Modern firearms use the same principles as muzzleloading firearms. The ignition and burning of gunpowder create pressure. This pressure propels projectile(s) down the bore and out of the muzzle. The first modern firearms used black powder. Since about 1890, modern firearms are designed to use smokeless gunpowder. Smokeless gunpowder creates greater pressures and should not be used in firearms designed for black powder. Watch what happens when the trigger is squeezed on this bolt action rifle.
Skin acts as a barrier between invaders (pathogens) and your body.
Digestive system defense has enzymes. The enzymes in your stomach, pancreas, and liver help destroy pathogens.
The circulatory system contains immune cells called lymphocytes, which protect the body against antigens (viruses, bacteria, etc. ) that invade the body.
The respiratory system is a layered defense mechanism which relies on components of both the innate and adaptive immune systems to protect the lungs and the rest of the respiratory tract against inhaled microorganisms.
The body’s innate immune system (nervous system), its first line of defense, recognizes infectious microorganisms such as bacteria, and initiates a generalized short-acting response while summoning the body’s adaptive immune cells to mount a sustained and targeted attack.
The thyroid gland... I think
Two people with different body sizes want to compare their strength levels when lifting the same object. For a fair comparison, what should they measure?
I believe the correct answer for this question is who can lift the longest :)
If you need more additional help, please feel free to leave me a comment below :)
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