Endocrine system

The **endocrine system** includes those organs of the body which produce hormones.
It helps to regulate metabolism, growth and development, tissue function, and plays a part also in mood.
The field of medicine that deals with disorders of endocrine glands is endocrinology.

In physiology, the endocrine system is a system of glands, each of which secretes a type of hormone directly into the bloodstream to regulate the body.

The endocrine system is in contrast to the exocrine system, which secretes its chemicals using ducts. The endocrine system is an information signal system like the nervous system, yet its effects and mechanism are different.

The endocrine system's effects are slow to start, and long-lasting in their response. The nervous system sends information quickly, and responses are generally short lived. Hormones are complex chemicals released from endocrine tissue into the bloodstream where they travel to target tissues and trigger a response.

Features of endocrine glands are, in general, they have no ducts, they have a good blood supply, and usually they have vacuoles or granules inside their cells, storing their hormones.

### Central nervous system

- **Hypothalamus** produces
    - Thyrotropin-releasing hormone (TRH) _Parvocellular neurosecretory neurons_
    - Gonadotropin-releasing hormone (GnRH)  _Neuroendocine cells of the Preoptic area_
    - Growth hormone-releasing hormone (GHRH)  _Neuroendocrine neurons of the Arcuate nucleus_
    - Corticotropin-releasing hormone (CRH)  _Parvocellular neurosecretory neurons_
    - Vasopressin_ Parvocellular neurosecretory neurons_
    - Somatostatin (SS; also GHIH, growth hormone-inhibiting hormone) _Neuroendocrince cells of the Periventricular nucleus_
    - Prolactin inhibiting hormone or PIH or Dopamine (DA) _Dopamine neurons of the arcuate nucleus_
    - Prolactin releasing hormone
- **Pineal body** produces
    - Melatonin (mainly)  _Pinealocytes_
- **Pituitary gland** (hypophysis) produces
    - **Anterior pituitary** lobe (adenohypophysis)
        - Growth hormone (GH) _Somatotropes_
        - Prolactin (PRL) _Lactotropes _
        - Adrenocorticotropic hormone (ACTH, corticotropin) _Corticotropes_
        - Lipotropin _Corticotropes_
        - Thyroid-stimulating hormone (TSH, thyrotropin) _Thyrotropes_
        - Follicle-stimulating hormone (FSH) _Gonadotropes_
        - Luteinizing hormone (LH)  _Gonadotropes_
    - **Posterior pituitary** lobe (neurohypophysis)
        - Oxytocin _Magnocellular neurosecretory cells_
        - Vasopressin (AVP; also ADH, antidiuretic hormone) _Magnocellular neurosecretory cells_
    - **Intermediate pituitary** lobe (pars intermedia)
        - Melanocyte-stimulating hormone (MSH) _Melanotroph_

### Thyroid

- **Thyroid** produces
    - Triiodothyronine (T3), the potent form of thyroid hormone _Thyroid epithelial cell_
    - Thyroxine (T4), also known as tetraiodothyronine: it is a  less active form of thyroid hormone (mainly) _Thyroid epithelial cell_s
    - Calcitonin  _Parafollicular cell_s

### Parathyroid

- Parathyroid hormone PTH triggers an increase in blood calcium levels.

### Muscles

- **Striated muscle** produces
    - Thrombopoietin  _Myocytes_

### Alimentary system

- **Stomach** produces
    - Gastrin (mainly)  _G cells_
    - Ghrelin  _P/D1 cells_
    - Neuropeptide Y (NPY)
    - Secretin _S cells_
    - Somatostatin  _D cells_
    - Histamine  _ECL cells_
    - Endothelin _X cells_
- **Duodenum** produces
    - Cholecystokinin  _I cells_
- **Liver** produces
    - Insulin-like growth factor (IGF) (mainly)  _Hepatocytes_
    - Angiotensinogen  _Hepatocytes_
    - Thrombopoietin _Hepatocytes_
- **Pancreas** produces
    - Insulin (mainly)  _β Islet cells_
    - Glucagon (also mainly)  _α Islet cells_
    - Somatostatin  _δ Islet cells_
    - Pancreatic polypeptide  _PP cells_

### Kidney

- **Kidney** produces
    - Renin (Primarily) _Juxtaglomerular cells_
    - Erythropoietin (EPO)  _Extraglomerular mesangial cells_
    - Calcitriol (the active form of vitamin D<sub>3</sub>)
    - Thrombopoietin

### Adrenal glands

- **Adrenal glands**
    - **Adrenal cortex** produces
        - Glucocorticoids (chiefly cortisol) _Zona fasciculata and Zona reticularis cells_
        - Mineralocorticoids (chiefly aldosterone) _Zona glomerulosa cells_
        - Androgens (including DHEA and testosterone) _Zona fasciculata and Zona reticularis cells_
    - **Adrenal medulla** produces
        - Adrenaline (epinephrine) (Primarily) _Chromaffin cells_
        - Noradrenaline (norepinephrine)  _Chromaffin cells_
        - Dopamine  _Chromaffin cells_
        - Enkephalin  _Chromaffin cells_

#### Male

- **Testes**
    - Androgens (chiefly testosterone) _Leydig cells_
    - Oestradiol _Sertoli cells_
    - Inhibin _Sertoli cells_

#### Female

- **Oestrous cycle**
    - **Ovarian follicle/Corpus luteum**
        - Progesterone _Granulosa cells, Theca cells_
        - Androstenedione  _Theca cells_
        - Oestrogens (mainly oestradiol) _Granulosa cells_
        - Inhibin _Granulosa cells_
    - **Placenta** (when a woman is pregnant)
        - Progesterone (Primarily)
        - Oestrogens (mainly oestriol) (Also primarily)
        - Human chorionic gonadotropin (HCG)  _Syncytiotrophoblast_
        - Human placental lactogen (HPL)  _Syncytiotrophoblast_
        - Inhibin _Fetal trophoblasts_
    - **Uterus** (when a woman is pregnant)
        - Prolactin (PRL) _Decidual cells_
        - Relaxin  _Decidual cells_

### Calcium regulation

- **Parathyroid** produces
    - Parathyroid hormone (PTH) _Parathyroid chief cell_
- **Skin** produces
    - Vitamin D<sub>3</sub> (calciferol)

### Miscellaneous

- **Heart** produces
    - Atrial-natriuretic peptide (ANP) _Cardiac myocytes_
    - Brain natriuretic peptide (BNP)  _Cardiac myocytes_
    - Adenosine  _Cardiac myocytes_
- **Adipose tissue**
    - Leptin (Primarily) _Adipocytes_
    - Oestrogens (mainly oestrone)  _Adipocytes_
- **Bone marrow** produces
    - Thrombopoietin

## Related pages

- Hormones
- Nervous system

## Other websites

- Journals Designed for Clinical Endocrinologists
- Islet cell antibody
- Binding of antibody to pancreas
- Kidshealth.org