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The Endocrine System:
Study Guide for 2022 lecture Final exam #1
1. What are Endocrine Glands? What are hormones? What are target organs or cells?
• Endocrine glands are ductless glands that secrete hormones into the blood (interstitial fluid
from there to blood).
• Hormones are a chemical secreted in small quantities by endocrine cells & alter the
physiological activity of the target cells.
• A target cell is where the hormone produces its effect, depending on how far the target organ
is from the site of hormone secretion there is 3 different actions:
o Endocrine: Long distance travel from the blood. Most are this type.
o Autocrine: affect the same cells that secrete it. (interleukin 2)
o Paracrine: affects neighboring cells. (Somatostatin in pancreas)
3. Give differences between endocrine, exocrine and mixed glands? Give examples of each.
• Endocrine glands are ductless. EX: thyroid, adrenal, pineal.
• Exocrine have ducts. EX: lacrimal, sweat, sebaceous.
• Mixed have both endocrine & exocrine parts, Ex: pancreas, hypothalamus.
4. Give three differences between regulation of body functions by endocrine system and by
nervous system.
• Endocrine deliver hormones by blood, Nervous has neurotransmitters that release in response
to impulses.
• Endocrine typically take longer (seconds-days), nervous is within seconds.
• Endocrines are usually far from the site of release, binds to receptors on or in target cells,
nervous are close to site of release, binds to receptors in postsynaptic membrane.
5. Know different types of hormones based upon their chemical nature. Give examples of each.
• Water Soluble: Amino acid-based hormones (combined by peptide bonds)
o Simple (Modified amino acids)
▪ Catecholamines (NE & E), Serotonin, melatonin
o Peptide hormone (Short chain of 3-49 amino acids)
▪ ADH & OT
o Protein hormones (Long chains of more then 50 AA)
▪ Insulin, gGh
• Lipid Soluble:
o Steroid Hormones: derived from cholesterol. Ex: hormones from adrenal cortex, testes
& ovaries.
o Thyroid hormones: T3 & T4
o Nitric Oxide Gas(NO)- Vasodilation, serves as a hormone & neurotransmitter.
• Eicosanoids (Below)
6. What are eicosanoids, prostaglandins, and leukotrienes? What are these made up of and
what is their role in the body?
• Eicosanoid: They are lipids derived from 20 carbon fatty acids & Arachidonic Acid. local
hormones derived from autocrine or paracrine.
o Prostaglandins (PG) helps with blood clotting, pain, inflammation depending on where
& when they are made
, Studymafia
o Leukotrienes (LT) signal chemicals that mediate allergy & Inflammation.
7. What is meant by hormone-target cell specificity and why does a hormone act on a specific
target?
• Target cells respond differently to the same hormone.
• Hormones don’t act on every cell of the body because only some cells have the receptors.
8. What are receptors? What is meant by down-regulation and up-regulation?
• Receptors are a region of an organ or cell that can respond by an external stimulus. Sensitivity
& Numbers.
• Up regulation: If there is too little hormone then the number of hormone receptors goes up.
• Down regulation: if there is too much hormone, the number of hormone receptors go down.
9. Explain in details the mechanism of hormone action by second messenger system and by
direct gene activation. What are the differences between the two mechanisms?
• Secondary messengers (action of Water Soluble Hormone) :
o Because it is not lipid soluble, it cannot diffuse through the lipid bilayer of the plasma
membrane to bind to the receptors inside target cells.
o A hormone binds to a receptor at the surface of the plasma membrane which is the
First Messenger. This will stimulate the production of a 2nd messenger; a common
form is the Cyclic Adenosine Monophosphate (cAMP). Another is the calcium
pathway (not listed)
▪ When it is bound it changes shape and then allows it to interact with a G
Protein (binds to molecules that nucleotide Guanine). It then exchanges the
GDP to GTP, so it is exchanging a guanine bound to 2 phosphates to a 3
phosphate which allows it to move throughout the cell membrane and interact
with Adenylate Cyclase and activates that.
▪ As an enzyme, that facilitates the conversion of ATP into cAMP. Because the
enzymes active site is on the inner surface of the plasma membrane, it happens
in the cytosol of the cell.
▪ cAMP activates several enzymes.
▪ Activated enzymes catalyze(causes) reactions that produce physiological
responses. Meaning less hormone is required to activate the protein since it can
cause a chain effect.
▪ After a while, cAMP is inactivated by an enzyme called Phosphodiesterase.
The cells response is turned off unless a new hormone binds to the receptor on
the plasma membrane.
The Endocrine System:
Study Guide for 2022 lecture Final exam #1
1. What are Endocrine Glands? What are hormones? What are target organs or cells?
• Endocrine glands are ductless glands that secrete hormones into the blood (interstitial fluid
from there to blood).
• Hormones are a chemical secreted in small quantities by endocrine cells & alter the
physiological activity of the target cells.
• A target cell is where the hormone produces its effect, depending on how far the target organ
is from the site of hormone secretion there is 3 different actions:
o Endocrine: Long distance travel from the blood. Most are this type.
o Autocrine: affect the same cells that secrete it. (interleukin 2)
o Paracrine: affects neighboring cells. (Somatostatin in pancreas)
3. Give differences between endocrine, exocrine and mixed glands? Give examples of each.
• Endocrine glands are ductless. EX: thyroid, adrenal, pineal.
• Exocrine have ducts. EX: lacrimal, sweat, sebaceous.
• Mixed have both endocrine & exocrine parts, Ex: pancreas, hypothalamus.
4. Give three differences between regulation of body functions by endocrine system and by
nervous system.
• Endocrine deliver hormones by blood, Nervous has neurotransmitters that release in response
to impulses.
• Endocrine typically take longer (seconds-days), nervous is within seconds.
• Endocrines are usually far from the site of release, binds to receptors on or in target cells,
nervous are close to site of release, binds to receptors in postsynaptic membrane.
5. Know different types of hormones based upon their chemical nature. Give examples of each.
• Water Soluble: Amino acid-based hormones (combined by peptide bonds)
o Simple (Modified amino acids)
▪ Catecholamines (NE & E), Serotonin, melatonin
o Peptide hormone (Short chain of 3-49 amino acids)
▪ ADH & OT
o Protein hormones (Long chains of more then 50 AA)
▪ Insulin, gGh
• Lipid Soluble:
o Steroid Hormones: derived from cholesterol. Ex: hormones from adrenal cortex, testes
& ovaries.
o Thyroid hormones: T3 & T4
o Nitric Oxide Gas(NO)- Vasodilation, serves as a hormone & neurotransmitter.
• Eicosanoids (Below)
6. What are eicosanoids, prostaglandins, and leukotrienes? What are these made up of and
what is their role in the body?
• Eicosanoid: They are lipids derived from 20 carbon fatty acids & Arachidonic Acid. local
hormones derived from autocrine or paracrine.
o Prostaglandins (PG) helps with blood clotting, pain, inflammation depending on where
& when they are made
, Studymafia
o Leukotrienes (LT) signal chemicals that mediate allergy & Inflammation.
7. What is meant by hormone-target cell specificity and why does a hormone act on a specific
target?
• Target cells respond differently to the same hormone.
• Hormones don’t act on every cell of the body because only some cells have the receptors.
8. What are receptors? What is meant by down-regulation and up-regulation?
• Receptors are a region of an organ or cell that can respond by an external stimulus. Sensitivity
& Numbers.
• Up regulation: If there is too little hormone then the number of hormone receptors goes up.
• Down regulation: if there is too much hormone, the number of hormone receptors go down.
9. Explain in details the mechanism of hormone action by second messenger system and by
direct gene activation. What are the differences between the two mechanisms?
• Secondary messengers (action of Water Soluble Hormone) :
o Because it is not lipid soluble, it cannot diffuse through the lipid bilayer of the plasma
membrane to bind to the receptors inside target cells.
o A hormone binds to a receptor at the surface of the plasma membrane which is the
First Messenger. This will stimulate the production of a 2nd messenger; a common
form is the Cyclic Adenosine Monophosphate (cAMP). Another is the calcium
pathway (not listed)
▪ When it is bound it changes shape and then allows it to interact with a G
Protein (binds to molecules that nucleotide Guanine). It then exchanges the
GDP to GTP, so it is exchanging a guanine bound to 2 phosphates to a 3
phosphate which allows it to move throughout the cell membrane and interact
with Adenylate Cyclase and activates that.
▪ As an enzyme, that facilitates the conversion of ATP into cAMP. Because the
enzymes active site is on the inner surface of the plasma membrane, it happens
in the cytosol of the cell.
▪ cAMP activates several enzymes.
▪ Activated enzymes catalyze(causes) reactions that produce physiological
responses. Meaning less hormone is required to activate the protein since it can
cause a chain effect.
▪ After a while, cAMP is inactivated by an enzyme called Phosphodiesterase.
The cells response is turned off unless a new hormone binds to the receptor on
the plasma membrane.
