Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

LIVER & FRIENDS > Fat Metabolism > Flashcards

Fat Metabolism Flashcards

1
Q

How is fat stored in the body

A
  • Most of the bodies fat is stored in adipocytes which form tissues called adipose tissues
  • Some is stored in hepatocytes
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What are triglycerides made of

A

Triglycerides (TGs or TAGs) consist of 3 fatty acids bound to a glycerol molecule

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

How much do triglycerides account for in body energy stores

what about proteins and carbs

A

It accounts for 78% of energy stored in the body

Proteins account for 21% and carbohydrates account for 1%

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

95% of dietary lipids are triglycerides, the rest consist of

A

phospholipids, free fatty acids (FFAs), cholesterol and fat soluble vitamins

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

what are lipids

A

They are esters of fatty acids and certain alcohol compounds

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

function of lipids

A
  • Energy reserves
  • Structural part of cell membrane
  • Hormone metabolism
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Function of Lipoproteins

A

They are used to transport cholesterol in the blood

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Where is HDL made

A

liver

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

Function of HDL

A
  • Removeexcess cholesterol from blood and tissue
  • They then deliver this cholesterol to the liver which secretes it into the bileor converts it into bile salts
  • Referred to as “good” cholesterol, since it removes cholesterol from plasma
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

where is LDL formed

A

formed in the plasma

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

How are LDLs taken up by cells

A

LDLs bind to plasma membrane receptors specific for a protein component of the LDLs and are then taken up by the cells via endocytosis

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

why are LDLs said to be bad

A

LDL cholesterol is said to be “bad” due to the fact that high plasma concentrations can be associated with increased deposition of cholesterol in arterial walls and a higher incidence of heart attacks

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

But why is LDL important

A

However, LDL is essential in supplying cells with the cholesterol they require to synthesise cell membranes and for steroid hormone production in the gonads and adrenal glands + aldosterone + cortisol

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

LDL function

A

The main cholesterol carriers and they deliver cholesterol to cells throughout the body

is essential in supplying cells with the cholesterol they require to synthesise cell membranes and for steroid hormone production in the gonads and adrenal glands + aldosterone + cortisol

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

What Is VLDL where made

and function

A

synthesised in hepatocytes - carries triglycerides from glucose in liverto adipocytes

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

Under resting conditions approximately half the energy used by muscle, liver and the kidneys is derived from the

A

catabolism of fatty acids

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

Most cells store some degree of fat, but most of the body’s fat is stored in adipocytes
how so

A

almost the entire cytoplasm of each adipocyte is filled with a single large fat droplet

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

what is adipose tissue

A

Clusters of adipocytes form adipose tissue, most which is in deposits underlying the skin or surrounding internal organs

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

What is the purpose of adipocytes

A

The function of adipocytes is to synthesise and storetriglycerides during periods of food uptake and the, when food is not being absorbed from the small intestine, to release fatty acids and glycerol into the blood for uptake & use by other cells in order to provide the energy required for ATP formation

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

1 RELEASE OF FATTY ACID TO MAKE ATP PROCESS

What does CoEnzyme A do

A

Molecule of coenzyme A link to the carboxyl at the end of a fatty acid

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

2 RELEASE OF FATTY ACID TO MAKE ATP PROCESS

what happens when a Molecule of coenzyme A link to the carboxyl at the end of a fatty acid

A

This step is followed by the breakdown of ATP —> AMP + 2Pi3.

The coenzyme A derivative of fatty acid then proceeds through beta-oxidation reactions

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

3 RELEASE OF FATTY ACID TO MAKE ATP PROCESS

What happens in the beta oxidation reactions

A

A molecule of acetyl coenzyme A is split off from the fatty acid and two pairs of hydrogen atoms are transferred to coenzymes (one pair to FAD and the other pair to NAD+)

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

4 RELEASE OF FATTY ACID TO MAKE ATP PROCESS

what happens after two pairs of hydrogen atoms are transferred to coenzymes (one pair to FAD and the other pair to NAD+)

A

The hydrogen atoms from the coenzymes then enter the oxidative phosphorylation pathway to form ATP

Another coenzyme A attaches to the fatty acid and the cycle is repeated

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

5 RELEASE OF FATTY ACID TO MAKE ATP PROCESS

what happens each passage through this sequence

A

Each passage through this sequence shortens the fatty acid chain by two carbons atoms until all the carbon atoms have transferred to coenzyme A molecules

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

6 RELEASE OF FATTY ACID TO MAKE ATP PROCESS

what happens when all the carbon atoms have transferred to coenzyme A molecules

A

These molecules then lead to the production of CO2 & ATP via the Kreb’s cycle & oxidative phosphorylation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

function of Lipoprotein lipase

A

Hydrolyses triglycerides in lipoproteins (chylomicrons & VLDLs) into 2 free fatty acids & 1 glycerol molecule

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

Function of Hepatic lipase

A
  • Expressed in the liver and adrenal glands
  • Converts IDL (intermediate density lipoprotein) into LDL thereby packaging it with more triglycerides to be released in the body
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

What secretes bile

A

Secreted in the liver by hepatocytes more or less continuously

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
29
Q

function of bile

A

Used to emulsify fats

Also serves as an excretory pathway for most steroid hormones, many drugs as well some toxins metabolised by the liver

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
30
Q

Where is bile stored and concentrated

A

Stored & CONCENTRATED in the gall bladdersince some NaCl & water are absorbed into the blood

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
31
Q

Where does the gall bladder lie

A

The gall bladder, lies at the junction of the right-mid-clavicular line & costal margin

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
32
Q

how is liver connected to GI TRACT

A

The livers connection with the GI tract is via the portal vein which collects blood from the superior mesenteric vein (which in turn is effectively the venous drainage of both the small and large intestines)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
33
Q

What drains small and large intestine

A

superior mesenteric which drains into portal vein

34
Q

The functional unit of the liver is

A

the hepatic lobule (formed by hepatic plates stacked on top of each other)

35
Q

What is a hepatic lobule

A

Hepatic lobules are hexagonal in cross-section with a portal triad at each corner

36
Q

what does the portal triad consist of

A
  • A hepatic portal vein
  • Hepatic artery
  • Bile duct
37
Q

Running up the centre of the lobule is the what

A

central vein which eventually becomes the hepatic vein

38
Q

what is the hepatic sinusoid

A

type of blood vessel (with fenestrated, discontinuous endothelium)

39
Q

Histology of hepatic sinusoid

A

type of blood vessel (with fenestrated, discontinuous endothelium)

40
Q

What happens at the hepatic sinusoid

A

Substances absorbed from the small intestine wind up in the hepatic sinusoid,
(where oxygen-rich blood from the hepatic artery and nutrient richblood from the portal vein is found hepatocytes are separated from the sinusoids by the space of disse)
either to reach the vena cava via the central vein or are taken up by the hepatocytes in which they can be modified

41
Q

what separates the sinusoids from the hepatocytes

A

space of disse

42
Q

what are the hepatic lobules

A

The hepatic lobules are wedge-like arrangements of hepatocytes around 1 to 2 cells deep which are surrounded by sinusoids (containing mixed portal/hepatic artery blood)

43
Q

Blood supply of liver

A

The liver is unique in that the majority of its blood supply comes from a vein
- the portal vein - which is responsible for 80% of the supply with the

remaining 20%supplied by the hepatic artery

44
Q

When the branches of artery and vein leave the portal triadthey join and blood is mixed as it enters the sinusoids where does it exit

A

It flows through the centre and exits via the central vein

45
Q

The sinusoids are lined with what

A

a continuos layer of specialised endothelial cells interspersed with Kupffer cells (the resident macrophage population)

46
Q

The formed bile heads are in what in relation to the blood

A

in the opposite direction to the blood

47
Q

purpose of stellate cells

A

On the undersurface there are cells called stellate cells which are responsible for producing the extracellular matrix in the space of disse

48
Q

what are bile canaliculi

A

Between adjacent hepatocytes are bile canaliculi - these are not true vessels (they do not have specialised walls) but are like a groove running along the side of the hepatocytes, they are bound together by tight junctions, gap junctions & desmosomes which crossboth cell membranes.

Actin filaments are found in the areas around the canaliculi and serve to pump the formed bile toward the bile ducts

49
Q

function of bile canaliculi

A

Actin filaments are found in the areas around the canaliculi and serve to pump the formed bile toward the bile ducts

50
Q

what forms the common bile duct

A

The bile ducts in the the hepatic lobules join either into the left or right hepatic ducts which in turn join to form the common hepatic duct

51
Q

what does the cystic duct do

A

joins the common hepatic duct to gall bladder , allowing bile to collect in the gall bladder

52
Q

what joins to form the common bile duct

A

After the cystic duct had joined the common hepatic duct, the duct becomes the common bile duct

53
Q

what is the ampulla of vater

A

the point where the common bile duct and the pancreatic duct join

54
Q

where does the pancreatic duct and the common bile duct enter the duodenum at what

A

These two ducts then enter the duodenum at the major duodenal papilla (2nd part duodenum)

55
Q

what is the sphincter of oddi

A

A sphincter around the two ducts, to regulate the entry of bile into the duodenum is

56
Q

6 major ingredients of the bile

A
  • Bile salts-Lecithin (a phospholipid)
  • HCO3
  • and other salts
  • Cholesterol
  • Bile pigments
  • Trace metals
57
Q

what are bile salts manufactured by

A

hepatocytes

58
Q

Bile salts, cholesterol & lecithin are aggregated into mixed micelles and MAINTAIN this aggregation in the gall bladder even when concentrated

what is the main reason for this

A

The main reason for this is that bile salts are powerful detergents which they need to be for their fat emulsification function (derived due to the fact that bile salts are anionic(negative)). However they are also capable of damaging cell membranes and so they are separated in micelles to reduce damage until they are required

59
Q

Function of H3CO3-

A

helps neutralise the acids in the duodenum

60
Q

The components of bile are secreted by TWO different cell types:

A
  • Hepatocytes; bile salts, cholesterol, lecithin & bile pigments
  • Epithelial cells lining the bile ducts; most of the HCO3- rich solution
61
Q

what stimulates the secretion of the HCO3- Rich solution by the bile ducts

A

Secretion of the HCO3- rich solution by the bile ducts, just like the secretion by the pancreas, is stimulated by secretin in response to the presence of acid in the duodenum

62
Q

Where does the gall bladder get its bile from

A

The gallbladder receives its bile from the common hepatic duct which is formed by the the left and right hepatic ducts

63
Q

how does bile enter the gallbladder and what happens here

A

The hepatic bile enters the gallbladder via the cystic duct and is stored & concentrated here - hepatic bile is relatively dilute and is then concentrated in the gallbladder

64
Q

Bile remains in the gall bladder until what

A

until the gallbladder contracts under the action of cholecystokin (CCK) - CCK is released due to amino + fatty acids in duodenum

65
Q

How is the vasculature of the gall bladder strange

A

The vasculature of the gallbladder is strange in that it the cystic artery supplied oxygenated blood to the gallbladder but it has no venous drainage. The gallbladder is stuck to the liver bed & blood drains from the gallbladder directly into the liver with no identifiable venous pathway

66
Q

What happens to the bile which is secreted into the intestinal tract

A

During the digestion of a fatty meal, most of the bile salts entering the intestinal tract via the bile are absorbed by specific Na+-coupled transporters in the jejunum and terminal ileum (largest amounts absorbed here)

67
Q

what happens to the bile salts which are absorbed from the intestinal tract

A

The absorbed bile salts are returned via the portal vein to the liver, where there are once again secreted into the bile

68
Q

what drives the uptake of bile salts from the portal blood

A

Uptake of bile salts from the portal blood into hepatocytes is driven by secondary active transport coupled to Na+

69
Q

what is the enterohepatic circulation

A

refers to the circulation of biliary acids, bilirubin, drugs or other substances from the liver to the bile, followed by entry into the small intestine, absorption by the enterocyte and transport back to the liver

basically This recycling pathway from the liver to the intestine

70
Q

How much bile is lost in faeces what replaces this

A

A small amount (5%) of the bile salts escape this recycling and is lost in faeces, but the liver synthesises new bile salts from cholesterol to replace it

71
Q

how often will bile be recycled during a meal

A

During the digestion of a meal, the entire bile salt content of the body may be recycled several times via the enterohepatic circulation

72
Q

what is bile made from

A

Bile is synthesised from cholesterol

The liver also secretes cholesterol extracted from the blood into the bile

73
Q

what is one of the mechanisms for maintaining cholesterol homeostasis in the blood

A

Bile secretion, followed by excretion of cholesterol in the faeces, is one of the mechanisms for maintaining cholesterol homeostasis in the blood

74
Q

How is cholesterol made insoluble in water but soluble in bile

A

Cholesterol is insoluble in water, and it solubility in bile is achieved by its incorporation into micelles (whereas in blood, cholesterol is incorporated into lipoproteins)

75
Q

when is bile secretion greatest

A

Although bile secretion is greatestduring & just after a meal, the liver is always secreting some bile

76
Q

What happens to hepatic bile when the sphincter of oddi is closed

A

When this sphincter is closed, the dilute bile secreted by the liver is shunted into the gallbladder - here the bile is concentrated as some of the NaCl & water is absorbed into the blood

77
Q

Surrounding the common bile duct at the ampulla of vater is a ring of smooth muscle known as the

A

sphincter of Oddi.

78
Q

what kind of system is the bile system

A

low pressure

79
Q

how is the bile system low pressure

A

So when the gallbladder fillswith bile it must exhibit adaptive relaxation - which is where the size increases but the pressure doesn’t (opposite of what happens when you blow up a balloon)

80
Q

Shortly after the beginning of a fatty meal what hormone is released, in response to what

A

the hormone cholecystokinin (CCK) is released in response to the presence of fat in the duodenum

81
Q

what does CCK do

A

CCK causes the gallbladder to contract & the sphincter of Oddi to relax resulting in the flow of bile down the cystic duct through the common bile duct and into the duodenum where it mixes with the food in the duodenum & lipid digestion occurs

LIVER & FRIENDS (11 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions