Because it stops the blood flowing out
The walls of the windpipe (trachea) are made of cartilage rings to prevent collapse and maintain an open passageway for air to flow in and out of the lungs. The stiff material provides support and protection to keep the trachea open during breathing and prevent blockages.
Cell Wall
The cell wall which is composed of cellulose
The cell wall
The C-shaped rings that support the wall of the trachea are made out of hyaline cartilage. These rings help maintain the structure and prevent collapse of the trachea during breathing.
The still part of a plant cell is called Cell Wall. This is the rigid outermost layer of a plant cell. It makes the cell stiff -providing the cell with mechanical support - and giving it protection. It is found just inside the cell wall and is made up of complex lipids (fats) and proteins.
Cell wall
Membranes do not have a stiff outside. I suspect the answer you are looking for is the cell wall, which is a stiff structure found outside the cell membrane of a plant cell, but separate from it.
Wash, using a stiff brush.
This layer is called a cell wall,
The wall of the trachea is rigid due to the presence of C-shaped cartilage rings that provide structural support and prevent collapse during breathing. These cartilage rings maintain the patency of the airway and help to protect and support the trachea.
The cell wall is an extra layer of protection for plant cells. The cell wall is stiff so as to keep the shape of the cell. Since plants must be stiff or else they will droop, having stiff cells makes that happen. Animal cells don't need to worry about having stiff cells because animal cells just float around throughout the organism...plant cells must be stiff and aligned next to each other.