The human brian is made up of more than 100 billion nerve cells called neurons. Each neuron is connected to as many as 25000 other neurons-so the brain has trillions and trillions of different pathways for nerve signals. Girls' brains weight 2.5% of their body weight, on average, while boy's brains weigh 2%. About 0.85 litres of blood shorts through your brain every minute. The brain may be as little as 2% of your body weight, but it demand 25% of your blood supply. An elephant's brain weighs four times as much as the human brain. However, our brains are far bigger in relation to our bodies than those of any other animal. The cerebral cortex is the outside of the brain, and if it was laid out flat, it would cover a bed. The left hemisphere (half) of the brain is usually the word side, where the speech centres are. The right half is the picture side. Conscious thoughts and actions happen in the cerebral cortex. A human brain has a cerebral cortex four times as big as a chimpanzee, about 20 times as big as a monkey's and about 300 times as big as a rat's. Unconscious, automatic activities such as breathing, hunger, sleep and so on are controlled by structures such as the hypothalamus and the hippocampus in the middle of the brain. The cerebellum mainly controls body co ordination and balance.
Health World’s ‘best’ vaccines could soon come to poor countries -By Vishnu /11/5/21 In the 6 months since Covid vaccines became available, those based on mRNA technology have scored top marks. So far, there are only two – made by Pfizer and Moderna – and both show 95% efficacy. Other types of vaccines are usually 80% or less efficacious. This difference affects not only the protection you get as an individual but also the protection available to the ‘herd’ or society. With a better vaccine a country can reach ‘herd immunity’ faster by vaccinating fewer people. But mRNA vaccines are still confined to the rich world. This is partly because supply is limited and those countries placed their orders first. Another reason is these vaccines get spoilt if they are not stored at extremely cold temperatures. The Pfizer shot initially required storage at -80°C. Poor countries couldn’t afford to buy specialised freezers for it in bulk. A fragile molecule Why do mRNA vaccines need ultra-cold stora
Comments
Post a Comment