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.
Liver
Thyroid gland
Spleen
My answer to the question is option A and B.
Thank you for coming to Brainly with your questions!
I believe the answer is:
Aorta, Left Ventricle, Left Atrium, Pulmonary Vein, Coronary Artery, <span>Bronchial veins.
I hope this helps you! Please mark Brainliest! Lemme know if I can help you with any further questions!
-Belle</span>
