Packet One - Kidney Overview Flashcards
Kidney Functions 6
Excretes wastes & foreign substances Maintain blood pH, osmolarity, glucose Regulation of: blood/ECF ionic composition blood volume blood pressure Acts as endocrine organ
Kidney acts as an endocrine organ by:
making renin, calcitriols, secreting renin
The kidneys are _______ on the posterior wall of the abdomen
retroperitoneal
Urine flows from the kidney to the _____ _____ through the _____
Urine is stored in the bladder until it is eliminated from the body via the _____
urinary bladder
ureters
urethra
At rest, the kidneys receive _____% of resting cardiac output via the ____ _____ which branch off the abdominal aorta.
Most of this blood flows through the ____ _____
and then the ____ capillaries
20-25%
renal arteries
Glomerular capillaries
peritubular
The filtered blood returns to the systemic circulation via the ____ ____ which empty into the inferior vena cava
renal veins
Where does filtration of blood occur?
Glomerular capillaries
Generally, where does reabsorption and secretion occur?
peritubular capillaries
Arteriole capillaries that allow Glomerular capillaries to maintain higher pressure than other capillaries in the body?
afferent and efferent arterioles
Which is required for adequate filtration of blood: High or low GC pressure?
High GC pressure
Sympathetic vasomotor nerves and local (kidney) factors help regulate:
GC blood flow & pressure
Part of the nephron that performs the first step of filtering blood is:
glomerulus
A glomerulus receives its blood supply from an _____ arteriole of the renal circulation
afferent
The glomerulus drains into an ____ arteriole rather than a venule
efferent
A glomerulus and its surrounding Bowman’s capsule constitute a ____ _____, the basic filtration unit of the kidney.
renal corpuscle
The rate at which blood is filtered through all of the glomeruli, and thus the measure of the overall renal function, is the _____ _____ _____.
glomerular filtration rate (GFR).
The _______ contain negatively charge coat (glycocalyx) that limits filtration of negatively charge molecules such as serum albumin
Podocytes
GFR = Kf [(PGC – PBS) – σ(πGC – πBS)]
`Kf= filtration coefficient PGC= Hydrostatic pressure in glomerular capillary PBS= Hydrostatic pressure in bowman’s space σ= Reflection coefficient πGC= Oncotic pressure in glomerular capillary πBS = Oncotic pressure in bowman’s space
The nephron performs 3 Basic Processes:
Glomerular Filtration
Tubular Reabsorption
Tubular Secretion
Functional Unit of the Kidney
Nephron
Blood-plasma filtered to produce filtrate is known as
Glomerular Filtration
Substances transported from the filtrate back to the blood-plasma: this process is known as
Reabsorption
Substances transported from the blood-plasma to filtrate is known as
Secretion
processed filtrate becomes urine which is transported to the bladder then excreted from the body is known as
Excretion
Excretion = Filtration + Secretion - ______
Reabsorption
Two major nephrons of the kidney
cortical and juxtamedullary nephron
80-85% of the ~ 1 million nephrons are ____ nephrons. Renal corpuscles are in outer cortex and loops of Henle are near the cortex
cortical
15-20% of nephrons are _____ nephrons with renal corpuscles close to medulla and long loops of Henle extend deep into medulla with ___ ____ enabling the formation of dilute or concentrated urine
juxtamedullary
vasa recta
_____ of bowman’s capsule are specialized to help produce the filtrate of plasma
Podocytes
help regulate glomerular filtration rate (GFR)
Mesangial cells
Podocytes & Mesangial cells surround different parts of the glomerular capillaries and form the ____ layer of Bowman’s capsule
visceral
_____ layer cells contain the filtrate and channel it toward the proximate tubule
Parietal
The Filtration Membrane has 3 layers:
Endothelial Cells
Basement Membrane
Podocytes
Water and small molecules can easily pass through the filtration membrane but ____ cells and most ___ ____ cannot
blood
plasma proteins
Cells of the proximal tubule are specialized for _____ and have an elaborate brush border to increase the ____ surface area
reabsorption
apical
Nearly 100% of glucose, amino acids and other nutrients; and ~ 60-80% of water and salts are reabsorbed in the ___ _____
proximal tubule
Histology of the Proximal Tubule: 5
simple cuboidal microvilli on luminal (apical) side Basal-end faces the basal lamina Tight junctions Large number of mitochondria (provides energy for active transport)
Cells of the Loop of Henle are specialized for ____ _____ and transport.
They help to produce the osmotic concentration gradient necessary to produce _____ urine
selective permeability
concentrated
Histology of the Descending Limb : 4
simple squamous epithelium
fewer microvilli on the luminal (apical) surface
fewer mitochondria
Permeable to water due to aquaporin water channels in both the apical and basolateral membranes
Histology of the Ascending Limb
simple columnar epithelial cells
not water permeable- Cells lack aquaporins on apical surface
apical and basolateral membranes have many transmembrane ion transport molecules
Ascending Limb reabsorbs:
Na+ and K+ as well as Cl-
Ascending Limb ______ co-transporters sensitive to _____
Na-K-Cl
Furosemide
Some cells of the Distal tubule and collecting ducts respond to hormones such as:
Aldosterone, ADH, ANP, PTH & others
Histology of the Distal Tubule
Simple cuboidal
small number of microvilli on apical surface
Large numbers of mitochondria for the active reabsorption of Na+ and Cl-
sodium-chloride symporter of Distal tubule are sensitive to:
Thiazide
Histology of the Collecting Duct
Few microvilli on apical membrane
mitochondria for active reabsorption of Na+ and Cl- ; K+ secretion
reabsorption of Na+ and Cl- ; K+ secretion in the collecting duct is regulated by:
aldosterone
Both DT and CD cells are ___ sensitive
ADH
______ hormone stimulates increase of aquaporins on apical membrane increasing the water permeability of collecting duct
antidiuretic
