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H' Hormones and their Actions

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Title: H' Hormones and their Actions


1
H. Hormones and their Actions
  • Hormone chemistry
  • Hormone synthesis - SKIP
  • Hormone receptors mode of action
  • Enzyme amplification
  • Modulation of target cell sensitivity
  • Hormone Interactions
  • Hormone clearance

2
1. Hormone Chemistry
  • Steroid hormones
  • Peptide hormones
  • Monoamines

3
Steroid hormones
  • Derived from cholesterol
  • made by gonads
  • estrogens
  • progesterone
  • testosterone
  • made by adrenal cortex
  • cortisol
  • corticosterone
  • aldosterone
  • DHEA

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Peptide hormones
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Monoamines
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3. Hormone transport
  • Transport proteins
  • Purpose to transport hydrophobic hormones in the
    blood
  • Allow them to travel in blood (water solvent)
  • Protect them from enzyme degradation in blood
  • Hydrophobic hormones
  • Steroid hormones
  • Thyroid hormone (T3 T4)
  • Bound hormone bound to transport protein
  • Unbound (free) hormone not bound to transport
    protein

12
4. Hormone receptors and mode of action
  • general info
  • Structure
  • Protein/glycoprotein
  • Specificity recognize only one hormone
  • Saturability finite number of receptors/cell
    when all are occupied by hormone molecules, no
    increase in binding can occur
  • Location
  • On cell membrane, nucleus, etc. of target cells
  • Function
  • To bind to and recognize hormone signal
  • Binding ? alter target metabolism

13
Steroid hormone receptors
  • Hydrodrophobic
  • Enter target cells thru plasma membranes
  • Enter nucleus and bind to receptors on DNA
  • Trigger protein synthesis in target cells
  • T4 is converted to T3
  • T3 binds to receptors on
  • Mitochondria? ? aerobic respiration
  • Ribosomes ? ? protein synthesis
  • Chromatin ? transcription ? ? mRNA synthesis
  • ? ? ATPase ? ? heat (calorigenic effect)

14
Peptides and catecholamines
  • Hydrophilic
  • Bind to cell surface receptors
  • Activate 2nd messenger cascades
  • Intracellular events activated by a hormone can
    be different in different target cells
  • ADH (different cascades in kidney vs. smooth
    muscle)

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4. Enzyme Amplification
  • One molecule of hormone can activate many
    molecules of enzyme inside a target cell ? many
    more molecules of product.

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5. Modulation of target sensitivity
  • Up-regulation more receptors, more sensitivity
  • Down-regulation fewer receptors, less sensitivity

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6. Hormone interactions
  • Synergistic hormones act together
  • Permissive first hormone enhances target
    response to second hormone
  • Antagonistic hormones oppose each other

24
V. Stress Adaptation
  • A. Introduction
  • B. The Alarm Reaction
  • C. The Stage of Resistance
  • D. The Stage of Exhaustion

25
Introduction
  • Definition any situation which upsets
    homeostasis and threatens physical or emotional
    well-being
  • General adaptation syndrome (GAS) (a.k.a., stress
    response)
  • ? EPI, cortisol
  • described in stages

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B. The Alarm Reaction
  • NE (sympathetic n.s.) EPI (adrenals)
  • Breakdown of stored glycogen ?? blood glucose
  • ? aldosterone ? water Na retention
  • ? angiotensin ? ? b.p.

27
C. The Stage of Resistance
  • Glycogen exhausted
  • Requires alternative fuels
  • Cortisol plays important role
  • ? CRH ? ACTH ? ? cortisol
  • Cortisol ? fat, protein, metabolism ? glycerol,
    FAs aas ? gluconeogenesis
  • Protein synthesis inhibited
  • Bad for immune system (cant make Abs)
  • poor wound healing, etc.

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D. The Stage of Exhaustion
  • Fat reserves important
  • When fat depleted ? homeostasis blocked
  • Protein breakdown begins ? energy
  • progressive wasting
  • Adrenals may fail
  • No glucocorticoids ? ? gluconeogenesis
  • aldosterone ? water retention, hypokalemia ?
    n.s. dysfunction, alkalosis (high blood pH), etc.
    ? potentially fatal

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VI. Eicosanoids
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VII. Endocrine Disorders
  • A. Hyposecretion Hypersecretion
  • B. Pituitary Disorders
  • C. Thyroid Disorders
  • D. Parathyroid Disorders
  • E. Adrenal Disorders
  • F. Diabetes Mellitus

32
Hyposecretion Hypersecretion
  • hyposecretion
  • diabetes incipidus hyposecretion of ADH
  • Hypersecretion
  • pheochromocytoma
  • Graves disease (toxic goiter)

33
B. Pituitary Disorders
  • Hypersecretion
  • acromegaly (GH hypersecretion - adult)
  • gigantism (GH hypersecretion - child)
  • Cushings Disease (ACTH)
  • Hyposecretion
  • pituitary dwarfism

34
C. Thyroid Disorders
  • Hyposecretion
  • congenital hypothyroidism
  • myxedema
  • Iodine deficiency
  • endemic goiter

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D. Parathyroid Disorders
  • Hypoparathyroidism
  • Hyperparathyroidism

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E. Adrenal Disorders
  • Hypersecretion
  • Cushings syndrome (cortisol)
  • tumor (ACTH)
  • Adrenogenital syndrome (angrogens)

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F. Diabetes Mellitus
  • Symptoms
  • POLYURIA (osmotic diuresis)
  • POLYPHAGIA
  • POLYDIPSIA
  • Hyperglycemia
  • Glycosuria
  • Ketonuria
  • ketoacidosis
  • Type I insulin-dependent
  • Type II non-insulin-dependent

38
VIII. Insight
  • Read about the discovery of insulin.
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