Endocrine System

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Endocrine System
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I. Nervous vs. Endocrine system
Electrical Neurotransmitter
Hormone
Fast (seconds)
Slower
Short
Longer
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II. Endocrine System
A. Hormones two classes

• Steroids gonads and adrenal cortex

• Protein based (amines, peptide, proteins)

B. Control of Hormonal secretions
1. Humoral (change in plasma
concentration levels)

• glucose changes monitored by insulin and
  glucagon

2. Nervous system control

• Sympathetic NS signals adrenal medulla to
  secrete epinephrine and norepinephrine

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3. Hormonal stimulation

• Hormone from one endocrine gland controls the
  release of a hormone from another gland

• Pituitary gland

• Ex. Hypothalamus -gt Pituitary-gtTSH -gtThyroid

C. Hormone interaction with target cell
1. Steroid intracellular receptors

• diffuse through membrane

• binds with intracellular receptor

• binds to DNA to promote RNA synth

• protein synthesis

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2. Protein extracellular receptors
a.) control channels
allow movement of ions
b.) synthesize 2nd messenger
activate enzyme
c.) activate G protein
control channels activate
enzyme (2nd mess)
d.) phosphorylate receptor
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Endocrine Glands
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I. Pituitary Gland
Anterior and Posterior lobes
A. Posterior - neurohormones
1. ADH/Vasopressin

• Reduces the volume of urine

• Trigger increase in solute conc of blood

decrease in blood pressure
(vasopressin)

• Target and effect kidneys reabsorb water

arterioles
increase blood pressure

• Underproduction diabetes insipidus

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2. Oxytocin

• contracts smooth muscle of uterus/milk ejection

• Trigger stretch of the uterus

Nursing

• Target and effect smooth muscles of the uterus

secretory cells of mammary glands
B. Anterior Pituitary
1. Secretion

• Releasing Hormone from Hypothalamus

release of Ant. Pit hormones
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2. TSH (thyroid stimulating hormone)

• Trigger Stress or exposure to cold

• Target Thyroid

• Negative feedback

3. ACTH (Adrenocorticotropic)

• Trigger Stress or low blood glucose level

• Target Adrenal cortex

4. LH and FSH (Luteinizing/Follicle-sti
mulating)

• Trigger Cyclic

• Targets Gonads

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5. Prolactin

• stimulates development of mammary glands and
  milk production

• Trigger Childbirth

• Target and effect Mammary glands -gt milk

Enhances release of progesterone from ovaries
6. Growth hormone (GH)

• stimulates growth in tissues/regulates
  metabolism

• Trigger stress, low blood glucose

• Target and effect most tissues

increase protein synth./breaks down
lipids
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II. Thyroid gland
A. T4/T3

• Trigger

Stress/cold Release of TSH
Requires iodine

• Target many tissues

• Effect Increase metabolism

protein synthesis
increase
production of ATP
B. Underproduction
C. Overproduction
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D. Calcitonin
Parafollicular cells of Thyroid

• Trigger increase calcium

• Target Bone

decrease break down of
bone (reduce Calcium)
III. Parathyroid gland
A. PTH

• Trigger decrease calcium

• Target Bone increase bone break down

Kidneys
calcium absorp
Intestine
calcium absorp
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IV. Pancreas
A. Hormones
1. Insulin

• Trigger high glucose levels

food intake
(ANS)

gastrointestinal hormones

• Target Liver, adipose, muscles

• Effect store glucose in tissues (glycogen)

convert amino
acids to proteins
2. Glucagon

• Trigger low glucose

Sympathetic
NS
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• Target Liver (mostly), adipose, skeletal
  muscle

Breaks glycogen into
glucose