What is the endocrine system, What does it do How does it do it?

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What is the endocrine system, What does it do
How does it do it?
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Overall Mechanism of Endocrine System

• Endocrine glands ? hormones ? blood?target cells
• Effect changes activity of target cells
• Target Cells- have receptors that bind hormones
• Up-Regulation- more receptors/more senstivitive
• Down Regulation- fewer receptors/less sensitive
• Dont confuse with Exocrine glands-- secrete
  substances onto surfaces of the body and acts
  locally, ex- sweat glands on skin

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The Endocrine System regulates 7 activities

• 1) Homeostasis during emergencies-infection,
  trauma, emotional stress, and dehydration.
• 2) Metabolism Energy balance
• 3) contraction of smooth cardiac muscle, and
• secretions by glands
• HYPOsecretion of
• Glucocorticoids-lethargic,
• low BP, weak,
• pigmentation

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Hormones help regulate different activities

• 4) Water Electrolytes
• 5) Immune System-T cell
• Simple Goiter- deficiency of Iodine, cant
  produce thyroxine
• Cushings Disease-due to
• hypersecretion of
• Glucocorticoids-adrenals

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Hormones help regulate different activities

• 6) Growth Development
• 7) Reproduction (sexual maturation, gamete
  production, fertilization, nourishment of
  embryo and fetus, and delivery of baby)

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The Nervous and Endocrine Systems together
regulate all activities of the body

• How do you think they compare?

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Nervous vs. Endocrine

• Nervous system is like email- fast, short, and
  one way
• Endocrine System is like a social media website-
  post it, later people read it, and some respond
  to it Email reference borrowed from Bozeman
  Biology, You Tube

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Comparison of Nervous and Endocrine Systems
Characteristic Nervous System Endocrine System
Mechanism of Control Neurotransmitters Hormones delivered via the blood
Cells Affected Muscles, glands, other neurons Virtually all body cells
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Comparison of Nervous and Endocrine Systems
Characteristic Nervous System Endocrine System
Type of Action That Results Muscle Contraction or Glandular secretion Changes in metabolic activity
Speed of Action Typically within milliseconds Seconds to hours or days
Duration of Action Generally briefer Generally longer
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Negative Feedback
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Postitive Feedback
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Some Hormones are Regulated by either

• Their Blood Levels ex. insulin, aldosterone
• OR
• The Hypothalamus via Releasing Hormones or
  factors, ex. TRH

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Mechanism of Hormone Action

• Hormones are released on demand
• Amount released determined by the bodys need
• Hormones act on target cells.
• Target cells have specific receptors that bind
  one or more hormones.
• Hormones only affect cells with its specific
  target receptor

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Receptors are Important to the Mechanism of
Hormone Action

• Different types of cells can have receptors for
  the same hormone, but responses may be different.
• Hormone binds to a cells receptor, to initiate a
  chain of events to cause target cells to alter
  their rate of function.

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Chemical Classes of Hormones

• 1) Lipid Soluble
• 2) Water Soluble

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Lipid Hormones- gonads, adrenal glands

• Steroid hormones made from cholesterol
• ex testosterone, estrogen
• Eicosanoids -made from fatty acids
• prostaglandins and leukotrienes- act as local
  hormones for pain, fever, tissue inflammation
• Aspirin, ibuprofen, acetaminophen block
  prostaglandin synthesis
• Prostaglandins inhibit HCl in stomach are
  (responsible for PMS, premature labor)
• Lipid Hormones diffuse through cell membrane

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Lipid-Soluble Hormones Diffuse Thru Cell Membranes

• Hormone binds and activates receptors, to turn
  genes on or off
• Newly formed RNA leaves nucleus, to make new
  proteins
• 3) New proteins alter cells activity to cause
  physiological response of that cell

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Protein Hormones are Water Soluble aka First
Messengers
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Water Soluble Protein Hormones bind to Membrane
Receptors and use Second Messengers

• Ex- insulin, glucagon, ADH
• Second Messengers (cAMP or Ca and Calmodulin)
  activate Enzymes