The second line of defence is a group of cells, tissues and organs that work together to protect the body. This is the immune system.
When a pathogen (disease-causing organism) invades the body, the neutrophils gather at the entry site and try to engulf it and destroy it.
A T helper cell will recognise only one pathogen. If the T helper cell recognises the invader, it will immediately clone to increase numbers.
After a few days of fighting off the pathogen, you will recover from your infection.
The 650 skeletal muscles in the human body contract when they receive signals from motor neurons, which are triggered from a part of the cell called the sarcoplasmic reticulum. Motor neurons tell your muscles to contract and the better you become at having those signals tell your muscles to contract, the stronger you can get.
Answer:
A.
Explanation:
just use your resources-..
