuse out into cell and interstitium, causing puffiness and swelling.

Decreasd glomerular filtration rate means less fluid in nephron tubules which signifies less fluid in the body. Due to less fluid in the body, our body deceased GFR so that less glomerular filtrate is formed, and thereby less urine is formed. Further, when GFR gets decreased ADH hormone is also secreted which helps in more water reabsorption from collecting duct and DCT. So again urine will be less. Moreover, RAAS also gets activated. This system also helps in more reabsorption of Na+ and water to restore fluid volume in our body. It also then tries to maintain GFR. So again volume of urine gets decreased.