Download Your Kidneys

Waste Excretion and Internal
Equilibrium
Chapter 12.1 (Part A)
Pgs. 378 - 380
A look at your kidneys
Kidneys are bean-shaped organs (two)
Each are about the size of your fist
They are located in the middle of your
back, just below your rib cage, on either
side of your spine.
They receive a huge amount
-- 20 percent -- of the blood
pumped by the heart
What do your kidneys do?
The large blood supply to your kidneys
enables them to do the following tasks:
1. Regulate the composition of your blood
keep the concentrations of various ions
and other important substances constant
 keep the volume of water in your body
constant
 remove wastes from your body (urea,
ammonia, drugs, toxic substances)
 keep the acid/base concentration of your
blood constant

What do your kidneys do?..cont
2. Help regulate your blood
pressure
3. Maintain your body's
calcium levels
Your kidneys receive blood from the renal artery,
process it, return the processed blood to the body
through the renal vein and remove the wastes
and other unwanted substances in the urine.
ureters
Urine flows from the kidneys
through the ureters to the
bladder.
Entry point of ureter
In the bladder, the
urine is stored until it urethra
Urinary
sphincters
is excreted from the
body through the urethra.
Urethral oriface
Deamination – removal of an amino
group from an organic compound
Urea – nitrogen waste formed from two
molecules of ammonia and one
molecule of carbon dioxide
Uric acid – a waste product formed
from the breakdown of nucleic acids
Inside the Kidney
A.
B.
C.
D.
E.
If you were to cut a kidney in half, you would
see the following parts:
renal capsule - a thin, outer membrane that
helps protect the kidney
cortex – the outer layer of the kidney
medulla – the area inside of the cortex
renal pelvis – the hollow area where the
kidney joins the ureter
ureter – a tube that conducts urine from the
kidney to the bladder
Label this Kidney!
From the descriptions
on the parts given, Renal
artery
label this kidney
Renal medulla
Renal
cortex
Renal vein
ureter
Renal pelvis
Further inside your Kidneys
If you look closely at the cortex and
medulla, you can see many tiny, tubular
structures
In each kidney, there are one million of
these structures, called nephrons
The nephron is a long thin tube that is
closed at one end, has two twisted
regions interspaced with a long hair-pin
loop, ends in a long straight portion and is
surrounded by capillaries.
Parts of the Nephron
Bowman's capsule – a cup-like structure
that surrounds the glomerulus
Proximal tubule – the section of the nephron
joining the Bowman’s capsule with the loop of
Henle.
Loop of Henle – the section of the tubule that
carries filtrate from the proximal tubule to the
distal tubule
Parts of the Nephron cont . .
Distal tubule – conducts urine from the
loop of Henle to the collecting duct
Collecting duct – a tube that carries
urine from nephrons to the renal pelvis
Nephron Has A Unique Blood Supply
Afferent arteriole – a small branch of the
renal artery that carries blood to the
glomerulus.
Glomerulus- high pressure capillary bed
that is the site of filteration.
Efferent arteriole – a small branch of the
renal artery that carries blood away from
the glomerulus to the peritubular
capillaries
Peritubular capillary – a member of
the network of small blood vessels that
surround the tubule of the nephron
Practice – Do questions 1-3 pg. 380