The Parathyroid Glands Most people have four On posterior surface of thyroid gland The Effects of Calcitonin Secreted from thyroid parafollicular (C) cells when blood calcium levels are high Calcitonin lowers Ca++ by slowing the calcium-releasing activity of osteoclasts in bone and increasing calcium secretion by the kidney Acts mostly during childhood Some Effects of Thyroid Hormone(Thyroxine) Increases the basal metabolic rate The rate at which the body uses oxygen to transform nutrients (carbohydrates, fats and proteins) into energyДЄffects many target cells throughout the body some effects are Protein synthesis Bone growth Neuronal maturation Cell differentiation15 Thyroid is composed of spherical follicles Follicle cells: produce thyroglobulin, the precursor of thryoid hormone (thyroxin) Colloid lumen is of thyroglobulin Parafollicular C cells: produce calcitoninДЄn example of a feedback loop Thyroxine (thyroid hormone) Hypothalamus TRF from the hypothalamus TSH from anterior pituitary Thyroxine from the thyroid The Thyroid Gland Anterior neck on trachea just inferior to larynx Two lateral lobes and an isthmus Produces two hormones Thyroid hormone: tyrosine based with 3 or 4 iodine molecules T4 (thyroxine) and T3Д¬alcitonin involved with calcium and phosphorus metabolism12 GH stimulates growth of skeletal epiphyseal plates and body to synthesize protein PRL stimulates mammary glands in breast to make milk MSH stimulates melanocytesДЇrom the posterior pituitary (neurohypophysis)structurally part of the brain ADH (antidiuretic hormone/vasopressin) stimulates the kidneys to absorp more water from the urine, raises blood pressure Oxytocin prompts contraction of smooth muscle in reproductive tracts, in females initiating labor and ejection of milk from breasts TSH stimulates the thyroid to produce thyroid hormone ACTH stimulates the adrenal cortex to produce corticosteroids: aldosterone and cortisol FSH stimulates follicle growth and ovarian estrogen production stimulates sperm production and androgen-binding protein LH has a role in ovulation and the growth of the corpus luteum stimulates androgen secretion by interstitial cells in testes9 The four tropic ones regulate the function of other hormones: Hypothalamus controls anterior pituitary hormone release Releasing hormones (releasing factors) of hypothalamus Secreted like neurotransmitters from neuronal axons into capillaries and veins to anterior pituitary (adenohypophysis) TRH (thyroid releasing hormone) -turns on* TSH CRH (corticotropin releasing hormone) -turns on ACTH GnRH (gonadotropin releasing hormone) -turns on FSH and LH PRF (prolactin releasing hormone) -turns on PRL GHRH (growth hormone releasing hormone) -turns on GH Inhibiting hormones of hypothalmus PIF (prolactin inhibiting factor) -turns off PRL GH (growth hormone) inhibiting hormone -turns off GH What the letters stand for TSH: thyroid-stimulating hormone ACTH: adrenocorticotropic hormone FSH: follicle-stimulating hormone LH: luteinizing hormone GH: growth hormone PRL: prolactin MSH: melanocyte-stimulating hormone ADH (antidiuretic hormone), or vasopressin 9. ACTH hormones, they regulate the function of other hormones 3. Two divisions: Anterior pituitary(adenohypophysis)ДЎ. The PituitaryPituitary secretes 9 hormones Hypothalamus_Anterior pituitary_ (adenohypophysis) _Posterior pituitary (neurohypophysis) Learn the 3 endocrine organs on this slide: Hypothalamus Pituitary (hyophysis) Pineal (a) Humoral: in response to changing levels of ions or nutrients in the blood (b) Neural: stimulation by nerves (c) Hormonal: stimulation received from other hormones Overview of the Endocrine System System of ductless glands that secrete hormonesHormones are messenger molecules Circulate in the blood Act on distant target cells Target cells respond to the hormones for which they have receptors The effects are dependent on the programmed response of the target cells Hormones are just molecular triggersД«asic categories of hormones Amino acid based: modified amino acids (or amines), peptides (short chains of amino acids), and proteins (long chains of amino acids) Steroids: lipid molecules derived from cholesterol 2Д®ndocrine Organs Purely endocrine organs Pituitary gland Pineal gland Thyroid gland Parathyroid glands Adrenal: 2 glands Cortex MedullaД®ndocrine cells in other organs Pancreas Thymus Gonads Hypothalamus3

Ppt sistem endokrin