Endocrine System

Functions of the Endocrine System

• Major functions include regulation of metabolism, growth and development, and maintenance of homeostasis.
• Also plays critical roles in mood regulation and reproductive processes.
• Not directly involved in voluntary muscle movement or sensory perception.

Target Cells of Hormones

• Target cells are located in specific tissues or organs throughout the body.
• They possess receptors that are specific to the hormones that act upon them.
• Hormonal signaling leads to changes in cellular activity when hormones bind to these receptors.

Types of Hormones and Solubility

• Lipid-soluble hormones, such as steroid hormones, can easily pass through cell membranes due to their affinity for lipid environments.
• Water-soluble hormones, such as peptide hormones, require receptor binding on the cell surface to exert their effects.

Hormone Entry into the Bloodstream

• After release, most hormones enter the bloodstream through surrounding capillaries.
• This circulation allows for distribution to various target cells throughout the body.

Hormones and Nuclear Receptor Binding

• Steroid hormones and thyroid hormones are examples of hormones that bind to receptors located in the nucleus.
• This interaction often leads to changes in gene expression and, consequently, cellular function.