nephronUrinary system of Man
It consists a pair of bean shaped organs called kidneys, a pair of ducts called ureters which arise from each kidney, a muscular sac like organ the urinary bladder and a tubule called urethra which arises from bladder and empties urine outside the body. The bladder end of urethra has a sphincter valve, which controls release of urine from the bladder.
Structure of kidney:
Each kidney is bean shaped organ which is about 10 cm long. They lie in the abdominal cavity being attached with dorsal body wall on either side of vertebral column. Each kidney is enclosed by a thin membranous covering called peritoneum and located on the top of each kidney is adrenal gland. The kidneys receive blood through paired renal arteries which directly arise from dorsal aorta. The blood is drained out from each kidney by a renal vein. Both renal arteries enter and renal veins leave kidney at the site called hilns.
A longitudinal section of kidney shows:
a)capsule: an outer thin envelope of tough fiberous tissue.
b)cortex: this is the outer part of kidney which makes 1/3rd of kidney
c)medulla: this is inner 2/3rd of kidney .it looks straited and darker.
d.pelvis: this is large ,funnel shapedspace towards the hilumof kidney.it collects urine and carries away to ureter.
Nephron:
Each kidney is composed of about a millions of uriniferous tubules or nephrons. nephron is the structural and functional unit of kidney.
Malphigian body: Each nephron begins with a spherical structure called malpighian body. It lies in the cortex of kidney. Malpighian body is composed of cup like Bowman’s capsule. Inside this cup lies a dense network of capillaries known as glomerulus. The Bowman’s capsule gives out a coiled tubule known as proximal convoluted tubule. It lies in the cortex region.
Tubule: Proximal convoluted tubule(pct) becomes narrow and moves down into the medulla, make a round turn and comes back in the cortex. this narrow turned tube is called as loop of henle. Thus it has a descending and an ascending limb. The ascending limb of the loop of Henle becomes larger in diameter in the cortex and forms a coil called distal convoluted tubule.Distal convoluted tubule(dct) finally opens into common collecting duct. The latter receives urine from a number of nephrons and drains into the pelvis of the kidney.
Afferent arteriole supply blood to glomerulus,which araise from renal arteriole. the blood from glomerulus is carried away by efferent arteriole. One of the network called peritubular capillaries is associated with proximal and distal convoluted tubules while the other one called vasa recta runs straight parallel besides the limbs of the loop of Henle.
It consists a pair of bean shaped organs called kidneys, a pair of ducts called ureters which arise from each kidney, a muscular sac like organ the urinary bladder and a tubule called urethra which arises from bladder and empties urine outside the body. The bladder end of urethra has a sphincter valve, which controls release of urine from the bladder.
Structure of kidney:
Each kidney is bean shaped organ which is about 10 cm long. They lie in the abdominal cavity being attached with dorsal body wall on either side of vertebral column. Each kidney is enclosed by a thin membranous covering called peritoneum and located on the top of each kidney is adrenal gland. The kidneys receive blood through paired renal arteries which directly arise from dorsal aorta. The blood is drained out from each kidney by a renal vein. Both renal arteries enter and renal veins leave kidney at the site called hilns.
A longitudinal section of kidney shows:
a)capsule: an outer thin envelope of tough fiberous tissue.
b)cortex: this is the outer part of kidney which makes 1/3rd of kidney
c)medulla: this is inner 2/3rd of kidney .it looks straited and darker.
d.pelvis: this is large ,funnel shapedspace towards the hilumof kidney.it collects urine and carries away to ureter.
Nephron:
Each kidney is composed of about a millions of uriniferous tubules or nephrons. nephron is the structural and functional unit of kidney.
Malphigian body: Each nephron begins with a spherical structure called malpighian body. It lies in the cortex of kidney. Malpighian body is composed of cup like Bowman’s capsule. Inside this cup lies a dense network of capillaries known as glomerulus. The Bowman’s capsule gives out a coiled tubule known as proximal convoluted tubule. It lies in the cortex region.
Tubule: Proximal convoluted tubule(pct) becomes narrow and moves down into the medulla, make a round turn and comes back in the cortex. this narrow turned tube is called as loop of henle. Thus it has a descending and an ascending limb. The ascending limb of the loop of Henle becomes larger in diameter in the cortex and forms a coil called distal convoluted tubule.Distal convoluted tubule(dct) finally opens into common collecting duct. The latter receives urine from a number of nephrons and drains into the pelvis of the kidney.
Afferent arteriole supply blood to glomerulus,which araise from renal arteriole. the blood from glomerulus is carried away by efferent arteriole. One of the network called peritubular capillaries is associated with proximal and distal convoluted tubules while the other one called vasa recta runs straight parallel besides the limbs of the loop of Henle.
very very nice text
ReplyDeletethanks
ReplyDelete