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CC 2 LAB > ADRENAL MEDULLA > Flashcards

ADRENAL MEDULLA Flashcards

1
Q

• any of a class of aromatic amines that includes a number of neurotransmitters

A

Catecholamines

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2
Q

Catecholamines (4)

A
  • DOPA
  • Dopamine (D)
  • Norepinephrine (NE)
  • Epinephrine (E)
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3
Q
  • derived from the sympathetic nerve endings
A

Norepinephrine (NE)

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4
Q
  • principal product of adrenal medulla
  • made only in the medulla
A

Epinephrine (E)

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5
Q

DOPA

A

L-3,4-dihydroxyphenylalanine

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6
Q

L-3,4-dihydroxyphenylalanine

DOPA

A

is a precursor molecule in the biosynthesis of catecholamines, including dopamine, norepinephrine, and epinephrine.

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7
Q

can cross the blood-brain barrier and is converted to dopamine, aiding in brain function.

A

DOPA

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8
Q

DOPA

Processes:
1. Formation: L-Tyrosine is hydroxylated by ________in the cytosol to form DOPA. This is the rate-limiting step in catecholamine biosynthesis.

2.	Conversion to Dopamine: DOPA is decarboxylated by \_\_\_\_\_\_in tissues like the adrenal medulla and neurons, producing dopamine.
A

tyrosine hydroxylase (TH)

aromatic amino acid decarboxylase (AADC)

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9
Q

L-Tyrosine Conversion to L-Dopa

Enzyme:________
Location:______ of adrenal medullary cells and other locations like sympathetic nerve terminals.
Function: Adds a hydroxyl group to L-tyrosine, forming L-Dopa (rate-limiting step in catecholamine synthesis).

A

Tyrosine hydroxylase (TH)

Cytosol

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10
Q

L-Dopa Conversion to Dopamine

Enzyme:_______
Location: Present in various tissues, including the adrenal medulla.
Function: Removes a carboxyl group from L-Dopa to produce_____

A

Aromatic amino acid decarboxylase (AADC)

dopamine (DA).

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11
Q

Dopamine Transport into Chromaffin Granules:

Transporter:_________
Mechanism: Acts as a dopamine-H+ exchanger, pumping dopamine into chromaffin granules (dense-core vesicles).

A

VMAT1 (Vesicular Monoamine Transporter-1)

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12
Q

Dopamine Conversion to Norepinephrine (NE):

Enzyme:_________
Location:__________
Function: Converts dopamine to norepinephrine (NE) by adding a hydroxyl group.

A

Dopamine beta-hydroxylase (DBH)

Inside chromaffin granules

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13
Q

Norepinephrine Conversion to Epinephrine (E):

Enzyme:_________
Location:__________ of adrenal medulla (unique to adrenal medulla).
Function: Transfers a methyl group from S-adenosylmethionine (SAM) to
norepinephrine to produce epinephrine (E).

A

Phenylethanolamine-N-methyl-transferase (PNMT)

Cytosol

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14
Q

Transport of Epinephrine Back into Chromaffin Granules:

Transporter:_____
________is reabsorbed into chromattin granules for storage.

A

VMAT1

Epinephrine

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15
Q

Storage

Catecholamines bind with______ and _____ to proteins called______, which help in storage.

• This binding makes the catecholamines osmotically inactive, preventing them from diffusing freely and maintaining a controlled storage state.

• Among the chromogranins,______ is the most abundant in humans and plays a major role in the regulation and packaging of catecholamines within these granules.

A

calcium (Ca2+) and ATP

chromogranins

chromogranin B

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16
Q
  1. Hormone Release:

• Mechanism:
- _______ trigger exocytosis of chromaffin granules.
- Both epinephrine (E) and norepinephrine (NE) are released into the bloodstream.

A

Calcium ions (Ca2+)

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17
Q

Physiologic Actions
•________
- coupled with G Protein (termed as GPCR)
• Alpha
• Beta

A

Adrenergic Receptors

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18
Q

Adrenergic Receptors Overview

Adrenergic receptors are a type of GPCR that, upon activation by catecholamines, initiate a cascade of intracellular signaling events.

These events typically involve the activation of intracellular second messengers, such as cyclic AMP (cAMP) or calcium (Ca²⁺), depending on the receptor subtype.

A

G-Protein Coupled Receptors (GPCRs)

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19
Q

Receptor???

Effectively Binds
Epinephrine, Norepinephrine

Effect of Ligand Binding
Increased free calcium

A

Alpha1

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20
Q

Recotor???

Epinephrine, Norepinephrine

Decreased cyclic AMP

A

Alpha2

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21
Q

Receptor???

Epinephrine, Norepinephrine

Increased cyclic AMP

A

Beta1

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22
Q

Receptor???

Epinephrine
Increased cyclic AMP

A

Beta2

23
Q

Adrenergic Receptors

  • ___is a post-synaptic receptor (three subtypes: 1A, 1B and 1D);

-___ is both post- and pre-synaptic receptor (three subtypes: 2A, 2B and 2C)

A

Alpha 1

Alpha 2

24
Q

Andrenergic Receptors
- _____ located mainly in the heart and cortex;
- _____ predominates in the lung and cerebellum;
- _____ in the adipose tissue
• significance in obesity

A

Beta 1

Beta 2

Beta 3

25
Q
  • a response when faced with severe external threat
  • centrally driven release of____, as well as activation of other aspects of sympathetic division of ANS
A

Fight-or-flight response

adrenaline

26
Q
  • increased heart rate and contractility
  • mobilization of fuel stores (muscle and fat)
  • piloerection
  • pupillary dilation
  • increased sphincter tone of bowel and bladder
A

Fight-or-flight response

27
Q

Short-term stress response

A
  1. Increased heart rate
  2. Increased blood pressure
  3. Liver converts glycogen to glucose and releases glucose to blood
  4. Dilation of bronchioles
  5. Changes in blood flow patterns leading to increased alertness, decreased digestive system activity, and reduced urine output
  6. Increased metabolic rate
28
Q
  1. Increased heart rate
  2. Increased blood pressure
  3. Liver converts glycogen to glucose and releases glucose to blood
  4. Dilation of bronchioles
  5. Changes in blood flow patterns leading to increased alertness, decreased digestive system activity, and reduced urine output
  6. Increased metabolic rate
A

Short term stress response

29
Q
  1. Retention of sodium and water by kidneys
  2. Increased blood volume and blood pressure
  3. Proteins and fats converted to glucose or broken down for energy
  4. Increased blood sugar
  5. Suppression of immune
    system
A

Long-term stress response

30
Q

Long term stress response

A
  1. Retention of sodium and water by kidneys
  2. Increased blood volume and blood pressure
  3. Proteins and fats converted to glucose or broken down for energy
  4. Increased blood sugar
  5. Suppression of immune
    system
31
Q

Adrenal Medulla
Specific Physiologic Actions
•
- this is predominantly an effect of epinephrine acting through beta receptors

A

increased rate and force of contraction of the heart muscle

32
Q

Adrenal Medulla
Specific Physiologic Actions
•
- norepinephrine, in particular, causes widespread vasoconstriction, resulting in increased resistance and hence arterial blood pressure

A

Constriction of blood vessels

33
Q

Adrenal Medulla
Specific Physiologic Actions
•
- assists in pulmonary ventilation

A

Dilation of bronchioles

34
Q

Adrenal Medulla
Specific Physiologic Actions
•
- this provides fatty acids for energy production in many tissues and aids in conservation of dwindling reserves of blood glucose

A

Stimulation of lipolysis in fat cells

35
Q

Adrenal Medulla
Specific Physiologic Actions
•

oxygen consumption and heat production increase throughout the body in response to epinephrine

  • medullary hormones also promote breakdown of glycogen in skeletal muscle to provide glucose for energy production
A

Increased metabolic rate

36
Q

Adrenal Medulla
Specific Physiologic Actions
•
- particularly important in situations where you are surrounded by velociraptors under conditions of low ambient light

A

Dilation of the pupils

37
Q

Adrenal Medulla
Specific Physiologic Actions
•
- an example is inhibition of gastrointestinal secretion and motor activity

A

Inhibition of certain “non-essential” processes

38
Q

Adrenal Medulla
Specific Physiologic Actions

• Common stimuli
(4)

A
  • Exercise
  • Hypoglycemia
  • Hemorrhage
  • Emotional distress
39
Q

Catecholamines
Degradation and Elimination
• METABOLITES (3)
• Excreted via the_____

A
  • Free Cathecolamines
  • Vanillylmandelic acid
  • Metanephrines

kidneys

40
Q

Catecholamines
Degradation and Elimination
• EXCRETION
- Free Cathecolamines
- Conjugated NE
- Metanephrines
- Vanillylmandelic acid

A

5%

8%

20%

30%

41
Q

Diseases

A

• Pheochromocytoma
• Neuroblastoma

42
Q

Diseases

  • Rare cathecolamine-producing tumors
A

Pheochromocytoma

43
Q

• Triad
- Diaphoresis
- Tachycardia
- Headache

A

Pheochromocytoma

44
Q

Pheochromocytoma

• Triad

A
  • Diaphoresis
  • Tachycardia
  • Headache
45
Q

• Pheochromocytoma

24-Hour Urine
•_______ is measured to verify the adequacy of the collection
•_______- preservative

A

Creatinine

25 mL of 6N HCI

46
Q

Pheochromocytoma

Plasma
•______ specimen colloection
• Patient in a_____ position in a quiet environment, and a heparin lock is inserted IV

• After______ minutes, collect blood in a_____

• Whole blood be kept in ice water until centrifuged

• Plasma should be separated within____ hours of phlebotomy

• Sample should be frozen immediately

A

Overnight fast

reclining

20-30mins; pre-chilled EDTA

2 hrs

47
Q

A rare tumor that produces excessive amounts of catecholamines (epinephrine, norepinephrine).

These tumors arise from chromaffin cells of the adrenal medulla or extra-adrenal sympathetic tissue.

A

Pheochromocytoma

48
Q

excessive sweating

A

Diaphoresis

49
Q

Pheochromocytoma

Urine Tests

  1. 24-Hour Urine Collection:
    • Measures levels of catecholamines and their metabolites:
    (3)
    • ______ is measured to verify the adequacy of the collection.
    • Preservative: 25 mL of _____is added to the collection container.
A

• Free norepinephrine (NE).
• Vanillylmandelic acid (VMA).
• Homovanillic acid (HVA).

Creatinine

6N HCl

50
Q

Pheochromocytoma

Plasma Tests
1. Pre-Procedure Preparation:
• ______fasting.
• The patient should remain in a_____ position in a quiet environment.
• A heparin lock is inserted intravenously.

  1. Sample Collection:
    • Blood is collected after_____ using a______ tube.
    • The sample must be kept in ice water until centrifuged.
  2. Sample Handling:
    • Plasma must be separated within _____of phlebotomy.
    • The sample should be frozen immediately for preservation.
A

Overnight; reclining

20-30 minutes; pre-chilled EDTA

2 hours

51
Q

Imaging Studies:

Highly sensitive for detecting catecholamines and their metabolites.

Identifies tumor size and location.

Provides detailed imaging of adrenal and extra-adrenal sites.

A

HPLC with Tandem Mass Spectrometry

CT (Computed Tomography)

MRI (Magnetic Resonance Imaging)

52
Q

Pheochromocytma
• Purpose: Differentiates catecholamine release from pheochromocytoma versus nervous system activity.

• Mechanism: ______, an alpha-adrenergic agonist, suppresses nervous system catecholamine release but does not affect tumor secretion.

A

Clonidine Suppression Test

Clonidine Suppression Test:

53
Q

Definition:
A tumor derived from neural crest cells, typically affecting children younger than 3 years.

_______ commonly arise in the adrenal medulla but can occur in other sympathetic nervous system sites.

A

Neuroblastoma

54
Q

• Key Features:
• High urinary levels of:
• Homovanillic acid (HVA)
• Vanillylmandelic acid (VMA)

A

Neuroblastoma

CC 2 LAB (35 decks)

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