URINARY SYSTEM
The various organs responsible for carrying g out these task include
2 kidneys
2 ureters
1 urinary bladder and a urethra
The kidneys are paired shape organs, located just above the waist, between the peritoneum and the posterior abdominal wall...it is behind the peritoneum, the main reason why it is said to be retroperitoneal
The peritoneum is a structure, that surrounds the organs of the abdominal cavity
Each kidney is 10 - 12 cm long
5 - 3 cm wide
3cm thick
It weights 135 - 150 g
The kidney has 2 poles ( superior and posterior)
2 surfaces (anterior and posterior)
2 borders (medial and lateral)
There's also an opening at the concave medial border of the kidney called the RENAL HILUM...it serves an entrance for the right and left renal artery and vein and the renal pelvis
Now the internal anatomy
The internal Anatomy consist of a superficial light red area called the renal cortex ....and a darker reddish brown inner layer called the renal MEDULLA.
The renal medulla in turn consist of several cone shaped structure called the renal pyramid, the medulla is also divided into a cortical and juxtaglomemerular ZONE.
The internal anatomy also have other structures like the renal pyramid, renal columns, renal papilla, minor and major calyce
The parenchyma constitute the renal cortex and medulla, within the parenchyma are functional units of the KIDNEY.
The nephron is the functional units of the kidney, it is responsible for production of URINE.
The nephron is divided into 2 main parts, namely
a) the renal corpuscle
b) the renal tubule
Blood plasma gets filtered in the corpuscle and the fluid passes through the renal tubule
the corpuscle consists of 2 parts...
a) glomerulus
b) glomerular ( bowman's capsule).
it is in the Bowman's capsule that filtration actually takes place
the filtered fluid then moves through to the tubule part of the nephron...and the tubule is divided into 3 parts
A proximal convoluted tubule, loop of henle, and distal convoluted tubule
The walls of the afferent and some efferent arterioles consist of smooth muscle fibers called juxtaglomerular cells...togeda with the macula densa, they constitute the juxtaglomerula apparatus... Which helps in regulation of blood pressure
the distal convoluted tubules contain 2 types of cells namely; the 1)principal cells,which contains receptos for ADH and aldosterone
2) the intercalated cells which play a role in homeostasis of blood PH
the distal convoluted tubules contain 2 types of cells namely; the 1)principal cells,which contains receptos for ADH and aldosterone
2) the intercalated cells which play a role in homeostasis of blood PH
Process of urine formation
Urine is formed through 3 main processes
1) Glomerular filtration : this is the first step of urine production, water and solutes in blood plasma moves across the wall of the glomerular capillaries into the glomerular capsule
2) Selective reabsorption
Water and solutes gets reabsorbed back to the blood....it starts from the PCT...and major absorption takes place here
3) Tubular secretion
As the fluid passes through the tubule and collecting ducts...there is secretion of other waste into it.
Evaluation of kidney functions
1)..urinalysis
2)...Blood urea nitrogen
3)...renal plasma clearance
urine drain from the papillary ducts to the renal papilla to minor calyx, to major calyx then into the renal pelvis...before it enters the ureters into the bladder
Each of the ureters transport urine from the renal pelvis to the bladder... The ureters are 25 - 30cm long
And they vary in diameter from 1- 10mm
They are also termed retroeritoneal, just like the kidneys
layers of the ureter
The ureter has 4 layers
1)mucosa
2)lamina propria
3)muscular is
4)Adventitia
Bladder
The bladder is a hollow distensible muscular organ situated in the pelvic cavity, posterior to the pubic symphisis...in males, it is directly anterior to the rectum.
In females, it is anterior to the vagina and inferior to the uterus
The bladder is spherical in shape when full, but shrinks when empty...it becomes pear shape and rize up to the abdominal cavity when very full...its capacity is 700 - 800 mls
It is smaller in females because of the space occupied by the uterus
It has 3 layers
1) deep mucosa
2 ) lamina propria
3)muscular layer.(destrusor muscle)
now to the urethral
The urethral is the last organ of the urinary system,in males it serve 2 functions
1 for excretion of urine to the exterior
2 for ejaculation
In males the urethra is 20 cm long
And is divides into 3 parts
i. The prostatic
ii. The membranous
iiiAnd the spongy urethra
In females it is shorter....just about 4cm long
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