Lipids Flashcards
What are the functions if white adipose tissue?
It is a complex metabolically active endochrine tissue with the following functions-
- Secretion of-
-hormones
-enzymes
-cytokines - Protection of organs
- Provides insulation
Name the different lipids that exist in the human body
Fatty Acids
Triglycerides
Phospholipids
Cholersterol
Steroid compounds (eg. oestrogen)
Sphingolipids (found in nerve cell membranes e.g. Myelin)
Glycolipids (lipids +carbohydrate) involved in cell identity
Cerebrosides (in the brain)
Fat doluble vitamins A, D, E, K
How many calories does each gram of fat provide?
9 kcal
Give 5 functions of lipids
- Energy (ATP production)
- Energy storage
- Cell membrane structure
- Thermal insulation (subcutaneous fat)
- Organ protection (visceral fat)
Define what it meant by a short chain fatty acid
One with fewer that 6 carbon atoms
Name the 3 most common SCFAs
Acetate, propionate and butyrate
Why is Butyrate particularly important for colon health
It is the primary energy source for colonocytes and supports intestinal tight junctions
It has an anti-inflammatoy effect on the colon
What is a Fatty Acid?
Hydrocarbon chains with an acid group at one end and a methyl group on the other
What are the properties of a medium chain fatty acid
-Has 6-12 carbon atoms
-Can travel directly to the liver where they can be used to create energy or ketones
-good source of energy before excercise
What are the properties of a long chain fatty acid?
-Have 14-22 carbon atoms
-Used the build cell membranes
What are the properties of Saturated fatty acids?
-Contain no CC double bonds
-All the carbons are completely saturated with hydrogen bonds
-Solid at room temperature
-Stable oil
-Best oil to cook with at high temperatures
What are the proerties of Unsaturated Fatty Acids?
-Contain 1 or more double bonds between carbons
-Liquid at room temperature
How many double bonds do Mono unsaturated fatty acids have?
One
How many bonds do Polyunsaturated Fatty Acids have and how does this affect it’s stability?
Several double bonds. This makes it more unstable as the more double bonds the less stable and the more susceptible to oxidisation it becomes.
What are trans fats and why are they to be avoided?
Unsaturated fats that are made saturated by the addition of hydrogen (hydrogenised).
To be avoided because-
-They stiffen cell membranes, making them prone to oxidation, and alters their permeability, impeding normal cell function
-They alter blood triglyceride and cholesterol levels which increases risk of CV disease, insulin resistance and cancer.
Explain the difference between a Cis fat and a trans fat?
Cis- The hydrogen atoms are on the same side as the double bond
Trans- The H atoms are on seperate sides of the double bond.
What is a Triglyceride?
Lipid mollecules made up of 1 unti of glycerol and 3 fatty acids.
They are the major form of dietary fat and the form in which fat is stored.
Why are high trglycerides considered bad?
Linked to atherosclerois.
What triggers the body to synthesise triglycerides?
Whenever caloric intake exceeds energy requirements.
Excess energy is converted to trglycerides in a process known as lipogenesis and excess ingested fat is taken up by adipose tissue
Where does Lipogenesis take place?
In adipose tissue and the liver
Define Lipogenesis?
The process through which acetyl-Co-A is converted to tryglycerides for storage in fat.
Define Lypolysis
When dietary energy is limited, the fatty acids from triglycerides are mobilised from adipocytes into circulation
What is Lipolysis stimulated by?
-Adrenaline and noradrenaline
-Adrenocorticotropic hormone (ACTH)
-Glucagon
-Growth hormone
-TSH and thyroxine
What is Lipolysis inhibited by?
Insulin
Insulin resistance=central adiposity
Describe the process of the convertion of fatty acids to energy
Fatty acids can cross the cell membrane, traverse the cytosol and reach the motochondria
What amini acid is needed to transport the fatty acid across the cell membrane?
Carnitine
Describe the process of Beta-oxidation
Fatty acids are broken down into 2-carbon blocks as acetyl CoA which is oxidised via the Krebs cylce to CO2 and H2O. Energy is then generated using the electron transport chain.
What triggers ketone production?
Glucose being in short supply
What is Ketogeneis?
acetyl-CoA is converted to the ketones-
acetoacetate or B-hydroxybutyrate
For most adults what is the maximum carbohydrate level in grams that will allow you to get into ketosis
40 g per day
Name 4 theraputic used of ketosis
-weightloss
-epilepsy management
-Parkinsons and Alzheimers disease
Describe the process of lipid digestion
-Gastric lipase in the stomach and pancreatic lipase in the duodenum separate the glycerol from the fatty acids
-The resulting 2 fatty acids and monoglyceride are transported into enterocytes where they are rebuilt in the cell, packaged into chylomicron and transported via the lymphatic system to the blood stream where they are used for energy or stored in adipose tissue.
How does Bile facilitate fat digestion?
Emulsifies the fat to increase the surface area
Name 3 things you can do to support fat digestion
- Chew food and avoid liquid aroung meal times
- Increase bile production by optimising stomach acis
- Good hydration to increase bile flow
What can you do to increase stomach acid levels?
-Zinc
-B6
-Eat bitter food before a meal (chicory, rocket)
-stress management
Which 2 amino acids are components of bile? Name some good sources
Glycine and Taurine
Sources- legumes, sea vegetables, spinach and eggs.
Which oil can stimulate bile secretion?
Olive oil
Why are the current dietary fat reccommendations problematic?
-the fat in low fat diets is often replaces with refined carbohydrates and sugar
-Fat is satiating limiting it can lead to overeating
-It fails to distinguish the types of fat
Name 3 benefits/theraputic uses for cocnut oil
-Contains MCTs which increase the number of calories burned
-Contains 50% lauric acid which helps form monolaurin. Both have antibacterial, antiviral and antifungal properties
-Can increase HDL and lower LDL
-Preliminary studies show positive outcomes in epilepsy and AZ disease.