the regulation of hormone secretion
TRANSCRIPT
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BIOLOGY IISCI 4210
Ms Nurul Jannah
AhswiniSumithraKavita
KerkNeelashini Yeok Yoon
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The Regulation of Hormone
Secretion by other Hormones
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Introduction
Chemical messenger produced by endocrine glands.
Endocrine glands are stimulated by three main components of body
Nervous System
Releasing -Hormones
Regulation of Level of Specific
Substances in Blood
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Releasing -Hormones
Hormone that stimulate the secretion of
other hormone.
4 main releasing-hormones
THYROTROPHIN RELEASING-HORMONES
CORTICOTROPHINRELEASING-HORMONES
GROWTH RELEASING-HORMONES
GORNADOTROPHINRELEASING HORMONES
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CORTICOTROPHINRELEASING - HORMONES
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• Also known as Corticotropin-releasing
factor (CRF) or Corticoliberin
• a peptide hormone and neurotransmitter
• found in most vertebrate tissues
• main function is the stimulation of the pituitary
synthesis of ACTH
• ACTH (Adrenocorticotropic hormone) modulates
the activity of the hypothalamic–pituitary–
adrenal axis during stress
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• "Stressful" situations include
• Regulates important cardiovascular, metabolic,
immunologic, homeostatic functions including
water balance
• Abnormally high levels of CRH have been found
in the cerebrospinal fluid of people that have
committed suicide
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Physical
• Trauma• Surgery• Exercise
Psychological
• Anxiety• Depression Physiological
• Hypoglecemia• Inflammation
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• secreted by the paraventricular nucleus (PVN)
of the hypothalamus
• also synthesized in peripheral tissues, such as
T-lymphocytes , and is highly expressed in the
placenta
• In the placenta, CRH is a marker that
determines the length of gestation and the
timing of parturition and delivery
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THYROTROPHINRELEASING - HORMONES
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Also called thyrotropin-releasing factor (TRF).
Produced by the hypothalamus in medial neurons of the paraventricular nucleus.
It is a tropic, tripeptidal hormone that stimulates the release of Thyroid-stimulating hormone (TSH) and prolactin from the anterior pituitary.
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• It travels across the median eminence to the anterior pituitary gland via the hypophyseal portal system.
• Then, stimulates the release of thyroid-stimulating hormone from cells called thyrotropes.
• Excess levels of TSH inhibit dopamine which will then stimulate the release of prolactin which in turn decreases Gonadotropin-releasing hormone (GnRH).
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• TSH regulates follicular cells of the thyroid gland to produce Thyroid hormones (T4 and T3).
• T4 and T3 are crucial for metabolism rate regulation and which will affect the whole body cells metabolism and growth.
• Prolactin is to induce the expression milk (lactation).
• It also has several secondary effects including downgrading levels of testerone and estrogen, stimulate the formation of myelin, and many others.
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The secretion of TRH which stimulating the secretion of TSH and other hormones in human.
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GONADOTROPHINRELEASING - HORMONES
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Gonadotropin-releasing
hormone (GnRH)
Luteinizing-hormone-releasing
hormone (LHRH)
Luliberin
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Characteristics and Functions
• Trophicpeptide hormone.• Synthesized from hypothalamus.• The peptide belongs to
gonadotropin-releasing hormone family.
Characteristics
• Control the release of follicle-stimulating hormone (FSH) and luteinizing hormone (LH) from anterior pituitary.
Functions
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Control of FSH and LH
• Releasing of FSH and LH are controlled by the size and frequency of GnRH pulses which by getting the feedback from androgens and estrogen.
Low frequency
• FSH is released.
High frequency
• LH is released.
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Secretion of GnRH in Male & Female
Male
GnRH is secreted at a constant
frequency.
Female
Frequency impulses varies
during menstrual cycle.
A large amount of GnRH will be released just
before ovulation.
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Importance of GnRH
• Pulsatile in all vertebrates
• Necessary for reproductive function.
• Controls a complex process of follicular growth, ovulation and corpus luteum maintenance in the female.
• For male, it controls the spermatogenesis.
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GROWTHRELEASING - HORMONES
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• known as growth-hormone-releasing factor (GRF, GHRF)
• Example: somatoliberin or somatocrinin
• 44[1]-amino acid peptide hormone
• produced in the arcuate nucleus of the hypothalamus
• appears in the human hypothalamus between 18 and 29 weeks of gestation
• It corresponds to the start of production of growth hormone and other somatotropes in fetuses
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ORIGIN OF(GHRH)
• released from neurosecretory nerve terminals of the arcuate neurons
• carried by the hypothalamo-hypophyseal portal system to the anterior pituitary gland
• This will stimulates growth hormone (GH) secretion by stimulating the (GHRH) receptor
• released in a pulsatile manner• GHRH also promotes slow-wave sleep directly
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Growth hormone is required for
normal postnatal growth bone growth
regulatory effects on protein, carbohydrate, and lipid
metabolism
Effect
GHRH stimulates GH production
Release; by binding to the GHRH
Receptor (GHRHR) on cells in the
anterior pituitary
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Thank You