Introduction(1) What are hormones?
(2) What are the functions of hormones?
(3) What are the types of hormones?– Amino Acids– Steroids– Eicosanoids
How do Hormones Work?(1) Action on Target Cells – Membrane permeability– Synthesis of proteins or enzymes
• Or inhibits
– Induces secretory activity– Stimulates mitosis
(2) Target-Specific– Target cell receptor sites – “Turns on cell” – “Dynamic”
How do Hormones Work?(3) Half-Life
(4) Interaction – Target Cells– Permissive – Synergistic – Antagonistic
(5) Control of Release – Negative feedback– Endocrine Gland Stimuli
• Humoral stimuli • Neural stimuli• Hormonal stimuli
Plasma Membrane Receptors Plasma Membrane Receptors (1) Second Messenger System – All amino acid hormones (except thyroid)
Plasma Membrane Receptors Plasma Membrane Receptors (2) Intracellular – Direct Gene Activation – Lipid soluble; steroid– Binds to intracellular receptors – Binds to DNA – Activates a gene
(1). Somatotroph cells produce GH
(2). Secretion – GHRH – stimulates release (GHIH) inhibits – Produced in the hypothalamus
(3). Effects– Anabolic – protein synthesis– Targets bones and muscles – Stimulates epiphyseal plates during
development
(4). Disorders – Gigantism and Acromegaly
Anterior Pituitary Hormones-HGHAnterior Pituitary Hormones-HGH
• (1). Also referred to as thyrotropin. – Produced by thyrotroph cells
• (2). Secretion – TRH or thyrotropin releasing hormone stimulates the release
of TSH – Negative feedback – rising levels of thyroid hormones
• ANIMATION
• (3). Effects – Moderates normal thyroid gland activity.
Thyroid-Stimulating HormoneThyroid-Stimulating Hormone
• (1). ACTH – adrenocorticotropic hormone secreted – corticotroph cells
• (2). Stimulation-Secretion– CRH – corticotropin-releasing hormone – hypothalamus
• Levels peak in the morning
– Negative feedback
• (3). Effects – Stimulates the Adrenal gland (cortex) to release Glucocorticoids
• Cortisol (stress hormone)
Adrenocorticotropic Hormones Adrenocorticotropic Hormones
(1). FSH and LH – gonadotrophic cells
(2). Stimulus-Secretion◦ Puberty ◦ GnRH – prompts the anterior pituitary to release hormones◦ ANIMATION
(3). Effects ◦ (a). LH
FSH - maturation of follicle Ovulation Stimulates interstitial cells - testosterone in males
◦ (b). FSH – stimulates gamete production; follicle development.
Gonadotropins Gonadotropins
(1). PRL or prolactin is a protein hormone. – Produced by the lactrotroph cells
(2). Stimulus – Secretion– PRH and PRH – PRH plays dominant role – dopamine prevents secretion
(3). Effects– Stimulate milk production in the breasts
Prolactin
(1). Production- hypothalamic neurons
(2). ADH or Antidiuretic Hormone – Reabsorption of water – collecting tubules – Release stimulated by – increasing osmolarity
• Diabetes insipidus
(3). Oxytocin– Stimulated release by positive feedback – contractions
during birth– Milk ejection – Synthetic – induce contractions
Posterior Pituitary Gland Hormones
(1). Produces TH or thyroid hormones ◦ T4 or thyroxin; T3 or triiodonthyronine
(2). Stimulus – Secretion◦ Hypothalamus (TRH) - Pituitary (TSH) --
TH ◦ Stress - cold, pregnancy – cause
hypothalamus to produce TRH.
◦ Rising TH levels – negative feedback to hypothalamus-pituitary axis.
(3). Effects ◦ Increases BMR ◦ body heat production (stimulates enzymes
to increase glucose oxidation)
Thyroid Gland
• (1). Myxedema – hypothyroid
• (2). Goiter
• (3). Cretinism – Infant hypothyroidism
• (4). Grave’s Disease – Hyperthyroid
Thyroid Imbalances
(1). Polypeptide hormone – Parafollicular cells of the thyroid – Lowers calcium blood levels– Reabsorption back into the bones
(2). Stimulus for release – 20% above normal levels for calcium blood levels – Lower than normal – inhibitory effect
(3). More important in childhood– Due to developing bones and keeps calcium levels in check
Calcitonin
(1). Cells in the parathyroid gland– Oxyphil and chief cells (secretes ) PTH
(2). Stimulus and Secretion– Hypocalcemia ----- PTH
Parathyroid Hormones
(1). Adrenal gland has two distinct regions◦ (a). Cortex - outer region◦ (b). Medulla - inner region
(2). Hormones produced – corticosteroids
◦ 12 total
(3). Steroid Hormones– Not stored in cells – rate of release depends on productivity
(4). Cortical regions ◦ (a). Zona glomerulosa – mineralocorticoids ◦ (b). Zona fasciculata – glucocorticoids ◦ (c). Zona reticualaris – adrenal sex hormones called
gonadocorticoids.
Adrenal Hormones
(1). Produced in the zona glomerulosa of the cortex◦ Mostly aldosterone◦ Balances ions and water
(2). Stimulus and Secretion◦ Renin-angiotensin mechanism ◦ Elevated K+ levels
(3). Disorders ◦ Aldosteronism ◦ Addison’s disease
Mineralocorticoids
(1). Produced in the zona fasciculata
– Metabolic hormones
(2). Cortisol is the main hormone – Gluconeogenesis; lipolysis;
protein metabolism
(3). Stimulation and secretion– ACTH from the anterior pituitary
(low levels of hormones)
(4). Disorders – Cushing’s syndrome– Addison’s disease
Glucocorticoids
(1). Androgens produced in the zona reticularis– Converted to testosterone and estrogen
(2). Stimulus and secretion– ACTH released from anterior pituitary
(3). Effects – Males – Female libido; pubic and axillary hair in females; estrogen
after menopause
Gonadocorticoids
Top Related