Niere (2)

What is the weight of a single Niere (kidney)?

Approximately 150g

How many Nieren (kidneys) does a human typically have?

Two, although one is sufficient to filter the blood

What percentage of the total blood volume is filtered by the kidneys per minute?

Approximately 20%, which equals about 1 liter of blood per minute in a resting state

Name the two main macro-structures of the kidney's interior.

The Nierenrinde (renal cortex) and the Nierenmark (renal medulla)

What is the name of the funnel-like structure that collects urine before it enters the ureter?

The Nierenbecken (renal pelvis)

Which tube leads from the kidney to the Harnblase (urinary bladder)?

The Harnleiter (ureter)

What is the name of the functional unit of the kidney?

The Nephron, and there are about 1 million of them per kidney

Name four specific Abfallstoffe (waste products) removed from the blood by the kidney.

Harnstoff (urea), Harnsäure (uric acid), Ammonium, and Kreatinin (creatinine)

What substance is a product of muscle metabolism and serves as a vital indicator of kidney function?

Kreatinin (creatinine)

Name three substances that the kidney selectively zurückhalten (retains/reabsorbs).

Glucose (sugar), Laktat (lactate), and Aminosäuren (amino acids)

Which hormone produced by the kidney regulates the number of red blood cells?

Erythropoietin (EPO)

Name the hormone produced by the kidney involved in platelet production.

Thrombopoietin

What are the three primary functions of a Nephron?

Filtration (in the glomerulus), Resorption (reabsorption), and Sekretion (secretion)

What are the two primary components of a Nephron?

The Glomerulus (filtration unit) and the Tubulus (tubule system)

What structure acts as the "active filter" in the kidney and consists of specialized cells?

Podozyten (podocytes)

What structure acts as the "passive filter" in the kidney?

The Glomeruläre Basalmembran (glomerular basement membrane), which is an extracellular matrix

Which two proteins primarily make up the Basalmembran (basement membrane)?

Laminine and Kollagene (collagens), specifically type IV collagen

What physical property prevents most proteins like Serumalbumin from being filtered?

Größe (size), as the filter is permselektiv (selectively permeable) based on molecular size

Besides size, what other property affects filtration in the Glomerulus?

Ladung (electrical charge), as negatively charged particles pass more difficultly because the membrane contains negative Heparansulfat

What is the definition of Clearance?

The volume of blood plasma (in ml) that is completely freed of a specific substance by the kidneys per minute

What is the formula for Clearance?

C = (Ux * V) / Px, where Ux is concentration in urine, V is urine volume, and Px is concentration in plasma

Why is the Clearance of Glucose normally zero?

Because it is fully filtered but then 100% rückresorbiert (reabsorbed) in the tubules

What is the average Glomeruläre Filtrationsrate (GFR) in a healthy adult?

Approximately 125 ml/min, which totals about 180 liters of primary urine per day

What primary pressure "pushes" fluid through the glomerular filter?

Hydrostatischer Druck (hydrostatic pressure), which is essentially the blood pressure

What pressure acts as a "counter-pressure" to filtration because proteins remain in the blood?

Kolloidosmotischer Druck (colloid osmotic pressure/oncotic pressure)

What is the net filtration pressure at the Glomerulus in normal conditions?

About 10 mm Hg

What is the Bayliss-Effekt (Bayliss effect)?

A myogenic Vaskokonstriktion (vasoconstriction) where blood vessels contract in response to high pressure to keep the GFR constant

What structure senses the Natriumchlorid (NaCl) concentration in the distal tubule to regulate GFR?

The Macula densa

How does Angiotensin II affect the kidney to increase filtration pressure?

It causes Vaskokonstriktion (vasoconstriction) of the efferent arteriole

What percentage of water and NaCl is reabsorbed in the Proximaler Tubulus?

Approximately 60% to 70%

What specific transporter is responsible for most glucose reabsorption in the proximal tubule?

SGLT-2 (Sodium-Glucose Linked Transporter 2)

What is a clinical side effect of SGLT-2 Hemmer (inhibitors)?

Glukosurie (glucose in urine), leading to thirst and increased urine volume

In terms of osmolarity, how is water reabsorbed in the Proximaler Tubulus?

It is iso-osmolar, meaning the osmolarity of the remaining urine does not change despite water loss

What is the Gegenstromprinzip (countercurrent principle)?

A mechanism in the Henle’sche Schleife (loop of Henle) that creates a high osmotic gradient in the medulla to concentrate urine

Is the absteigender Ast (descending limb) of Henle's loop permeable to water?

Yes, it is wasserdurchlässig, but it does not allow ions to pass

Is the aufsteigender Ast (ascending limb) of Henle's loop permeable to water?

No, it is wasserundurchlässig, but it actively transports ions out

How does Harnstoff (urea) contribute to urine concentration?

It recirculates between the collecting duct and the loop of Henle to maintain the hyper-osmolar environment in the medulla

Which hormone regulates the insertion of Wasserkanäle (water channels/aquaporins) into the collecting duct?

ADH (Vasopressin / Antidiuretic Hormone)

Why does drinking alcohol lead to increased urination?

It inhibits the production of ADH, preventing water reabsorption in the Sammelrohr (collecting duct)

What is Diabetes insipidus?

A disease where the ADH system fails (due to lack of ADH or receptor issues), leading to massive Wasserverlust (water loss)

What is the primary indicator of a damaged glomerular filter appearing in the urine?

Proteinurie (proteinuria), specifically the appearance of albumin

What genetic disease is caused by mutations in Kollagen 4 and damages the basement membrane?

Alport-Syndrom (Alport syndrome)

What are Diuretika (diuretics)?

Drugs that inhibit reabsorption of ions and water to increase urine output and lower Blutdruck (blood pressure)

What is Hämodialyse (hemodialysis)?

A treatment for kidney failure where blood is cleaned of waste products like Harnstoff across a semipermeable membrane

What happens to the Konzentration (concentration) of Inulin as it passes through the proximal tubule?

It increases significantly because water is removed while the Inulin amount remains the same

What percentage of Bikarbonat (bicarbonate) is reabsorbed in the proximal tubule?

About 90%

What is Solvent Drag?

The passive transport of dissolved ions between cells (paracellular) along with the flow of water

Which hormone regulates NaCl reabsorption and potassium secretion specifically in the Sammelrohr?

Aldosteron

What defines Fanconi’s Syndrom?

A generalized defect in the Resorption (reabsorption) functions of the proximal tubule

What is the maximum osmolarity a human kidney can achieve in the medulla?

Approximately 1200 mOsmol/l

Why can desert animals concentrate urine much more than humans?

They have much longer Henle’sche Schleifen (loops of Henle) reaching deeper into the medulla

How does the Vasa recta (blood system) support the kidney's concentration ability?

It maintains the osmotic gradient by removing reabsorbed water and solutes without washing out the gradient

What is Diabetes mellitus in the context of the kidney?

A condition where blood glucose is so high that the SGLT-2 transporters are overwhelmed, leading to glucose and water in the urine

Name a genetic disease affecting the Laminin proteins of the basement membrane.

Pierson-Syndrom (Pierson syndrome)

What is the role of Carboanhydrase in the proximal tubule?

It is an enzyme linked to the reabsorption of Bikarbonat (bicarbonate)

What is the Vms (transepithelial potential) in the proximal tubule?

It is initially negative and then becomes slightly positive

Which diuretic group acts specifically on the aufsteigender Ast (ascending limb) of Henle's loop?

Schleifendiuretika (loop diuretics)

What describes the movement of water following an osmotic gradient between cells?

Parazellulär (paracellular) transport

What is the typical osmolarity of human blood plasma?

Approximately 300 mOsmol/l

What is Glukosurie?

The presence of glucose in the urine