When muscles contract, the protein filaments within them slide past one another, causing the muscle to shorten and feel hard. This process involves actin and myosin filaments interacting within muscle fibers, resulting in the characteristic hardness of contracted muscles.
A musculotropic substance acts on muscle tissue. It specifically targets and affects smooth muscle cells, resulting in changes to muscle contraction and relaxation.
The substance which makes plants woody is lignin. The wood part of plants ( bark in trees ) is made entirely of xylem which is the transport vessel that carries water from the roots to the leaves. Since wood is made of lignified xylem which is very hard, it makes it woody and hard.
The main substance that makes nails tough and hard is a protein called keratin. Keratin is also found in hair and skin, providing structure and strength to these parts of the body. Proper hydration, diet, and nail care can also contribute to keeping nails healthy and strong.
This substance is called as neurotransmitter. Here it is acetylcholine.
Acetylcholine is the neurotransmitter released by the nervous system that excites muscle cells, leading to muscle contraction.
Calcium and phosphorus
Calcium carbonate
Lignin is the substance that makes wood hard. It is a complex organic polymer that fills the spaces between cellulose fibers in wood, providing rigidity and strength to the material.
Lactic acid. While it doesn't actually cause pain by itself (it causes muscle fatigue), a buildup of it can.
Chitin
exoskeleton
Keratin... it's a natural substance that makes the nail harden.
A herniation is the protrusion of muscle substance through a tear.
Enamel, it is the hardest substance in the human body.
Clay makes good bricks because it is a stable substance. This substance gets hard and withstands a great amount of pressure.
A musculotropic substance acts on muscle tissue. It specifically targets and affects smooth muscle cells, resulting in changes to muscle contraction and relaxation.
muscle that push hard to wall