Renal Protein Metabolism, Absorption and Excretion Flashcards
4 different cells in the glomerulus
Glomerular endothelial cells
Podocytes
Mesangial cells
Parietal epithelial cells
Contraction of mesangial cells can constrict the capillary lumen which results into
Alteration of blood flow into the glomerular tuft influencing glomerular filtration
The GEC are lined by
Filamentous glycocalyx
T or F: the glomerular capillaries are heavily perforated with transcellular pores and surrounded by smooth muscles
False they are not surrounded by smooth muscles
The glomerular capillary pores are also known as
fenestrae
What is the function of fenestrae
It makes the glomerular capillaries efficient portals for the rapid passage of high volumes of fluid characteristic of renal filtration
These are fibrous lattice of negatively charged glycoproteins
Glycocalyx
This is an integral component of the GFB acting as intermediary sieving matrix
GBM
Most indispensable component of GBM
Type IV collagens and laminins
Defining feature of normal fully differentiated podocytes
Their cytoarchitecture that resembles the stellate body shape of an octopus
Neighboring podocytes are physically adjoined thru their FPs via unique intercellular junctions called the
SD
Gene that encodes a member of Ig family of cell adhesion molecules that fxns in the glomerular filtration barrier in the kidney
NHS1, Nephrin
Function of the slit diaphragm
Ultrafilter to exclude albumin and other plasma molecules in the formation of urine
Mutation of NPHS1, Nephrin
Finnish-type congenital nephrosis 1 (severe proteinuria and loss of slit diaphragm and foot processes)
Gene that encodes the protein that plays a role in the regulation of glomerular permeability
Podocin
Mutations in Podocin results in
Steroid resistant nephrotic syndrome
Diagnostic hallmark of a compromised GFB
Proteinuria (more specifically albuminuria
Examples of small linear or cyclic peptides
Angiotensin
Kinin
Vasopressin
Examples of large polypeptide hormones
Insulin
Glucagon
Atrial natriuretic factor
Low mol weight proteins comprise
Hormones
Enzymes
Immunoprotein fragments
Tissue specific antigens
T or F: LMWP have specific renal receptors
False, they do not have specific renal receptors except for hormones
Most important of the circulating plasma proteins
Intermediate sized protein (albumin)
Example of large sized proteins
Fibrinogen and immunoglobulins
Longest part of the renal tubule
Proximal convoluted tubule
Multiligand receptors responsible for the constitutive uptake of a vast variety of filtered plasma proteins
Megalin and cubilin
Most prevalent mode by which LMWP and polypeptides are extracted by the kidney is by
- Filtration
- Endocytic uptake
- Hydrolysis
- Return of the resulting amino acids to the circulation
Amino acid transport types are classified according to
Specificity and sodium dependence
Transporter for neutral amino acids
B0AT1
Transporters for hlycine and proline
PAT2 and IMINO
Glutamate transporter
EAAT3
Normal urinary protein excretion
<150mg/24 hour
Normal albumin excretion
<30mg
Major urinary protein
Tamm Horsfall protein
Where is the Tamm horsfall located
Luminal face of the thick ascending limb of Henle and early distal convoluted tubules of nephron
Functions of TH protein
It takes part in the water impermeability of TAL
Plays a protective role towards pyelonephritogenic pathogens such as E.coli
Most abundant protein in urine of healthy individuals
THP
Stones may form d/t defective urinary THP d/t lack of
Sialic acid
types of protein detected by UPEP
Albumin
Globulins
UPEP test is done to
Help determine the cause of protein in the urine
As a screening test to measure the various amts of proteins in the urine
LMWP and a member of the lipocalin protein superfamily
Alpha 1 microglobulin
An increase in the urinary concentration of alpha 1 microgobulin indicates
Proximal tubule injury and/or impaired proximal tubular function
Gold standard in the measurement of alpha 1microglobulin
24-hour urine collection
Alpha 2 microglobulin is synthesized locally by
Macrophages, fibroblasts and adrenocortical cells
group of globular proteins in plasma that are more mobile in alkaline or electrically charged solutions than gamma globulins but less mobile than alpha globulins
Beta globulins
protein found on the surface of nucleated cells and functions as part of the human immune system.
Beta 2 microglobulin
Reference range of beta 2 microglobulin in urine
0-0.3ug/mL
These are monoclonal immunoglobulin light chains found in urine (and plasma) of some patients with myeloma or other lymphoid malignancies
Bence Jones Proteins
The glomerular filtration barrier is a dynamic and highly selective filter that sieves on the basis of
Molecular size
Electrical charge
The function of the kidney, filtering blood and concentrating metabolic waste into urine, takes place in an intricate and functionally elegant structure called the
Renal glomerulus
