1: Renal functions, basic processes, and anatomy Flashcards
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List 7 functions of the kidneys
- water and electrolyte balance
- acid base balance
- blood pressure and extracellular fluid volume regulation
- excretion of metabolic waste and foreign substances
- regulation of RBC production
- regulation of Vitamin D production and Ca, P balance
- gluconeogenesis (more prominent after prolonged fasting)
List 3 metabolic waste products (uremic toxins) the kidneys excrete and name their origin
urea - from protein
creatinine - from muscle creatine
uric acid - from nucleic acid
How does erythropoietin production differ between the adult and during embryonic development?
adult - produced by interstitial cells in the cortical interstitium near the border of the renal cortex and medulla
embryonic development - produced by the liver
What cells produce erythropoietin?
Peritubular interstitial cells in the cortical interstitium at the border between the renal cortex and medulla
What is the stimulus for erythropoietin production?
reduction in the partial pressure of O2 in the local environment of the secreting cells
Why does erythropoietin production fall in CKD?
reduction in the renal metabolism - less oxygen consumption by cells - local PO2 will be higher - less stimulus for erythropoietin production and secretion
What fraction of the fluid entering the glomerulus is transferred into the renal tubules
0.2 i.e., 1/5
name the structures
What are the interstitial cells of the kidneys and what do they produce?
fibroblasts and immune cells
collagen, proteogylcans, glycoproteins, cytokines
How does the structuring of the cortex and medulla differ?
the tubules and capillaries in the cortex are arranged very randomly
the tubules and capillaries in the medulla are organized in parallel arrays
Name these structures
What part of the kidney does the proximal tubule lie in?
the convoluted proximal tubule lies within the cortes, while a short straight segment descends a short way into the outer medulla
Where does the descending thin limb of the loop of Henle begin?
All descending thin loop of Henle limbs begin between the border of the outer and inner stripe of the outer medulla
Describe the difference in location between long and short loops of Henle
- long loops reach into the inner medulla, any part of the ascending loop that is still within the inner medulla will remain thin
- all thick ascending limbs begin at the border of the inner and outer medulla
- short loops will not have a thin ascending portion
Where does the loop of Henle end?
The final part of the thick ascending loop of Henle reaches into the macula densa - after which it turns into the distal convoluted tubule
What are the parts of the collecting duct?
cortical collecting duct
outer medullary collecting duct
inner medullary collecting duct
Explain how the types of cells differ between segments of the nephron
- up to the distal convoluted tubules each segment has their own specific epithelial cells
at the distal convoluted tubules - has principal cells and intercalated cells - the principal cells are section specfic between the convoluted tubules, connecting tubules, and collecting ducts
- the end of the medullary collecting duct only contains inner medullary collecting-duct cells
Name the 3 parts of the juxtaglomerular apparatus (JGA)
- Granular cells - differentiated smooth muscle cells in the walls of the afferent arteriole, contain granulaes with the hormone RENIN
- Extraglomerular mesangial cells -
- Macula densa cells - detectors of flow rate and composition of fluid within the end of the thick ascending loop of Henle
Regulates glomerular filtration rate, renal blood flow, and affects blood pressure
Explain the defintion of filtration, secretion, reabsorption, and excretion by the kidneys
filtration - water and solutes leaving the vascular system and entering the Bownman’s space
secretion - substances transported into the tubular lumen from the epothelial cells
reabsorption - subtances moved from the lumen across the epithelium into the interstitium and then capillaries/blood
excretion - substances exiting the body
What percentage of blood entering the glomerular capillaries is filtered versus goes to the efferent artioles?
20% (1/5) filtered
80% continues to the efferent arterioles
List the 3 most important metabolic processes in the tubules
- gluconeogenesis
- ammonium synthesis from glutamine
- bicarbonate production
Give a brief overview of the function of each of these parts of the nephron:
- glomerulues
- proximal tubule
- loop of Henle
- distal tubule
- cortical collecting duct
- medullary collecting duct
- glomerulus - filtration
- proximal tubule - reabsorption of 2/3 of filtered water, Na, and Cl, reabsorption of all useful organic molecules (glucose, AAs, etc.), reabsoprtion of K, P, Ca, bicarbonate
- loop of Henle - reabsorption of 20% of filtered Na and 10% of filtered water –> makes luminal fluid more diluted, contains macula densa
- distal tubule - reabsorb 5% each of water and Na
- cortical and medullary collecting ducts + connecting tubules - water and Na reabsorption in response to ADH, angiotensin II, aldosterone
- medullary collecting duct acid abd base excretion, urea excretion
Where are renal corpuscles located?
throughout the cortx
