Final answer:
Mammalian steroid hormones participate in endocrine signaling by sending hormones through the bloodstream to distant target cells. This type of signaling typically results in longer-lasting effects. Ion channels are crucial for ion transport across the cell membrane, as ions cannot pass through the lipid bilayer without them.
Step-by-step explanation:
Mammalian steroid hormones are involved in endocrine signaling, which is the communication method that involves signals sent from distant cells through the bloodstream. Endocrine signals usually have a slower onset but a more sustained impact compared to other signaling types. In endocrine signaling, the hormones secreted into the extracellular fluid by endocrine glands such as the pituitary gland, diffuse into the blood or lymph and can travel significant distances to reach target organs or cells.
The secretion of hormones by the pituitary gland, as mentioned, is a clear example of endocrine signaling, where the hormones act on distant cells after being transported through the circulatory system. Unlike other forms of signaling like autocrine or paracrine, endocrine signaling can regulate activities over the entire body and maintain homeostasis over longer periods.
As for ion channels, they are necessary for transporting ions into or out of cells because ions are charged particles that cannot diffuse through the hydrophobic lipid bilayer of the cell membrane. Ion channels are proteins that provide a pathway for ions to pass through the membrane in response to a signal or a gradient.