biomandal

              The CNS is the site of processing of information and control. The structure of CNS is derived from the embryological component. Prosencephalon ·     Becomes the thalamus, hypothalamus, and cerebral cortex. Mesencephalon ·     Becomes the mid brain. Rhombencephalon ·     Becomes the pons, medulla, and cerebellum.   Human Brain: The human brain is well protected by the skull. The skull is composed of two sets of bones-cranium and facial. The brain is covered by three layer called cranial meninges. ·     Durometer: The outer layer of the cranial meninges. Its tough and thick, made up of fibrous tissue. ·     Arachnoid: The middle layer made up of delicate connective tissue. ·      Pia mater: The inner layer which is in contact with brain tissue. Subdural space: It is the space b/w dura mater and arachnoid. Subarachnoid space: It is the...

Mechanism of Impulse Transmission Across a Chemical Synapse The cytoplasm of the synaptic knob has round, a tiny sac called synaptic vesicles which contain neurotransmitter. Neurotransmitters are the chemical which is involved in the transmission of impulses across chemical synapses but not in electrical synapses.                    When a wave of depolarization reaches the pre-synaptic membrane, the calcium channel open. Due to the opening of calcium channel.  Ca²+ diffuse inside the cytoplasm of the synaptic knob. As a result, the synaptic vesicles move towards the pre-synaptic membrane and fuses with the plasma membrane of the synaptic knob. It leads to the rupture of synaptic vesicle and releases neurotransmitter in the synaptic cleft. This releases neurotransmitter binds to the specific receptors present on the post-synaptic membrane. This binding opens the ion channel in the post-synaptic neuron,     ...

Stomach: It is located in the upper left portion of the abdominal cavity and has three region –a cardiac, fundic, pyloric. Small intestine: It has three region –           i.             Duodenum: U –shaped   ii.             Jejunum iii.             Ileum: longest and highly coiled Pyloric sphincter regulates the opening of stomach into duodenum. The wall of the intestine has thin layers  of longitudinal and circular muscle. Mucosa has irregular folding called plicae circulare(folds of Kerckring) and villi . Crypts of Leiberkuhn  has epithelial cells which secrets mucus, Paneth cells which secrets enzymes and argentaffin cells which secrets hormones. Diffused patches of lymphoid tissues are present all through the body but aggregate in ilium to form Pey...

Shoot apical meristem develop into reproductive meristem which later develops into inflorescence axis over which floral primordia develop.The primordia gives rise to buds and into flower in which the androecium and gynoecium develop . Stamen: The anther is a bilobed structure often a longitudinal grove runs b/w them. It’s a four-sided structure consisting of four microsporangia which form pollen sac and gives rise to pollen grains. Thus anther is tetraspornagiate . The structure of Microsporangia: It consists of homogenous meristematic cells called the primary sporogenous cells which form microspore mother cell. Anther wall: Structure of Microsporangia                     1.                Epidermis: It’s the outermost layer. Provides protection. The epidermis of Arceuthobium develops fibrous thickening and is called exothecium. 2.  ...