home ][ anatomy & physiology ][ massage therapy ][ links ][ contacts ][ help

Anatomy & Physiology >> Endocrine System >> Hormones


Sex Hormones

Diseases and Disorders


The Endocrine System


The endocrine system is responsible for the delivery of chemical messengers or hormones. These messengers are secreted directly into the blood (thus endo-crine) especially by a gland, without passing through a duct in order to enter the blood.

Hormones are grouped together by their function, not by their structure. Some are made of protein, such as insulin, while others are steroids (adreno-corticoid hormones), glycoproteins (FSH, LH, TSH) and derivatives of single amino-acids (T4, T3). All hormones, however, are produced in a gland and then transported to an area or organ they control.

Fig. 1 Location of hormone production

Hormones play an important role in homeostasis and are also responsible for the development and growth of the human body. In addition to this, the sex hormones control aspects of reproduction, i.e. the menstrual cycle in women.

The following describes which hormones each gland is responsible for producing, its function and control:

  Hormone Function Control
Hypothalamus   Releasing and inhibiting hormones Control of anterior pituitary Hormone and metabolite feedback
Posterior Pituitary   Oxytocin Ejection of milk

Uterine contraction (birth)
Hormone and nerve feedback
  ADH Anti-diuretic Hormone

(aka vasopressin)
Reduces urine volume Blood concentration (osmosis)
Anterior Pituitary FSH Follicle Stimulating Hormone Spermatogenesis (males)

Follicular development (females)
Plasma oestrogen and progesterones levels
  LH (females)

ICSH (males)
Luteinising Hormone

Interstitial Cell Stimulating Hormone
Ovulation and maintenance of corpus luteum (females)

Testosterone secretion (males)
Plasma oestrogen

Plasma testosterone
    Prolactin Stimulates milk production Hypothalmic hormones
  TSH Thyrotrophin Synthesis and release of thyroid hormones Plasma thyroxine levels
  ACTH Adrenal Cortex Hormone Synthesis and release of adrenal cortex hormones Plasma ACTH
  HGH Human Growth Hormone Protein synthesis, growth (bones) Hypothalmic hormones
  MSH Melanocyte Stimulating Hormone Melanin synthesis and secretion Sympathetic Nervous System
Parathyroid   Parathormone Increases blood Ca
Reduces blood PO4
Plasma Ca and PO4 levels
Thyroid   Thyroxin Regulation of BMR (base metabolic rate)
Growth and development
    Triiodothyronin Regulation of BMR
Growth and development
    Calcitonin Decrease blood Ca Plasma Ca levels
Thymus   T lymphocytes Immunity Plasma proteins
Pineal   Melatonin Melanin production Sympathetic Nervous System
    Seratonin Control circadian rhythms Sympathetic Nervous System
Adrenal Cortex   Corticosteroids Metabolism of proteins and carbohydrates in response to stress. Stress Adaptation ACTH
    Mineralocorticoids (Aldosterone) Na retention in kidney

NA and K levels, reaises BP
Plasma Na and K levels

Low blood pressure
Adrenal Medulla   Adrenaline Increased heart rate. Dilation of skeletal arterioles. Increased blood glucose etc. Sypmathetic Nervous System
    Noradrenaline Constriction of arterioles therefore BP raises Nervous System
Islets of Langerhans   Insulin (beta cells) Blood glucose converted to glycogen. Increased cell uptake, i.e. reduces blood glucose Plasma glucose and amino acid levels
    Glucagon (alpha cells) Breakdown of glycogen to glucose, i.e. increases blood glucose levels Plasma glucose levels
Ovarian Follicle   Oestrogen Secondary sexual characteristics. Oestrous cycle FSH and LH
    Progesterone Gestation. Inhibition of ovulation LH
Testis   Testosterone Secondary characteristics FSH and LH (ICSH)