Describe how negative feedback regulates the secretion of most hormones. Explain how the pituitary gland functions as the master gland of the body. What are the endocrine functions of the pancreas? Sketch a section of the thyroid gland and detail several thyroid follicles.

Describe how negative feedback regulates the secretion of most hormones

Negative feedback is the most well-known mechanism and is directly linked to homeostasis. Most hormone secretions are regulated in this way. It is characterized by being a mechanism that reduces a certain stimulus, reversing the direction of change.

Example: Thyroid function: When the hormones produced by this gland are low, the production of HRT by the hypothalamus occurs, which stimulates the production of TSH by the pituitary. TSH reaches the thyroid, stimulating the synthesis of its hormones: T3 and T4. When these hormones increase, the secretion of HRT and TSH is also inhibited, thus reducing the synthesis of thyroid hormones.

Explain how the pituitary gland functions as the master gland of the body

The pituitary gland is a small gland that is located at the base of the brain. Many classify it as the master gland in the body, because the hormones it produces regulate the functioning of other glands. Because it consists of different types of endocrine cells, the pituitary gland is divided into two parts: the adenoipophysis (or anterior lobe of the pituitary) and neuroipophysis (posterior lobe of the pituitary).

What are the endocrine functions of the pancreas?

The endocrine function of the pancreas corresponds to its ability to produce insulin and glucagon, two hormones that guarantee adequate blood sugar levels. These hormones are produced on the islets of Langerhans, a group of cells that have the shape of a sphere.

Sketch a section of the thyroid gland and detail several thyroid follicles

Each follicle consists of a layer of cubic follicular cells that surround a central colloid-filled lumen. The follicles, which vary in size, increase during glandular stimulation.

Thyroid follicular cells derive from the endoderm and show a typical ultrastructure of peptide hormonal secretion. Cellular height varies from scaly (in the inactive glands) to cylindrical (during stimulation). In addition, thyroid cells differ from other endocrine cells in that they store an intermediate form of their secretion product (thyroglobulin) extracellularly in the colloid, rather than internally in cytoplasmic secretory granules. Stimulation by thyroid-stimulating pituitary hormone (TSH) signals an increase in the body's need for energy, increasing the synthesis and secretion of thyroid hormones thyroxine (T4) and triiodothyronine (T3).

Explanation:

the level of progesterone is low at the pre-ovulatory phase of the cycle but it gradually increases and the levels are high at the luteal phase. if pregnancy occurs, the level of progesterone will be high throughout the pregnancy.

if egg is fertilized and the mother gets pregnant, progesterone starts preparing the uterus for the implantation. it starts building up the lining of uterus and make it hostile of the period of pregnancy.