Kidneys Flashcards by Ghosn Al-Khulaidi

List the key functions of the kidney

Regulate fluid osmolality/volume
Regulate electrolyte balance
Acid/base balance
Excrete metabolic product and foreign substances
Produce/excrete hormones
Gluconeogenic

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Where does filtration start

Glomerulus

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Functioning unit of kidney

Nephron

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Forces influencing filtration in kidney

Hydrostatic pressure/blood pressure
Colloid osmotic pressure
Fluid pressure in bowman’s capsule

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Briefly explain what generates colloid osmotic pressure

Protein in plasma but not in bowmans capsule

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When is autoregulation of GFR constant

Arterial BP between 80-180

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What will be filtered in blood

Up to 70 kd
H29
Na/k/ck
Mg/glucose/ urea/ creatinine / insulin

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What is not filtered in kidney

Over 70 kd
Proteins
Immunoglobulins
Ferritin
Cells

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Where does reabsorption occur

In proximal tubule

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How is surface area increased in proximal tubule

Brush border

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What is meant by isoosmotic in proximal tubule

Solute and water reabsorbed are coupled

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In proximal tubule explain the effect of tight junction

Increase permeability for paracellular transport

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What is reabsorbed and what is secreted in reabsorption

Glucose/aa /organic absorbed completely
Some phosphate
Ca and water in para to sodium
Secretion of h+\ uric acid and drugs

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In proximal convoluted tubule, how are glucose aa/ water reabsorbed

Active transport

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What can excess saturation in urine indicate

Kidney disease

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Components of loop of henle

Ascending
Descending
Macula densa

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Effect of different absorption on urine

Water reabsorbed = concentrated
Water secreted = dilute

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Where is calcium absorbed

In descending limb

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Difference between medulla and cortical of loop of henle

Medulla no pth
Cortical pth

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How is water absorbed in descending limb

Passively

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How is interstitial hypertonicity maintained

Active absorption of sodium from THIck ascending limb

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Describe how differenr areas of loop of henle have different permeability

Descendinf permeable to water
Ascending permeable to nacl

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Role of the thick ascending limb

Pump for nacl

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Describe the Distal nephron

Compromises distal convoluted tubule & collecting duct allowing regulation of reabsorption and secretion

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In the distal nephron, what receptors does it have

Receptors hormone for regulation of water /solute

In distal convoluted tubiuke, how is calcium absorbed

Under pth

Site of action for adh

Collecting duct

Water absorption influenced by

Adh Medullary hypertonicity

what do distal nephrons reabsorb

Sodium Secrete h ions Secrete k ions under influence of aldosterone Generate new bicarbonate

Importance of urea

From protein breakdown Amino groups removed Ammonia converted to urea

In kidneys describe importance of urea

Helps maintain high osmolarity gradient in medulla region= drive water reabsorption

Process of urea recycling

Adh increases reabsorption of h20 in vasa recta + urea Urea recycled

Why is it important to keep concentration of urea hugh in interstitial fluid

Maintain high concentration gradient in medulla

Importance if na reabsorption

Account for over 90% of ECF osmotic activity When na above load = ECF osmotic activity increased

What can a change in ECF lead to

Matching expansion/reduction of plasma volume leading to increase or decrease of BP

Extracellular volume afffects ….

Blood pressure

Types of control in distal nephron

Allows for production of conc/dilute urine = influence ECF volume

What happens when blood volume is low in regards to secretion and absorption

Decrease water secretion Increase nacl absorption

How do you increase nacl absorption

Detection Areas in nephron to alter absorption Signal response Response

The process ofnincreasing/ decreased nacl absorption

Fine tuning

What does aldosterone act on

Distal nephron Increasing nacl absorption And signalling to brain to keep water there

In distal nephron what must be present for nephron to be permeable

Vasopressin

What can changes in medulla lead to

+Hypertonic medulla= More aquaporins in collecting duct= concentrated urine produced -Hypotonic = doesnt allow concentrated urine to be produced

Maximum vasopressin at collecting duct

Collecting duct freely permeable to water

Absence of vasopressin at collecting duct

Collecting dict impermable to h20

Factors affecting release of vasopressin

Osmolarity greater than 280 Descrrased atrial stretch due to low BV Low BP

Relationship between plasma osmolarity and vasopressin

Directly proportional

What happens if blood pressure is too high

As a result of increased BP= Increased stretch detected ANP released Vasopressin inhibitted Increase GFR -Renin No aldosterone = low BP

Effect of decreased circulating volume

Increased renin via juxtglomerular cells

Juxtaglomerular cells release renin in response to

Sympathetic nervous system stimulation Decrease filtrat osmo Low sodium levels in macula densa Decreased stretch due to decreased blood flow

Role of sympathetic nervous system in urination

Contract internal sphincter & relax detrusor muscle

Role of para system in urination

Relax internal urethral Contract detrusor muscle

Role of somatic control in urination

Vountary control of both internal and external muscles

When do kidneys secrete erythropoietin

Hypoxia due to decreased rbc Reduced oxygen availability Increased tissue demand for oxygen

Enhanceed erthropoeitin increases

Rbc in circulating blood Xoygen carrying ability of blood

Recall the erythropoietin mechanism

Hypoxia/- rbc Kidney and liver release erythropoietin Ery stimulate rbc in bone marrow Enhand eryth= increased rbc Increased 02 carrying ability of blood

Where are epo cells found

Interstitium of renal parenchyma

Process of synthesis of epo cells

De novo in response to hypoxia so no detectable storage of hormone

Mechanism by which hypoxia leads to EPO synthesis -Activation

Epo bind to specific molecules on cell surface aka epo receptors Activation of epo = intracellular signal in immature erythroid cells promote survival

What do EPOs promote

Proliferation Erythroid differentiation

Epo cells lead to

Increased rate of eryth differentiation Increased red cell mass

Dietart requirment

Proteins/lipid /irons Iron in liver spleen and bone marrow

Where is IC iron stored

Protein iron complexes eg ferritin/ hemosiderin

When might epo levels be low

Humans with end stage renal failure , low epo serum conc Restored once renal transplant successfull