The human body has four types of tissues. What part of the eye uses muscle tissue for opening and closing movements? (1 point)
O Retina
Sclera
Iris
Cornea
The correct answer is Iris.
The part of the eye that uses muscle tissue for opening and closing movements is the iris.
To answer this question, we need to understand the four types of tissues in the human body and then identify which part of the eye uses muscle tissue for opening and closing movements.
The four types of tissues in the human body are epithelial tissue, connective tissue, muscle tissue, and nervous tissue. Epithelial tissue covers the surfaces of the body, connective tissue supports and connects different body parts, muscle tissue generates force and movement, and nervous tissue transmits and processes information.
Now, let's identify which part of the eye uses muscle tissue for opening and closing movements among the options given:
1. Retina: The retina is located at the back of the eye and contains specialized cells that detect light and transmit visual information to the brain. The retina does not have a direct role in the opening and closing movements of the eye.
2. Sclera: The sclera is the tough, white outer coating of the eye. It provides structural support and protection but does not have muscle tissue responsible for eye movements.
3. Iris: The iris is the colored part of the eye surrounding the pupil. It contains smooth muscle fibers that can contract or relax to adjust the size of the pupil, controlling the amount of light entering the eye. When the smooth muscle fibers contract, the pupil becomes smaller, and when they relax, the pupil becomes larger. Therefore, the iris is the part of the eye that uses muscle tissue for opening and closing movements.
4. Cornea: The cornea is the clear, dome-shaped surface that covers the front of the eye. It plays a significant role in focusing light onto the retina but does not have muscle tissue responsible for eye movements.
Based on this information, the correct answer is the iris, as it uses muscle tissue for opening and closing movements of the eye.