Download renal-structure-helps-function

Composition of urine
2
Substance
Water
Protein
Glucose
Plasma / %
90
8
0.1
Urine / %
95
0
0
Increase
-
Urea
Uric acid
Ammonia
0.03
0.004
0.0001
2
0.05
0.04
67x
12x
400x
Creatinine
Na+
K+
0.001
0.32
0.02
0.075
0.35
0.15
75x
1x
7x
ClPO43SO42-
0.37
0.009
0.002
0.60
0.27
0.18
2x
30x
90x
3
Sources
Where do these come from?
 Water
 Protein
 Glucose
 Urea
 Uric acid
 Creatinine
 Ammonia
4
Sources
 Water
ingested drink and food / metabolic
water
 Protein ingested food / tissue breakdown
 Glucose ingested food / glycogen / other
compounds
 Urea
deamination / urea cycle
 Uric
acid metabolism of nucleotide bases
 Creatinine metabolism of creatine (creatine
phosphate)
 Ammonia deamination
5
Processing in the kidneys
 Ultrafiltration
 Selective
reabsorption
 Secretion
 Osmoregulation
Function of renal system is to filter waste
from the blood, form and secrete the urine.
6
glomerulus
branch of renal
artery
Bowman’s
capsule
DCT
PCT
collecting
duct
branch of
renal vein
capillaries
loop
How does the
structure of the
nephron help it
carry out its
function?
Malphigian body – the Bowman’s capsule
and Glomerulus

The Malphigian body, composed of
Bowman’s capsule and the
glomerulus, is the site of ultrafiltration
of the blood

The pressure of the blood in the
glomerulus is high because the
efferent vessel carrying blood away
from the Malphigian body is narrower
than the afferent vessel which brings
blood into it.

Fluid is forced out of the capillaries
under this pressure, passed through
the basement membrane , which
retains the plasma proteins, and then
the remaining ultrafiltrate passes into
the Bowman’s capsule and on into
the Proximal convoluted tubule.
Proximal tubule


Active reabsorption of
the glucose and of 67% of
sodium ions which have
left the blood, also
causing active
reabsorption of water
and chloride ions.
Microvilli on the lining
epithelial cells provide an
increased surface area
for reabsorption.
http://www.biologymad.
com/resources/kidney.sw
f - use the drop down box
and click on ‘proximal
10
tight junction
filtrate
blood
microvilli
large surface
area
mitochondria – ATP for active transport
11
PCT cells are adapted to their functions
• tight junctions between cells to ensure transcellular movement
•microvilli to give a large surface area for absorption
• mitochondria to form ATP for active transport
• infoldings of basal membrane to allow movement of substances into
the blood
Loop of Henle


This is where the urine is
concentrated and water
is conserved. A large
surface area is available
for reabsorption.
http://www.biologymad.co
m/resources/kidney.swf - go
to the drop down box and
click on ‘loop’
Distal Tubule

It is involved in the
concentration of the
urine, the removal of
unwanted substances
from the blood and
control of blood pH.
Ureter
 The ureters are muscular tubes that transport
urine from the kidneys to the urinary bladder.
Ureters have three layers of tissue:
 1. Fibrous outer coat
 2. Muscular layer
 3. Inner mucosal layer
The muscle layer is the functional layer, using
peristalsis to move the urine along.
 Bladder
The urinary bladder is a sac for the
temporary storage
of urine. The outer surface is
covered with fibrous connective
tissue.
Inside the connective tissue is a
muscular. This smooth muscle
contracts to expel urine from the
bladder. The next tissue layer is the
'submucosa,' an elastic fibrous
membrane that supports the mucosa,
which lines the inside of the bladder.
When the bladder is
empty, the mucosa has many folds
termed 'rugae.' The
rugae and transitional epithelium
allow the bladder to
stretch when filled with urine.
 http://www.biologymad.com/resources/ki
dney.swf