Biology Notes

Neurotransmitters and receptors Did you know there are billions of neurons—and trillions of synapses—in your amazing brain? ^1 1 start superscript, 1, end superscript  (No wonder you can learn anything, including neurobiology!) Most of your synapses are  chemical synapses , meaning that information is carried by chemical messengers from one neuron to the next. In the article on synapses, we discussed how synaptic transmission works. Here, we’ll focus on  neurotransmitters , the chemical messengers released from neurons at synapses so that they can “talk” to neighboring cells. We’ll also look at the receptor proteins that let the target cell “hear” the message. Neurotransmitters: Conventional and unconventional There are many different kinds of neurotransmitters, and new ones are still being discovered! Over the years, the very idea of what makes something a neurotransmitter has changed and broadened. Because the definition has expanded, so...

Excretion in Invertibrate Excretion in Planaria Habitat : Planaria is a fresh water invertebrate.   Excretory product: planaria remove ammonia and it is ammonotlic. This excretion occurs by two methods, diffusion, specialized excretory system. Excretory organs: Planaria has simple tubular excretory system called protonephiridia. Protonephridia arranged in two longitudinal trunk one on each side of the body. Each track consists of a network of tubules without internal openings. These tubules divide into small branches which open in flame cells. Tubules open on the outside by small opening called nephridiophores. Structure of flame cell: Flame cells are club shaped hollow cells. Each flame cell contains nucleus, cytoplasm and internal cavity. Group of cilia is present in the cavity. Cilia perform a movement like a flame of candle. Flame cells also has many cytoplasmic elongations. Mechanism of excretion: Flame cells absorb wastes and push them into the c...

Chromosome Chromosome During cell division the chromatin material change into thread like structure called chromosome. Chromosomes are also called physical basis of hereditary. On the chromosomes small bodies are located call genes. There are thousands of genes are present in an organisms.Genes are the unit of heredity. These genes contain hereditary character which are transfered from one generation to another by the help of chromosomes. Chromosomes were discovered by a biologist waldyer in 1876. After that in  1908 Sutton identified the function of chromosomes,that they take part in the transfer of hereditary characters.      ( Next post will be about Structure of chromosomes)