Chapter 17.3, Problem 2AYLO

Summary Introduction

To discuss:

The anatomy of the thymus, its involution, hormones, and functions.

Introduction:

Hormones are chemical messengers secreted by the endocrine glands or neurosecretory cells into the extracellular fluids. The secreted hormones reach the target cells through the bloodstream and they stimulate responses of other tissues or cells. Hormones bind only to specific cells based on their corresponding receptors present on cells. Hormones act through chemical signals. They regulate growth, development, blood pressure, metabolism, fluid concentration, and homeostasis in the body. Both the positive and negative feedback mechanism may regulate hormone pathways. Positive feedback amplifies the stimulus, whereas negative feedback dampens the stimulus and stops the pathway.