The document discusses the hypothalamic-pituitary axis and its role in regulating hormone release and function. It describes the hormones released by the anterior and posterior pituitary glands, their targets, and functions. Negative feedback loops control hormone levels. The hypothalamus regulates pituitary hormone secretion through releasing and inhibiting factors.
The document discusses the hypothalamic-pituitary axis and its role in regulating hormone release and function. It describes the hormones released by the anterior and posterior pituitary glands, their targets, and functions. Negative feedback loops control hormone levels. The hypothalamus regulates pituitary hormone secretion through releasing and inhibiting factors.
The document discusses the hypothalamic-pituitary axis and its role in regulating hormone release and function. It describes the hormones released by the anterior and posterior pituitary glands, their targets, and functions. Negative feedback loops control hormone levels. The hypothalamus regulates pituitary hormone secretion through releasing and inhibiting factors.
The document discusses the hypothalamic-pituitary axis and its role in regulating hormone release and function. It describes the hormones released by the anterior and posterior pituitary glands, their targets, and functions. Negative feedback loops control hormone levels. The hypothalamus regulates pituitary hormone secretion through releasing and inhibiting factors.
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Hypothalamic-Pituitary Axis
• Oleh : • I DEWA MADE RUSPAWAN NIM : 1590271010
PROGRAM DOKTOR ILMU KEDOKTERAN
2015 Hypothalamic-Pituitary Axis • The hypothalamus and pituitary gland form a complex interface between the nervous • system and the endocrine system. • The brain can influence the activity of Neurosecretory cells and hormones can influence • the release of other hormones. Anterior Pituitary • The six major anterior pituitary hormones are peptides. • The Six Major Anterior pituitary hormones are: • 1. Thyroid Stimulating Hormone (TSH or thyrotropin) • 2. Follicle Stimulating Hormone (FSH, a gonadotropin) 3. Luteinizing Hormone (LH, a gonadotropin) 4. Adrenocorticotropic Hormone (ACTH, or corticotropin) 5. Growth Hormone (GH) 6. Prolactin (PRL) Targets and Functions of the Anterior Pituitary Hormones
1. TSH – target thyroid gland and stimulates
secretion of thyroid hormone (TH). 2. FSH – targets follicles in the ovaries of females and stimulates growth of follicle and production of estrogen. In males it targets the testes and stimulates sperm cell production. 3. LH – targets follicle, triggers ovulation and increases secretion of progesterone. In males it stimulates testosterone production. 4. ACTH – targets the adrenal cortex and causes the secretion of glucocorticoids. 5. GH - targets most bodily tissues and stimulates metabolism and growth of those tissues. 6. PRL - targets the breasts in females. Stimulates breast development and lactation. Posterior Pituitary • Is composed primarily of neuronal tissue. • Is connected to the supraoptic and paraventricular nuclei of the hypothalamus via axons in the infundibulum. • Stores two major neurohormones for later release. 1. ADH (vasopressin) – stimulates water reabsorption by kidneys. 2. Oxytocin – stimulates labor contractions during birth. • Release of posterior pituitary and hypothalamic hormones is identical to neurotransmitter release by other neurons. • Molecules that function as hormones in the hypothalamic-pituitary axis are often neurotransmitters, neuromodulators, or paracrines in other places in the body. Hypothalamic Hormones • Are the first in a series of hormones that ultimately leads to the secretion of hormones by specific endocrine glands. • Several of the hypothalamic hormones stimulate tropic hormones in the anterior pituitary. • Observe the following diagram closely to see how hypothalamic hormones influence the regulation of secretions of other endocrine glands. • For each hormone series, negative feedback loops control circulating levels of the target gland hormones. • Negative feedback from the target gland can be directed at the anterior pituitary, the ventral hypothalamus or both. • The hypothalamic hormones also maintain the anterior pituitary and the tropic hormones help to maintain their target endocrine glands. • In some instances hormones of one series will cause the secretion of the hormones of another series (i.e. TH stimulates secretion of GH). • Prolactin (PRL) is unique because its primary stimulus from the hypothalamus is inhibitory except after birth when milk production begins. KELENJAR HIPOFISE - HIPOTALAMUS • Kelenjar pituitari : - Hipofisis anterior ( adenohipofisis ) a. Hormon pertumbuhan/metabolisme b. Adrenokortikotropin c. Thyroid-stimulating hormone d. Prolaktin e. Gonadotropin :(FSH, LH )-Aktifitas gonad dan aktivitas reproduksi. • Sekresi Hipofisis anterior diatur oleh hormon releasing factor dan inhibiting factor hipotalamus yang disekresi dalam hipotalamus al : TRF=Thyroid-stimulating hormone releasing factor = pengeluaran thyroid-stimulating hormon. CRF=Corticotropin releasing factor = pengeluaran adrenokortokotropin - GRF= Growth-hormone releasing factor=pengeluaran hormon pertumbuhan. - LRF = Luteinizing hormone releasing factor = pengeluaran luteinizing hormone - FRF = Follicle stimulating hormone releasing factor = pengeluaran folicle-stimulating hormone - PIF = Prolactin inhibitory factor=penghambat sekresi prolaktin. Pada Wanita FSH: • Menstimulasi ovarium untuk memproduksi steroid • Ovarium akan menghasilkan estradiol selama fase folikuler dan progesteron selama fase luteal • Lonjakan pada pertengahan siklus, dengan LH, memicu ovulasi LH : • Menstimulasi ovarium untuk menghasilkan steoroids • Lonjakan pada pertengahan siklus memicu ovulasi • Ingat, hormon luteinizing ternyata folikel menjadi korpus korpeus dengan memicu ovulasi Pada Pria FSH : • Menstimulasi sel Sertoli untuk menghasilkan protein androgen-binding (ABP), sehingga merangsang spermatogenesis • FSH juga merangsang sel Sertoli untuk menghasilkan inhibin, yang memberikan umpan balik negatif terhadap hipofisis anterior untuk mengurangi sekresi FSH • Merangsang sel-sel Leydig untuk menghasilkan testosteron LH : • Testosteron memberikan umpan balik negatif terhadap hipofisis anterior dan hipotalamus