1. ENDOCRINE SYSTEM GLANDS 2 TYPES 1.Exocrine gland: Ducts, Lumen and Surfaces. 2.Endocrine gland : No ducts. Secrete chemical messengers called hormones directly into the blood stream into the plasma, where it is dissolved and transported throughout entire body.

2. Hormones are substances that are secreted by one group of cells that affects the physiology of another group of cells (Organs). Every cell is exposed to the hormone, but not every cell responds to it. For a cell to respond to hormone, the cell must have a functional hormone receptor. Influences only specific tissues: Target cells that have a receptor for that particular hormone.

4. ENDOCRINE GLANDS Hypothalamus Pituitary Gland Thyroid Gland Parathyroid Glands Adrenal Glands Pancreas Ovaries Testes

5. Control of Hormone Secretion The endocrine system is controlled by the pituitary gland and the hypothalamus. Always controlled by feedback loops. Concentration declines/reduces below a minimum: more hormone is secreted. Concentration exceeds/increases maximum: Hormone production is halted.

6. Control of Hormones Release Three Mechanisms Humoral Trigger  Blood Neuronal Trigger  Nervous system Hormonal Trigger  Hormones

8. Hypothalamus This is located at the base of the brain. The hypothalamus controls the endocrine system by controlling the pituitary gland. – Secretes releasing hormones to cause the pituitary to release hormones. – Secretes inhibiting hormones to turn off secretion of pituitary hormones.

9. Hypothalamus Regulation The hypothalamus produces hormones which affect the anterior pituitary, for example: Thyroid Stimulating Hormone Releasing Hormone (TSH-RH) – Causes adeno-hypophysis to secrete TSH – TSH affects thyroid gland to secrete TH Thyroid Stimulating Hormone Inhibiting Hormone (TSH-IH) – Causes adeno-hypophysis to stop secreting TSH so thyroid gland stops secreting thyroid hormone The hypothalamus affects the adeno-hypophysis, and that’s about it.

10. Some Hypothalamus Hormones Growth Hormone Releasing Hormone (GH-RH) Prolactin Releasing Hormone (PRL-RH) Thyroid Stimulating Hormone Releasing Hormone (TSH-RH) Adrenocorticotropic Hormone Releasing Hormone (ACTH-RH) Melanocyte Stimulating Hormone Releasing Hormone (MSH-RH) Follicle Stimulating Hormone Releasing Hormone (FSH-RH) Luteinizing Hormone Releasing Hormone (LH-RH)

11. Hypothalamus Hormones Growth Hormone Inhibiting Hormone (GH-IH) Pro-lactin Inhibiting Hormone (PRL-IH) Thyroid Stimulating Hormone Inhibiting Hormone (TSH-IH) Adreno-corticotropic Hormone Inhibiting Hormone (ACTH-IH) Melanocyte Stimulating Hormone Inhibiting Hormone (MSH-IH) Follicle Stimulating Hormone Inhibiting Hormone (FSH-IH) Luteinizing Hormone Inhibiting Hormone (LH-IH)

12. Pituitary Gland Secretes nine 9 major hormones Attached to the hypothalamus by the infundibulum (stalk) Two basic divisions of the pituitary gland – Adeno-hypophysis (anterior lobe) – Neuro-hypophysis (posterior lobe)

13. HORMONES BY ANTERIOR PITUITARY TSH = Thyroid stimulating hormone ACTH = Adreno corticotropin hormone FSH = Follicle stimulating hormone LH = Luteinizing hormone MSH = Melanophore stimulating hormone GH = Growth Hormone PRL = Prolactin

14. Two important hormones secreted by posterior pituitary ADH (Vasopressin) Oxytocin

15. Adeno-hypophysis Growth hormone (GH) – Causes the body to grow Prolactin (PRL) – Stimulates lactation (milk production) in females – Stimulated lacrimation (desire to cry) – Decreased in adolescent males so it decreases desire to cry Thyroid Stimulating Hormone (TSH) – Causes the thyroid gland to release thyroid hormone

16. Adeno-hypophysis Adrenocorticotropic hormone (ACTH) – Acts on adrenal cortex to stimulate release of cortisol – Helps to reduce when a person has stress Melanocyte-stimulating hormone (MSH) – Darkens skin pigmentation – Increases during pregnancy – Also has effects on appetite and sexual arousal Follicle-stimulating hormone (FSH) – Present in males and females, affects both – Stimulates maturation of sex cells Luteinizing hormone (LH) – Induces ovulation in females – Induces testosterone in males

17. Neuro-hypophysis Oxytocin – Childbirth contractions Anti-diuretic hormone (ADH) – Signals kidneys to increase water reabsorption Di-Uresis : means more passage of urine. Anti- : means reduces urine production by absorbing more water from the kidneys.

18. THYROID GLAND Largest endocrine gland in the body. Weight about 20 – 25gm. – Located along the midline of the neck – Secretes two hormones. Thyroid hormone Calcitonin

19. Thyroid Hormones Thyroid hormone (TH)  T3,T4 – Acts on most cells of the body – Increases metabolic rate – Controlled by hormonal mechanism – Iodine is needed to make TH Calcitonin – Lowers blood calcium levels in children – Slows osteoclasts to allow for bone deposition – Regulates metabolism Increases protein synthesis Promotes glycolysis, gluconeogenesis, glucose uptake Calcitonin: calcium metabolism 19

20. Thyroglobin If a segment has two iodines, it is called T2. If there are 3 iodines attached, it is called T3 (Tri-iodothyronine). If it has 4 iodines, it is T4 (thyroxine). The T3 and T4 are then released into the bloodstream. Those thyroglobulin segments that have only 1-2 iodines are recycled for parts and are not released. 20

21. T4 is the most abundant form, but it is inert (inactive). T3 has more activity on the cells. So, T3 gets used first by the body cells. T4 takes longer to be ready; one iodine has to drop off. As T3 is used up, T4 is being converted to more T3. To make thyroid hormone, you need iodine in your body. Iodized salt has enough to meet this need. Without enough iodine in the diet, thyroid hormone cannot be made, no matter how much TSH is present. 21

22. ACTIONS OF THYROID HORMONE Increases GI motility Increases mental activity Increases endocrine activity Promotes growth and brain development in the fetus and young children Stimulates fat metabolism Excites CNS Causes sleep difficulty

23. Thyroid Hormone Effects All cells respond to thyroid hormone, increasing their metabolic rate (heart rate speeds up, beats with greater force, more nutrients are used, etc). Too much thyroid hormone is hyperthyroidism; these people are thin and active. When levels of TH are too low, it is called hypothyroidism; these people are overweight, move slowly, have no energy.

24. TH also stimulates neurons; the person feels more alert, observing their environment with more interest. When there is too much TH, they get muscles tremors and increased blood glucose levels (hyperglycemia). With not enough TH, they lose interest, become sluggish, they get low blood glucose levels (hypoglycemia). 24

25. Thyroid Pituitary Hypothalamus TSH-RH TSH TH Hypothalamus makes TSH-RH (Thyroid stimulating hormone releasing hormone) Pituitary makes TSH (Thyroid stimulating hormone) Thyroid gland makes TH (Thyroid hormone)