Chemical Signals in Animals

GoiterGoiter

Two Primary Systems of Internal Communication and Regulation.

Nervous System• Quick responses to sudden environmental

changes.• Pulling your hand a way from a hot flame.

Endocrine• Longer lasting and slower response

• Chemical response• Control of metamorphosis of a butterfly.

Endocrine Glands

Endocrine glands• Ductless glands that secrete substances

directly into the blood stream.

Exocrine Glands• These glands have ducts

• Secrete mucus, sweat and digestive enzymes.

Nervous System and Endocrine System are Closely Related

Many endocrine organs contain nervous tissue called neurosecretory cells.• Secrete hormones in response to a stimulus.

• Epinephrine is a hormone and a neurotransmitter.• Produced by adrenal glands as the “fight or flight”

hormone and is a neurotransmitter that is involved in nerve cell communication.

Peptide Verse Steroid Hormones

Peptide Hormones are protein based hormones.• Signal Transduction Pathways.

• Response is faster but do not last as long.

Steroid Hormones are lipid based• Pass through the membrane and to a receptor in the

cytoplasm that bind to a promoter and activate a gene.

• These responses take longer to initiate but have a longer duration.

Insects Possess Hormones that affect Metamorphosis

Local RegulatorsLocal Regulators Target Cells that are adjacent to the cells that are Target Cells that are adjacent to the cells that are

secreting the message.secreting the message. Growth FactorsGrowth Factors

Proteins that stimulate cell proliferationProteins that stimulate cell proliferation– Nerve Growth FactorNerve Growth Factor

– Nitric OxideNitric Oxide Stimulate cell destruction in the immune systemStimulate cell destruction in the immune system Stimulate vasodialation in the circulatory systemStimulate vasodialation in the circulatory system Functions as a neurotransmitter in the nervous system.Functions as a neurotransmitter in the nervous system.

– ProstaglandinsProstaglandins Modified fatty acids derived from lipidsModified fatty acids derived from lipids Stimulate uterine contractions, fever, inflammation and the Stimulate uterine contractions, fever, inflammation and the

sensation of pain.sensation of pain. PGE and PGF are antagonistic and stimulate the contraction PGE and PGF are antagonistic and stimulate the contraction

and dilation of blood vessels in the lung.and dilation of blood vessels in the lung.– PheromonesPheromones

Chemical signals that serve as communication between Chemical signals that serve as communication between animals.animals.

Warning signals, territorial ,markers.Warning signals, territorial ,markers.

Peptide Hormones and Second Messengers

Cyclic AMP is a cytoplasmic messenger that is activated when a single hormone molecule binds to the receptor on the surface of the cell that initiates a cascade of biochemical reactions.• Amplification of the response results in one

hormone molecule activating the release of thousands of products.

• Epinephrine catalyzes glycogen hydrolysis.

Signal Transduction

45-03a-NonsteroidHormone.mov

Steroid Hormone Receptors

45-03b-SteroidHormone.mov

Hypothalamus and Pituitary Glands. Hypothalamus

• Controls the pituitary• Neurosecretory cells release hormones that control the pituitary gland.

• Important connection between the endocrine and nervous system. Pituitary

• “Master Gland”• Anterior and Posterior

• Posterior pituitary stores and releases hormones produced by the hypothalamus.

• Releases

• ADH –water absorption in the kidney

• Oxytocin-uterine contractions and milk production in the mamary glands.

Anterior Pituitary

Produces its own hormones and releases• Growth Hormone-Stimulate growth factors

produced in the liver called somatomedins which stimulate cartilage and bone growth.• Excessive GH production causes gigantism and

acromegaly.

• GH deficiency causes hypopituitary dwarfism.

MidgetMidget too little GHtoo little GH

Giant Giant too much GHtoo much GH

Anterior PituitaryAnterior Pituitary Prolactin(PRL)Prolactin(PRL)

– controls mammary gland growth and d the synthesis of milk in controls mammary gland growth and d the synthesis of milk in mammals.mammals.

– delays metamorphosis in amphibiansdelays metamorphosis in amphibians– regulates salt and water balance in fish.regulates salt and water balance in fish.

Tropic hormonesTropic hormones– Thyroid Stimulating HormoneThyroid Stimulating Hormone (TSH) (TSH)

Stimulates the release of ThyroxinStimulates the release of Thyroxin– Follicle Stimulating Hormone (FSHFollicle Stimulating Hormone (FSH))– Lutineizing Hormone (LH)Lutineizing Hormone (LH)

Involved in reproductionInvolved in reproduction Adrenocorticotropin (ACTH)Adrenocorticotropin (ACTH)

– Causes the adrenal cortex to secrete steroid hormones Causes the adrenal cortex to secrete steroid hormones involved in “fight or flight” responses.involved in “fight or flight” responses.

Melanocyte Stimulating Hormone (MSH)Melanocyte Stimulating Hormone (MSH)– Involved in color changes in amphibians.Involved in color changes in amphibians.

Endorphins and EnkephalinsEndorphins and Enkephalins– Produced by certain neurons in the brain and inhibit pain Produced by certain neurons in the brain and inhibit pain

reception.reception.

Stimulation of the Anterior Pituitary

Releasing factors are produced at the base of the hypothalamus and are released by capillaries in an area called the median eminence

Thyroid Gland

Calcium Balance

Pancreas

Adrenal Glands

Fight or Flight