RENAL- Functional Histology of the Kidney Flashcards

1
Q

what is the function of the kidney

A

homeostasis of blood
plasma composition - water, ions, organic waste products
blood pressure - through enzyme renin
erythrocyte content - secretion of erythropoietin

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2
Q

what is the functional unit of the kidney

A

the nephron - blood is filtered at a molecular level to produce urine - retains cells and large proteins - reabsorbs small molecules

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3
Q

describe the structure of the nephron

A
bowman capsules 
glomerulus
proximal convoluted tubules
loop of Henle -thin arm
loop of Henle - thick arm
distal convoluted tubule
collecting tubule
collecting duct 
papilla
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4
Q

what is the glomerulus

A

site of ultrafiltration - filtration / dialysis of blood through extremely fine molecular filter

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5
Q

what are the three layers of glomerular filter

A

cytoplasm of capillary endothelial cell of glomerulus

thick, fused basement membranes of capillary podocytes

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6
Q

what is the function of the proximal convoluted tubule

A

reabsorption from ultrafiltrate
active transport across membrane into the cell- small molecules like Na, glucose and amino acids
pinocytosis - macromolecules, broken down in lysosomes and returned to blood
passive influx - water, cl-

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7
Q

what is the structure of the renal tubule

A

long microvilli for high surface area, lytic enzymes on surface to break down macromolecules
pinocytotic vesicles carrying macromolecules to lysosomes
many mitochondria to duel active transport

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8
Q

what is the function of the loop of henle

A

reabsorption of water and salts from the filtrate

passive flux across the epithelium by osmosis and concentration gradients

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9
Q

what is the structure of the loop of henle

A

thin
squamous epithelium to allow passive flux
minimum of organelles

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10
Q

what is the function of the DCT

A

homeostasis by regulated active transport and exchange of ions (Na/K/H/HCO3)

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11
Q

what is the structure of the DCT

A

cuboidal epithelium - thicker than squamous to reduce passive flux and accommodate organelles
few, short microvilli
many mitochondria to fuel active transport

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12
Q

what are the functions of the collecting ducts

A

transport of urine to ureter

water homeostasis- passive reabsorption of water regulated through epithelial permeability

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13
Q

what is the structure of the collecting duct

A

cuboidal to columnal epithelium to prevent passive flux of water and urea
specialised dense membrane at cell contacts

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14
Q

what is the role of the macula densa

A

sensing Na in the DCT

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15
Q

what is the role of the juxtaglomerular cells

A

release renin - in response to lower Na in the DCT - renin indirectly increases vascular tone (blood pressure) and sodium resorption

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16
Q

name the cellular layers of the ureter

A

starting from inner - transitional epithelium
dense connective tissue (lamina propria)
layers of smooth muscle (peristalsis)
adventitia

17
Q

describe some features of the transitional epithelium

A

only found in ureters and bladder
specialised - impermeable to urine (noxious)
changes appearance on stretching

18
Q

what makes protects the cells from the toxic effects of urine

A

plaques of specialised (urine resistant) plasma membrane in apical cells of transitional epithelium
these plaques are made of transmembrane proteins called uroplakins
in a contracted bladder - the ridged plaques are invaginated forming irregular pits in the cytoplasm, allowing cell surface to decrease

19
Q

what are the downside of the transitional epithelium

A

cystitis

urinary tract infections - the transitional epithelium are highly impermeable - leukocytes of the immune system cannot readily penetrate

20
Q

why are UTIs common in women

A

female urethra is shorter

risk of contamination from anal region

21
Q

how can UTI’s be prevented

A

plenty of fluids