Question

describe the excretory system

Answer 1

The excretory system of human beings includes a pair of kidneys, a pair of ureters,a urinary bladder and a urethra. Kidneys are located on either side of vertebral column. Urine produced in the kidneys passes through the ureters into the urinary bladder where it is stored until it is released through urethra.

Just as carbon dioxide is removed from the blood in the lungs , nitrogenous wastes such as urea are removed from blood in the kidneys. A cluster of very thin walled blood capillaries perform this. each capillary cluster is associated with cup shaped end of a tube that collects filtered urine. Each kidney has large number of these filtration units called nephron.Some substances in initial filtrate such as glucose, amino acids , water are selectively reabsorbed as the urine flows through the tube.

The urine forming in each kidney enters ureter which connects the kidneys with urinary bladder. Urine is stored in urinary bladder until the pressure of the expanded bladder leads to the urge to pass it out through urethra. The bladder is muscular so we can usually control the urge to urinate as a result of nervous control.

Answer 2

$\huge\underline\mathcal\red{Excretory \: sys. \: organs}$

The human excretory system organs include:

A pair of kidneys

A pair of ureters

A urinary bladder

A urethra

$\huge\underline\mathfrak\purple{Kidney}$

Kidneys are bean-shaped structures located on either side of the backbone and are protected by the ribs and muscles of the back. Each human adult kidney has a length of 10-12 cm, a width of 5-7 cm and weighs around 120-170g.

The kidneys have an inner concave structure. The blood vessels, ureter and nerves enter the kidneys through the hilum, which is a notch at the inner concave surface of the kidney. The renal pelvis, a large funnel-shaped space is present inner to the hilum, is has many projections known as calyces.

$\huge\underline\mathcal\red{Structure \: kidney}$

The structure of the kidney is explained below:

$\huge\underline\mathfrak\purple{Capsule}$

The outer layer is called the capsule. Inside the kidney, there are two zones- the outer zone is the cortex and the inner zone is the medulla. The cortex extends in between the medullary pyramids as renal columns called columns of Bertin.

$\huge\underline\mathfrak\purple{Nephron}$

Nephrons are the functional units of the kidney. Each nephron has two parts- glomerulus and renal tubule.

Glomerulus consists of a bunch of capillaries formed by afferent arterioles. Blood from glomerulus is carried away by efferent arterioles.

The renal tubule starts with a cup-like structure called Bowman’s capsule and this encloses the glomerulus. The malpighian body consists of glomerulus and Bowman’s capsule. The highly coiled structure in the tubule next to the Bowman’s capsule is the proximal convoluted tubule.

$\huge\underline\mathfrak\purple{Henles \: loop}$

The next part of the tubule is Henle’s loop which has an ascending and a descending limb. The ascending loop continues as a distal convoluted tubule. The distal convoluted tubules of many nephrons open into the collecting duct.

The cortical region of the kidney comprises of malpighian corpuscle, proximal convoluted tubule and distal convoluted tubule and the medullary region contains a loop of Henle.

There are two types of nephrons – cortical and juxtamedullary. In the case of cortical, the loop of Henle is very short and extends only a little into the medulla. In juxtamedullary, the loop of Henle is very long and runs deep into the medulla.

$\huge\underline\mathfrak\purple{Ureter}$

A pair of thin muscular tubes called the ureter comes out of each kidney extending from the renal pelvis. It carries urine from the kidney to the urinary bladder.

$\huge\underline\mathfrak\purple{Urinary \: bladder}$

It is a muscular sac-like structure, which stores urine. The urinary bladder is emptied by the process of micturition, i.e. the act of urination.

$\huge\underline\mathfrak\purple{Urethra}$

This tube arises from the urinary bladder and helps to expel urine out of the body. In males, it acts as the common route for sperms and urine. Its opening is guarded by sphincter muscles.

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