Continuation of Lipids to Lipid Digestion (copy)
Chapter 1: Introduction
Discussion on protein metabolism and urea cycle
Urea cycle is the end product of protein metabolism
Urea cycle is also known as Krebs Hensulate Urea Cycle or Ornithine Cycle
Urea cycle involves two nitrogen atoms: ammonia and aspartic seeds
Urea cycle is closely linked to the citric acid cycle
Chapter 2: Urea Cycle Steps
Formation of carbamoyl phosphate from ammonia and carbon dioxide
Conversion of carbamoyl phosphate to citrulline
Conversion of citrulline to argininosuccinate
Conversion of argininosuccinate to arginine
Conversion of arginine to ornithine with the help of urea
Chapter 3: Hyperammonemia and Enzyme Deficiencies
Hyperammonemia is a condition characterized by high levels of ammonia in the blood
Different diseases associated with urea cycle enzyme deficiencies: pachyhyperammonemia type 1, hyperammonemia type 2, hyperornithinemia, citrullinemia, argininosuccinic aciduria, hyperarginemia
Each disease is associated with a specific enzyme deficiency and has characteristic features and inheritance patterns
Chapter 4: Treatment and Metabolic Defects
Treatment for argininosuccinate deficiency involves providing excess arginine in the diet and restricting total protein intake
Metabolic defects in amino acid metabolism, such as phenylketonuria (PKU), can result in mental retardation and other developmental abnormalities
PKU is caused by a deficiency of phenylalanine hydroxylase and is the most common clinical inborn error of amino acid metabolism
Newborn screening tests, including PKU screening, are done to prevent mental retardation
Chapter 1: Phenylketonuria (PKU)
Elevated levels of phenylketones in urine can be detected using ferric chloride test
Positive test indicated by transient blue-green color in urine
Early detection is important for treatment
Treatment involves a diet low in phenylalanine, such as tapioca cassava
After 5 years, patient can have a normal diet
Chapter 2: Maple Syrup Urine Disease (MSUD)
MSUD is a branched chain ketoaciduria
Symptoms include poor feeding, lack of energy, seizures, mental and physical retardation
Diagnosis is done using mass spectrometry
Treatment involves a restricted diet, frequent testing, and IV fluids
sugars are avoided in patients
Chapter 3: Albinism
Albinism is a group of conditions with a defect in tyrosine metabolism
Results in deficiency in production of melanin
Different types include oculocutaneous albinism, ocular albinism, Hermansky-Pudlak syndrome, Chediak-Higashi syndrome, and Griscelli syndrome
Symptoms include vision problems, sensitivity to light, impaired vision, and blindness
Diagnosis is done through genetic testing or family history
Treatment involves managing symptoms, such as wearing sunglasses and protective clothing
Chapter 4: Homocystinuria
Homocystinuria is a defect in homocysteine metabolism
Symptoms include intellectual disability, failure to grow, seizures, and megaloblastic anemia
Treatment involves vitamin B6 supplements and avoiding high protein foods
Chapter 5: Alkaptonuria
Alkaptonuria is a defect in phenylalanine and tyrosine degradation
Characterized by black urine
Diagnosis is done through ferric chloride and Benedict's tests
Other genetic disorders affecting amino acid catabolism are listed in a table
Chapter 6: Glycinuria
Glycinuria is a rare disorder characterized by high excretion of glycine in urine
Increased tendency for formation of oxalate renal stones
Urinary oxalate level is normal in patients with glycinuria
Chapter 1: Primary Hyperoxaluria and Tyrosinemia
Primary hyperoxaluria is a disorder characterized by increased urinary oxalate and deposition of oxalate in various tissues.
Urinary oxalate is endogenous in origin, not due to dietary consumption of oxalate.
Primary hyperoxaluria is caused by a defect in glycine transaminase and impairment in glyoxylate oxidation.
Tyrosinemia type 2, also known as Richter Hanhardt syndrome, is a defect in the enzyme tyrosine transaminase.
Results in blockade in the degradation pathway of tyrosine and accumulation of tyrosine and its metabolites.
Symptoms include dermatitis, eyelashes, mental retardation, and disturbed self-coordination.
Neonatal tyrosinemia is a temporary condition caused by the absence of the enzyme pyruvate dioxygenase.
Responds to ascorbic acid, which overcomes the substrate strict inhibition of the enzyme.
Chapter 2: Parkinson's Disease
Parkinson's disease is a common disorder characterized by muscular rigidity, tremors, expressionless face, lethargy, and involuntary movement.
Linked with decreased production of dopamine, a neurotransmitter associated with happiness.
Treatment includes dopa or levodopa, which helps increase dopamine levels.
Chapter 3: Hartnup's Disease
Hartnup's disease is a hereditary disorder of tryptophan metabolism.
Symptoms include dermatitis, ataxia, mental retardation, and low plasma levels of tryptophan.
Increased urinary output of indole acetic acid and indolepyruvic acid.
Impairment in absorption and transport of tryptophan and other neutral amino acids.
Chapter 4: Cystinuria
Cystinuria is a common inherited disease characterized by increased excretion of cysteine.
Defective carrier system leads to exclusion of cysteine and other amino acids in urine.
1 in 7,000 people are affected by cystinuria.
Chapter 5: Amino Acid Metabolism Disorders
Table of inborn errors of amino acid metabolism includes phenylketonuria, tyrosinemia, cystinuria, cystinosis, homocystinuria, and more.
Chapter 6: Amino Acids as Neurotransmitters
Glycine is an inhibitory neurotransmitter in the spinal cord.
Dopamine and serotonin are neurotransmitters associated with happiness and regulation of cerebral activity and behavior.
Phenylalanine is involved in the synthesis of norepinephrine and epinephrine.
Chapter 7: Protein Sources and Allergies
Nuts are an excellent source of protein and consuming them regularly reduces the risk of heart attacks and heart diseases.
Other protein sources include meats, seafood, poultry, eggs, dairy products, soy, quinoa, and buckwheat.
Allergies to nuts and seafood can be managed by consuming alternative protein sources.
Chapter 8: Introduction to Lipids
Lipids are organic substances made of fatty acids and their derivatives.
They are insoluble in water and considered hydrophobic.
Lipids are important dietary constituents due to their high energy value, fat-soluble vitamins, and essential fatty acids.
They serve as a long-term energy source, thermal insulator, and component of cell membranes.
Chapter 9: Functions and Classification of Lipids
Triglycerides are a secondary energy source, thermal insulator, and protect tissues from physical trauma.
Cholesterol is a precursor of biological hormones, source of bile acids, and component of cell membranes.
Phospholipids are components of cell membranes and associated with vital life processes.
Lipids are classified into simple lipids, compound lipids, and derived lipids.
Chapter 10: Simple Lipids
Simple lipids include neutral fats (triglycerides) and waxes.
Neutral fats are composed of glycerol and fatty acids.
Waxes are esters of higher alcohols and have various functions.
Chapter 11: Fat-Soluble Vitamins
Fat-soluble vitamins include vitamin A, D, E, and K.
Vitamin A is responsible for vision and immune system function.
Sources of vitamin A include carrots, sweet potatoes, spinach, and cantaloupe.
Vitamin D has various functions and can be obtained from sunlight exposure and certain foods.
Bone Development, Immune System, and Moods
Fatty fish, beef liver, eggs, and mushrooms are rich in vitamins for bone development, immune system, and moods.
Sunflower seeds are a good source of vitamins for skin health, antioxidant properties, and fat digestion.
Vitamin K and its Sources
Vitamin K is essential for blood clotting, bone and tissue development.
Leafy greens, broccoli, Brussels sprouts, asparagus, and cauliflower are good sources of vitamin K.
Compound or Complex Lipids
Compound or complex lipids consist of glycerol, fatty acids, nitrogenous base, and phosphoric acid.
Phospholipids contain phosphate and phosphoric acid, with three types: gensilecithin, c cephaline, and liposetal.
Gensilecithin is also known as phosphatidylcholine, which contains choline as a nitrogenous base.
Cephaline is also known as phosphatidyl ethanolamine.
Lipositol is also known as inositol.
Phosphatidylserine contains serine as a nitrogenous base.
Types of Phospholipids
Plasma lecithin resembles leucine and cephalicine in structure.
Sphingomyelin contains sphingosine and choline as nitrogenous base.
Glycolipids are fatty acids that contain carbohydrates and nitrogenous base.
Derived Lipids
Derived lipids are the products of hydrolysis of simple and compound lipids.
They include saturated and unsaturated fatty acids, monoglycerides, glycerides, squalene, carotenoids, and vitamins D, E, and K.
Cholesterol is a major component of cell membranes and is involved in the synthesis of steroids, bile acids, and vitamins.
Intake of cholesterol should not exceed 300 milligrams per day.
LDL is the bad cholesterol, while HDL is the good cholesterol.
Good and Bad Fats
Monounsaturated and polyunsaturated fats are considered good fats.
Olive oil, nuts, oily fish, and avocado are examples of good fats.
Saturated and trans fats are considered bad fats.
Butter, cheese, creams, cakes, and fried foods are sources of bad fats.
Types of Fatty Acids
Saturated fats have all carbon atoms bonded to hydrogen atoms and raise blood cholesterol.
Unsaturated fats, such as monounsaturated and polyunsaturated fats, lower bad cholesterol.
Omega-3 and omega-6 fatty acids reduce the risk of heart diseases and lower LDL cholesterol.
Trans fats are unsaturated fats created through hydrogenation and increase bad cholesterol while lowering good cholesterol.
Sources of Trans Fats
Trans fats can be found in fast foods, packaged foods, baked goods, frozen foods, and chips.
Benefits of Reading Food Labels
Reading food labels helps in selecting foods low in trans fats and saturated fats.
Avoid products that contain hydrogenated, fractionally hydrogenated, or partially hydrogenated oils.
Esters and Fats
Esters are fatty acids combined with glycerol to form fats.
Simple glycerides have the same fatty acid chain, while mixed glycerides have different fatty acid chains.
Animal fats, butter fat, and human fat have different fatty acid compositions.
Chemical Properties of Lipids
Lipids have various chemical properties that contribute to their functions in the body.
Hydrogenation
Hydrogenation converts carbon double bonds to single bonds in unsaturated fats
Hydrogen gas is bubbled through heated oil in the presence of nickel
Oxidation of double bonds occurs in the presence of oxygen and microorganisms
Products of hydrogenation are short chain fatty acids and aldehydes with disagreeable odors
Saponification
Saponification is the hydrolysis of fats by an alkali to form soaps
Fats are hydrophobic and resist water, while soaps are hydrophilic and water-loving
Fats have a long chain hydrocarbon tail and a hydrophilic head
Saponification involves the formation of carboxylic acid group fatty acids
Digestion of Fats
Complete hydrolysis of fats occurs through the action of bile and lipases
Bile emulsifies and solubilizes fats for digestion
Incomplete digestion of fats can still occur with the help of lipases
Fatty acid esters are resistant to hydrolysis and can be absorbed and deposited in fat tissue
Unabsorbed fats or fatty acid esters are excreted in feces
Intestinal Absorption of Fats
40% of ingested triglycerides are hydrolyzed to fatty acids and glycerol
3 to 10% of triglycerides are absorbed as 3-glycerides
The rest are partially hydrolyzed to become beta monoglycerides
Glycerol is water-soluble and absorbed via the portal route
Fatty acids are water-insoluble and predominantly absorbed via the intestinal lymph
Lipid Metabolism
Lipolysis is the breakdown of lipids
Lipolysis will be discussed in the next meeting
Lipid metabolism will be the topic of the next discussion