Flashcards in Renal - Physiology and Diagnostics Deck (70)
What is the functional subunit of the kidney?
True or False: Nephron numbers increase over time.
False - they decrease over time; 10% drop in numbers every 10 years after the age of 40
What are the components of the nephron?
Glomerulus and tubules
What is the glomerulus?
a capillary bed
What is the glomerulus surrounded by?
What does the glomerulus produce?
What surrounds the tubules of the nephron?
What is the function of the tubules?
To transport and alter urine
Where is there high hydrostatic pressure in the nephron? What occurs here? Is it selective or non-selective?
In the globerulus, there is increased filtration and it is non-selective
Where is there low hydrostatic pressure in the nephron? What occurs here? Is this process selective or non-selective?
In the tubules, there is increased reabsorption and it is a selective process
What do the two different capillary systems allow for?
individual adjustments of filtration/reabsorption
What are the subsections of the tubule?
Proximal tubule, loop of henle, juxtaglomerular complex, distal tubule, connecting tubule, collecting tubule, and collecting duct
What is the volume and composition of urine dictated by?
Glomerular filtration rate, tubular reabsorption rate, and tubular secretion rate
What is the filtration fraction through the glomerulus?
The ultra-filtrate that the glomerulus produces is almost identical to plasma except for what?
There is a lower protein content and a lower content of protein-bound molecules (calcium and FA)
What are the 3 layers of the glomerulus?
Fenestrated epithelium, basement mebrane, and podocytes (epithelial cells)
Decribe the fenestrated endothelium.
It is composed of large pores and is negatively charged
Describe the basement membrane of the glomerulus.
It is composed of a collagen/proteoglycan mesh and is negatively charged
Describe the podocytes of the glomerulus.
It is separated by slit pores and is negatively charged
What are the consequences for the ultrafiltrate?
Retention of larger, negatively charged molecules within the plasma
What can glomerular diseases cause (think about the ultrafiltrate)?
Urinary loss of larger proteins - albumin and antithrombin
What determines the glomerular filtration rate (GFR)?
Glomerular hydrostatic pressure, capsular hydrostatic pressure, glomerular oncotic pressure, and filtration coefficient
What mechanisms are involved in reapsorbtion/secretion in the tubules?
transporters and pinocytosis
What occurs in the proximal tubule?
reabsorption, pinocytosis, and secretion
What is reabsorbed in the proximal tubule?
65% of Na+ and water, and >98% glucose and amino acids
What molecules undergo pinocytosis in the proximal tubule?
What is secreted in the proximal tubules?
Oxalate, urate, catecholamines, and drugs such as penicillin
What inibitors works at the level of the proximal tubules?
Carbonic anhydrase inhibitors
Normally, the proximal tubules should reabsorb all glucose in the urine. What happens in the proximal tubules in diabetes mellitus patients?
They get overwhelmed by the amount of glucose in the urine and can only reabsorb so much (transport maximum is exceeded). This results in glucosuria