Renal Flashcards
What do you call the maintenance of the internal environment compatible with life?
Homeostasis
What is the net gain of water per day?
Zero: Fluid gained per day = fluid lost per day
Which organ system contributes to homeostasis by adjusting water and electrolyte levels?
Renal System: mainly by producing urine
What is urine?
Urine is an ultrafiltrate of blood
Waste product from Proteins
Urea
Waste product from Purines
Uric Acid
Waste product from Muscles
Creatinine
Waste product from RBCs
Bilirubin
Excretion of variable amounts of water and sodium; Involved in RAAS
Blood pressure regulation
Excretion of excess acids and bases
Regulation of Acid- Base balance
Increases RBC production in response to hypoxia
Production of Erythropoeitin (EPO)
Produces glucose during the starvation state
Gluconeogenesis
Location of Kidney
T12-L3
Weight of Kidney
150g
Highly-fenestrated, responsible for GFR
Glomerular Capillaries
Supplies O2 & glucose to the tubular cells
Peritubular Capillaries
Secretes Erythropoietin (EPO)
Interstitial Cells
Hairpin loop-shaped peritubular capillaries of the juxtaglomerular nephrons that participate in countercurrent exchange
Vasa Recta
Capacity of the Urinary Bladder
600ml
Urge to urinate
150ml
Reflex contraction of the Urinary Bladder
300ml
Bladder muscle
Detrusor muscle
Internal Urethral Sphincter
Involuntary
External Urethral Sphincter
Voluntary
Functional and Structural Unit of Kidney
Nephron
of Nephrons per kidney
1 million
75% of nephrons
Cortical Nephrons
25% of nephrons
Juxtamedullary Nephrons
Location of Cortical Nephrons
Renal Cortex
Location of Juxtamedullary Nephrons
Corticomedullary Junction
Loops of Cortical Nephrons
Short
Loops of Juxtamedullary Nephrons
Long
Capillary Network of Cortical Nephrons
Peritubular Capillaries
Capillary Network of Juxtamedullary Nephrons
Vasa Recta
The only capillaries in the body which drain into arterioles
Glomerular Capillaries
50x more permeable than skeletal muscle capillaries; Highly fenestrated with pores 8 nanometer in diameter
Capillary Endothelium
Capillary endothelium secretes:
Nitric Oxide & Endothelin-1
Have large spaces; With Type IV Collagen, Lainin, Agrin, Perlecan, Fibronectin
Basement Membrane
Found in between capillaries; Contractile, mediates filtration, take up immune complexes; Involved in Glomerular Diseases
Mesangial Cells
Cells of capillary endothelium
Podocytes
Parts of Podocytes
Foot processes Filtration slits with filtration slit diaphragm
Filtration Slit Diaphragm is made up of:
NephrinNEPH-1PodocinAlpha-actinin 4CD2-AP
“Glomerular cells of the Afferent Arterioles”; At the walls of Afferent Arterioles; Secrete Renin
JG Cells
Found in the walls of the Distal Convoluted Tubule; Monitor Na+ concentration in the DT (and consequently, blood pressure)
Macula Densa
“Visceral Epithelium” of the kidney
Podocytes
“Parietal Epithelium” of the kidney
Bowman’s capsule
What are the filtration and charge barriers?
EndotheliumBasement membraneFoot processes of Podocytes
What is the charge of this charge barrier and what does it block?
NegativePrevents filtration of albumin and other negatively-charged proteins
Movement from Glomerular Capillaries to Bowman’s space
(Glomerular) Filtration
Movement from tubules to interstitium to peritubular capillaries
(Tubular) Reabsorption
Movement from peritubular capillaries to interstitium to tubules
(Tubular) Secretion
(Amount Filtered) - (Amount Reabsorbed) + (Amount Secreted)
Excretion
Amount filtered in the glomerular capillaries per unit time
GFR
Normal GFR
125ml/min or 180L/day
GFR/RPF
Filtration fraction
Filtered freely
20 angstrom or less
Not filtered at all
> 42 angstrom
Afferent Arteriole Dilatation
GFR increases
Afferent Arteriole Constriction
GFR decreases
Efferent Arteriole Dilation
GFR decreases
Efferent Arteriole Constriction (moderate)
GFR increases
Efferent Arteriole Constriction (severe)
GFR decreases
Increased GC Hydrostatic pressure
GFR increases
Increased GC Oncotic pressure
GFR decreases
Increased BS Hydrostatic pressure
GFR decreases
Increased Kf
GFR increases
What are the causes of decreased Kf?
Renal Diseases DMHPN
What is the cause of increased BS hydrostatic pressure?
Urinary Tract Obstruction
What are the causes of decreased GC hydrostatic pressure?
Hypotension (Decreased arterial pressure)ACE-I (Decreased efferent arteriole constriction)Sympathetic Activity (Increased afferent arteriole constriction)
What are the hormones that will increase GFR?
EDFRPGE2PGI2BradykininGlucocorticoidsANPBNP
Which hormone will preserve GFR?
Angiotensin II (preferentially constricts efferent arteriole)
Which hormone will increase Renal Blood Flow (RBF)?
HistamineDopamineANPBNP
What is one possible effect of ACE-I in a patient with HPN secondary to Renal Artery Stenosis?
Renal Failure
(Renal Artery Pressure-Renal Vein Pressure) / Total Renal Vascular Resistance; Exhibits local autoregulation at BP between 75-160mmHg
Renal Blood Flow
What do you call massive sympathetic stimulation that results in massive vasoconstriction of the kidneys?
CNS Ischemic Response
“Constant sodium load delivered to distal tubule”; Primary Mechanism for Autoregulation of GFR
Tubuloglomerular Feedback
Vasoconstricts afferent arteriole
Adenosine
Vasodilates afferent arterioles
Nitric Oxide
“Percentage of solute reabsorbed is held constant”; Buffers effects of drastic GFR changes in urine output
Glomerulotubular Balance
Substance start to appear in the urine; Some nephrons exhibit saturation
Renal Threshold
All excess substance appear in the urine; All nephrons exhibit saturation
Renal Transport Maximum