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HLSC 126 - Human Physiology I > Chapter 6 > Flashcards

Chapter 6 Flashcards

1
Q

Hormones

A

-secreted by ductless endocrine glands to the blood
-travel to target cells
-produced in small amounts
-regulate and direct particular functions

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2
Q

Receptors

A

-found in target cells
-where hormones will bind
-protein molecules

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3
Q

Hydrophilic Hormones

A

-highly water soluble
-categorized by length as either: a) peptide hormones or b) catchecholamines

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4
Q

Peptide Hormones

A

-short length
-short chain of amino acids bound with peptides
-synthesized in rough endoplasmic reticulum
-packaged in the golgi complex
-stored in large amounts in secretory granules
-secreted by exocytosis
-transported freely in the blood
-receptors on surface of target cells
-majority of hormones
-ie. insulin

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5
Q

Mechanism of Peptide Hormones

A

-channel changes
or
-second messenger system to alter activity of target proteins that produce the effect

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6
Q

Catecholamines (protein) Hormones

A

-long
-also bound with peptides
-derivatives of the amino acid: tyrosine
-synthesized in cytosol
-stored in chromaffin granules
-released by exocytosis
-receptor side on plasma membrane (surface)

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7
Q

Circulation of Catecholamines

A

-50% are bound to plasma proteins
-50% freely circulate in the blood

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8
Q

Catecholamine Mechanism of Action

A

second messenger system alters activity of target proteins that produce the target effect

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8
Q

Adrenal Cortex

A

-produces cortisol and adrenaline

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8
Q

Catecholamine Examples

A

-are hormones from the adrenal medulla; the inner part of the adrenal gland
-ie. norepinephrine, epinephrine, dopamine

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8
Q

Adrenal Gland

A

-above the kidneys
-consists of an inner medulla and an outer cortex

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9
Q

Lipophilic Hormones

A

-have high lipid solubility and are poorly soluble in water
-categorized by a) steroid hormones and b) thyroid hormones

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10
Q

Steroid Hormones

A

-derivatives of cholesterol
-synthesized by modification of cholesterol
-not stored (cholesterol is stored in lipid droplets)
-secreted by simple diffusion
-transported via binding to plasma proteins
-receptors are located inside the target cell

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11
Q

Steroid Hormone Mechanism of Action

A

activation of specific genes to make new proteins that produce the effect

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12
Q

Steroid Hormone Examples

A

-hormones from the adrenal cortex
-hormones from the gonads (testes and ovaries)

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13
Q

Thyroid Hormones

A

-also tyrosine derivatives
-secreted by thyroid gland
-synthesized and stored in colloid
-secreted by endocytosis
-transport via binding to plasma proteins
-receptor site is inside target cell

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14
Q

Amine Hormones

A

catecholamines and thyroid hormones grouped together because they are both tyrosine derivatives

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15
Q

Mechanism of Thyroid Hormones

A

activation of specific genes that make new proteins to produce the effect

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16
Q

Examples of Thyroid Hormones

A

-hormones from thyroid follicular cells

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17
Q

Process of DNA copying

A

-transcription: MRNA goes to cytoplasm where it is decoded (translation)
= brand new protein is made

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18
Q

NASCENT protein

A

-an original protein that has never been made
-gives a brand new response
-ie. estrogen during puberty

19
Q

Complexity of Endocrine function

A
  1. a single gland may produce multiple hormone
  2. a single hormone may be secreted by more than one gland
  3. a single hormone may have more than one type of target cell
  4. rate of secretion varies
  5. target cell may be influenced by more than one hormone
20
Q

Cyclic AMP Second Messenger System

A

-steps in the cAMP second messenger system to initiate a cellular response in the cell

21
Q

Step 1: cAMP

A

-binding of first messenger to its surface membrane receptor
-activates enzyme adenylylcyclase which is located on the cytoplasmic side of the membrane
-G protein found on inner membrane surface acts as the middle man
-unactivated G protein consists of alpha, beta, and gamma subunits
-the G proteins are activated in response to the binding of first messengers on surface receptors
-receptor attaches to the G protein, activating the alpha subunit
-alpha subunit breaks away and moves along inner surface membrane until reaching effector protein
-effector protein is an ion channel or an enzyme
-alpha links with effector (adenylyl cyclase) and alters its activity

22
Q

Step 2: cAMP

A

-adenylyl cyclase induced conversion of ATP to cAMP by cleaving off 2 phosphates

23
Q

Step 3: cAMP

A

-intercellular 2nd messenger, cAMP, tiggers series of biochemical steps to bring about the response initated by 1st messenger
-to begin, cAMP activates protein kinase A (PKA), an enzyme

24
Q

Step 4: cAMP

A

-protein kinase A attaches a phosphate group from ATP (phosphorylation) to a target protein; such as an enzyme

25
Q

Step 5: cAMP

A

-phosphorylation causes the protein to change shape and function
-this change is the target cells response to the first messenger
-ie. an enzyme that regulates a metabolic even may be increased or decreased

26
Q

Step 6: cAMP

A

-after the response:
-first messenger is removed
-alpha subunit rejoins beta and gamma to restore the inactive G protein complex
-cAMP is inactivated so the message is erased and the response is stopped

27
Q

key note for cAMP 2nd messenger system

A

-steps involving the first messenger, receptor, and G protein, and effector protein occur in the plasma membrane
-all these steps lead to the activation of the second messenger
-extracellular messenger cannot enter the cell
-cAMP the 2nd messenger triggers events in the cell to initiate a response

28
Q

examples where cAMP is used

A

-modifying heart rate
-forming female sex hormones in ovaries
-breakdown of stored glucose in the liver
-control of water conservation during urine formation
-perceptions of sweet taste via taste bud

29
Q

Calcium Second Messenger System

A

-used by some cells instead of cAMP

30
Q

Step 1: calcium

A

-binding of the first messenger to surface receptor by means of a G protein
-alpha subunit breaks away
-activates the enzyme phospholipase C (PLC), this is the effector protein

31
Q

Step 2: calcium

A

-PLC breaks down phospharidylinositol biphohsphate (PIP2) into either a) IP3 (inositol triphosphate) or b) DAG (diacylglycerol)

32
Q

Step 3a: calcuim

A

-IP3 is responsible for mobilizing Ca2+ to increase cytosolic Ca2+

33
Q

Step 4a: calcium

A

-calcium takes over the role of second messenger, bringing about the response of the first messenger
-many of the Ca2+ events are triggered by the activation of calmodulin (Ca2+ binding protein)

34
Q

Step 5a: calcium

A

-activated calmodulin activates calmodulin dependent protein kinase (CaM kinase)

35
Q

Step 6a: calcium

A

-CaM kinase phosphorylates inactive target protein

36
Q

Step 7a: calcium

A

-altered protein brings about the desired cellular response

37
Q

Step 3b-5b: calcium

A

-DAG simultaneously sets off another second messenger pathway
-DAG activates protein kinase C (PKC) which brings about cellular response by phosphorylating cellular proteins

38
Q

Cascade of events

A

-second messenger pathways amplify an initial stimulus
-ie. receptors activate many adenylyl cyclase molecules which activate even more cAMP molecules, influencing many enzymes, producing many products
-so 10 adenylyl cyclase can initiate 10 million molecules of a secretory response

39
Q

Lipophilic Hormones

A

-bind with intracellular receptors and primarily produce their effects in their target cells by activating specific genes
-activation of genes cause the synthesis of new proteins

40
Q

Step 1: lipophilic

A

-free lipophilic hormone diffused through plasma membrane and binds with receptor (can be in cytoplasm or nucleus)

41
Q

Step 2: lipophilic

A

-each receptor has a region for binding with hormone and another region for binding with DNA
-when hormone is bound to receptor, receptor binds with DNA at the hormone response element (HRE)

42
Q

Step 3: lipophilic

A

-binding of receptor with DNA turns on a specific gene within the target cell
-the gene contains the code for synthesizing a given protein
-code is transcribed into MRNA

43
Q

Step 4: lipophilic

A

-new MRNA leaves nucleus and enters cytoplasm

44
Q

Step 5: lipophilic

A

-MRNA binds to a ribosome
-MRNA directs the synthesis of the new proteins

45
Q

Step 6: lipophilic

A

-new protein produces the target cells response to the hormone

46
Q

Nervous System

A

-rapid response
-brief in duration
-target tissues are muscles, glands, adipose tissue

47
Q

Endocrine System

A

-slow response
-longer in duration
-targets many tissues in the body

HLSC 126 - Human Physiology I (5 decks)

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