The iris in the human eye contracts and expands, controlling the amount of light that reaches the retina. What types of muscle control this?To which skeletal system does the sternum belong?

1. sphincter muscle and dilator muscle

2. Axial skeleton

Explanation:

1.The iris in the human eye is responsible for controlling the exposure of of light that reaches the retina. The movement of iris is controlled by a muscles called sphincter muscle and dilator muscle. sphincter muscle constricts the pupil in bright light while dilator muscle expands the pupil.

2.  Sternum belongs to the axial skeleton, which is a long flat bone located in the central part of the chest. Axial skeleton consists of 80 bones and strenum is one of them. Axial skeleton functions to provide protection to vital organs such as brain, heart and lungs. Strenum functions to protect heart.

homeostasis is the tendency towards a relatively stable equilibrium between interdependent elements, especially as maintained by physiological processes. and this is how it applies to the integumentary system. back to top. skin functions in homeostasis include protection, regulation of body temperature, sensory reception, water balance, synthesis of vitamins and hormones, and absorption of materials. when body temperature falls, the sweat glands constrict and sweat production decreases.