Brainscape's Knowledge GenomeTM


Top Flashcards (Certified)
All Flashcards

Biochem + Metabolism > Steroids > Flashcards

Steroids Flashcards

1
Q

What is the parent molecule to all steroids?

A

Cholesterol

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What are the 4 main functions of cholesterol?

A

Membrane structure
Bile Acids
Steroid hormones
Vit D

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

True/False: cholesterol synthesis is not tightly regulated

A

false. It is tightly regulated

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What percent of animal cell membranes is cholesterol?

A

30%

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What are the 3 main cell membrane functions of cholesterol?

A

-Maintaining cell fluidity
-Important for overall stability, durability, and integrity
-Obviates the need for a cell wall

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Define amphipathic

A

having both polar and non polar parts

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What are the 3 main components of cholesterols structure?

A
  • polar head: OH group
    -rigid steroid ring structure
    -nonpolar hydrocarbon tail
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What part of the cholesterol interacts with polar head groups of phospholipids?

A

the hydroxyl group

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What percent of cholesterol is endogenous? dietary?

A

endogenous=1/2 - 2/3
dietary= 1/3-1/2

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Where does cholesterol come from in herbivores?

A

biosynthesis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Describe the basic lipoprotein structure

A

-Apoproteins (peripheral and integral)
-TG and cholesterol esters comprise the interior
-Phospholipids, free cholesterol, and apoproteins comprise the surface

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What are the 4 main lipoproteins?

A

Chylomicrons
VLDL
LDL
HDL

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What are the functions of the 4 lipoproteins?

A

-CM: packaging of dietary lipids, delivery to circulation via lymphatics
-VLDL: Transport TG from the liver to tissues
-LDL: Cholesterol transport from liver to extrahepatic tissues
-HDL: Cholesterol “reverse transport” from tissues to liver

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Where are the 4 lipoproteins made?

A

-CM: intestines
-VLDL: liver
-LDL: derived from VLDL so the liver
-HDL: derived from VLDL so the liver

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What form does cholesterol exist in the blood?

A

cholesterol esters

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Why is cholesterol esterified before transport?

A

The ester group makes cholesterol more hydrophobic, so it makes it easier to package since it will want to be buried inside the lipoproteins

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

Describe the digestion/absorption of dietary cholesterol

A

same as triglycerides, is absorbed into jejunal mucosal cells from a mixed micelle, esterified in the mucosal cell, packaged into a CM, inters the blood via lymphatics

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What enzyme esterifies cholesterol?

A

acyl-CoA cholesterol transferase

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What is the fate of cholesterol once it has entered systemic circulation?

A

It is taken up by the liver where it can be temporarily stored or packaged into VLDL for export

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

What are the 3 main ways cholesterol can leave the liver?

A

-Secreted into VLDL
-Free cholesterol secreted in the bile
-Conversion to bile acids/salts

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

What enzyme is integral to circulating HDL particles and is involved in the esterification of cholesterol once it enters the HDL particle from tissues?

A

lecithin cholesterol acyltransferase

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

What 3 ways can you alter blood cholesterol levels?

A

-Saturated fat intake increases LDL cholesterol levels
-Dietary sugars increases the production of LDL by the liver
-Soluble fiver and plant sterols can decrease cholesterol absorption by the GI system

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

What is the primary route of cholesterol excretion?

A

Biliary excretion

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

What form is cholesterol excreted as?

A

cholesterol or bile acids

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
What percent of the excreted+ dietary cholesterol mixture is available for absorption in the gut?
~1/3
26
What is the carbon source of cholesterol?
Acetyl CoA
27
What is the rate limiting step of cholesterol biosynthesis?
HMG-CoA reductase
28
How can dietary cholesterol regulate biosynthesis?
it decreases it
29
Where is HMG-CoA reductase present in the cell?
the endoplasmic reticulum membrane, with the catalytic domain in the cytosol
30
What 3 things can inhibit HMG-CoA reductase?
mevalonate (its direct product) cholesterol bile acids
31
What 3 things can cause hypocholesterolemia
-inherited conditions -hyperthyroidism: increased number of LDL receptors, so higher clearance -severe liver disease: decreased synthesis
32
What is the main cause of hypercholesterolemia in dogs?
hypothyroidism: decreased levels of LDL receptors and other effects
33
Where are primary bile acids synthesized?
in the liver from cholesterol
34
How is bile acid synthesis regulated?
feedback inhibition of their own synthesis and on hepatic cholesterol synthesis
35
How are bile acids converted to bile salts?
conjugated with glycine or taurine
36
What are the two primary bile acids made in the liver?
chenodeoxycholic acid cholic acid
37
What is the rate limiting step in bile acid synthesis?
cholesterol 7alpha- hydroxylase
38
Where are secondary bile acids made?
the intestine
39
What are the 3 secondary bile acids?
deoxycholic acid, lithocholic acid, ursodeoxycholic acid
40
True/False bile acid spillover into peripheral circulation is normal after a meal?
true
41
What can result in increased levels of circulating bile acids not post prandial?
liver dysfunction
42
Quickly describe the life of a bile acid/salt
Biles salts form micelles, they are largely reabsorbed in the ileum, then cleared from portal circulation after passing through the liver
43
How are secondary bile acids formed in the intestine?
they result from bacterial action in the colon. There is partial dehydroxylation and removal of glycine and taurine to yield deoxycholic acid and lithocholic acid
44
Why is ursodiol used clinically in cats/dogs with hepatobiliary deases?
Because ursodeoxycholic acid is relatively hydrophilic and believed to protect the liver from the damaging effects of the two hydrophobic bile acids which are retained on cholestatic disorders
45
Describe bile acids in clinical diagnostics
Serum bile acid test used to assess hepatobiliary function. It can give a diagnosis of various liver disorders in which bile acids cannot be cleared by the liver
46
Describe a portosystemic shunt
an abnormal blood vessel that allows blood to flow directly from the intestine to the general circulation, bypassing the liver
47
What are 4 signs of a portosystemic shunt?
-Failure to thrive -Stunted growth -CNS signs -High protein meal can precipitate an episode
48
Why can a high protein meal precipitate an episode in animals with a portosystemic shunt?
Because NH4 is high after protein metabolism and it is not being excreted
49
What are the 3 main functions of bile?
-dietary lipid emulsification to aid in digestion -alkalinizing fluid in the intestine that neutralizes acidic digesta from stomach -excretion
50
What are the 3 main steroid hormones
-mineralcorticoids -glucocorticoids -sex steroids
51
Where are steroid hormones mainly produced?
adrenal cortex
52
cholesterol is needed as a substrate to synthesize steroid hormones, what are the donating pools of cholesterol for this process?
-de novo -circulating LDL or HDL
53
What is the mechanism of action for steroid hormones?
affect expression of genes via intercellular receptors
54
steroid hormones act by binding to their receptors with ____ affinity and ____
high affinity and specificity
55
How do we use glucocorticoids clinically?
highly effective anti-inflammatory medications for allergic rxns, skin conditions, asthma. They are also immunosuppressive
56
What is the clinical use of mineralcorticoids
-Tx for addisons disease -Spironolactone is a mineralcorticoid antagonist
57
Why are estrogens fatal to dogs and cats?
estrogens cause fatal bone marrow suppression
58
How do bile acids act as hormones?
they bind to specific receptors and affect gene transcription
59
What are the two families of receptors that bile acids can bind to?
-nuclear receptors -cell membrane g protein coupled receptor (mainly brown adipose and intestine)
60
What do bile acids, as a hormone, regualte?
glucose, lipid, and energy metabolism

Biochem + Metabolism (15 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2025 Bold Learning Solutions. Terms and Conditions