In this video lecture, educator introduces the endocrine system and how coordination of body functions occur by chemical messengers. Body’s chemical messenger systems interact with one another to maintain homeostasis.
There are three general classes of hormones as
- Protein/peptide hormone
- Steroid hormone
- Amine hormone
There is a feedback control mechanism for controlling hormones. According to mode of transportation, hormones can be hydrophobic or hydrophilic.
Hormone signals must be turned off when they have served their purpose. Educator explained mechanism of hormonal action. Receptors can be regulated by either down regulation or up regulation mechanism. After activation of hormones, there is intracellular signaling. Neurotransmitter substances, such as acetylcholine and norepinephrine, combine with receptors in the postsynaptic membrane. According to links, there are three types of receptors 1. Ion-channel 2. G-Protein 3. Enzyme.
Adrenal and gonadal steroid hormones, thyroid hormones, retinoid hormones, vitamin D are involved in intracellular receptors and activation of genes. Educator explains second messenger mechanism, adenylyl cyclase-camp system, Ca-calmodulin 2nd messenger system and phospholipid 2nd messenger system. Steroids and thyroid hormones act on genetic machinery.
Measurement of hormones concentration in blood can be done by two methods radioimmunoassay and ELISA test.