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ANATOMY AND PHYSIOLOGY
Kidney
TABLE OF CONTENT
1) General Introduction
2) Anatomy of Urinary System
3) Urine Formation
4) Control System
1) filter blood plasma, separate
wastes, return useful materials to
the blood, and eliminate the
wastes.
2) regulate blood volume and
osmolarity.
3) produce hormones
1.
2.
3.
renin
erythropoietin
calcitrol
4) regulate acid-base
balance of the body
fluids.
5) detoxify superoxides, free
radicals, and drugs.
Imagine
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LOCATION AND EXTERNAL ANATOMY
OF KIDNEYS



Located retroperitoneally
Lateral to T12–L3 vertebrae
Average kidney


Hilus



12 cm tall, 6 cm wide, 3 cm
thick
On concave surface
Vessels and nerves enter and
exit
Renal capsule surrounds the
kidney
- The medial surface of the kidney is concave with a hilum carrying
renal nerves and blood vessels.
The renal parenchyma is divided into an outer cortex and inner
medulla.
Extensions of the cortex (renal
columns) project toward the
sinus, dividing the medulla into
6-10 renal pyramids. Each
pyramid is conical with a blunt
point called the papilla facing
the sinus.
The Nephron
- Most components of the
nephron are within the cortex.
The Nephron
- The kidney contains 1.2 million nephrons, which are the functional units
of the kidney.
- A nephron consists of :
i. blood vessels
afferent arteriole
glomerulus
efferent arteriole
ii. renal tubules
proximal convoluted tubule
loop of Henle
distal convoluted tubule
The Nephron
glomerulus
efferent arteriole
proximal
convoluted
tubule
blood
distal
convoluted
tubule
blood
afferent arteriole
Loop of Henle
The glomerulus is enclosed in a two-layered glomerular (Bowman's) capsule.
Proximal
tubule
NEPHRON-TUBULAR SYSTEM
1. Proximal convoluted
tubule
2. Descending loop of
Henle
3. Ascending loop of
Henle
4. Distal convoluted
tubule
5. Collecting duct
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The kidney produces urine through 4 steps.
1) Glomerular Filtration
The Filtration Membrane
From the plasma to the capsular space,
fluid passes through three barriers.
foot processes
fenestrated epithelium
basement
membrane
The Filtration Membrane
Almost any molecule smaller than 3 nm can
pass freely through the filtration membrane
into the capsular space.
These include:
Water, electrolytes, glucose, amino acids, lipids, vitamins, and
nitrogenous wastes
Kidney infections and trauma commonly damage the filtration
membrane and allow plasma proteins or blood cells to pass through.
Glomerular Filtration Rate (GFR)
- is the amount of filtrate formed per minute by the two kidneys
combined.
- For the average adult male, GFR is about 125 ml/min.
- This amounts to a rate of 180 L/day.
- An average of 99% of the filtrate is reabsorbed, so that only 12 L of urine per day is excreted.
Diagram of renal corpuscle structure: A – Renal corpuscle B – Proximal tubule C –
Distal convoluted tubule D – Juxtaglomerular apparatus 1. Basement membrane
(Basal lamina) 2. Bowman's capsule – parietal layer 3. Bowman's capsule
THE FORMATION OF URINE

3 processes involved in the formation of urine.



Simple filtration
Selective reabsorbtion
 Hormonal control Parathyroid hormone, calcitonin
 Anti diuretic hormone
 Aldosterone
Secretion
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Maintaining Water/Electrolyte Balance
Figure 15.9
Dialysis machine