Eicosonoids: arachidonic acid

Question 1

What is the precursor of eicosanoids?

Answer 1

arachidonic acid

Question 2

Where is arachidonic acid isolated from?

Answer 2

arachis or peanut oil

Question 3

What is the number of carbons in eicosanoids?

Answer 3

20

Question 4

What is the number of carbons in arachidonic acid?

Answer 4

20

Question 5

What is the number of double Bonds in arachidonic acid?

Answer 5

4

Question 6

What type of hormones are eicosanoids?

Answer 6

paracrine local hormones

Question 7

What are paracrime hormones? ( 3 points)

Answer 7

• they act only near the point of hormone synthesis
• specific effect on target cells near the site of formation
• rapidly degraded, so they are not transported to distal sites within the body

Question 8

eicosonoids are involved in intercellular signaling and …..

Answer 8

intracellular signal cascades

Question 9

What are the functions of eicosunoids?

Answer 9

- inflammation
majority are pro-inflammatory ; some are anti-inflammatory
- fever
- Pain associated with injury or disease
due to inflammation Rxn
- Regulation of blood pressure
vaso dilation or vaso constriction
- Gastric acid secretion
- Blood clotting
stimulation or inhibition → balance
- immune system modulation
- control of reproductive processes & tissue growth
labor → some stimulate contraction of the uterus
- regulation of sleep/wake cycle

Question 10

What is the full naming of arachidonic acid?

Answer 10

5,8,11,14- eicosatetraenoic acid

Question 11

What parent molecule is arachidonic acid released from?

Answer 11

phospholipids by different phospholipases

Question 12

Structure of phospholipids

Answer 12

glycerol + 2 fatty acids + PO4 (negatively changed)

Question 13

Are phospholipids Hydrophobic or hydrophilic?

Answer 13

amphipathic
- fatty acid tail: hydrophobic
- PO4: hydrophilic head

Question 14

What are lipases?

Answer 14

enzymes that hydrolyze specific lipids

Question 15

What are the most abundant lipases?

Answer 15

phospholipases A1, A2, C, D

Question 16

Site of cleavage of A1 & A2

Answer 16

hydrolyze ester Bonds of intact glycerophospholipids at C-1 and C-2
they remove one fatty acid producing a lysophospholipid

Question 17

After the action of an A-Type phospholipase, 2nd fatty acid is removed by … ?

Answer 17

lysophospholipase

Question 18

PhosphatidyI choline → ( phospholipase A1) →

Answer 18

fatty acid + 2-acyl lysophosphatidyl choline

Question 19

PhosphatidyI choline → ( phospholipase A2 ) →

Answer 19

fatty acid + 1-acyl lysophosphatidyl choline

Question 20

True or false
phospholipases are not specific

Answer 20

false
some phospholipases act on one type of glycero phospholipids
phosphatidylcholine - specific phospholipase C

Question 21

True or false
esterases attack ether links of plasmologens

Answer 21

false
they are specific to ester linkages

Question 22

What are Plasmalogens?

Answer 22

subclass of cell membrane glycerophospholipids
- vinyl-ether Bond on C1
- polyunsaturated fatty acid on C2

Question 23

attack site of phospholipases c and D

Answer 23

one of the phospho diester bonds on the head group
D: Remove alcohol group
C : Removes phosphate head + alcohol group

Question 24

PhosphatidyI inositol → (phospholipase C ) →

Answer 24

diacyl glycerol (DAG)

Question 25

What are the 2 pathways for the synthesis of arachidonic acid?

Answer 25

by phospholipase A 2 or by phospholipase C

Question 26

What are corticosteroids?

Answer 26

PLA 2 inhibitors or anti-inflammatory

Question 27

How are cortico steriods considered anti-inflammatory

Answer 27

they inhibit PLA2 expression which reduces archidonate release

Question 28

What signal cascade is responsible for the activation Of PLA 2

Answer 28

PAF: platelet activating factor