Lecture 2 - kidney Flashcards
What are the functions of the kidney?
- Excrete waste and foreign substances
- Electrolyte balance
- ECF volume
- Arterial pressure
- Acid base balance
- produce and secrete hormones
How much of the body bass does the kidney account for?
0.5 %
How much of the cardiac output does the kidney account for?
20%
How much of O2 consumption does the kidney account for?
5 %
How many nephrons in each kidney?
1,000,000
What are the types of nephrons?
- ) Cortical
2. ) Juxta medullary
What percentage of nephrons are cortical?
80 %
How much blood does the kidney recieve per minute?
1.2-1.3 L per min
What are the capillary beds to the kidney?
- ) Glomerular Capillaries
- ) Peritubular capillaries
- ) Vasa recta
The glomerulus is like a ….
filter
The nephron is the …….. of the kidney
functional unit
What is a nephron comprised of?
Renal corpsucle and renal tubule
What is the renal corpsucle made of ?
Glomerulus and surrounding bowmans capsule
What is the glomerulus ?
ball of capillaries
What happens in the glomerulus?
Urine is filtered.
What does the filtration barrier of the glomerulus consist of?
- ) endothelial cells of glomerular capillaries
- ) glomerular basement membrane
- ) podocytes of the bowmans capsule
What are the components of the renal tubule?
- ) proximal convoluted tubule
- ) loop of henle (middle section)
- ) distal convuluted tubule and collecting duct
What happens at the proximal convuluted tubule?
majority of the water, potassium, chloride and sodium that was filitered are reabsorped, as well as all of the glucose and amino acids.
What happens at the loop of henle?
it has a hairpin configuration with a thin descending limb and both a thin and thick ascending limb. In the thin descending limb water reabsorption occurs. Then sodium reabsorption occurs in the two parts of the ascending limb – this is both active and passive.
What happens in the distal convuluted tubule?
role in the absorption of many ions, and in water reabsorption. The distal convoluted tubule can be subdivided into two distinct regions, the early and late sections. The collecting duct also plays an important role in urea recycling.
What kind of cells are present in PCT and the TAL and why?
S1 - have high rates of solute trasnport, abundant mitochondria, extensive microvilli on the luminal plasma membrane and infoldings of the basolateral membrane. THese cells are rich in basolateral Na-K ATPase
S2 segment - only the PCT and so there are prominent basolateeral infolding but less microvilli and mitochondria than S1. This is due to the participation of S2 in secretory transport.
S3 - abundunt microvilli but basolateral infoldings and mitochondria are less prominent than S1.
What are S1 cells?
S1 - have high rates of solute trasnport, abundant mitochondria, extensive microvilli on the luminal plasma membrane and infoldings of the basolateral membrane. THese cells are rich in basolateral Na-K ATPase
What are S2 cells?
S2 segment - only the PCT and so there are prominent basolateeral infolding but less microvilli and mitochondria than S1. This is due to the participation of S2 in secretory transport.
What are S3 cells?
S3 - abundunt microvilli but basolateral infoldings and mitochondria are less prominent than S1.
What are the cells in the loop of henle?
Thin limbs - flattened cells with no mitochondria and little ATPase activity.
Collecting ducts - have three kinds of cells - 1.) priniciple cells (reabsorb NA+ and secrete K+ and Cl-) with lots of water channels (aquaporins) and Na-K ATPase, 2.) alpha (secrete H+) and beta (secrete HCO3-) intercalated , 3.) mitochondria rich cells with abundant proton- ATPases.
What is the role of juxtaglomerular apparatus?
it senses fluid and salt delivery and so it can alter the GFR in response. This is called the tubuloglomerular feedback.
When there is a decrease in pressure in the afferent arteriole, the AA acts as a baroreceptor and it stimulates the release of renin from granular cells which eaeds to vasoconstricition.
What does the JGA consist of?
glomerular afferent and efferent arterioles and the specialized tubular epithelial cells called the macula densa
What are the inputs to the kidney from the ANS?
The sympathetic arm which releases noradrenaline and dopamine.
Major effects of the sympathetic arm on the kidney?
- ) vasoconstriction
- ) sodium reabsorption
- ) increase in renin secretion
What are the three steps to urine ?
- ) glomerular filtration
- ) Tubular reabsorption
- ) tubular secretion
