Skeletal System Parts & Function With Diagram | Biology Blog

                                       Skeletal System 

In the human being, the skeletal system is consist of a framework of bones and cartilage which provide protection to the soft tissues and cell that is embedded in our body. In an adult, human, have a total number of 206 bones found in ts body. There are two types of Skeletal systems found in the human body known as endoskeleton and exoskeleton. The exoskeleton is ectodermal in origin formed outside the body and is non-living whereas endoskeleton is mesodermal in origin formed inside the body and it is living by nature.   During early embryonic development the endoskeleton is made up of notochord and cartilage but later on, this notochord is replaced by the vertebral column, and cartilage is replaced by bones.

The skeletal system is grouped into two principal divisions - Axial Skeleton and Appendicular Skelton.

Axial Skelton -  Axial Skeleton is comprised of 80 bones distributed along the main axis of the body.

The skull, vertebral column, sternum, and ribs constitute an axial skeleton. 

• The skull is composed of two sets of bones - cranial and facial, that total to 22 bones.
  
  
• Cranial bones are 8 in number ( frontal, parietal, occipital, temporal, ethmoid, and sphenoid ). They form the hard protective structure covering cranium for the brain.
  
  
• The cavity of the sphenoid bone is called sella turcica in which the pituitary gland is present.
  
  
• The facial region is made up of 14 bones ( inferior turbinals -2, vomer - 1, mandible -1, maxilla- 2, zygomatic - 2, nasal-2, palatine - 2, lacrymal- 2 ) which form the front part of the skull.
  
  
• A single U shaped bone is presently known as Hyoid Bone at the base of the buccal cavity which is not attached to any other bone of the body.
  
  
• The tongue is attached to the hyoid bone. 

• The middle ear consists of 3 tiny bones - malleus, incus, and stapes, collectively known as Ear Ossicles. The joint between  Malleus and Incus is called Hinge Joint and between Incus and Stapes is called the Ball and Socket Joint. 

Vertebral column - There are 26 serially arranged vertebrae that are found which are placed dorsally. This vertebra extends to form the base of the skull and form the main framework of the trunk. The vertebral column protects the spinal cord, support the head and saves as the point of attachment for the ribs and musculature of the back.

Sternum - Sternum is a long flat bone locate din the central part of the chest.  it connects to the ribs via cartilage and forms the front part of the cartilage.  The function of the Sternum is to protect the delicate organs of the body like the Liver, Lungs, and heart.

Ribs -  In human there are 12 pairs of ribs are present in the ribcage. the first seven pairs of the ribs are called True Ribs. they are attache dorsally to the thoracic vertebrae and ventrally to the sternum with the help of hyaline cartilage. These ribs are called Veretebrosternal ribs. The 8th, 9th, and 10th pairs of ribs do not articulate directly with the sternum but join the seventh rib with the help of hyaline cartilage. These are called False Ribs.

Appendicular Skeleton -  the bones of the limb along with their girdles constitute the Appendicular skeleton. 

• Each limb is made up of 30 bones.
• The bones of the hand are humerus, radius, ulna, and carpals.
• the phalangeal formula is 23333.

• The femur thigh bone is the longest, sharpest, and heaviest bone of the body. Along with the femur, tibia, and fibula, tarsals, metatarsal, and phalanges are the bone of the legs.
  
  
• The phalangeal formula is 23333.
  
  
• A cup-shaped bone called patella covers the knee ventrally ( knee cap ).  
  

Self-Pollination & Cross- Pollination And Their Controversies

                                     Types Of  Pollination 

The transfer of pollen grains from the stigma of a pistil is known as Pollination. Pollination in flowering plants occurs by two methods- self-pollination and cross-pollination. 

Self Pollination - Self Pollination involves the transfer of pollen grain from the anther to the stigma of the same flower or genetically similar flower. It is of two types - 

Autogamy - Transfer of pollen grains from the anther to the stigma of the same flower is known as Autogamy. It occurs by the three methods - 

Self Pollination  showing by A& B and cross-pollination is shown by B & C 

• Cleistogamy - Some Plants never open to ensure complete self-pollination. This condition is called Cleistogamy. For example - oxalis, viola.
• Homogamy - Anther and stigma of the bisexual flower of the same plants mature at the same time. This condition is called Homogamy. For example - Mirabilis, potato, sunflower, etc.
• Bud Pollinatiton - Anther and stigma of the bisexual flowers of some plants mature before the openings of the buds to ensure self-pollination. For example - wheat, rice, pea. 

Geitnogamy - When anther of one flower is transferred to the stigma of another flower borne on the same plant, then this condition is known as Geitonogamy. 

Advantage Of Self - Pollination - 

• Chances Of Pollination are more.
•  Self Pollination maintains the purity of race and avoids mixing.
•  It needs not to produce a large number of pollen grains. 

Disadvantage Of Self - Pollination -

• No possibility of the introduction of new desirable characters.
• Undesirable characters can not be eliminated. 
• It does not help in evolution. 

Cross-Pollination - Transfer of pollen grains from the flower of one plant to the stigma of another plant flower, is known as Cross-Pollination or Allogamy.  

Types - There are two  types of  cross-pollination

• Xenogamy - The pollination in which the pollen grains of one flower transferred to the stigma of another flower of the same species is known as Xenogamy. 
  
  
• Hybridism - The pollination in which pollen grains of one flower is transferred to the stigma of another flower of different species is known as Hybridism.  

Adaptations Of Cross-Pollination - 

Self-Incompatibility - In this condition, the pollen of one flower is not able to fertilise the ovules of the same flower even in their favourable conditions.

Dicliny - In many angiosperms the stamen and carpels are found in different flowers, then this condition is known as Unisexuality or Dicliny. It is of two types - 

• Monoecious -  When male and female part of the flower present at the same time then this condition is called Monoecious. For example - Maize, castor. 
  
  
• Dioecious - When male and female part of the flowers present on the different flower of different plants. For example - Cannabis sativa 

Dichogamy - In many angiosperm plants, the male and female parts do not mature at the same time then these conditions are known as Dichogamy. The conditions in dichogamy are may be of two types -

•  Protandry - The conditions in which the anther part mature earlier than the carpels. For example -Sunflower.
  
  
• Prtogyny - The condition in which the carpel mature earlier than the stamen. For example - Rose.

Herkogamy - In some homogenous flowers there are some adaptations due to which self -pollination can not possible like in flowers the stigma projects beyond the stamens so that the pollen grains do not fall on it. 

Heterostyly - The flowers may be of different types based on the length of stamens and style and due to this effective pollination is not possible in flowers of its own types. 

   

 

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Kingdom Fungi - Habitat , Features , Reproduction |Biology Blog

                                       Kingdom  Fungi 

Introduction - The Fungi are heterotrophic organisms, lacking the ability to produce their own food, as they are without chlorophyll. The term Fungi has been derived from the Latin word meaning -Mushrooms. They can be defined as chlorophyllous organisms with nucleated, somatic bodies and cell wall made of cellulose and chitin or both, and they reproduce sexually as well as asexually. The study of fungi is known as Mycology. Organisms of this group are parasites or saprophytes. It include about 1,00,000 species . They have thallus like structure,i.e., the body is not differentiated. 

Habitat -  The fungi grow in multiple habitats. In fact, they grow in every available habitat where organic matter, living or dead is found. Most of them are terrestrial. Some fungi are aquatic. The aquatic fungi are considered to be primitive. Many fungi are found in drinking water. They contaminate both our food and water. They are present all the time in the air we breathe. The fungi prefer to grow in damp, dark and humid places. 

Structure -  Fungi are simple thalli like organisms which are not differentiated into root, stem, and leaf-like structures. Their body consists of a thin branched threadlike structure called Hyphae. Many hyphae join together to form a network-like structure called mycelium. In some fungi hyphae are septate, i.e., the septum is not found in their hyphae, such hyphae are called Aseptate.  Aseptate fungi are multinucleated, in such condition, hyphae are called Coenocytic. 

Cells of fungi contain all membrane-bound cell organelles such as ribosomes, mitochondria, endoplasmic reticulum, Golgi complex, etc like other eukaryotic cells but chloroplasts are not found in them. 

Features - 

• They are either parasites or saprophytes. 

• They are found everywhere, where organic matter is found. Most of them are terrestrial. Some inhabitant the cells of living organisms and some are aquatic. 

• The cell wall is made up of chitin, but in some species, the cell wall is made of cellulose. 

• They absorb food and other substances, either through the entire surface of mycelium or by rhizoids. 

• Plastids are not found in their cells. 

• They have three types of reproduction; vegetative reproduction, asexual reproduction, sexual reproduction.

• They have food in the form of glycogen oil droplets. 

How Neurons Are Formed : Biology Blog

                                    Structure Of Neuron

All animals have a very important functional neural system in their body which is comprised of highly specialized cells called Neurons which can detect, receive and transmit different kinds of stimuli. Every neuron is made up of a cell body and cell process (Dendron and axon ).                                                   

• Cell Body or Cyton -   It contains uninucleated cytoplasm. Except for centriole, all cell organelles are found in the cytoplasm . The centriole is absent in the nerve cell thus cell division is absent .
• Nissl's granules - Endoplasmic Reticulum and ribosomes form granules like structures called Nissl's Granules.

• Cell Process -  

1. Dendron - The fine branches like structure extend out from the neuron is called dendrites . Some receptors are also present on it which receive the stimuli and produce Centripetal Conduction. The number of dendrites on neurons may vary.
2. Axon - It is the longest cell process of cyton . axon is covered by Axolemma . The terminal end is a button shape called Synaptic Knob. Each branch of Axon terminates on a  Synaptic Knob having  Neurotransmitter. Axon is covered by a layer of a phospholipid called Myelin Sheath . Myelin Sheath is covered by  thin cell membrane called Schwann Cells. Some gaps are found between the myelin sheath called Nodes of Ranvier.

Types Of Neurons - 

• Unipolar -  It is a single process arises from the cyton. It can be seen in the nervous system of the embryo.
• Bipolar -The two process arises from the cyton. It is found in the retina of our eyes. 
• Multipolar - The neuron which has one axon but many dendrons, just like most of the neurons of our body. 

Plant Leaf Structure: Class 11 Biology

                                  Leaf Structure In Plants 

                                                                                                                                         

Hello Students!    

As you know leaves are an important part of the plant that carries out photosynthesis to help the plant to exist. Photosynthesis is the process in which light energy is converted into chemical energy i.e.,  plants use carbon dioxide and water and convert them into oxygen and Glucose which is further use by the plants in the form of food.

 But do you know how the leaf is consists of?  

The plants have some thin, flat organs present at the lateral side of each node known as Leaves.

Parts of a leave -  A leaf consist of some basic structure like leaf base, petiole, and lamina. 

• Leaf Base -   This is the part where a leaf attaches to the stem. Leaf base has two small leaf-like structures called stipules.
  
  
• Petiole -    petiole is long, thin, stalk that links the leaf blade to the stem. 
  
  
• lamina -- Lamina is also known as Leaf Blade. It is the green , flat surface of the leaves . It consists of small branches veins that run along the middle of the lamina is called Midrib. The Midrib divides the surface of the leaf into two- veins and veinlets. These veins and veinlets give rigidity to the leaf blade and help in the transportation of water and other substances. 

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