Yogy's biology

  09 Control and Coordination - part 16 - Major endocrine glands Major endocrine glands : A. Hypothalamus : It is  ectodermal  in origin.  Located at the  floor of diencephalon.  Major function  : Maintain homeostasis. Controls the secretory activity of  pituitary gland  by the  release and inhibiting hormones .  All hormones of hypothalamus are  peptide hormones .  They are secreted by the  neurosecretory cells  so they are called  neurohormones .  Hormones secreted by hypothalamus are :  ADH, Oxytocin. 1. Adrenocorticotropin Releasing Hormone :  It stimulates the release of  ACTH  by the  anterior pituitary gland. 2. Thyrotropin Releasing Hormone :  Stimulates the release of  TSH  by anterior pituitary gland. 3. Gonadotropin Releasing Hormone (GnRH) :  It stimulates pituitary to secrete gonadotropins. 4. Prolactin Inhibiting Hormone (Prolactostatin) :   It inhibits prolactin release by anterior piturary gland. 5. Somatostatin :  It inhibits the release of growth hormone. 6. Somatotro

  09 Control and Coordination - part 15 - Endocrine system Endocrine system : Controls body activities by means of chemical messengers called  hormones .  Hormones are released directly  into the blood .  The hormone is carried all over the body via blood.  However the message is relayed only to the  target organs  which are stimulated to carry out specific process which include activities like  growth and development . Chemical nature of hormones I. Amines :  These are simple amines. Catecholamines  secreted by  adrenal medulla ,   epinephrine and non-epinephrine and melatonin  from  pineal gland.  Some are modified from the amino acids. e.g.,  Thyroxine. II. Peptide hormones :  Consist of long or short chains of  amino acids.  e.g.  Hormones of hypothalamus   oxytocin, ADH, GnRH. III. Protein hormone : Insulin, glucagon TSH, FSH, LTH, GH, relaxin . IV. Fatty acid derivatives :- Prostaglandin V. Steroid hormones :  These hormones are  lipid soluble. Derived from  cholesterol and other