__________________: the study of hormones, their receptors, the intracellular signaling pathways they invoke, and the diseases and conditions associated with them. - PowerPoint PPT Presentation

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__________________: the study of hormones, their receptors, the intracellular signaling pathways they invoke, and the diseases and conditions associated with them.

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Title: __________________: the study of hormones, their receptors, the intracellular signaling pathways they invoke, and the diseases and conditions associated with them.


1
  • __________________ the study of hormones, their
    receptors, the intracellular signaling pathways
    they invoke, and the diseases and conditions
    associated with them.
  • What are hormones?
  • Major endocrine glands?
  • Physiological processes controlled by hormones?

Fig 7-2
2
Hormones
  • Known since ancient times
  • Secreted by cells into the blood
  • Transported to distant targets
  • Effective at very low concentration
  • Bind to receptors
  • Hormone action must be of limited duration

3
Classification of Hormones
  • 3 main types
  • Peptides and proteins
  • Steroids
  • Amines
  • Differ on basis of synthesis, storage, release,
    transport and cellular mechanism of action
    (review Table 7-1)

4
Peptide (Protein) Hormones
  • Synthesis as preprohormone ? post-translational
    modification to prohormone ? then hormone
  • Storage release?
  • Short half-life (mins.)
  • Most common type

Fig 7-4
Fig 7-3
5
Peptide Hormone Processing
Fig 7-4
6
Insulin Activation
C peptide
Active insulin molecule
Fig 7-4
7
Cellular Mechanism of Action for Peptide Hormones
  • Lipophobic ? how does message get into cell?
  • Usually rapid cellular response because existing
    proteins are modified
  • cAMP 2nd messenger system most common

8
Steroid Hormones
  • All derived from cholesterol
  • Where synthesized?
  • Storage release?
  • Transport in blood?
  • Longer half-life
  • Mechanism of action

Fig 7-6
Fig 7-7
9
Amine Hormones
  • Derived from one or two amino acids
  • 3 groups
  • Tryptophan ? Melatonin
  • Tyrosine ? Catecholamines behave like
    peptide hormones
  • Tyrosine ? Thyroid hormones behave like
    steroid hormones

Fig 7-8
10
Mechanism of Action of Amine Hormones
Like peptide hormones E NE dopamine Like
steroid hormones Thyroid hormones
11
Control of Hormone Release
  • All endocrine reflex pathways have similar
    components
  • Stimulus / input signal
  • Integration (where?)
  • Output signal (hormone / neurohormone)
  • Physiological action
  • Negative feedback turns off reflex
  • One Hormone may follow gt 1 reflex pathway pattern

Fig 7-9
12
Simple Endocrine Reflex
  • Endocrine cell acts as sensor AND integrating
    center ? no afferent pathway ? responds by
    secreting hormone
  • Example PTH ? increases Ca2 in plasma

Fig 7-10
Fig 6-31/?
13
NeurohormoneReflex
  • NH release by modified neurons upon NS
    signal
  • 3 major groups of Neurohormones
  • Catecholamines from adrenal medulla
  • Hypothalamic neurohormones from posterior
    pituitary
  • Hypothalamic neurohormones acting on anterior
    pituitary

Fig 6-31/?
14
Neurohormones of Posterior Pituitary
  • Other name of gland?
  • 2 neurohormones
  • Both are peptides (9 aa) transported in
    secretory vesicles via axonal transport

Fig 7-12
15
Anterior Pituitary
  • Secretes 6 Hormones (names?)
  • A Trophic (tropic) hormone controls the secretion
    of another hormone
  • Hypothalamic trophic hormones and the
    hypothalamic-hypophyseal portal system

Fig 7-13
16
Negative Feedback Loops in the Hypothalamic-anteri
or pituitary axis
Hormones serve as negative feedback
signals Short-loop vs. long-loop negative
feedback. Feedback patterns important in
diagnosis of ES pathologies
17
Hormone Interactions
  • Multiple hormones can affect a single target
    simultaneously
  • Three types of hormone interactions
  • Synergism
  • Permissiveness
  • Antagonism

18
Synergism
  • Combined action of hormones is more than just
    additive!
  • Example Blood glucose levels synergistic
    effects of glucagon, cortisol and epinephrine

Fig 7-18
19
Permissiveness
  • Hormone A will not exert full effect without
    presence of hormone B.
  • Example Thyroid hormone growth hormone

Antagonism
Antagonistic hormones have opposing physiological
actions Hormone B diminishes the effect of
hormone A (mechanisms?) Hormone Antagonists and
Cancer Tamoxifen
20
Endocrine Pathologies
  • Unbalance leads to disease
  • Due to
  • Hypersecretion (excess)
  • Hyposecretion (deficiency)
  • Abnormal target tissue response

21
Hypersecretion
  • Due to ?
  • Iatrogenic (could lead to gland atrophy)
  • ________
  • Symptoms Exaggerated Effects
  • Examples
  • Cushings Syndrome
  • Gigantism
  • Graves disease

22
Example Hyperthyroidism (Review pp. 756 761)
  • Most common cause Graves' disease
  • Autoantibodies (TSI) bind to TSH receptor and
    stimulate thyroid hormone production
  • This activation by TSI is not subject to the
    normal negative feedback loop.

Left exophthalmus in Graves disease
23
Hyposecretion
  • Due to ?
  • Symptoms Normal effects of hormone diminished or
    absent
  • Examples
  • Addisons disease
  • Dwarfism
  • Hypothyroidism

24
Example Hypothyroidism
  • Most common cause in US chronic autoimmune
    thyroiditis (Hashimoto's thyroiditis Chronic
    thyroiditis )
  • Other causes
  • surgical removal of the thyroid gland
  • radioactive iodine treatment
  • external radiation
  • a deficiency in dietary iodide consumption
    (endemic or primary goiter)

25
Hypothyroidism cont.
  • Symptoms
  • During childhood
  • stunted growth
  • retardation
  • lethargy
  • low body temp.
  • In adulthood
  • Bradycardia
  • weight gain
  • lethargy
  • low body temp.

26
Abnormal Tissue Responsiveness
  • Hormone levels normal, target unresponsive
  • Due to
  • Abnormal hormone / receptor interaction
  • Abnormal signal transduction

27
Diagnosis of Endocrine Pathologies
  • Primary Pathology
  • Defect arises in last integration center in the
    reflex
  • Examples?
  • Secondary Pathology
  • Defect arises in one of the trophic integration
    centers
  • Examples?

28
Which of the sets of lab values below would
indicate Graves disease? Explain.
Patient Serum T4 Serum TSH
A 6 µg/dl 1.5 µU/ml
B 14 µg/dl .25 µU/ml
C 2.5 µg/dl 20 µU/ml
D 16 µg/dl 10 µU/ml
Normal 4.6-12 µg/dl 0.5 - 6 µU/ml
29
The End
Graves disease
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