Explain Neuron & Write three classification of nerve.

 Neuron

Nerve cell or neuron is the unit of the nervous system. The human nervous system consists of billions of neurons plus supporting cell. Neuron are the specialized cells that are able to conduct nerve impulses from receptors to coordinators and from coordinators to effectors. In this way the communicate with each other and with other types of body cell.

Location:

                   The nucleus and most of the cytoplasm of neurons is located in the cell body. 

Dendrites & Axons:

                                          Different processes extend out from the cell body. These are called dendrites and axons.

Dendrites conduct impulses towards cell body and axons conduct impulses away from the cell body.

Schwann cells:

                              Schwann cells are special neurological cells located at regular intervals along axons, In some neurons Schwann cell secrete fatty layer called myelin sheath.

Nodes of Ranvier:

                                   Between the areas of myelin on an axon,  there are no myelinated points called Nodes of Ranvier. 

Saltatory: 

                     Myelin sheath is an insulator so the membrane coated with this sheath does not conduct nerve impulse. In such impulses are called saltatory (jumping) impulses. This increases the speed of nerve impulse.

On the basis of the function, neuron are of three types.

• Sensory neurons
• Interneurons
• Motor neurons

Sensory Neuron:

                                  Conduct sensory information (nerve impulse) from receptors towards the CNS. Sensory neurons have on dendrite and one axon.

Interneuron:

                          From brain and spinal cord. They receive information, interpret them and stimulate motor neurons. They have many dendrites and axons.

Motoneuron:

                          Carry information from interneurons to muscle or glands (effectors). They have many dendrites but only one axon.

Nerve

 A nerve means the union of several axons that are enveloped  by covering made of lipid.

Classification:

• Sensory nerve
• Motor nerve
• Mixed nerve

Sensory nerve:

                              Contain the axons of sensory neurons only.

Motor nerve: 

                           Contain the axons of  motor neurons only.

Mixed neuron:

                              Contain the axons of both i.e. sensory and motor neurons.

Write down the steps of functionality of kidney.

 Functioning of kidney

The main function of kidney is urine formation, which takes place in three steps.

• Pressure Filtration
• Selective Reabsorption
• Tubular Secretion

Functioning of kidney 

Pressure Filtration:

                       When blood enters the kidney via the renal artery, it goes to many arterioles, and then to the glomerulus . The pressure of blood is very high and so most of the water, salt, glucose and urea of blood is forced out of glomerulus capillaries. This material passes into the Bowman's capsule and is now called Glomerulus Filtrate.

Selective Reabsorption:

                                               The second step is the selective reabsorption. In this step about 99% of the glomerulus filtrate is reabsorbed into the blood capillaries surrounding renal tubule. It occurs through osmosis, diffusion and active transport. Some water and most of the glucose is reabsorbed from the proximal convoluted tubule. Here, salts are reabsorbed by active transport and then follows by osmosis. The descending limb of loop of Henle allows the reabsorption of water while the ascending limb of loop of Henle allows the reabsorption of salts. The distal convoluted tubule again allows the reabsorption of water into the blood.

Tubular Secretion:

                                      The third step is tubular secretion . Different ions, creatinine, urea etc. are secreted from blood into the filtrate in renal tubule. This is done to maintain blood at normal pH (7.35 to7.45).

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Define urine & Explain osmoregulatory function of kidney.

 Urine

The filtrate present in renal tubules is known as urine. It moves into collecting ducts and then into pelvis.

Osmoregulatory function of kidney

Osmoregulation:

                                  Is defined as the regulation of the concentration of the water and salt in blood and other body fluids. Kidney plays important role in osmoregulation by regulating the water fluids whereas excess intake of water dilutes them.

Osmoregulation of kidney

Hypotonic:

                       When there is excess water in body fluids, kidney from dilutes (Hypotonic) urine. For this purpose, kidney filter more water from glomerulus capillaries into Bowman's capsule. Similarly less water is reabsorbed and abundant dilute urine is produced. It brings down the volume of the body fluids to normal.

Hypertonic:

                        When there is shortage of water in body fluids, kidney filter less water from glomerulus capillaries and the rate of reabsorption of water is increased. Less filtration and more reabsorption of water produce small amount of concentration (hypertonic) urine. It increases the volume of body fluids to normal. This whole process is under hormonal control.

Hypotonic & Hypertonic

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Why Kidney Stone happen & what is Renal Failure?

 Kidney Stone

When urine becomes concentrated, crystals of many salts eg calcium oxalate, calcium and ammonium phosphate, uric acid etc. are formed in it. Such large crystals cannot pass in urine and form hard deposits called Kidney Stone.

kidney stones

Most stones start in kidney. Some may travel to ureter or urinary bladder.

Causes:

               The major causes of kidney stones are age, diet (containing more green vegetables, salts, vitamins C,D), recurring urinary tract infection , less intake of water, and alcohol consumption.

Symptoms:

                      The symptoms of kidney stones include severe pain in kidney or in lower abdomen, vomiting, frequent urination and foul-smelling urine with blood and pus. 

About 90% of all kidney stones can pass through the urinary system by drinking plenty of water. In surgical treatment, the affected area is open and stones are removed.

Lithotripsy:

                       Lithotripsy is another method of removal of kidney stones. In this methods, non electrical shock waves from outside are bombarded  on the stone in the urinary system. Waves hit the dense stones and break them. Stones become sand-like and are passed through urine.

Kidney(Renal) Failure

Kidney failure means a complete or partial failure of kidneys to function.

Renal Failure

Causes:

               Diabetes mellitus and hypertension are the leading causes of kidney failure. In certain cases, sudden interruption in the blood supply to kidney and drug overdoses may also result in kidney failure.

Symptoms:

                       The symptoms of kidney failure is the high level of urea and other wastes in blood, which can result in vomiting, nausea, weight loss, frequent urination and blood in urine. Excess fluids in body may also cause swelling in legs, feet face and shortness of breath.

Treatment:

                       The kidney failure is treated with dialysis and kidney transplant.

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Write a note on Dialysis.

 Dialysis

Dialysis means cleaning of blood by artificial ways.

Methods:

                There are two methods of dialysis.

1. Peritoneal Dialysis
2. Haemo Dialysis

Peritoneal Dialysis:

                                        In this type of dialysis, the dialysis fluid is pumped for a time into the peritoneal cavity which is the space around gut. This cavity is lined by peritoneum. Peritoneum contains blood vessels. When we place dialysis fluid in peritoneal cavity, waste materials from peritoneal blood vessels diffuse into the dialysis fluid, which is then drained out. This type of dialysis can be performed at home, but must be done every day.

Haemodialysis:

                                In haemodialysis, patient's blood is pumped through an apparatus called Dialyzer. The dialyzer contains long tubes, the walls of which act as semi-permeable membranes. Blood flows through the tubes while dialysis fluid flows around the tubes. Extra water and wastes moves from blood into the dialysis fluid. The cleansed blood is then returned back to body. The haemodialysis treatments are typically given in the dialysis center.

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Write a note on structure and function of kidney.

 Structure of Kidney

Colour of kidney:

                                   Kidney are dark red bean shaped organ.

Size of kidney: 

                             Each kidney is 10cm long, 5cm width thick and weights about 120 grams.

Location:

                   They are placed against the back wall of abdominal cavity just below diaphragm , one on either side of the vertebral column. They are protected by the last 2 ribs. The left kidney is little higher than the right.

Hilus: 

            The concave side of the kidney faces the vertebral column. There is a depression called Hilus, near the Centre of  the concave area of kidney. 

Kidney shows two regions

Renal cortex:

                          is the outer part of the kidney and it is dark red in colour.

Renal medulla:

                                is the inner part of the kidney and is pale red in colour. Renal medulla consists of several cone shaped areas called renal Pyramids. Renal pyramids projects into a funnel-shaped cavity called renal Pelvis which is the base of ureter.

Structure of kidney

Function of Kidney

The function unit of kidney is called nephron. There are over one millions nephrons in each kidney. 

Parts of Nephron:

                                    There are two parts of nephron i.e. Renal Corpuscle and Renal Tubule.

Renal corpuscle is not tubular and has two parts i.e. glomerulus and Bowman's capsule. Glomerulus is a network of capillaries while Bowman's capsule is a cap shaped structure that encloses glomerulus.

Renal Tubule:

                            It is the part of nephron which starts after Bowman's capsule. Its first portion is called the proximal convoluted tubule. Next portion is U-shaped and is called Loop of Henle. The last portion of renal tubule is called the Distal convoluted tubule. 

Collecting Duct:

                                 The distal convoluted tubule of many nephrons open in a single collecting duct. Many collecting ducts join together to form several hundred Papillary Ducts which drain into renal pelvis.

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Osmotic adjustments in plants & Explain its three groups.

Osmotic adjustment in plants

On the basis of  available amount of water and salt, plants divided into three groups.

Hydrophytes:

                           Those plants which live partially submerge or completely in freshwater. Such plants do not face the problem of water shortage. They have developed mechanisms for the removal of extra water from their cells. Hydrophytes have broad leaves with a large number of stomata on their upper surfaces. This characteristics helps them to remove the extra amount of water.

Example:

                  Water lily.

Hydrophytes plants

Xerophytes: 

                        They live in dry environments. They possess thick, waxy cuticle over their epidermis to reduce water loss from internal tissues. They have less number of stomata to reduce the rate of transpiration. Such plants have deep roots to absorb maximum water from soil. 

Example:

                  Cacti (singular cactus).

Xerophytes plants

Halophytes:

                         They live in sea water and are adapted to salty environment. Salts enter in the bodies of such plants due to their higher concentration in sea water. 

Example:

                  Sea grass.

Halophytes plants

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