details of hormones of pituitary glands and their regulation

1. Hormones of pituitary gland
Presented by: Zainab Akram
Presented to: Mam Amna Younus

2. INTRODUCTION
 Human body has variety of systems.
 Physiological functions are regulated and
maintained.
 Nervous system
 Endocrine system

3. NERVOUS SYSTEM
Control all the activities of the
body.
Central nervous system
Peripheral nervous system

4. Endocrine system
 Endocrine system regulates the body functions – hormones
 Signalling processes
 Endocrine glands - secrets hormones - ductless glands
 Pituitary gland
 Thyroid gland
 Parathyroid gland
 Pancreas

5. Pituitary gland
 Master gland
 Controls all the other glands of the
endocrine system
 Main role behind its activity is
hypothalamus
 Sends the signals to the pituitary,
which in turn secrets the hormones to
perform different functions

6. • Pituitary gland have a size of a
pea. It includes three lobes in it.
Interior
Intermediate
Posterior
• Interior lobe of posterior pituitary
produces different hormones
while, posterior part is associated
with nerve control

7. Hormones
 Endogenic compound
 Growth hormones
 Thyroid stimulating hormones
 Adrenocorticotropic hormone
 Prolactin
 Luteinizing hormone
 Follicle stimulating hormone

8. Thyroid stimulating hormone
 Thyrotropin
 Controls production of thyroid hormone – thyroxine
(metablic rate, heart and digestive functions, brain
development, muscle control)
 Binds to receptors located on cells of thyroid gland.
 TSH bind to these receptors.
 Causes these cells to produce thyroxin and
triidothyronine.

9. Alpha subunit:
 92 amino acids sequence
 Stimulation of adenylate cyclase
Beta subunit:
 118 amino acids sequence
 Determine the receptor specificity

10. Function
 Provide positive and negative feedback

11. Diseases
Hypothyroidism
 Thyroid gland does not produce
enough thyroid hormones
 Upset normal balance of chemical
reactions, joint pain, infertility,
heart disease
 Fatigue, depression, weight gain,
thinning of hairs, pain and welling
in joints.
Hyperthyroidism
 Thyroid gland produces too much
of the hormone thyroxin
 Accelerate the body metabolism
 Sudden weight loss, sweating,
rapid heartbeat, nervousness,
irritability
 Anti-thyroid medications and
radioactive iodine

12. GROWTH HORMONE(GH):
SOURCE:
Growth hormone is released from the
anterior pituitary gland in the blood
stream.
TRANSPORT:
Growth hormone is transported in
blood by GH-binding proteins
(GHBPs).

13. Role of GH:
Metabolic Effects:
 GH stimulates protein anabolism in many tissues that causes increased amino
acid uptake, increased protein synthesis and decreased oxidation of proteins.
 It also stimulates the transcription of DNA to RNA. RNA, in turn accelerates the
synthesis of proteins in the cells.
 It enhances the utilization of fat by stimulating triglyceride breakdown and
oxidation in adipocytes.
 GH increases the translation of RNA in the cells and thus ribosomes are
activated and more proteins are synthesized.
 It suppresses the abilities of insulin to stimulate uptake of glucose in
peripheral tissues and enhance glucose synthesis in the liver.

14. Role of growth hormone in bones:
 In bones:
 GH increases the synthesis and deposition of proteins by
chondrocytes and osteogenic cells
 Multiplication of chondrocytes and osteogenic cells by
enhancing the intestinal calcium absorption
 Formation of new bones by converting chondrocytes into
osteogenic cells
 GH increases the length of the bones, until epiphysis
fuses with shaft, which occurs at the time of puberty.
After the epiphyseal fusion, length of the bones cannot be
increased.

15. Role of GH in bones:

16. Regulation of GH Secretion:
 Hypothalamus and feedback mechanism play an
important role in the regulation of GH secretion.
 Stimulation of GH secretion:
 GH secretion is stimulated by:
 1. Hypoglycemia
 2. Fasting
 3. Starvation

17. REGULATION OF GH:
4. Exercise
5. Stress and trauma
6. Initial stages of sleep.
 Inhibition Of GH Secretion:
1. Hyperglycemia
2. Increase in free fatty acids in blood
3. Later stages of sleep.

18. Diseases:
 Acromegaly
 In adults, excessive growth hormone for a long period of time produces a condition known as acromegaly.
 Symptoms:
 swelling of the hands and feet and altered facial features
 high blood pressure
 diabetes and heart disease.
 CAUSES:
 due to benign tumors of the pituitary gland, which produce growth hormone.
 Gigantism:
 It is increased growth hormone levels in children before they reach their final height, which can lead to excessive growth
of long bones, resulting in the child being abnormally tall.


19. Gonadotropins:
 Luteinizing hormone (LH) and follicle-stimulating hormone (FSH) are
called gonadotropins because they stimulate the gonads (in males, the
testes, and in females, the ovaries).
 Cells that secrete gonadotropins are called Gonadotrophs.
 Luteinizing Hormone:
 LH is a glycoprotein made up of one α-subunit and one β-subunit.
 The α-subunit has 92 amino acids and β-subunit has 141 amino acids.
 Role of LH in males:
 In males, LH is known as interstitial cell-stimulating hormone (ICSH) and it
stimulates the interstitial cells in testes. This hormone is essential for the
secretion of testosterone.

20. Role of LH in females:
 In females, LH:
 1. Causes maturation of vesicular follicle into Graafian follicle along with
follicle-stimulating hormone
 2. Induces synthesis of androgens from theca cells of growing follicle
 3. responsible for ovulation
 4. necessary for the formation of corpus luteum
 5. Activates the secretory functions of corpus luteum.

21. Follicle-Stimulating Hormone:
 It is a glycoprotein made up of one α-subunit and a β-subunit.
 The α-subunit has 92 amino acids and β-subunit has 118 amino acids.
 Functions:
 In males,
 FSH acts along with testosterone and accelerates the process of
spermiogenesis.
 In females FSH:
 1. Causes the development of Graafian follicle from primordial follicle
 2. Stimulates the theca cells of Graafian follicle and causes secretion of
estrogen.

22. Regulation of Gonadotropin Secretion:
 The principle regulator of LH and FSH secretion is gonadotropin-releasing
hormone (GnRH, also known as LH-releasing hormone).

23. Diseases:
Hypogonadism
Diminished secretion of LH or FSH can
result in failure of gonadal function
(hypogonadism).
 This results in males as failure in
production of normal numbers of sperm.
 In females, cessation of reproductive
cycles is commonly observed.

24. Prolactin:
 Prolactin is a single chain polypeptide with
199 amino acids.
 It is secreted by so-called lactotrophs in the
anterior pituitary.
 Functions:
 Prolactin is necessary for the final
preparation of mammary glands
 for the production and secretion of milk.

25. Regulation of prolactin:
 Dopamine serves as the major prolactin-inhibiting factor. Dopamine is
secreted into portal blood by hypothalamic neurons and inhibits both
the synthesis and secretion of prolactin.

26. Hyperprolactinemia:
 Hyperprolactinemia is an excessive secretion of prolactin and
it is a relatively common disorder in humans. This condition has
numerous causes, including prolactin-secreting tumors and
therapy with certain drugs.

27. Adrenocorticotropic Hormone (ACTH,
Corticotropin):
 Adrenocorticotropic hormone, stimulates the adrenal cortex.it
stimulates secretion of glucocorticoids such as cortisol.
 ACTH is secreted from the anterior pituitary in response to
corticotropin-releasing hormone from the hypothalamus.
 Corticotropin-releasing hormone is secreted in response to
many types of stress.
 Secretion of adrenocorticotropic hormone is controlled by three
inter-communicating regions of the body, the hypothalamus,
the pituitary gland and the adrenal glands. This is called the
hypothalamic–pituitary–adrenal axis.

28. Regulation of ACTH:
 Secretion of adrenocorticotropic hormone is controlled by three inter-
communicating regions of the body, the hypothalamus, the pituitary
gland and the adrenal glands. This is called the hypothalamic–
pituitary–adrenal axis.

29. DISEASES:
Higher than normal levels of adrenocorticotropic hormone may be
due to:
 Cushing's disease – this is the most common cause of increased
adrenocorticotropic hormone. It is caused by a benign tumour
called an adenoma located in the pituitary gland, which
produces excess amounts of adrenocorticotropic hormone.
 Lower than normal levels of adrenocorticotropic hormone may
be due to:
 Conditions affecting the pituitary gland, e.g. hypopituitarism.
 Side-effect of pituitary surgery or radiation therapy.

30. Posterior Pituitary
 The posterior pituitary is actually an extension of the neurons of the periventricular
and supraoptic nuclei of the hypothalamus.
 Neurosecretory cells in the hypothalamus release oxytocin (OT) or ADH into the
posterior lobe of the pituitary gland.
 The periventricular nuclei produce the hormone oxytocin, whereas the supraoptic
nuclei produce ADH.
 Classification:
• Pars nervosa region constitutes the majority of the posterior pituitary and is
the storage site of oxytocin and vasopressin.
• The infundibular stalk bridges the hypothalamic and hypophyseal systems.

32. Hormones of Posterior Pituitary:
• Two hormones are classically considered as being related to the posterior
pituitary: oxytocin and vasopressin.
 Oxytocin:
• Its action is mediated by G-Protein coupled oxytocin receptors.
• Oxytocin receptors are expressed by neurons in many parts of the brain and
spinal cord, including the amygdala, ventromedial
hypothalamus, septum, nucleus accumbens, and brainstem.
 Functions:
• Milk ejection reflex: oxytocin acts at the mammary glands, causing milk to be
'let down' into subareolar sinuses, from where it can be excreted via
the nipple.

33. • Uterine Contraction: oxytocin causes contractions during the second and third stages
of labor.
• Due to its similarity to vasopressin, it can reduce the excretion of urine slightly.
• Cardiac Effect: The hormone may play a role in the embryonal development of the heart
by promoting cardiomyocyte differentiation.
• Modulation of hypothalamic-pituitary-adrenal axis activity: It indirectly inhibits release
of adrenocorticotropic hormone and cortisol and, in those situations, may be considered
an antagonist of vasopressin.
• Preparing fetal neurons for delivery: The maternal oxytocin reaches the fetal brain and
induces a switch in the action of neurotransmitter GABA from excitatory to inhibitory on
fetal cortical neurons.
• Feeding: Oxytocin neurons in the para-ventricular hypothalamus in the brain may play a
key role in suppressing appetite under normal conditions and that other hypothalamic
neurons may trigger eating via inhibition of these oxytocin neurons.

34. Vasopressin:
• A hormone synthesized as a peptide prohormone in neurons in
the hypothalamus, and is converted to ADH.
• ADH has two primary functions. First, it increase the reabsorption of water.
Second, ADH constricts arterioles, and raises arterial blood pressure.
Tonicity of fluids:
• Vasopressin regulates the tonicity of body fluids.
Functions in kidney:
• Increasing the water permeability of distal convoluted tubule and collecting
duct cells in the kidney.
• Increasing permeability of the inner medullary portion of the collecting duct
to urea by regulating the cell surface expression of urea transporters.
• Acute increase of sodium absorption across the ascending loop of henle.

35. Function in Central nervous system:
• Vasopressin is released into the brain in a circadian
rhythm by neurons of the suprachiasmatic nucleus.
• Vasopressin is involved in aggression, blood pressure
regulation, and temperature regulation.
• Recent evidence suggests that vasopressin may have
analgesic effects