Chemical Signals in Animals

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Chapter 45

• Chemical Signals in Animals

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Basic info. on endocrine system

• Involves hormones-to excite secreted into
  blood.
• Cells that respond to hormones are called target
  cells. May be distant from origin.
• Endocrine system-made of ductless
  glands-secrete into bloodstream.
  (Exocrine-secrete to surface)

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• Relationship to nervous system endocrine system
  contains neurosecretory cells. Ex.
  Epinephrine/Adrenaline-secreted by adrenal gland
  affects responses (fight-or flight) and acts as a
  neurotransmitter.
• Both controlled by feedback

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Hormones and invertebrates

• Hormones control reproduction molting water
  balance, etc.
• Ex. Ecdysone-produced by arthropods to trigger
  molting.
• Brain hormone-increase in this production
  stimulates gland to produce ecdysone.
• Juvenile hormone-maintains insect in larval stage

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Signal transduction

• Hormones usually attach to protein receptor of
  plasma membrane.
• May initiate response of substance in cytoplasm
  or nucleus.
• Ex. Human growth hormone. Causes bone cells to
  produce secretion.

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• Hormone may enter cell to cause signal
• Ex. Steroid hormones-enter because they are
  lipids and can cross cell membrane.
• Bind to intracellular receptors that behave as
  transcription factors-directly effect mRNA
  production from DNA.

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Hormones may have affect on one tissue or
many. Ex. Sex hormones-affect gender
characteristics. Tropic hormones-those whose
target cells are part of another endocrine gland.
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Pituitary Gland

• Located at base of brain once referred to as
  master gland.
• Produces tropic hormones-ones that have an effect
  on another endocrine gland.

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• Hypothalamus receives brain signals which in turn
  stimulate pituitary gland.
• Makes releasing hormones to turn on and
  inhibiting hormones to turn off pituitary
  secretions.

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ADH/vasopressin

• Antidiuretic hormone (ADH)-causes reabsorption of
  water by kidneys.
• Released if osmolarity of blood increases.
  (solute concentration).
• As dilute blood reaches brain, shuts down release
  of ADH.

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Growth hormone-stimulates bone cells
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Pineal gland

• Secretes melatonin.
• Melatonin regulates functions based on light
  intensity.
• Seasonal depression-high melatonin level due to
  low light intensity in winter.

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Parathyroid

• Releases PTH-raises blood Calcium level.
• Calcium comes from bone-released by
  osteoclasts-bone destroying cells.
• PTH also stimulates inactive vitamin D (from food
  or made by skin when absorbing sunlight) to
  become active.
• Vitamin D helps in calcium absorbance from food.

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Thyroid gland

• Calcitonin-lowers Ca ion levels in blood.
• Thyroxin and triiodothyronine
• Both contain iodine
• Both secreted but most converted to
  triiodothyronine by target cells.
• Secretions controlled by TSH of
  hypothalamus/pituitary.
• Involved in overall metabolism rate.

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Pancreas

• Islets of Langerhans-cells that secrete two
  hormones.
• Alpha cells-secrete glucagon
• Beta cells secrete insulin.
• Only brain cells can take up glucose without
  insulin.
• Glucagon breaks down glycogen in the liver.

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Diabetes-refers to excess urine.

• Diabetes mellitus-insufficient insulin OR loss of
  response to insulin.
• Kidneys secrete glucose, raises osmolarity which
  causes thirst.
• Fat used as fuel-forms acids which change blood
  pH.
• Type I-insulin dependent-autoimmune-childhood.
• Type II-non-insulin dependent-deficiency of
  insulin or response to. Can be managed by diet.

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Adrenal gland

• Made of medulla and cortex.
• Medulla secretes epinephrine and norepinephrine.
• Secreted due to stress.

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• Epinephrine increases heart rate dilates
  bronchiole tubes constricts some blood vessels
  while dilating others. Why might this be
  important?
• Norepinephrine maintains blood pressure and acts
  as a neurotransmitter.

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• Adrenal Cortex
• Stimulated by ACTH from pituitary
• Produce corticosteroids-two types-glucocorticoids
  and mineralocorticoids.
• Glucocorticoids-involved in glucose metabolism
  from proteins
• Mineralocorticoids-ex. Aldosterone-involved in
  reabsorption of sodium ions and water by kidney.
  
• Released as response to stress.

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• Gonadal hormones
• Androgens-ex. Testosterone (also produced by
  adrenal cortex)
• Estrogens
• Progesterone-important to maintaining pregnancy.

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Negative feedback
Secretion of TSH causes increase in thyroxin
production Normal thyroxin tells pituitary to
shut down production of TSH.
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Positive Feedback Mechanism

• Fewer examples than negative feedback.
• One response causes a continued and increased
  response
• Ex. Childbirth-oxytocin-produced by pituitary
  gland-causes contractions of uterus. Causes more
  oxytocin to be released causing more
  contractions.
• What happens when labor is induced?

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Diabetes Insipidus

• By Sean Prideaux

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• Types of Diabetes Insipidus
• Central DI
• Gestational DI
• Nephrogenic DI
• It is a diabetes in which water is reabsorbed by
  the kidneys, instead of going into the blood
• It can be caused by kidney damage or pregnancy,
  but is most commonly caused by a deficiency of ADH

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• ADH (antidiuretic hormone) is a hormone created
  by the pituitary gland
• It then goes to the kidney, where it regulates
  water absorption
• A diuretic increases urination levels, so
  naturally an ADH decreases it
• In DI, through various reasons, the kidneys dont
  have enough ADH or they cannot use it.
• One common treatment is the use of the hormone
  vasopressin, another antidiuretic hormone

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HYPERTENSION as Related to Endocrine System

• Causes
• Too much aldosterone
• Pituitary gland
• Growths
• Metabolic syndrome
• Other diseases
• Endocrine system cause Hypertension?
• Hormones
• Symptoms
• High blood pressure
• Increased blood pressure
• Headache
• Fatigue
• Shortness of breath
• Dizziness

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HYPERTENSION as Related to Endocrine System

• Hypertension increases risk of
• Heart attack
• Stroke
• Kidney disease
• Death
• Primary or Secondary?
• Secondary Hypertension
• Pituitary and Adrenal glands?
• excess hormone production
• dysfunction

• Cure
• Surgery to remove tumor
• Surgery to remove growths
• Diet changes and medicine to lower blood pressure

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Acromegaly

• Gland Pituitary Gland
• Hormone Excess of hGH produced after puberty.
• Causes Tumors on Pituitary Gland

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Acromegaly

• Symtoms Enlarged hands and feet, may change
  facial features (more pronounced jaw, brow, nose
  and lips).
• Treatments Lower levels of hGH, Remove tumors,
  drug and radiation therapies.

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Hyperparathyroidism

• Involves the parathyroid glands

• Causes a secretion of excess parathyroid
  hormone (PTH)

• Symptoms (caused by high levels of calcium)
• -Joint pain
• -Weakened bones
• -Nausea, vomiting, constipation
• -Lack of an appetite
• -Kidney stones
• -Excessive thirst or urination
• -Memory loss, anxiety, fatigue

By Josh Smith
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• Diagnosis occurs after finding high levels of
  calcium and low levels of phosphorus in the blood

Treatments -Surgery to remove the enlarged
gland(s) -Taking calcimimetics a drug that
stops the secretion of PTH -Drinking water and
exercise (for mild cases) -Eating calcium rich
foods and avoiding alcohol, soda, and coffee
(For improving the symptoms)
Informational Sites -http//endocrine.niddk.nih.g
ov/pubs/hyper/hyper.htmsymptoms -http//www.umm.e
du/altmed/articles/hyperparathyroidism-000086.htm
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Hypoparathyroidism

• Reduced parathyroid hormone production due to a
  damage to the parathyroid glands
• Muscle spasms, cramping, dry skin and hair due to
  low calcium levels
• Short term treatment - IV Calcium
• Long term - Vitamin D3 and Calcium
  Supplements

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Type I diabetes mellitus

• It lacks of an endocrine gland
• The pancreas produce insufficient insulin
• Insulin is a hormone that is needed to convert
  sugar (glucose), starches and other food into
  energy needed for daily life.
• Frequent urination
• Unusual thirst
• Extreme hunger
• Unusual weight loss
• Extreme fatigue and Irritability

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Type I diabetes mellitus

• Treatment involves injecting insulin under the
  skin for it to get absorbed into the blood stream
  where it can then access all the cells of the
  body that require it. Shots are the most widely
  used method.
• http//www.youtube.com/watch?vQWJJ3M3xss4
• Universal blue circle symbol for diabetes

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Hypoglycemia

• An abnormally low level of sugar in the blood.
• Over secretion of insulin by the pancreas in
  response to a rapid rise in blood sugar or
  glucose.
• The blood sugar plummets below the level
  necessary to maintain well-being.

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Graves Disease

• Joey Showtis
• 1st Hour

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Graves Disease

• Graves' disease is the most common form of
  hyperthyroidism, occurring when the immune system
  mistakenly attacks the thyroid gland and causes
  it to overproduce the hormone thyroxine. This
  higher thyroxine level can greatly increase the
  body's metabolic rate. This can cause anything
  from a change in mood to a change in physical
  appearance.

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Symptoms/Treatments

• Anxiety, Irritability, Difficulty sleeping,
  Fatigue, A rapid or irregular heartbeat, A fine
  tremor of your hands or fingers, An increase in
  perspiration, Sensitivity to heat Weight loss,
  despite normal food intake, Brittle hair,
  Enlargement of your thyroid gland (goiter),
  Change in menstrual cycles, Frequent bowel
  movements
• Antithyroid drugs, radioiodine therapy and
  surgery to remove the thyroid gland are effective
  treatments for Graves' disease. Subtotal
  thyroidectomy surgery, an operation that removes
  the majority of the gland so that the thyroid
  does not overproduce thyroid hormones is also a
  treatment option.

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Myxedema

• Young Min Cha

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What causes Myxedema

• Hypothyroidism this condition can be caused by a
  lack of thyroid hormone(EP, produce thyroxin).
• Goiter not enough iodine
• Hashimotos thyroiditis autoimmune disease
  attacks the thyroid gland.

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Symptoms and Treatments

• Skin gets thick and coarse(rough)
• Change shape of face
• Slow speech
• Mental dullness
• Treatments making sure a person has enough
  thyroxin( take a pill with thyroxin or iodine)

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Goiter
Thyroid Gland
Endocrine gland involved
Goiter- enlargement of the thyroid gland
Primary function of thyroid gland
Concentrate iodine from the blood to form thyroid
hormones
Hypothalamus senses low level of thyroid hormone
The shortage of thyroid hormones
Caused by iodine deficiency (most common cause)
Send thyroid stimulating hormone (TSH) to thyroid
Stimulates and enlarge the thyroid gland to
produce thyroid hormone
Goiter
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Sandy Chen
http//www.thyroid.org/index.html
American thyroid association
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Cushings Disease

• Exogenous Cause (from outside the body)

-Taking high levels of steroid hormones called
glucocorticoids
--for organ transplant or inflammatory disease
Endogenous Cause (from within the body)
Body produces too much cortisol hormone
Pituitary Cushings- pituitary gland tumor
secretes excess cortisol
Adrenal Cushings- adrenal gland tumor secretes
excess cortisol
Ectopic Cushings- (tumor outside pituitary)
adrenal system secretes cortisol
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Symptoms

• -Upper body obesity
• -rounded face
• -fatigue
• -high blood pressure
• -depression
• -fragile/bruised skin

Treatment
Exogenous Cushings - reduce medication that
produces symptons
Pituitary/Adrenal - remove tumor with surgery,
radiation, or drug therapy
Ectopic - cancer treatment, e.g, surgery,
radiation, chemotherapy
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ADDISONS DISEASE
Chelsie Bivens

• Due to adrenal insufficiency (Adrenal glands are
  located just above the kidneys.)
• Addisons disease occurs from damaged adrenal
  glands which cannot produce enough of the hormone
  cortisol and the hormone aldosterone.

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ADDISONS DISEASE CONTINUED

• Symptoms include
• Sudden penetrating pain in the lower back,
  abdomen, or legs
• Severe vomiting and diarrhea
• Dehydration
• Low blood pressure
• Loss of consciousness
• Treatment includes
• Cortisol is substituted with a synthetic
  glucocorticoid such as hydrocortisone or
  prednisone. If aldosterone is also lacking, it
  is replaced with doses of a mineralocorticoid.
  These are both steroids which would be in
  shortage due to adrenal insufficiency.

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Seasonal Affective Disorder (SAD)

• Symptoms
• Depression -weight gain
• Over sleeping
• Fatigue
• loss of concentration

Produces too much Melatonin. (a.k.a. Sleep
Hormone)
Melatonin causes other endocrine glands to
slow/stop production.
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• Treatment
• Light Therapy
• Antidepressants
• Moving to sunnier climate

• Quick Facts
• Occurs during fall through winter months
• Called Winter Blues
• Reverse SAD
• Information By Mayo Clinic Medline Plus

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• Symptoms fatigue, nervousness, headaches,
  depression, dizziness, sudden hunger, a craving
  for sweets, faintness
• Treatment eating or drinking a small amount of
  glucose-rich food, eat small and frequent meals
  during the day