Lec 1 endocrine thyroid 1

Endocrine
Lec: 1 Dr. Mohammed Alhamdany
Functional anatomy and physiology:
Most hormone release from endocrine glands are under the control of pituitary gland and hypothalamus except for example the adrenal zona glomerulosa (regulated by the renin–angiotensin system), parathyroids (regulated by calcium concentrations) and pancreas(regulated by glucose level).
Anterior pituitary hormone secretion is controlled in turn by substances produced in the hypothalamus and released into portal blood, which drains directly down the pituitary stalk. Posterior pituitary hormones are synthesized in the hypothalamus and transported down nerve axons, to be released from the posterior pituitary.
Hormone release in the hypothalamus and pituitary is regulated by numerous stimuli and through feedback control by hormones produced by the target glands which are either positive or negative feedback, this is called axes.
Paracrine is defined as hormone release from cell to affect adjacent cell such as neurotransmitter, while autocrine define as hormone secrete from cell to affect same cell.
The endocrine axes include:
1- Thyroid: thyrotrophin-releasing hormone TRH (in H.) TSH (in anterior P.) T4 and T3 (in T. gland) Metabolism.
Feedback: T3 can feedback TRH.
2- Sex hormone: GnRH (gonadotrophin-releasing hormone) in H LH, FSH
( in anterior P) Oestrogen, Progesterone, Androgen in Gonads: testes or ovaries Reproduction.
feedback: estrogen, Progesterone ,Androgen, Prolactin, Inhibin can feedback GnRH.
3- Lactation: TRH and Dopamine (suppress) Prolactin (ant. P) Breast Lactation.
Feedback: Estrogen and Stress can feedback Dopamine.
4- Growth: GHRH and Somatostatin GH in (ant. P.) IGF1 and IGFBP3 (insulin like growth factor -1 and its binding protein (in the liver) Growth, IGF-1 can feedback GHRH.
5- Adrenal: CRH in H ACTH in ant. P. Cortisol and Androgen in Adrenal cortex Stress.
Feedback: Stress and Cortisol can feedback CRH (which secrete in Circadian rhythm).
6- Water balance: ADH in hypothalamus secrete to post. P. (also affect ACTH) Distal nephron Water balance.
Feedback: Osmolality and Intravascular volume can feedback ADH.
7- Parturition and Lactation: Oxytocin in hypothalamus secrete to post. P. Uterus and Breast Parturition and Lactation