C-8 8. Excratory System
C-8 8. Excratory System
C-8 8. Excratory System
Excretory system
8. Excretory system/urinary system
The Urinary System is a group of organs in the body concerned
with filtering out excess fluid and other substances from the
bloodstream.
The organs, tubes, muscles, and nerves that work together to
create, store, and carry urine are the urinary system.
The urinary system includes two kidneys, two ureters, the bladder,
two sphincter muscles, and the urethra.
The substances are filtered out from the body in the form of urine.
Urine is a liquid produced by the kidneys, collected in the bladder
and excreted through the urethra.
Urine is used to extract excess minerals or vitamins as well as
blood corpuscles from the body.
The kidneys are the main organs of homeostasis because they
maintain the acid base balance and the water salt balance of the
2 blood.
Functions of the Urinary System
Excretion.
Homeostasis
Conserving water, salts, and electrolytes.
The most important roles of the kidneys are:
Regulation of plasma ionic composition
Regulation of plasma osmolarity
Regulation of plasma volume
Regulation of plasma hydrogen ion concentration (pH)
Removal of metabolic waste products and foreign substances from
the plasma: Secretion of Hormones
They continuously maintain the proper balance between water and
salts in the blood and they help to maintain the blood PH at 7.35-
7.45.
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Structures of Urinary system
1. The ureters- The convey urine from the kidneys to the urinary
bladder.
2. The urinary bladder- The function of the urinary bladder is the
temporary storage of urine
The sphincter muscles close and opening of the bladder into the
urethra
3. The urethra- is a muscular tube that drains urine from the urinary
bladder and conveys it out of the body.
Common for sperm and urine in males
4. Kidneys:- The primary function of the kidney is to make urine
and purify the blood.
Each kidney removes waste materials, and other chemicals which
are not required by body.
The right kidney is slightly lower than left kidney. WHY?
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The Structure of kidney
The frontal section of the kidney reveals 3 distinct regions. Such
are:-
1. Renal cortex: the outer region just inside the renal capsule;
light red in color and granular in appearance.
2. Renal medulla: Extensions of the renal cortex between the
renal pyramids are called renal columns. Together, the renal
cortex & medulla form the parenchyma of the kidney where
urine is formed.
3. Renal pelvis: The renal pelvis collects urine that is formed in
the renal cortex and medulla.
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Parts of kidney
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Nephron
Nephron:- is basic structural and functional unit of the kidney
chief function to regulate water and soluble substances by
filtering the blood, reabsorbing what is needed and excreting
the rest as urine as carry out the processes that form urine.
Nephrons-the renal cortex & medulla of each kidney contain
over 1 million microscopic tubules called nephrons.
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Parts of nephron
1. Glomerulus- the glomerulus is a capillary tuft that receives
its blood supply from an afferent arteriole of the renal
circulation.
2. capsule:- Bowman's capsule (glomerular capsule) the site of
the ultrafiltration of the blood.
3. First coiled (convoluted) tubule: is where much of the
reabsorption takes place.
4. Second coiled (convoluted) tubule: where the main water
balancing is done.
5. Collecting duct: where the liquid (essentially urine) is
collected.
6. Loop of Henle: where the urine is concentrated and more
water is conserved. Salt concentrate.
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Cont…
Nephrons are classified into 2 types based on the location of the
loop of Henle:
i. Cortical Nephrons- the loop of Henle is mostly in the cortex
and penetrates a little into the medulla.
ii. juxtamedullary Nephrons- the loop of Henle penetrates
deeply into the medulla
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