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For the purpose of regulating ________, the body is continually receiving interpreting and responding to stimuli. The two main system the of the body that are responsible for this are the _________ and the __________ systems.
homeostasis, nervous, endocrine
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Through the use of mediator molecules, homeostatic mechanisms are strictly controlled. In the endocrine system these molecules are called __________.
hormones
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Hormone
- a mediator molecule secreted from one part of the body that circulates via the body fluids to cells in another part of the body.
- they are secreted into the interstitial fluid, then typically to the bloodstream gaining access the the entire body.
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"Target Cells"
- A specific cell that responds to the hormone due to the presence of peripheral or intracellular receptors.
- They are the specific targets of hormones, hence the name.
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The Endocrine system
- consists of the pituitary, thyroid, parathyroid, adrenal and pineal glands
- There are other organs and tissues that secrete hormones but they are not exclusively endocrine glands: Hypothalamus, thymus, pancreas, ovaries, testes, kidneys, stomach, liver, small intestine, skin,heart, and placenta
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The study of endocrine glands and hormones is called ______________.
endocrinology
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The endocrine system is made up of _______ and _______ endocrine organs that, together with the _________ _______ coordinate vital functions in an effort to maintain _________.
primary, secondary, nervous system, homeostasis.
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__________ function to regulate the chemical composition and ________ of the blood, metabolism and energy balance, contraction of smooth and cardiac muscle fibers, glandular secretion, growth and development, reproduction, sleep-wake cycles, and some _______ functions.
Hormones, volume, immune
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True or False
Hormones are not very powerful molecules
False
- hormones are very powerful
- Their not present in large amounts but their effects are quite dramatic
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What are the endocrine systems functions?
- Control of composition and volume of internal environment
- Regulate metabolism and energy balance
- contraction of smooth and cardiac muscle fibers
- Influence glandular secretions
- Regulation of sleep-wake cycles
- Emergency control during physical and mental stress (trauma, starvation, hemorrhage, etc.)
- Integration of growth and development
- Reproductive control
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True or False
Molecules can be both neurotransmitters and hormones; it just depends on how they are used.
True.
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What is the difference between Nervous and Endocrine systems?
- Nervous
- -Nurotransmitters
- -local chemical release across a synapse
- -targets: muscle cells glands and other neurons
- -Onset of action: milliseconds
- -Acton duration: milliseconds
- Endocrine
- -Hormones
- -Responses are usually distant rom the site of release
- -Targets: cells throughout the body(any cell)
- -Onset of action: seconds to hours to days
- -Action duration: generally longer
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___________ are released from neurons to act locally in response to a nerve impulse. They bind to _________ in a post synaptic membrane near the sight of ________.
Neurotransmitters, receptors, release
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____________ can be delivered to ______ throughout the body, and binds to receptors in or on the _______ cell.
Hormones, cells, target
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Hormone receptors
- They are simply cellular proteins
- like other proteins they can be synthesized, broken down, and synthesized again.
- Target cells can dictate the number of receptors available to bind hormone.
- -Up-regulation: increased responsiveness by increasing receptor numbers
- -Down-regulation: Decreased responsiveness by decreasing receptor numbers
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Circulating hormones
Hormones secreted into the interstitial fluid and then into the bloodstream
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paracrines
Hormones secreted into the interstitial fluid that act on neighboring cells
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Autocrines
Hormones secreted into interstitial fluid that act on the same cell that secreted it.
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What types of hormones are Lipid-soluble hormones?
- Steroid hormones
- thyroid hormones
- Nitric Oxide
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What types of hormones are Water-soluble hormones?
- Amine hormones
- Peptide and Protein hormones
- Eicosanoid Hormones
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True ore False
Lipid-Soluble hormones can diffuse into a cell and bind directly to intracellular receptors.
True.
a substance can more easily move into a cell if it is: small, neutrally-charged, or lipid-soluble
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Water-soluble hormones must...
stimulate a cellular change by binding to membrane receptors and initiating a change in the cell indirectly.
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Chemical Classes of Hormones:
Water-soluble
- Water-soluble hormones freely circulate in the bloodstream.
- they cant pass through the cell membrane
- Examples are:
- -Amines
- -peptides and proteins
- -Eicosanoids
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Chemical Classes of Hormones:
Lipid-solulble
- Most of the available lipid-soluble hormone is carried in the blood by transport proteins.
- They can freely diffuse through the cell membrane.
- Examples are:
- -steroid hormones
- -thyroid hormones
- -Nitric Oxide (gas)
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True or False
Solubility dictates how hormones will be carried in the blood.
true.
The blood is 55% plasma, and the plasma is 92% water
In this water soluble environment, water-soluble hormones can circulate as "free" hormones; they aren't attach to any other molecules.
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In the blood, lipid-soluble hormones must be bound to _____ ______. By binding to these proteins, the _____ solubility of these hormones is increased.
transport proteins, water
These also keep the smaller lipid-soluble hormones from getting filtered into the kidney and lost in the urine.
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True or false
Where most of the water-soluble hormones are free in the blood, only 0.1-10% of lipid-soluble hormones are free.
true.
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True or false
Whatever the nervous system does there is usually a corollary response by the endocrine system.
True.
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