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Explain Deformities of skeleton.

Deformities Of Skeleton

Human skeleton supports an upright body. Sometimes our skeleton system becomes weak and results in deformations. The causes of the deformations are available e.g.

 Genetics Causes

Cleft Plate, a condition in which palatine processes of maxilla and palatine fail to fuse. The persistent opening between the oral and nasal cavity interferes with sucking. It can lead to inhalation of food into the lungs causing aspiration pneumonia.

Microcephaly, the small sized skull is caused by some genetic defect.

 Arthritis covers over 100 different types of inflammatory of degenerative diseases that damage the joints .

Osteoarthritis, is the most common chronic arthritis, which is a degenerative joint disease also caused by genetic defect.

Hormonal Causes

Osteoporosis is a group of diseases in which bone resorption out paces bone deposit. In this case bone mass is reduced and chemical composition of the matrix remains normal. Osteoporosis mostly occurs in aged women, which is related to decreased estrogen level. Other factors which may contribute include, insufficient exercise, diet poor in calcium and protein, smoking. etc.

Estrogen replacement therapy offers the best protection against osteoporotic bone fractures.

Nutritional Causes

Osteomalcia (soft bone) includes a number of disorders in which the bones receive inadequate minerals. In this disease, calcium salts are not deposited and hence bones soften and weaken. Weight bearing bones of legs and pelvis bend and deform. The main symptom is the pain when height is put on affected bones.

Rickets is another disease in children with bowed legs and deformed pelvis. It is caused by deficiency of calcium in diet or vitamin 'D' deficiency. It is treated by vitamin 'D' fortified milk and exposing skin to sunlight to cure disorder.

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Write a note on joints.

 Joints

Joints occurs where bones meet. They not only hold our skeleton together, but also gives it the mobility. Joints have three categories.

1. Immovable joints
2. Slightly movable joints
3. Freely movable joints

Freely movable joints also have three types.

1. Hinge joints
2. Ball and socket joint

Joints also classified on the basis of the structure.

• Fibrous Joints:

                             These joint are held together by short fibers embedded in connective tissues. Such joints are present in the skull, and they fix teeth into the jaws. 

• Cartilaginous Joints:

                                              These joints allow little or no movement . Hyaline cartilage forms joint between growing bone. The bones held together by fibrous cartilage are found between vertebrae at the point where coxal bones meet in front of the pelvis.

• Synovial Joints:

                                     These joints contain a cavity filled with fluid and are adapted to reduce friction between the moving joints. The joint is surrounded by a layer of connective tissues called "Fibrous Capsule"  and their inner layer the synovial membrane. Some parts of capsule may be modified to form distinct Ligament, holding the bones together.

Based on the structure and movement allowed, the synovial joints can be classified further into major categories.

Synovial joints

•  Hinge Joint:

                              The joint that allows the movement in two directions. These are at elbow and knee. At these joints, pair of muscles are arranged in the same plane as that of joints. One end of each muscle, the origin is fixed to the immovable bone on one side of the joint and the other end of muscles, the the insertion is attached to the far side of the joint.

•  Ball & Socket joints:

                                              The joint that allows the movement in several directions. Such joints have at least two pairs of muscles present perpendicular to each other. They provide maximum flexibility. Hip joint and shoulder joint are the examples of ball & socket joints.

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Explain commercial application of plant hormones.

 Commercial Applications

Commercial Application

Auxins

• Discovery of IAA led to the synthesis of wide range of compounds by chemists. The synthetic auxins are economical than IAA to produce and often more active because plants generally do not have necessary enzymes to break them down.

Synthetic Auxins:

• NAA ( Naphthalene acetic acid)
•  Indole propionic acid

Stimulates fruiting- help natural fruit set. Sometimes causes fruit setting in absence of pollination (Parthenocarpy).

• 2,4D (2,4 Dichloro phenoxy acetic acid)

Selective weed killer. Kills broad leaved species (dicots). Used in cereal crops and lawns to eliminate weeds.

Inhibits sprouting of potatoes.

Prevents premature fruit drop ( retard abscission).

Gibberellins

• GA promote fruit setting e.g. in tangerines and pears and are used for growing seedless grapes. (Parthenocarpy) and also increase the berry size.

• GA3 is used in the brewing industry to stimulate a-amylase production in barely and this promotes malting.

• To delay ripening and improve storage life of bananas and grape fruits.

Cytokinins 

• Cytokinins delay aging of fresh leaf crops, such as cabbage and lettuce (delay of senescence) as well as keeping flowers fresh. They can also be used to break dormancy of some seeds.

Abscisic Acid

•  Abscisic acid can be sprayed on tree crops to regulate fruit drop at the end of the season. This removes the need for picking over a large time- span.

Ethene

•  Ethene induces flowering in pineapple. Stimulates ripening of tomatoes and citrus fruit. The commercial compound ethephon break down to release ethene in plants and is applied to rubber plant to stimulate the flow of latex.

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Write down plants hormones.

 Plant Hormones

Some of the special substances produced by the plants which influence the growth and plant responses to various stimuli are given below.

Plant Hormones

(a) Auxins:

• In stem, promote cell enlargement in region behind apex. Promote cell division in cambium.

• In roots, promote growth at very low concentration. Inhabit growth at higher concentration e.g. geotropism. Promote growth of roots from cuttings and calluses.

• Promote bud initiation in shoots but sometimes antagonistic to cytokinins and is inhibitory.

• Cause delay in leaf senescence in a few species.

(b) Gibberellins:

• Promote cell enlargement in the presence of auxins. Also promote cell division in apical meristem and cambium.

• Promote "bolting" of some rosette plants.

• Promote bud initiation in shoots of chrysanthemum callus.

• Cause delay in leaf senescence in few species.

• Break bud and seed dormancy.

• Promote leaf growth and fruit growth.

(c) Cytokinins:

• Promote stem growth by cell division in apical meristem and cambium.

• Promote stomatal opening.

• Cause delay in leaf senescence.

• Inhibitory primary root growth.

• Promote lateral root growth.

• Promote bud initiation and leaf growth.

(d) Abscisic:

• Promote bud and seed dormancy.

• Promote flowering in short day plants, and inhibits in long day plants.

• Sometimes promotes leaf senescence.

• Promote abscission.

• Promote closing of stomata under condition of  water stress.

(e) Ethene:

• Inhibits root growth.

• Break dormancy of bud.

• Promotes fruit ripening.

• Promotes flowering in pineapple.

• Inhibits stem growth.

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Write a note on Ear.

 Ear

Hearing is important as vision. Our ear helps us in hearing and also to maintain the balance or equilibrium of our body.

Ear

 Ear has three parts.

• External Ear
• Middle Ear
• Inner Ear

External Ear:

                           External ear consists of pinna, auditory canal and ear drum (tympanum). 

Pinna is the broad external part, made of cartilage and covered with skin. It helps to direct sound waves into auditory canal.

There are special glands in the walls of auditory canal, which produce wax. The wax and the hairs in auditory canal protect ear from small insects, gems and dust. 

In addition to this, they help to maintain the temperature and dampness of auditory canal. Auditory canal ends in ear drum. This thin membrane separates external ear from middle ear.

Middle Ear:

                        Middle ear is a chamber after external ear. Three small bones, called middle ear ossicles, are present in a chain in middle ear. Those movable bones includes malleus, incus and stapes. 

Malleus is attached with ear drum, them comes out incus and finally stapes that is connected with a membrane called oval window. Oval window separates middle ear from inner ear. Middle ear also communicates with nasal cavity through Eustachian tube. This tubes regulates the air pressure on both sides of ear drum.

Inner Ear:

                     Inner ear consists of three parts 

• Vestibule
• Semicircular canals
• Cochlea

Vestibule is present in the center of inner ear.

Three canals called semicircular canals are posterior to the vestibule.

The  cochlea is made of three ducts and wraps itself into a coiled tube. Sound receptor cells are present within the middle duct of cochlea.

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Write a note on Spinal Cord?

 Spinal Cord

The spinal cord is in fact a tubular bundles of nerves. It starts from brain stem and extends to lower back. Like, brain, spinal cord is also covered by meninges. The vertebral column surrounds and protect spinal cord.

Spinal Cord

The outer region of spinal cord is made of white matter (containing myelinated axons). The central region is butterfly shaped that surrounds the central canal. Its made of grey matter (containing neuron cell bodies).

31 pairs of spinal nerves arise along spinal cord. These are " Mixed Nerves" because each contains axons of both sensory and motor neurons.

At the point where a spinal nerve arises from spinal cord, There are two roots of spinal nerve.

•  The dorsal root contains sensory axons and ganglion where cell bodies are located.
• The ventral root contains axons of motor neurons.

Functions:

• It serves as a link between body parts and brain. Spinal cord transmits nerve impulses from body parts to brain and from brain to body parts.
• Spinal cord also acts as coordinator, responsible for some simple reflexes.

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