EXCRETORY SYSTEM OF THE BODY ARE AS FOLLOW
– The kidneys are pair of excretory organs situated on posterior wall of abdomen one on each side of the vertebral column behind the peritoneum.
– They remove waste products of metabolism and excess of water and salts from the blood and maintain its pH.
• Shape of kidney :
✓ Bean shaped
✓ Poles – upper and lower
✓ Borders – medial and lateral
✓ Surfaces – anterior and posterior.
• Upper pole : It is broad and is in close contact with corresponding suprarenal gland.
• Lower pole : It is pointed.
• Anterior surface : Irregular.
• Posterior surface : Flat.
• Lateral border : Convex.
• Medial border : concave.
* Hilum :
– Depression present in the middle part.
– Order of structures in hilum from front to back are ,
(1) Renal vein
(2) Renal artery
(3) Renal pelvis.
• Extension of kidney :
– Vertically extend from upper border of 12th thoracic vertebra to the centre of the body of 3 rd lumbar vertebra.
– Right kidney is slightly lower than left.
• Dimensions of kidney :
– 11cm long , 6cm broad and 3cm in thickness.
– wieghs about 150g in males and 135g in females.
• Coverings of kidney :
(1) Fibrous capsule : It is a thin membrane which closely invest the kidney.
(2) Perirenal fascia : It is a layer of adipose tissues lying outside the fibrous capsule.
(3) Renal fascia : Fibroareolar sheath which surrounds kidney and perineal fat.
(4) Pararenal fascia / fat : consists of variable amount of fat lying outside the renal fascia.
• Structure of kidney :
– The nacked eye examination of kidney shows the outer reddish brown cortex and the inner pale medulla.
– Renal medulla is made up renal pyramids ( 10 conical masses ).
– Renal cortex is divided into 2 parts
(1) The cortical arches
(2) The renal columns .
– Each uriniferous tubules contains nephron
– Nephron is the functional unit of kidney.
• Arterial supply :
– It is by renal artery which is a branch arising from the abdominal aorta.
– Near the hilum the renal artery divides into anterior and posterior branches which further divide to form segmental branches to supply the kidneys.
• Venous drainage :
– It is by the renal vein which drains into the inferior venacava.
• Lymphatic drainage :
– It is through lateral aortic nodes located at level of origin of the renal arteries.
• Nerve supply :
– It is supplied by renal plexus of nerves.
– This contains sympathetic T10 – L1 fibres which are chiefly Vasomotor .
– The efferent nerves of the kidney belongs to the segment T10- T12.
– they are the pair of narrow thick walled muscular tubes that convey urine from kidneys to urinary bladder.
– They lie deep to peritoneum closely apply to posterior abdominal wall ( in upper part ), and to the lateral pelvic wall ( in lower part ).
• Length of ureter :
– 10 inches long .
– Out of which the upper 5 inches lie in the abdomen and lower 5 inches lies in the pelvis
– Diameter : 3mm
• Course of ureter :
– Ureter begins within renal sinus of funnel shaped dilutation called renal pelvis .
– The pelvis comes out of the hilum of the kidney descends along the medial margin gradually it narrows till at the lower end of the kidney.
– It becomes the ureter proper.
– The ureter passes downwards and slightly medially on the psoas major muscle and enters the pelvis by crossing in front of termination of common iliac artery.
– In the lesser pelvis ureter at the first runs downwards and slightly backwards and laterally opposite to the Ischial spine it turns forwards and medially to reach the base of the urinary bladder .
– The ureter enters the bladder wall obliquely to open into it at lateral angle of its trigon.
• Ureter is slightly constricted at 3 places ;
(1) At pelvic ureteric junction
(2) At the brim of the lesser pelvis.
(3) Bladder wall.
• Parts of ureter :
(1) Renal pelvis
(2) Abdominal part
(4) Intra vesicle part.
• Blood supply :
– Upper part receives blood from the branches of renal artery.
– Middle part receives branches from the Abdominal aorta
– Pelvic part is supplied by branches from the vescicles , middle rectal artery and uterine vessels.
• Nerve supply :
– Ureter is supplied by sympathetic T10-L1 segment of spinal cord and parasympathetic S2-S4 nerves .
– They reach the ureter through renal aortic and hypogastric flexus.
– All the nerves appears to be sensory in function.
3] Urinary bladder
– Urinary bladder is a muscular reservior of urine which lies in the anterior part of the pelvic cavity.
• Size , Shape and Position
– The bladder varies in size, shape and position According to the amount of urine it contains and it also depends upon the age of the person.
– When empty it lies entirely within the pelvic but as it fills it expands and extends upwards into the abdominal cavity reaches upto the umbeicus or even higher.
• External features of urinary bladder :
– Empty bladder us tetrahedral in shape and has an apex directed forwards , a base or fundus directed backwards.
– A neck which is the lowest of the bladder and most fixed part of the bladder.
– It has got 3 surfaces ;
√ Right and left inferiolateral surfaces.
– 4 borders ;
√ 2 lateral borders
√ 1 anterior and 1 posterior borders.
• Full bladder :
– ovoid in shape and has an apex directed upwards towards the umblicus in neck directed downwards
– 2 surfaces : anterior and posterior surface.
– The apex is connected to the umblicus by medial umblical ligament which represents the oblitarated embryonic urachus.
– The base in the female is related to the uterine cervix and the vagina.
– In male the upper part of base is separated from the rectum by recto vesicle pouch and coils of of intestine.
– The lower part of the base is separated from the rectum by seminal vescicles and termination of vast difference.
• Neck of urinary bladder–
It is the lowest and most fixed part of bladder that lies 3-4 cm behind the lower part of pubis symphysis and it is pierced by internal urethral orifices.
– In males it is completely covered by peritoneum and is in contact with sigmoid colon and coils of terminal ilium.
• Inferolateral surfaces :
– These are devoid of peritoneum
– In the male each Inferolateral surface is related to the pubis, puboprostatic ligament, retropubic fat and levator muscle
– In a female the relations are same except that the pubovescicle ligament.
• Ligaments :
– It has got true ligament and false ligament.
* True ligament :
– They are the condensation of pelvic fascia around neck and base of Bladder.
(1) It has got lateral true ligament which extends from the side of the bladder to the tendinous arch of the pelvic fascia
(2) The lateral puboprostatic ligament , it is directed medially and backwards , it extends from the anterior end of tendinous arch of the pelvic fascia to upper part of the prostatic sheath.
(3) The medial puboprostatic ligament , it is directed downwards and backwards , it extends from the back of the pubic bone to prostatic sheath.
(4) The medial umblical ligament which is the remnant of the urectus.
(5) Posterior ligaments of bladder , directed backwards and upwards along the vesicle plexus of veins.
It extends in each side from the base of the bladder to the internal iliac vein.
* False ligament :
– They are peritoneal folds which do not form any support to the bladder , they include ;
(1) The median umblical folds.
(2) Lateral false ligament.
(3) Posterior false ligament .
• Capacity of urinary bladder :
– The mean capacity of the bladder in an adult male is 220 ml , filling beyond 220ml causes a desire to maturate filling upto 500 ml may be tolerated but beyond this it becomes painful.
• Arterial supply:
– It is by superior and inferior vesicle artery.
• Venus drainage :
– It is through the vesicle venus plexus which drain into the internal iliac veins.
• Lymphatic drainage :
– It drains to external iliac nodes.
• Nerve supply :
– It is supplied by the vesicle plexus of nerves which contains both sympathetic and parasympathetic fibres.
– The parasympathetic fibres are derived from S2, S3 , S4 ligaments and are motor to destrusor muscle and inhibitory to sphincter vascichae.
– The sympathetic fibres derived from T11- L2 segments and are inhibitory to destrusor and motor to sphincter vescichae.
– pain sensation caused by distention or spasm of the bladder wall are carried mainly by parasympathetic nerves and partly by sympathetic nerves.
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