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Paracrine messengers have what characteristics
They are secreted locally and act on tissues in close proximity, but are too short lived to be carried far by the blood
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Prostaglandins are an example of what kind of messenger
Paracrine messenger
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What are the characteristics of hormones
Soluble substances that are carried by the blood stream to coordinate responses from multiple organs and tissues
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Insulin is an example of what kind of messenger
Hormone
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Epinephrine is an example of what type of messenger
Hormone
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Norepinephrine is a neurotransmitter of what type of neurons
Post ganglionic, sympathetic, noradrenergic neurons
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Steroids are made primarily where
In specialized endocrine glands
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Cholesterol, testosterone, and cortisol are examples of
Steroid hormones
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All steroid hormones have the ability to have what effect
Regulate transcription factors
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What are the only two thyroid hormones
- Thyroxine (T4)
- Triiodothyronine (T3)
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What elemental component of thyroid hormones makes them unique from almost all other substances in the body
They have iodine in their structure
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What is the role of Thyroid hormones
They increase the metabolic rate and have developmental effects (This is why they are crucial at birth)
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Thyroid hormones are made from
Protein bound tyrosine
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Oxygenase
Enzyme that uses molecular oxygen as one of the substrates
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Prostaglandins are made where
In all tissues
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Cyclooxygenase is a key enzyme in the synthesis of what, and how does it work
- Prostaglandins, Thromboxane, and Prostacyclin
- It adds a carbon ring and oxygen
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Catecholamines function as both
Hormones and neurotransmitters
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What are two primary Catecholeamines
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Where is epinephrine a major hormone
Adrenal medulla
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What breaks down the Catecholamines
- MAO and COMT
- MAO removes the nitrogen
- COMT attaches a methyl group
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Most hormones found in the body are which type
- Proteins or small peptides
- Made by non-endocrine tissues
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Pituitary hormones belong to what category of hormones
Protein/Small peptides hormones not synthesized by endocrine tissue
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What are some Hormone-like proteins
Cytokines and Growth factors
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Growth Hormone and Prolactin fall under what family
Protein Hormone family
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LH, FSH, and TSH fall under what hormone family
Glycoproteins (Protein hormones)
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Adrenocorticotropic hormone (ACTH), Oxytocin, Vasopressin (ADH), and endorphins fall under what family
Small peptide hormones
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What is the difference between Insulin, Proinsulin, and Preproinsulin
- Preproinsulin is proinsulin before the signal peptide is removed (still in ribosome)
- Proinsulin is insulin before the C-peptide is removed
- Insulin lacks the C-peptide and Signal peptide
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What portion of preproinsulin is found in the ER
Proinsulin
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Proinsulin is necessary for creating what in eventual insulin
Disulfide bonds
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Where do the disulfide bonds found in insulin form
In the ER
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What is used to cut out the C-peptide from the proinsulin
Endopeptidase (prohormone convertase)
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What is the difference in concentration of C-peptide and insulin, and why is it important
- They are exactly equal
- It is used to test for the amount of insulin in the body
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Why is C-peptide a better marker then Insulin for blood insulin levels
- It lasts longer in the blood
- Can be used in patients that get insulin injections that don't contain the C-peptide (measuring endogenous secretion only)
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What is the path to make Angiotensin II in the blood stream
- Kidney pressure is high
- Renin is released
- Renin breaks Angiotensinogen to Angiotensin I
- Angiotensin Converting Enzyme (lungs and capillaries) converts Angiotensin I to Angiotensin II
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What is the effect of Angiotensin II in the blood stream
- Increases blood pressure
- Contracts smooth muscle on vessels directly
- Causes the release of Aldosterone from the adrenal cortex causing retention of water by the kidneys
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Where and When is Renin secreted
Juxtaglomerular cells when the intraglomerular pressure is too low
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ACE inhibitors do what
- Inhibit Angiotensin Converting Enzyme and are therefore used for Hypertension
- They also inhibit the break down of Bradykinin (vasodilator)
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What is the most common method for determining Hormone levels in the blood
- Radioimmunoassay
- - Utilizing radioactively labeled hormones and a specific antibody for the Hormone
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Arachidonic acid is a precursor for what Eicosanoids
- Prostaglandins
- Thromboxane
- Prostacyclin
- Leucotrienes
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Arachidonic acid (20 carbon amino acid) is made into Eicosanoids via what Enzymes
- Cyclooxygenase
- - Prostaglandins
- - Thromboxane
- - Prostacyclin
- 5- lipoxygenase
- - Leucotrienes
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Eicosapentaenoic acid is important why
It is a precursor to Prostaglandins and is an Omega-3 fatty acid (Arachidonic acid - Omega-6)
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Phospholipase A2
Breaks down membrane lipids to Arachidonic acid
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What is the first stable product of prostaglandin synthesis
PGH2
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What does the subscript of PGE2 (Prostaglandin E) represent
The number of double bonds outside the ring
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Prostaglandins have what types of actions
- Platelet aggregation
- Vasodilation
- Uterine contraction
- Inflammation
- Fever
- Reduced gastric acid secretion
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What are the roles of Thromboxane (TXA2) and Prostacyclin in platelet activation
- Prostacyclin increases cAMP preventing platelet activation
- Thromboxane decreases cAMP triggering platelet activation
- They are working equally against each other when there is no damage in the tissues
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5-lipoxygenase is important for
Making biologically active products from polyunsaturated fatty acids (Arachidonic acid), most importantly Leucotrienes
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What are the systemic effects of Leucotrienes
They participate in inflammation and allergy response (contract bronchial smooth muscles)
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Glucocorticoid drugs have what effect
Anti-inflammatory steroids that inhibit phospholipase A2 preventing it from releasing Arachidonic acid from membranes, thus decreasing both Leucotrienes and Prostaglandins
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Non steroidal anti-inflammatory drugs (NSAIDs) have what affect
- They inhibit Cyclooxygenase preventing the formation of Prostaglandins but not Leucotrienes
- They reduce inflammation, pain, fever, and platelet aggregation
- Can cause gastritis and peptic ulcers
- Contraindicted with asthma
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What are the isoenzymes of cyclooxygenase and their locations in the body
- COX-1 Most tissues
- COX-2 WBC
- COX-3 Brain (important for pain and fever)
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Aspirin is used for prevention of MI's because
It inhibits COX-1 in platelets, it also inhibits COX-3, and even COX-2 at high doses
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What over the counter drug inhibits COX-3
Acetominophen (important for pain and fever)
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