Wk 26 Flashcards
(71 cards)
What are the 5 roles of the kidneys in homeostasis?
Fluid and electrolyte balance
Acid base balance
Endocrine functions
Waste excretion
Blood pressure control
What are the 3 major tasks the kidney performs to produce urine?
Filtration
Reabsorption
Secretion
What are the 3 parts of the kidney? anatomy
Cortex
Medulla
Pelvis
What does the cortex contain? (filtering apparatus- 2 things)
Renal corpuscles and convoluted tubules
What does the medulla contain? 3
Blood vessels
Loops of Henle
Collecting ducts
What does the pelvis of the kidney do?
Receives urine and sends to ureters
What are the kidney artery and vein?
Renal artery and renal vein
What are the functional units of the kidneys?
Nephrons
What are the 2 classes of nephrons?
Which are more common?
Cortical nephrons (more common -85%)
Juxtamedullary nephrons
How do kidneys maintain fluid and electrolyte balance…
What determines electrolyte balance?
What is it largely regulated by?
Balance of filtration, reabsorption, secretion (excretion of water and electrolytes must match intake)
Endocrine signals
How do kidneys maintain acid-base balance?
What affects concentrations and pH in tubules?
Bicarbonate buffer system
Electrolyte concentrations
What hormones (not all hormones) does the kidney produce? 4
Erythropoetin (in response to cellular hypoxia)
Renin
Prostaglandins
Vitamin D
What 6 hormones have affects on the kidney?
Atrial natriuretic peptide (reduce blood vol)
Antidiuretic hormone (increases blood vol)
Aldosterone (increase blood vol)
Cortisol
Parathyroid hormone
Calcitonin
What is the Juxtaglomerular Complex made up of?
Part of the afferent arteriole, just before it enters the Bowmen’s capsule and a set of the DCT of the same nephron
What do juxtaglomerular cells do?
They contain renin so when the systolic blood pressure is low in the afferent arteriole, they release renin which activates the angiotensin system which increases BP
What are macula densa cells?
What do they do?
Modified DCT cells in the juxtaglomerula complex
They are sensitive to Na conc co when there is lower BP, there is lower amounts of Na coming by so it stimulates the release of renin via juxtaglomerula cells
What are Lacis cells/ Polkissen cells?
Extra glomerular mesangial cells
What is the waste excreted by the kidneys?
Nitrogenous wastes (urea, creatinine)
By-products of metabolism (Ammonia, uric acid, urea, creatinine)
Protein deamination occurs in the liver and the product is ammonia (NH3) which is toxic.
What does it turn into?
NH3 goes into the urea cycle and produces urea (which is excreted by the kidneys)
Nucleic acid components (nucleosides) are metabolised into…
Pyrimidines (cytosine, uracil and thymine)=
Purines (adenine, guanine)=
Pyrimidines= NH4 (which enters urea cycle)
Purines= uric acid
What does the urea cycle and where does it take place?
It converts ammonia to urea
Takes place in the mitochondria and cytosol of hepatocytes
What is creatinine the breakdown product of?
Creatine and phosphocreatine
What is Azotaemia?
Increased circulating nitrogenous products (BUN- blood urea nitrogen) due to kidneys not excreting waste properly
What are the effects of Nitrogenous wastes (primarily urea and creatinine) on the CNS?
How do the nitrogenous wastes affect the digestive system?
How does it affect the skin?
Confusion
Seizures
Coma
Loss of appetite
Nausea
Mucosal bleeding
Pruritus and ‘uraemic frost’ on skin as urea crystalises