Lecture 4 - Macronutrients (LIPIDS) Flashcards
Fatty acids linked together to a glycerol backbone
Fats (triglyceride)
Cholesterol, phospholipids, waxes, and steroids are all examples of…
Lipids
Lipids are the most _____________ sources of energy and can be nutritionally beneficial for animals with low appetites
Concentrated
Are lipids polar (water soluble) or non-polar (water insoluble)?
Non-polar (thus providing a way for water insoluble nutrients to be absorbed)
Fatty acids that are NOT attached to glycerol are called…
Free fatty acids or non-esterified fatty acids (NEFA)
True or False: Free-fatty acids vary in their number of non-saturated carbon double bonds (C=C), and a higher number of non-saturated bonds means higher fluidity for the structure
True
True or False: Free fatty acids are less prone to rancidity and oxidative damage
False; they are MORE prone to damage from these factors
Common dietary fatty acids come from (3 main sources)…
Animal sources, marine sources (algae and fish), and plant sources
How are fatty acids numbered?
Number of carbons, number of double bonds, and double bond location
Example 1: Palmitic acid (16:0)
Example 2: Eicosapentaenoic acid (EPA; 20:5) n-3
True or False: While some essential fatty acids can be synthesized by gut microbes, some are required in the diet
True
An essential omega-6 fatty acid for dogs and cats that is important for immune function and skin barrier function
Linoleic acid
Corn oil, safflower oil, walnut oil, canola oil, and cottonseed oil are all high in which type of fatty acid?
Linoleic acid
An essential omega-6 fatty acid in cats which can be metabolized from linoleic acid (inefficient process in cats) and is important for immune function and reproductive success in queens
Arachidonic acid
Animal fats, such as chicken and eggs, are high in which type of fatty acid?
Arachidonic acid
Essential omega-3 polyunsaturated fatty acid that is plant-based and ensures adequate neuronal function; may be transformed to long chain omega-3 fatty acids in some species (not typically in cats and dogs)
Alpha linolenic acid
Long-chain omega-3 fatty acids important for neural function and development; comes from marine sources
(2 fatty acids)
EPA (eicosapentaenoic acid)
DHA (docosahexaenoic acid)
Vitamins A, D, E, and K are all examples of what type of vitamins?
Fat soluble vitamins
True or False: Fat soluble vitamins (such as vitamin A, D, E, and K) carry a lower risk for excess
False; there is a HIGHER risk for excess in fat soluble vitamins rather than water soluble vitamins
What is the general composition of lipoproteins?
Droplets of fats surrounded by a single layer of phospholipids
What is the function of lipoproteins?
Transportation of hydrophobic lipid molecules n blood plasma or other ECFs
True or False: Small lipoproteins have a higher density
True
Triacylglycerols, proteins, and diameter are all factors that determine a lipoprotein’s ___________.
Density
True or False: Lipoproteins with more triacylglycerols are lighter in terms of density
True
Why are chylomicrons water soluble?
They have a phospholipid monolayer
In chylomicrons, non-polar lipids are located on the _________ whereas the water soluble phospholipids are in the _____________.
Inside; envelope
Lipoprotein responsible for fat transport from gut to peripheral tissues
Chylomicrons
Lipoprotein responsible for delivering lipids from peripheral tissue to liver
HDL (high density lipoproteins)
Lipoprotein formed when triglycerides are removed from VLDL by lipoprotein lipase enzyme (LPL) and become smaller and denser
LDL (low density lipoprotein)
Lipoprotein assembled in the liver from triglycerides, cholesterol, and aplipoproteins; transports endogenous products to peripheral tissues
VLDL (very low density lipoproteins)
What is stage 1 of fat digestion?
Fat is emulsified with bile acids
(hydrophobic portion of bile acid interacts with the lipid, while hydrophilic domains remain at the surface)
What is stage 2 of fat digestion?
Hydrolysis of triglyceride into monoglyceride and free fatty acids by pancreatic lipase
Why is stage 1 of fat digestion required before stage 2 can occur?
Because pancreatic lipase (PL) is water soluble
What is stage 3 of fat digestion?
Reformation of triglyceride molecules in the enterocytes (in the small intestines)
What is stage 4 of fat digestion?
Triglycerides are packaged with phospholipids, cholesterol, and protein (specifically apoprotein B) to create chylomicrons
What is stage 5 of fat digestion?
Chylomicrons are absorbed through lymphatic vessels in the intestines which drain into the thoracic duct
What is stage 6 of fat digestion?
Thoracic duct is drained into the jugular vein
What is the function of lipoprotein lipase?
Breakdown of triglycerides and allow fat absorption in peripheral tissues
What happens to chylomicron remnants after fat digestion and absorption is completed?
They are transported to the liver
_____ and ____ are formed in the liver from triglycerides and cholesterol, and they are transported from the liver to peripheral tissues
VLDL; LDL
Which type of lipoprotein ends up returning to the liver and is cleared from the bloodstream?
LDL
Medium chain triglycerides (MCTs) are commonly found in…
(Hint: two answers, types of oil)
Palm kernel oil and coconut oil
How are MCTs primarily absorbed?
Through the portal vein system (likely in addition to lymphatic system in dogs and cats)
How long are medium chain triglyceride hydrocarbon tails?
6 to 12 carbons long
Hyperlipidemia, chylothorax, and lymphangiectasia are all disorders of…
Lipid absorption
The accumulation of lymphatic fluid (chyle) in the pleural space; often idiopathic in nature, but may be linked to heart disease, enlarged thyroid, heartworm disease, and several other pathologies that disrupt chyle flow
Chylothorax
(Extra info: reported in dogs and cats, rare in horses)
How is chylothorax often diagnosed?
PE findings (usually respiratory signs), radiograph changes, analysis of chest fluid via thoracocentesis
What are some treatment options for chylothorax?
- Emergency chest tube placement
- Surgical intervention (i.e. thoracic duct ligation)
- Low-fat diet (to reduce fluid lipid content, may reabsorb)
- Nutraceuticals (Rutin - used to stimulate MQs to help break down protein in fluid)
Pathological dilation of intestinal lymph vessels; may be the result or cause of another enteropathy; clinical signs include chronic diarrhea, weight loss, protein loss (pleural effusion/low albumin), and low calcium and vit D (seizures/tremors/ataxia/lethargy)
Intestinal lymphangiectasia
How is intestinal lymphangiectasia diagnosed?
- PE/relevant clinical signs
- Lab results (low albumin, cholesterol, lymphocytes, and calcium)
- Endoscopy reveals abnormal intestinal mucosa
- Intestinal biopsies
How is intestinal lymphangiectasia treated?
- Anti-inflammatory/immunosuppressive drugs
- Low fat diet (to avoid long chain triglycerides)
- Careful supplementation with fat soluble vitamins
Turbidity in a sample (such as blood plasma or serum) caused by accumulation of lipoprotein particles
Lipemia
An increase in triglycerides and cholesterol in the blood
Hyperlipidemia/hyperlipoproteinemia/dyslipidemia
Increased cholesterol in the blood
Hypercholesterolemia
Increased triglycerides in the blood
Hypertriglyceridemia
Most common cause for hyperlipidemia; it results in an increase in chylomicrons
Eating a meal
(Extra note: also called prandial; the period after eating a meal, when the hyperlipidemia occurs, is post-prandial)
What causes primary hyperlipidemia?
Genetics/familial causes
What causes secondary hyperlipidemia?
Disease
(Examples: renal disease, diabetes, Cushing’s disease, hypothyroidism, neg energy balance in overweight animals)
A rare recessive autosomal disorder in cats resulting from reduced LPL
Inherited Fasting Hyperchylomicroanemia (Primary Hyperlipidemia)
True or False: In terms of hyperlipidemia in dogs, lipoprotein accumulation differs depending on the breed of dog
True
(Example: mini schnauzers tend to have increased VLDL or VLDL and chylomicrons)
True or False: Clinical signs and therapy approaches for primary hyperlipidemia differ according to the type of lipoproteins involved
False; clinical signs and therapy approaches are the same regardless of the type of lipoproteins involved
Pancreatitis, dystrophic changes, insulin resistance, hepatobiliary disease, and seizures are all clinical signs for…
Primary hyperlipidemia (in dogs)
How is primary hyperlipidemia in dogs diagnosed?
- Elevated serum triglycerides and cholesterol
- Moderate hypertriglyceridemia may be suspected
What must be ruled out before officially diagnosing a dog with primary hyperlipidemia?
- Check if the dog has recently eaten (must be fasted prior to bloodwork)
- Underlying metabolic disease
Low fat diet, long-chain polyunsaturated omega-3 fatty acids (PUFA), fibrates, niacin, and statins (HMG-CoA reductive inhibitors) are all possible treatment options for…
Primary hyperlipidemia (in dogs)
What is the most efficient way to treat secondary hyperlipidemia in dogs?
Treat the underlying condition causing the hyperlipidemia
What are some of the most common causes of secondary hyperlipidemia in ponies?
Stress, gestation, disease
A condition resulting from lipid accumulation in the liver as a result of them being mobilized there as an energy source
Hepatic lipidosis
