Hormones

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Hormones
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Hormones

• Chemical signals that affect the activity of
  other glands and tissues.
• Hormones drive development, growth, puberty and
  reproduction.
• Secreted from ductless glands.
• All glands in the endocrine system are ductless
  glands.

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Hormones

• Hormone comes from a Greek word meaning to
  excite.
• Hormones cause cells to respond, change, produce
  specific proteins that will direct our bodies.
• Hormones are bioactive molecules secreted by
  Endocrine Glands that travel to target tissues
  via the blood stream.

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Types of Hormones

• Steroid Hormones
• These are all derived from cholesterol.
• Examples testosterone, estrogen, progesterone,
  mineralicoids, glucocorticoids.
• Steroids can cross the plasma membrane!

• Protein Hormones
• These are made of Amino Acids.
• Examples Insulin, Hypothalmus signaling
  hormones.
• Protein hormones cannot cross the plasma membrane!

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Steroid hormones

• Always have the same complex of four carbon rings
  (ie sex hormones)
• Do NOT bind to the plasma membrane can enter
  freely as they are lipids
• Once inside the bind to receptors in the
  cytoplasm or nucleus.
• Hormone-receptor complex binds to DNA
• Enzyme synthesis follows
• Slow acting

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Types of Hormones

• Steroid Hormones
• These are all derived from cholesterol.
• Examples testosterone, estrogen, progesterone,
  mineralicoids, glucocorticoids.
• Steroids can cross the plasma membrane!

• Protein Hormones
• These are made of Amino Acids.
• Examples Insulin, Hypothalmus signaling
  hormones.
• Protein hormones cannot cross the plasma membrane!

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Peptide hormones

• Amino acids/ modified amino acids/
  peptide/glycoprotein or protein
• The receptors are on the plasma membrane
• When hormone binds to receptor
• Activates an enzyme to produce cyclic AMP (cAMP)
• This activates a specific enzyme in the cell,
  which activates anotherand so on
• Known as an enzyme cascade

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• Peptide hormones
• Each enzyme can be used over and over again in
  every step of the cascade.
• So more and more reactions take place.
• The binding of a single hormone molecule can
  result in a 1000X response.
• Fact acting, as enzymes are already present in
  cells.
• Steroid hormones
• Act more slowly.
• It takes more time to synthesize new proteins.
• Effects are longer lasting.

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ANY QUESTIONS?
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Endocrine System

• Endocrine--endo means within. This is a system
  which controls body function through hormones.
• Endocrine System is composed of a number of
  glands.
• Glands are specialized tissues that produce a
  hormone or product.

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Endocrine Glands

• Endocrine glands produce a variety of hormones
  which drive very different processes.
• Many glands are controlled by the Hypothalamus
  and Pituitary glands.
• We will focus on how the endocrine system and
  hormones produced play a role in reproduction
  later on.

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Pineal Gland

• Located in the brain.
• Produces the hormone melatonin. -primarily at
  night.
• This is a modified amino acid
• Get sleepy when levels are high.
• Awaken when its light and levels are low
• Circadian rhythms.

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Hypothalamus

• Regulates the internal environment through the
  autonomic system.
• Heart beat, body temperature water balance.
• Controls the glandular secretions of the pitutary
  gland.
• Connected to the pitutary gland by a stalk-like
  structure.

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Hypothalamus

• Produces antidiuretic hormone (ADH). It is a
  peptide
• Produces Oxytocin. Also a peptide
• Stores both of these in the Posterior pituitary
  gland.

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Posterior pituitary

• releases the hormone Oxytocin.
• Although made in the hypothalamus, posterior
  pituitary actually releases it.
• This causes contractions during childbirth and
  milk letdown during nursing.
• positive feedback stimulates an effect that
  always increases.
• Positive feedback in NOT a way to maintain stable
  conditions and homeostasis

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Posterior pituitary

• Hypothalamus produces antidiuretic hormone (ADH).
  It is a peptide.
• Neurons in the Hypothalamus determine when
  water-salt balance of blood is incorrect and
  blood is too concentrated.
• Tells posterior pituitary to release ADH
• ADH reaches kidneys and causes more water to be
  reabsorbed into the blood.
• Blood becomes dilute ADH is no longer produced
  - Negative feedback

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Anterior pituitary

• Connected to hypothalamus via portal
• Hypothalamus controls this by producing
• hypothalamic releasing hormones.
• hypothalamic inhibiting hormones.
• Hormones produced by Anterior pituitary
• thyroid stimulating hormone (glycoprotein)
• adrenocorticotropic hormone (peptide)
• gonadotropic hormones (steroids)
• Growth hormone (protein)

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Growth Hormone

• Promotes
• skeletal and muscle growth
• Controls the rate at which amino acids enters
  cells thus the rate at which protein synthesis

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Thyroid glands

• Made up of many spherical structures made up of
  thyroid cells filled with
• Triiodthyronine (T3)
• Thyroxine (T4) (Both iodinated amino acids)
• Increase metabolic rate more glucose is broken
  down, and more energy is utilized.
• No target organ

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Parathyroid glands

• Produces the hormone
• Parathyroid hormone (PTH) a peptide
• Causes the blood phosphate to decrease and blood
  calcium levels to increase
• Does this in conjunction with the hormone
  calcitonin produced by the thyroid

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Calcitonin and parathyroid hormone (PTH) work
together to maintain normal blood calcium
levels. Antagonistic action PTH causes
phosphate levels in the blood to decrease and
calcium to release from bone. Also causes
kidneys and the intestines to adsorb
calcium. Calcitonin causes bones to absorb
calcium if levels are too high.
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Thymus Gland

• Found just beneath the sternum
• Lymphocytes from bone marrow pass through this to
  form T-lymphocytes
• Caused by the hormone thymosin (peptide)
• Immune system

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Adrenal Glands

• These sit atop of the kidneys
• Consists of
• Adrenal medulla
• Adrenal cortex
• NOT connected to each other
• adrenocorticotropic hormone from the hypothalamus
  and anterior pituitary stimulates the adrenal
  cortex glands

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Adrenal glands how they do what they do!
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Adrenal Medulla

• IS UNDER NERVOUS CONTROL
• This produces
• Epinephrine (adrenaline)
• Norepinephrine (nor-adreneline)
• Both modified amino acids
• Heart rate and blood pressure up
• Blood glucose levels rise
• Muscles become energized
• The effects are short-term

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Adrenal glands how they do what they do!
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Adrenal Cortex

• Affected by adrenocorticotropic hormone (ACTH).
• Which in turn stimulates the production of
• Mineralocorticoids (steroid) regulate salt and
  water balance increased blood volume pressure.
• Glucocorticoids (steroid) regulate
  carbohydrate, protein and fat metabolism
  increase in blood pressure
• Also small amounts of both male and female sex
  hormones.

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Regulation of blood pressure and volume
When sodium ions levels are high- so a high
blood volume a glucocorticord (cortisol) makes
the heart release atrial natriuretic hormone
(ANH) Kidneys excrete sodium ions and water
follows. Volume and pressure return to normal.
When sodium ions levels are low- a low blood
volume makes kidneys secrete renin
(ENZYME) Adrenal cortex secretes a
mineralocorticoid (Aldosterone), which makes the
kidneys reabsorb sodium ions and thus water.
Volume and pressure return to normal.
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Pancreas

• Lies between kidneys and small intestine
• Pancreatic islets (islets of langerhans)
• Produce insulin (protein)
• Produce glucagon (protein)
• regulates blood sugar levels

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Insulin is released into the blood when sugar
levels are high. Stimulates the uptake of
glucose by cells, especially in the liver, where
it is stored as glycogen. Glucose supplies fat
cells the ability to make fat (glycerol fatty
acids fat)
Glucagon is released into the blood when sugar
levels are low. Stimulates the liver to break
down glycogen to glucose and release. fat cells
are broken down, taken up by liver and make into
glucose released. Antagonistic action
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Diabetes

• Type I insulin-dependant diabetes
• Pancreas is not producing insulin
• Thought to be brought on by an environmental
  agent (virus) destroy pancreatic islets
• Type I noninsulin-dependant diabetes
• Pancreas producing insulin
• Liver and muscles cells dont respond
• Thought to be caused by being inactive/obese

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Diabetes

• Type II symptoms often overlooked. One estimate
  suggests 7 million Americans have Type II
  diabetes without knowing it.
• It is estimated that a further 9 million
  Americans have Type I diabetes.

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Long term complications of diabetes

• Blindness
• Kidney disease
• Heart disease
• Stroke
• Reduced circulation
• Gangerene in arms and legs

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Hormones from other tissues

• Heart produces atrial natriuretic hormone
• Leptin
• Protein hormone produced by fat tissue
• Sends a signal to the hypothalamus that you have
  had enough to eat.
• Obese people have a genetic mutation which makes
  either
• Inactive leptin
• No receptor cells in the hypothalamus

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Summary
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Types of Hormones

• Steroid Hormones
• These are all derived from cholesterol.
• Examples testosterone, estrogen, progesterone,
  mineralicoids, glucocorticoids.
• Steroids can cross the plasma membrane!

• Protein Hormones
• These are made of Amino Acids.
• Examples Insulin, Hypothalmus signaling
  hormones.
• Protein hormones cannot cross the plasma membrane!

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Endocrine overview

• Hormones are released by glands.
• Hormones are released by feedback.
• Our body works to carefully regulate hormone
  levels.
• Negative feedback usually controls hormone
  secretion.

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Hormone Action

• Hormones cause cells to change.
• Hormones can result in changes in gene expression
  (DNA-RNA-Protein).
• Hormones can result in enzyme cascades which
  control our metabolism.
• Hormones drive our reproductive systems.