Hormones of the Body

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Hormones of the Body

• Well go through all the glands and the
  hormones they produce in this PowerPoint
  Presentation!

By Dawn Tamarkin, Ph.D.Springfield Technical
Community College
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The Hypothalamus the Pituitary Gland-- Master
Endocrine Glands!

• The Hypothalamus
• Located in the brain, this region controls most
  endocrine secretions
• Mainly regulatory hormones are released here.
  Most control the pituitary gland

• The Pituitary Gland
• Descending from the hypothalamus, this gland has
  two halves anterior posterior
• The anterior half secretes mainly regulatory
  hormones
• The posterior half secretes hormones, but
  manufactures none

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Hormones secreted by the Hypothalamus Anterior
Pituitary Gland

• Hypothalamus Anterior Pituitary
• GHRH (GH-releasing) GH (growth hormone)
• SS (somatostatin, GH-inhib)
• CRH (corticotropin-rel) ACTH (adrenocorticotropic
  )
• GnRH (gonadotropin-rel) LH (luteinizing hormone)
• FSH (follicle-stimulating)
• PRH (PRL-releasing) PRL (prolactin)
• PIH (PRL rel-inhibiting)
• TRH (thyrotropin-rel) TSH (thyroid stimulating)

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What do these anterior pituitary hormones do?

• Growth Hormone
• stimulates cells to grow and divide
• increases amino acid transport rate and protein
  synthesis
• increases fat metabolism
• Typically, GH is secreted during sleep.
• GH secretion increases when malnourished

• GH influences bone growth via somatomedin
• GH in blood
• GH arrives in liver
• liver secretes somatomedin
• cartilage divides
• bones grow!

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Problems with GH

• Too much GH in children leads to gigantism
• Too much GH in adults leads to acromegaly
• Too little GH in children leads to dwarfism

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Other Anterior Pituitary Hormone Functions

• ACTH
• works on the cortex of the adrenal gland,
  influencing the release of cortisol
• stress can increase CRH secretion which will
  increase ACTH secretion
• negative feedback when adrenal cortex hormones in
  blood decrease CRH secretion

• LH FSH
• LH in females and in males leads to sex hormone
  secretion
• FSH in females causes growth and development of
  egg cell-containing follicles in the ovary, and
  causes estrogen secretion
• FSH in males instigates sperm production
• both hormones are regulated by GnRH, which is not
  significant in concentration until puberty

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More Anterior Pituitary Hormone Functions

• PRL
• In females, PRL promotes lactation
• In males, PRL decreases LH secretion (note that
  too much PRL would then decrease androgen levels
  and cause sterility)
• Controlled by both PRH and PIH

• TSH
• works on thyroid gland to either cause or inhibit
  its secretion of hormones
• works on thyroid gland to affect its growth (too
  much TSH leads to a goiter)
• negative feedback via thyroid hormones in blood
• stress or cold temperatures can change TSH
  secretion

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The Posterior Pituitary Lobe

• No hormones are made here. They are made in the
  hypothalamus and just released here.
• Two peptide hormones are released from the
  posterior pituitary lobe (the neurohypophysis)
• ADH (antidiuretic hormone or vasopressin)
• OT (oxytocin)

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Function of Posterior Pituitary Lobe Hormones

• ADH
• as an antidiuretic, ADH decreases urine
  formation by having kidneys conserve water
• also can contract smooth muscle cells, as found
  in blood vessels-- this causes an increase in
  blood pressure
• ADH release triggered by osmoreceptors and
  inhibited by stretch receptors in blood vessels

• OT
• In females, contracts the uterine wall smooth
  muscles
• In females, helps to eject milk when lactating
• No known function in males, although in both
  males and females, OT can have some antidiuretic
  effects

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The Thyroid Gland

• Structure This bilobed gland contains many
  follicles. A follicle is a group of cells
  encircling a lumen. The lumen contains material
  called colloid (a glycoprotein) within it. As
  hormones are produced by the cells, the hormones
  are either released into the colloid or directly
  into the blood.
• There are also extrafollicular
  hormone-secreting cells, called C cells. These
  are found between lumina.
• Hormones Produced
• Thyroxine (T4) made in follicle
• Triiodotyronine (T3) made in follicle
• Calcitonin made by C cells

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About the Thyroid Hormones...

• T3 and T4
• Function metabolism regulation (break down
  carbohydrates and fats, synthesize proteins)
• Can only be made by follicular cells when iodides
  are available
• Somewhat hydrophobic and get carried by proteins
  in the blood.
• Controlled by anterior pituitary lobe TSH
• T3 more effective, T4 more abundant

• Calcitonin
• Function decrease blood calcium levels and
  blood phosphate levels (by helping them get
  deposited in bone, and by stimulating excretion
  of them by kidneys)
• Controlled by blood calcium levels and digestive
  chemicals

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Problems with the Thyroid Gland

• Hyperthyroidism
• high metabolic rate, hyperactivity, sensitivity
  to heat, protruding eyes
• Graves disease when hyperthyroidism is due to
  an autoimmune problem (TSH is mimicked by
  autoantibodies)
• Hypothyroidism
• in the adult low metabolic rate, sensitivity to
  cold, sluggishness
• in an infant cretinism-- stunted growth, mental
  retardation, abnormal bone formation
• Hashimotos disease when hypothyroidism is due
  to an autoimmune problem (autoantibodies attack
  and destroy follicular cells)
• goiter no T3 and T4 can be made because not
  enough iodides were ingested.

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Lets Review

• What glands and hormones did welearn about so
  far?

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Hypothalamus Anterior Pituitary

• Hypothalamus Anterior Pituitary
• GHRH (GH-releasing) GH (growth hormone)
• SS (somatostatin, GH-inhib)
• CRH (corticotropin-rel) ACTH (adrenocorticotropic
  )
• GnRH (gonadotropin-rel) LH (luteinizing hormone)
• FSH (follicle-stimulating)
• PRH (PRL-releasing) PRL (prolactin)
• PIH (PRL rel-inhibiting)
• TRH (thyrotropin-rel) TSH (thyroid stimulating)

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Your books review diagram
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Posterior Pituitary Thyroid Gland

• Posterior Pituitary
• ADH
• OT
• Both of these hormones are made in the
  hypothalamus their release is regulated by the
  brain.

• Thyroid Gland
• T3 (regulated by TSH)
• T4 (regulated by TSH)
• calcitonin (NOT regulated by the pituitary!)

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Moving on to More Glands!

• We still have the following left
• Parathyroid Gland
• Adrenal Gland both the Medulla and the Cortex
• Pancreas
• Pineal
• Other, including thymus and reproductive glands

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Parathyroid Gland

• This gland only secretes one hormone
  Parathyroid Hormone (or PTH)
• PTH function (we began learning this when we
  studied bone)
• increases blood calcium (Ca2) levels and
  decreases blood phosphate (PO42-) levels

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PTH function (continued)

• How does PTH work?
• PTH causes Ca2 PO42- to be released from bone
  into blood (by increasing osteoclast activity)
• PTH causes the kidneys to remove PO42- ions from
  the urine
• PTH increases vitamin D production, so that you
  absorb more Ca2 during digestion
• PTH is regulated by blood calcium levels-- not by
  other glands!

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Adrenal Glands

• An adrenal gland is found on top of each
  kidney. Each adrenal gland has two regions that
  carry out separate functions!
• The adrenal medulla
• The adrenal cortex

We will cover each of these two regions
separately in the next few slides.
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The Adrenal Medulla

• Acts very much like a part of the sympathetic
  nervous system (fight or flight)
• Secretes two amines
• norepinephrine (20)
• epinephrine (80)
• Stimulated by preganglionic neurons directly, so
  controlled by the hypothalamus as if part of the
  autonomic nervous system, NOT by tropic hormones

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The Adrenal Cortex

• Acts like a regular endocrine organ
• Secretes many hormones, but most importantly
  secretes the following steroids
• aldosterone
• cortisol
• sex hormones
• Aldosterone and cortisol require further
  explanation (while sex hormone production will be
  covered later this semester)

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More about Adrenal Cortex Hormones

• Aldosterone
• Considered a mineralocorticoid
• Regulates mineral electrolyte levels in the
  blood (for example Na and K ions)
• How is aldosterone controlled?
• blood plasma ion concentrations affect its
  secretion directly (but not always strongly)
• kidney secretes renin in response to altered
  electrolyte levels, which triggers angiotensin
  activation in the blood, which leads to
  aldosterone secretion
• ACTH from the anterior pituitary can cause
  aldosterone secretion

• Cortisol
• Considered a glucocorticoid
• Overall effect of cortisol
• Helps to keep blood glucose concentration within
  a normal range between meals
• Specific actions of cortisol
• increases amino acid concentration in the blood
  (by inhibiting protein synthesis in select
  tissues)
• promotes use of fat for energy production in our
  bodies (rather than glucose)
• stimulates the liver to synthesize glucose (not
  from carbohydrates, but from amino acids and
  glycerol), called gluconeogenesis

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The Pancreas

• This gland has both endocrine and exocrine
  functions well only cover the endocrine portion
  now (exocrine is for digestion)
• The endocrine portion of the gland contains three
  types of cells, each making a different hormone,
  arranged into groups called Islets of Langerhans
• alpha cells secrete glucagon
• beta cells secrete insulin
• delta cells secrete SS (somatostatin)
• Note that these pancreatic hormones are involved
  in blood glucose regulation, and problems with
  them can lead to diabetes.

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Blood Glucose Regulation by the Pancreas

• Glucagon
• It works on the liver to cause the production of
  glucose via
• glycogenolysis
• gluconeogenesis
• It is regulated by blood glucose levels directly
• secreted when blood glucose drops (before next
  meal)
• Prevents hypoglycemia

• Insulin
• It works on the liver to remove glucose from the
  blood via
• making glycogen
• preventing gluconeogenesis
• increasing glucose transport into cells
• It is also regulated by blood glucose levels
  directly
• Prevents hyperglycemia

Note glucagon and insulin work in opposition,
and their combined effects control blood glucose
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Pineal Gland

• Secretes only one hormone melatonin
• Involved in your circadian rhythm (your
  recognition of day and night times)
• melatonin secretion decreases in the day
• melatonin secretion increases at night
• Melatonin is also involved in longer rhythms,
  like monthly and seasonal and is thought to be
  involved in the female menstrual cycle and maybe
  in the onset of puberty

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Other Endocrine Glands

• Thymus Gland secretes thymosins which are
  involved in white blood cell production
• Reproductive glands (the gonads) the ovaries
  and the testes produce sex hormones
• Others too specific for now, well get to them
  as we continue this semester.

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The End!