Nephrones And Glomerulus

Front 1

number of nephrones

Back 1

Healthy kidneys contain approximately 1 million indi­
vidual nephrons.

Front 2

Nephrone parts

Back 2

Each nephron consists of a glomerulus,
, a proxi­
mal renal tubule, a loop of Henle, a distal renal tubule
and a collecting duct,

Front 3

Func of nephrone

Back 3

which is responsible for ultrafiltration of blood

Front 4

func of tub str

Back 4

which together are responsible for
selective reabsorption of water and electrolytes that
have been filtered at the glomerulus (see Fig. 16.2,
p. 430).

Front 5

fate of most of glum filtrate

Back 5

Under normal circumstances, more than 99% of
the 170 litres of glomerular filtrate that is produced each
day is reabsorbed in the tubules.

Hint 5

amt of glum filt/day

Front 6

Remainder fluid fate

Back 6

The remainder passes through the collecting ducts of multiple nephrons and
drains into the renal pelvis and ureters

Front 7

Glomerulus?

Back 7

The glomerulus comprises a tightly packed loop of capil­
laries supplied by an afferent arteriole and drained by
an efferent arteriole. .

Front 8

Bowman's cap?

Hist?

Back 8

It is surrounded by a cup­shaped
extension of the proximal tubule termed Bowman’s
capsule, which is comprised of epithelial cells

Front 9

Func of glom?

wht is GBM?

Back 9

Blood
that enters the glomerulus undergoes ultrafiltration
across the glomerular basement membrane (GBM),
(Fig.
17.1C and D)

Hint 9

which is formed by fusion of the basement membranes
of tubular epithelial and vascular endothelial cells

Front 10

How circ molec pass to GBM

Back 10

The glomerular capillary endothelial
cells contain pores (fenestrae), through which circulat­ing molecules can pass to reach the underlying GBM.
(Fig. 17.1E).

Hint 10

Fenestrae

Front 11

Glom epith cell also called?

Back 11

Glomerular epithelial cells (podocytes) have multiple
long foot processes which interdigitate with those of the
adjacent epithelial cells

Hint 11

digitation

Front 12

Func of podocytes?

Back 12

As well as maintain­
ing a selective barrier to filtration, podocytes are involved
in regulating turnover of the GBM

Front 13

Loc of mesangial cells

Back 13

. Mesangial cells lie in
the central region of the glomerulus. They have contrac­tile properties similar to those of vascular smooth muscle
cells but also have macrophage­like properties.

Hint 13

property

Front 14

Protein size permeable

Back 14

Under normal circumstances, the glomerulus is
impermeable to proteins the size of albumin (67 kDa) or
larger, while proteins of 20 kDa or smaller are filtered
freely. .

Front 15

b/w 20 -67kDA

dep upon?

Back 15

The ability of molecules between 20 and 67 kDa
to pass through the GBM is variable and depends on the
size (smaller molecules are filtered more easily) and
charge (positively charged molecules are filtered more
easily)

Front 16

Lipid filteration

Back 16

Very little lipid is filtered by the glomerulus

Front 17

Autoregulation of BP in Glom?

Back 17

Filtration pressure at the glomerulus is normally
maintained at a constant level, in the face of wide vari­ations in systemic blood pressure and cardiac output, by
alterations in muscle tone within the afferent and effer­
ent arterioles. This is known as autoregulation. .

Front 18

When is Renin Secreted?

wht it cleaves?

to release?

cleaved by?

to prd?

Back 18

When there is a reduction in renal perfusion pressure, renin is released by specialised smooth muscle cells in the juxta­glomerular apparatus. Renin cleaves angiotensinogen
to release angiotensin I, which is further cleaved by
angiotensin­converting enzyme (ACE) to produce angi­otensin II
(Fig. 17.1D)

Front 19

Short term rest of glom perf pressure

Back 19

This restores glomerular perfusion pressure in the short term by causing vasoconstriction
of the efferent arterioles within the kidney and by induc­
ing systemic vasoconstriction to increase blood pressure
and thus renal perfusion pressure.

Front 20

long term

Back 20

In the longer term,
angiotensin II increases plasma volume by stimulating
aldosterone release, which enhances sodium reabsorp­
tion by the renal tubules

Front 21

Back 21

Front 22

Histology of a normal glomerulus

Back 22

Histology of a normal glomerulus

Front 23

Back 23

Hint 23

Schematic cross-section of a glomerulus, showing five
capillary loops, to illustrate structure and show cell types

Front 24

Back 24

Hint 24

Electron micrograph of the filtration barrier. (GBM =glomerular basement membrane