Questions

Because arteries have to have thick walls for use of protection. Its when you get to veins where the walls get thinner. And the use of the heart is to pump blood to all of the cells and organs in the body so it would be to transport blood away from the heart.

i.e. 

Arteries = Away from the Heart 
Veins = Back to the Heart.

A sarcomere is the basic unit of striated muscle tissue. It is the repeating unit between two Z lines.

Skeletal muscles are composed of tubular muscle cells (myocytes called muscle fibers or myofibers) which are formed in a process known as myogenesis. Muscle fibers contain numerous tubular myofibrils. Myofibrils are composed of repeating sections of sarcomeres, which appear under the microscope as alternating dark and light bands. Sarcomeres are composed of long, fibrous proteins as filaments that slide past each other when a muscle contracts or relaxes.

A muscle fiber from a biceps muscle may contain 100,000 sarcomeres.

Civil Services Day is celebrated in India every year on 21st April. The Union Home Minister Shri Rajnath Singh inaugurated the two-day 11th Civil Services Day program (20-21 April) in New Delhi.

In a first, China is planning to send mini-ecosystems — containing potato seeds and silkworm eggs — to the Moon next year, in an attempt to study how the organisms develop on the lunar surface. The 3-kilogramme mini-ecosystem, developed by research teams led by Chongqing University in China, will be sent to the Moon by the Chang’e 4 scheduled to be launched in 2018, authorities announced at the Global Space Exploration Conference. An 18-centimetre-tall cylinder will carry potato seeds and silkworm eggs to be incubated.

The first Indian woman to ever win an Olympic medal for India was Karnam Malleswari who won a bronze medal at the Sydney Olympics 2000 in the Women's 69 kg category in Weightlifting.

Karnam Malleswari is a retired Indian weightlifter. In 1995 she received the Rajiv Gandhi Khel Ratna, India's highest sporting honour, and in 1999 the civilian Padma Shri award.

After that Indian women who won Olymic medals to India was : 

1. Mary Kom at the London 2012 Summer Olympics won bronze medal in women's boxing.

2. Saina Nehwal was the first Indian to win a medal in Badminton at the Olympics, by winning the Bronze medal at the London Olympics 2012.

3. Sakshi Malik became the first Indian woman to win a medal in Wrestling. She won the Bronze medal in Women's 58 kg freestyle wrestling in 2016 Summer Olympics held in Rio.

4. P.V. Sindhu became the first ever Indian woman to win the Silver medal at the Olympics, by reaching the Badminton final at Rio Olympics 2016.

Africa is the second largest continent both by popolation and area wise. Asia being first by both popolation and area wise.