Endocrine System

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Endocrine System

• Types of hormones and homeostasis
• Negative feedback
• Endocrine glands overview
• The pituitary
• Posterior pituitary
• Anterior pituitary
• Thyroxin - metabolism
• PTH and Calcitonin - blood calcium
• Insulin / glucagon blood sugar
• Adrenal Glands
• Other glands

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Recap Homeostasis

• Homeostasis is a state of equilibrium where an
  organisms internal environment remains
  relatively constant, despite ongoing
  environmental changes.

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Recap Negative Feedback

• prevents chemical imbalances in the body.
• Once the body has responded to a change in the
  environment, the effect is detected, receptors
  are activated, and further response is inhibited.

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Examples of Negative Feedback
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Two Categories of Glands

• Exocrine Glands products do not enter the
  bloodstream, but are released by ducts or tubes
  into a body cavity, or out of the body.
• Ex) sweat glands, and salivary glands.

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• Endocrine Glands release hormones into the blood
  stream

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Hormones in the Body
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Hypothalamus

• Produces Anti-Diuretic Hormone and Oxytocin
• -stored in the posterior pituitary gland
• Produces releasing and inhibiting factors to
  control the pituitary gland

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Pituitary Hormones

• Pituitary Gland
• the master gland

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Posterior Pituitary stores and releases ADH and
oxytocin
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• Anti-Diuretic Hormone (ADH) increases water
  re-absorption by the kidneys when the blood
  becomes too concentrated with solutes
• Diabetes insipidus excessive urination,
  dehydration and thirst resulting from a lack of
  ADH, usually caused by a tumor

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• Ex) Oxytocin stimulates uterine contractions
  during childbirth, and triggers initial milk
  production
• Pitocin is a synthetic form of oxytocin that is
  often given to induce labour.

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• Anterior Pituitary produces hormones which are
  controlled by releasing factor secreted by the
  hypothalamus.

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• Ex) Thyroid Stimulating Hormone (TSH)
  stimulates the thyroid gland to release thyroxin
  (controls metabolism) and calcitonin (controls
  blood calcium)

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• Ex) Adrenocorticotropic Hormone (ACTH)
  stimulates the adrenal cortex to release
  aldosterone and cortisol which regulate the
  release of fatty acids in the blood and regulate
  fat metabolism

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• Ex) Prolactin Hormone (PRL) stimulates milk
  production in the mammary glands after birth,
  suckling or other stimulation may result in the
  let down reflex

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• Ex) Follicle Stimulating Hormone (FSH)
  stimulates the production of gametes (sperm and
  egg) in the male and female reproductive systems
• Ex) Luteinizing Hormone (LH) stimulates the
  production of hormones (estrogen, progesterone
  and testosterone) in the male and female
  reproductive systems

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• Ex) human Growth Hormone (hGH) regulates the
  growth of bones and tissues during childhood by
  assisting amino acids across cell membranes for
  protein synthesis.

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• Gigantism overproduction of growth hormone
  during the growth years, results in very large
  individuals (7-9 ft)
• often have diabetes and other medical issues.

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• Acromegaly overproduction of growth hormone
  during the adult years, results in excessive
  growth of the cartilage of the nose, hands, feet,
  jaw, tongue and internal organs.

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The Worlds tallest woman.Defen is 34 years old
and 7ft 8" tall.
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• Dwarfism underproduction of growth hormone
  during the growth years and adolescence, results
  in individuals of short stature with
  proportionate or disproportionate size.

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• Extra Melanocyte Stimulating Hormone (MSH)
  affects skin pigmentation

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Thyroid Gland

• The thyroid gland is responsible for the
  secretion of two hormones
• Thyroxin increases the rate of cellular
  respiration by increasing oxygen uptake in cells
• -Regulates metabolism

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• Calcitonin decreases the concentration of blood
  calcium
• -Decreases the rate that calcium leaves the
  bones, reduces intestinal uptake of calcium, and
  reduces reabsoprtion of calcium by the kidneys.
  (Works in opposition to parathyroid hormone)

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Thyroid Disorders

• Hyperthyroidism excessive production of
  thyroxin results in nervousness, weight loss,
  sweating, tachycardia, hyperactivity
• Hypothyroidism underproduction of thyroxin
  results in sluggishness, depression, weight gain,
  tiredness, goiter
• Goiter may also be caused by a lack of iodine in
  the diet.

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• Cretinism hypothyroidism in a developing infant
  results in permanent and severe retardation and
  stunted growth
• Thyroid Surgery

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Parathyroid Gland

• a set of four pea-sized glands embedded in the
  posterior portion of the thyroid.

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• Parathyroid Hormone (PTH) increases blood
  calcium
• increases removal of calcium ions from bones and
  increases re-absorption of calcium ions from the
  kidneys.

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• Tetany underproduction of the parathyroid (low
  blood calcium) resulting in muscle spasms,
  convulsions and nervous twitches
• Osteoporosis demineralization of the bones due
  to overproduction of the parathyroid, or lack of
  calcium
• very common after menopause due to lowered
  estrogen levels (estrogen counters the effect of
  PTH)

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The Pancreas

• Islets of Langerhans are glandular clusters of
  cells in the pancreas that produce insulin and
  glucagon

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• Alpha cells produce glucagon, which stimulates
  the conversion of glycogen to glucose by the
  liver raising blood glucose
• Beta cells produce insulin, which stimulates
  the uptake of glucose by the bodys cells,
  lowering blood glucose

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Regulation of Blood Sugar
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Blood Sugar Disorders

• Diabetes Mellitis sugar diabetes or
  hyperglycemia
• blood sugar is very high (while cellular glucose
  is too low)
• increased urination, fruity odour on the breath,
  weight loss, fatigue, blindness

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• Type I /Juvenile Onset the inability to produce
  insulin, degeneration of beta cells
• Type II / Adult Onset decreased insulin
  production or ineffective use of insulin (may be
  related to insulinase)

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• Diabetic Coma slow onset, lack of insulin that
  result in the brain being deprived of glucose,
  and eventually shutting down (insulin is
  required)
• Insulin Shock sudden excess amount of insulin
  causing dizziness, sweating, hunger, confusion,
  normal urine output (sugar is required)
• main

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Adrenal Glands

• located just above the kidneys
• composed of outer cortex and an inner medulla
  which produce different hormones.

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Adrenal Medulla

• Adrenaline/Epinephrine released to elicit the
  fight or flight response during short term
  stress, causes
• increased blood glucose
• increased heart rate
• increased metabolism
• increased blood flow to the skeletal muscles
• decreased rate of digestion
• relaxes smooth muscles in the walls of the
  bronchioles

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Adrenal Cortex -stimulated by Adrenocorticotropic
Hormone

• Produces three classes of hormones
• Sex hormones small amounts of both male and
  female sex hormones are released by the adrenal
  cortex. Over-activity causes masculinization of
  females and feminization of males.

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• Cortisol is a glucocorticoid( steroid that
  binds with glucocorticoid receptors)
• -long term stress
• -breaks down muscle proteins to produce amino
  acids which are converted into glucose in
  response to stress
• stimulates the metabolism of fatty acids raising
  the blood glucose.
• counter the inflammatory response.

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• Aldosterone is a mineralocorticoid (steroid
  that binds to mineralocorticoid receptor).
• regulates Na/K levels and maintains blood
  pressure.
• promotes absorption of Na ions by the kidney,
  drawing in water and thus increasing blood
  pressure.

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Adrenal Disorders

• Cushings Syndrome over activity of the adrenal
  cortex resulting in edema, moonlike face,
  masculinization of females, and high blood sugar.

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• Addisons Disease under-activity of the adrenal
  cortex resulting in low blood pressure, acidosis,
  fainting, increased risk of infection and
  bronzing of the skin.

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Extra Other Hormones

• Thymus secrete thymosin that stimulates
  maturation and differentiation of the T-cells in
  the immune system (most active in children with
  developing immune systems)

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• Melatonin secreted by the pineal gland,
  regulates circadian rhythms such as sleep/wake
  cycles, migration, mating and sexual development.

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• Prostaglandins
• made by tissue not glands
• Not delivered in blood
• Act on the cells that make them or nearby tissue
• Link

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• Pheromones are messengers that act between
  individuals of a species, secreted to attract a
  mate, mark territory, provide warning of danger.