Chemical Control and Integration
Summary:
This article provides an overview of hormones and their classification based on their chemical nature, their role in regulating physiological processes, and how they bind to receptors on target cells to initiate specific responses. The article also discusses various endocrine organs such as the hypothalamus, pituitary gland, thyroid gland, parathyroid gland, adrenal gland, and gonads. Additionally, the article mentions other endocrine glands, such as the heart, liver, and skin and local hormones, such as prostaglandins, leukotrienes, cytokines, and interferons. The article also includes diagrams of different glands of the human endocrine system.
Excerpt:
Chemical Control and Integration
Hormones are non-nutrient chemicals that act as neurotransmitters.
❖ TYPES OF HORMONES ON THEIR CHEMICAL NATURE:
| Peptide, Polypeptide and Protein Hormones | Steroid Hormones | Iodothyronines | Amino Acid Derivatives |
| ● Insulin
● Glucagon ● Pituitary hormones ● Hypothalamic hormones |
● Cortisol
● Testosterone ● Estradiol ● Progesterone |
Iodinated amino acids with a diphenyl ether ring in the side chain.
● Thyroxine |
● Epinephrine
● Norepinephrine |
❖ MECHANISM OF HORMONE ACTION:
● MODE OF STEROID ACTION:
Chemical Control and Integration
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OTHER ENDOCRINE GLANDS:
- Heart:
- Cardiocytes of the heart’s atria secrete peptide hormones Atrial Natriuretic Factor (ANF).
- ANF inhibits the release of renin from JGA, inhibits NaCl
- Reduces aldosterone release from adrenal
- Liver:
- Produces angiotensinogen, which is converted into angiotensin II in the presence of
- Angiotensin stimulates the adrenal cortex to produce
- Skin:
- Vitamin D exists in two forms: Calciferol or D2, and cholecalciferol or Calcitriol is an active form of D3.
- Increases absorption of calcium and phosphorus in the small intestine and accelerates bone
- Deficiency causes rickets in children and osteomalacia in adults.
LOCAL HORMONE:
- Prostaglandins (PGs):
- Long chain unsaturated fatty acids.
- Their traces are sufficient to cause contractions of smooth muscles.
- Prostaglandins of seminal vesicles mix with semen.
- Leukotrienes (LTs):
- Mediators of allergic response.
- The release of leukotrienes increases when some allergic agents combine with antibodies like Ig E.
- Cytokines:
- Secreted by eosinophils of blood and mast cells of connective tissues.
- Regulate immune reactions.
- Interferons:
- Secreted into ECF by cells infected with viruses.
- Protect neighbouring cells from viruses.
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