Midtterm nr 4 - Kidney Flashcards
What is the primary function of the kidney ?
- To maintain the isovolemia, isoionia
and isosomosis of the organism. - Extremely important role in elimination of hydrogen ions.
- Regulation of the acid/base equilibrium (isohydria) of the body also relates to the activity of the kidney.
What is the Its excretory function of the kidney?
Facilitates the elimination of the natural by-products (urea, uric acid)
Breakdown of the medicines administered by the veterinarian.
The excretion and chemical neutralization
of the toxic materials is partly also the duty of the kidney.
The kidney besides the regulation of isovolemia plays a significant role in?
Regulation of the circulation through the role of Angiotensin-II.
What kind of organ is the kidney?
The kidney is an endocrine organ
The kidney is an endocrine organ, which process does it participate in ?
Angiotensin II production
Takes part in blood formation (erythropoietin)
Bone metabolism (D-hormone production), —Heat production
(activation of the thyroid gland hormones)
Prostaglandin production is also significant.
How much of the cardiac output flows through the kidney?
Close to one quarter of the cardiac output flows through the kidney.
Most important physiological functions
of the Kidney?
Maintenance of HOMEOSTASIS
(isovolemia, isosmosis, isoionia, isohydria)
• Conservation of essential substances:
(water, electrolytes, glucose, aminoacids)
• Participation in acid-base balance
• Participation in Cardiovascular regulation
(especially through Angiotensin II synthesis)
• Elimination of exogenous and endogenous organic components (protein-metabolic endproducts, toxins, medicines.)
• Hormone production(direct or indirect): 1-25-OH-D3; erythropoetin; PGE2; T3 (from T4 converted by kidney deiodase)
Which species does not have the renal pelvis?
Bovine
What is the is the functional unit of the kidney?
The NEPHRON
What are the Elements of the Nephron?
-Malpighi-body (Bowman capsule;Glomerulus)
-Tubulary system:
(proximal tubule, Henle loop, Distal tubule,Collecting tubule)
What is the Basic Functions of the Nephron:
FILTRATION
REABSORPTION
SECRETION
EXCRETION
What is the Distribution of the Nephrons?
15% Juxtamedullary nephron
85 % Cortical Nephron
What is the basic structure of a nephron?
Each kidney consists of about one million nephrons.
The nephron is made up of a Malpighi body (Bowman capsule and glomerulus)
and its tubule.
The tubule is made up of a number of sections, what are they?
You could draw.
Proximal tubule: PCT and PST
Henle loop: DTL, ATL, TAL,
Distal tubule DCT and CNT
Colecting Duct: CCD and MCD
Finally urine flows to the Renal-Pelvis, through the Papillae
Urine is formed as a result of a
three phase process?
- Simple filtration
- Selective and passive reabsorption
- Excretion.
Filtration?
Filtered amount
Urinary output
Proteins and filtration
Filtration
The Filtered amount is
125 ml/min or 180L/day .
Urinary output: 1.5 L per day (about 1 ml/min),
Most of them are reabsorbed from the tubules.
PROTEINS are NOT filtered.
What does the filtration barrier consists of?
Three layers:
Fenestrated endothelium,
The glomerular basement membrane (GBM), Epithelial podocyte, foot processes with their interconnecting slit diaphragms.
The GBM is a molecular support composed of ???
Tightly cross-linked type IV COLLAGEN,
Laminin,
Nidogen, and
Proteoglycans.
What can bee used against glomerular proteins?
Monoclonal antibodies
The clinical course of CSN finish type is ?
Massive proteinuria, leading in
Persistent oedema and
Recurrent infections leading to
Death.
Due to this nephron-specific expression, the protein has been termed??
NEPHRIN
What is a NEPHRIN?
A protein belonging to the Ig (immunoglobulin) superfamily.
What does the NEPHRIN consist of?
Cell - Cell interactions:
The EC part of the nephrin has 8 Ig-like
modules and 1 fibronectin (type III-like) module.
The IC part has nine tyrosine
residues, responsible for ligand binding (following phosphorylation).
Kidney Circulation (PORTAL CIRCULATION) What are the 2 capillary beds?
Glomerular
Peritubular
Special circulation of Inner Medullary Zone: The Vasa Recta is ??
A portion of the peritubular capillary system which enters the medulla where the solute concentration in the interstitium is high.
It acts with the loop of Henle to concentrate the urine by a complex mechanism of counter current exchange.
If the vasa recta did not exist, the
high concentration of solutes in the medullary interstitium would be
washed out.
What are the 3 innervations of the kidney?
Sympathic
Parasympathic
Pain-sensing fibers in the capsule
What is the oldest examination method of the renal function?
- The analysis of the urine and the plasma
- Comparison of those by quantitative and qualitative analysis.
An inevitable method of the clinical diagnostic examination of the kidney is?
The ultrasound examination.
The examination methods of the kidney functions are?
Clearance
Micropuncture
Isotope measurements
Ultra sound
What does the clearance method tell us?
Clearance = volume (of plasma) from which all test substances are removed/min (cleared).ml/min.
It is a measure of the ability of the kidney to remove a
substance from the blood plasma and to forward it to the urine
Clearance is a VIRTUAL MEASURE
Does all filtered substances have a clearance?
All filtered substances have a clearance value.
What does it mean that a substance is exclusively filtered? And what is their clearance?
They are neither reabsorbed, or secreted - e.g. inulin
Their clearance is equal to the rate
of glomerular filtration rate (GFR)
What does it mean that some substances are entirely secreted?
Like para-amino-hyppuric acid), the
clearance of these gives the renal plasma flow (RPF)
When comparing the clearance of a substance with the inulin clearance which the substance is excreted?
If its clearance is higher than that of the inulin,
Then it is secreted,
if smaller, then it is Reabsorbed.
CL>CLinulin = its secreted
CL
Why is the clearance of glucose = 0?
Because it is totally reabsorbed
Why is the The clearance of urea is smaller than that of inulin?
since it is partly reabsorbed but excreted as well.
What is true about the clearance of para-amino-hippuricacid?
The clearance of para-amino-hippuricacid, PAH is constant at low plasma concentrations
(within a relatively broad range).
What is true about the clearance of inulin?
The inulin is typically such a substance that is only filtered: it is neither reabsorbed nor secreted.
According to this its
concentration in the plasma does NOT influence its clearance even under extremely high values.
Filtration/Secration? Clearance? cPHA cInulin cUrea cGlucose
cPHA - Filtration + Secretion, c = 600ml/min
cInulin - Filtration only, c=125ml/min
cUrea - Filtration + Rediffusion, c= 80ml/min
cGlucose - Filtration + Rediffusion, c = 0
Physiologic Renal Extraction is somewhat <1
Due to..?
„RESTING” nephrons
What is the formula of Renal extraction?
E= (Pa – Pv)/Pa
Pa= arterial concentration of substance Pv= venous concentration of substance Pa = Pv ---> E = 0 Pv = 0 E = 1
What is the extraction?
It Characterizes the ability of the kidney to eliminate a subtance from the organism
The extraction is maximal when…..?
The substance entering on the arterial side does not appear at all on the venous side (E=1).
This rarely happens due to
circulatory conditions.
The extraction is minimal when…..?
When the entire amount of the investigated
substance appears on the venous side and nothing gets into the urine (E=0).
This is the situation with the matters of vital
importance, getting into the primary urine (like glucose, amino acids etc.)
Renal Plasma Flow - how manny % of blood flows through the Kidney?
25%of blood flows through the kidney
What is RPF ?
RPF –> Fick Principle –> Law of Conservation of Matter
What is the equation of RPF?
Pa x RPF = (Pv x RPF) + (U x V)
RPF = U xV / (Pa – Pv)
RPF = (UxV/Pa) / (Pa – Pv)/ Pa = C/E
RPF= C/E
U: mg/ml in urine
P: mg/ml inplasma
V: ml/minute urine
What are the Distribution of blood flow in tissue layers of kidney?
Cortical?
Outer Medullary?
Inner Medullary zone?
Distribution of blood flow in tissue layers of kidney
90 % Cortical
8 -9 % outer Medullary
1 -2 % inner Medullary zone (exclusively v. recta!)
What is GFR, the glomerular filtration rate ?
The amount of filtrate produced per unit time by all of the nephrones of the two kidneys.
It is one of the most important parameters of
renal function.
GFR Under 80 - 250 mmHg mean?
Arterial pressure, the kidney maintains its value at a constant level with the help of auto regulative mechanisms.
(except in dog, where it may change physiologically in case the
mean arterial pressure is changing)
The GFR can be measured by ?
Inulin and creatinine.
Its average value is
120 ml/ min.
What is Filtered load (FL, mg/min)?
Filtered load of a given substance is the
amount of it that is ultrafiltered per unit time [mg substance/min]
(its other name is: filtration capacity).
What are the Factors In Association With GFR?
- Substantial changes of RBF do not substantially influence GFR (autoregulation).
- Changes of GP(Glom.Pressure) results in similar changes of GFR (however Autoreg. reduces that change).
- Extreme increase in CP(Capsular Press.) reduces the GFR (i.e. ureter obstruction).
- Increase of GCP (Glom.Colloid Osmotic Press.) decreases GFR
(1 Hgmm increase = 5 – 10% GFR decrease ). - Glom.Membr.Permeab.(pathogenic) decreases GFR.
- Reduced Total Filtr.surface (nephrectomy): decreases GFR.
What are the Basic Processes of Kidney Function?
- Filtration
- Tubulary reabsorption
- Tubulary secretion
- Excretion
Effective filtration pressure?
DRAWING + values
If If Glucose FL > 350 mg/min (> 17 mmol/l) – (Glucosuria will happen)
For example at?
Diabetics
Pregnancy
At normal GFR, Tmax is achieved at ?
Glucose however starts appearing in urine already at ?
Tmax is achieved at 17 mmol/L (300 mg%)
Glucose however starts appearing in urine already at 10
Excretion is ?
The sum of Filtration and Secretion.
The excretion is carried out in three phases?
A, Linear phase,
B, the SDL (=self depression limit) phase (more and more cells become
unable to secrete, so the excretion is decreased),
C, the Saturation phase, when the excretion curve is paralel with the
filtration
What is the Function of JGA?
- Renin (enzyme) production
- SENSOR of salt- and water-metabolisme
• BARORECEPTOR – Sensory organ of
circulation
• Hormone Production: Angiotensin-II production
What are the steps of The Renin Angiotensin System (RAS)?
Liver Angiotensinogen Angiotensin I Angiotensin II Angiotensin III Degradation products
Drawing
The RAS can also be found in?
It can be found also in CNS & Adreno-Cortex
