University of Zakho Metabolism Module Lecture One PDF

University of Zakho College of Medicine Metabolism Module / Session One Lecture One Dr Lina Yousif Mohammed Email: [email protected] Metabolism Module / Session One Lecture One Ov...

University of Zakho College of Medicine Metabolism Module / Session One Lecture One Dr Lina Yousif Mohammed Email: [email protected] Metabolism Module / Session One Lecture One Overview of nutrient metabolism Metabolic energy Metabolic rate Nutritional requirements  Aims of the lecture To understand the overall functions of metabolic processes in the body, including: Components of the overall energy utilization of the body. How this is met by nutrition? The essential components of the human diet.  Energy All living things use energy constantly to: Resist entropy - Constant repair Support growth Support the activity of tissues In the case of mammals & birds to maintain constant body temperature  Energy Capacity to perform work Cells perform different type of work – Biosynthetic – Transport – Mechanical – Electrical Energy exists in many inter-convertible forms. Raw materials Raw materials Body constituents must be made from basic materials: – Derived from diet - Essential nutrients – Inter-converted and combined by Expenditure of Energy ted and combined by  Metabolism GIT Blood Tissues Food Inter conversion ↓ ↑ Nutrient→→ Nutrient →→ Storage ↓ ↑ Loss (feces) Loss (kidneys) Utilization →→ Synthesis ↓ Oxidation →→ Energy ↓ ← Waste products  Metabolism Is the processes which derive energy and raw materials from food stuffs and use them to support Repair, Growth, and Activity of the tissues of the body  Metabolism Catabolism – Breaks down large molecules to small molecules to release Energy Anabolism – uses Energy to make molecules for growth and maintenance  Chemical bond energy All chemical reactions: – Involve breaking and formation of chemical bonds – Breaking bonds releases energy making them uses energy Reactions where more energy is released than used are exergonic Reactions where more energy is used than released are endergonic  Coupling Metabolism is all about coupling the energy released by exergonic reactions to that needed for endergonic reactions. Needs an intermediate process –The ADP/ATP cycle ATP- ADP cycle  Nutrition We eat about 500Kg of food a year, providing: – Energy – General purpose building blocks including amino acids, carbohydrates, lipids – Specific nutrients including vitamins & minerals – Water – Fibers  Blood Contains many chemicals – Nutrients from diet on way to tissues for Utilization Storage Inter-conversion – Nutrients released from storage on way to utilization elsewhere – Materials produced in cells for blood itself Proteins, clotting factors etc – Waste products from tissues on way to excretion  Blood concentrations Concentration of most things in blood is constant: – Supply from nutrients is fluctuating – Demand for substances very variable Some cells must: – Store nutrients – Interconvert molecules At variable, but controlled rate  Tissues affecting nutrient concentrations Tissue Storage Interconversion Utilisation Kidney No Yes Yes Liver Yes Yes Yes Adipose tissue Yes No Yes Skeletal muscle Yes No Yes Red blood cells No No Yes Heart muscle No No Yes Brain No No Yes  Nutrients & waste products in fasting blood plasma Glucose 5 mmol.l-1 Amino acids 2 mmol.l-1 Triacyl glycerol 2 mmol.l-1 Cholesterol 5 mmol.l-1 Fatty acids 0.5 mmol.l-1 Nutrients & waste products in fasting blood plasma Lactate & Pyruvate 97% of population  Energy Intake & Body weight If energy intake equals expenditure, the body weight will be stable. If intake exceeds expenditure, the energy stores will increase. If expenditure exceed intake: First energy stores will deplete, then other body components (principally protein) will be utilized to provide energy  Body composition 70 kg man 100 kg man Carbohydrate (kg) 1 1 Lipid (kg) 11 39 Protein (kg) 11 12 Mineral 4 4 Water 42 43  Energy Stores Very short term stores of energy rich molecules in muscle – few seconds Carbohydrate stores for immediate use as glycogen – 0.1 kg in liver – 0.3 kg in muscle – Don’t last long - minutes or hours depending on activity Long term stores in adipose tissue as lipid – 11x37000kJ - About 40 days Muscle protein can be converted to carbohydrate – Support tissues (lipids cannot) – About 6kg available – By Gluconeogenesis  Ideal Body Weight That associated with long life Body Mass Index :Weight in kg divided by height in m squared  BMI Male Female 30 Obese  Obesity A major potentially preventable cause of death in developed world – Diabetes – Hypertension – Heart disease – Gall bladder disease  Malnutrition Malnutrition: is any condition caused by an in-balance between what an individual eats and what that individual requires to maintain health. It results from eating too little (under-nutrition) or too much (over-nutrition) and may also be caused by an incorrect balance of nutrients.  Protein-energy malnutrition This clinical condition is seen in starving adults and children. Starvation in adults leads to loss of weight due to loss of subcutaneous fat and muscle wasting.  Protein-energy malnutrition Major potentially preventable cause of death in developing world Marasmus: is the type of protein-energy malnutrition most commonly seen in children under the age of 5. The child looks emaciated(very thin and week) with obvious signs of muscle wasting and loss of body fat although there is no oedema. The hair is thin and dry, diarrhea is common and anaemia may be present. Kwashiorkor : occurs typically in a young child displaced from breastfeeding by a new baby and fed a diet with very low protein content. The child is apathetic, lethargic and anorexic (loss of appetite). There is generalized oedema. The abdomen is distended(swollen) owing to hepatomegaly (enlarged liver) and/or ascites (accumulation of fluid in peritoneal cavity). The serum albumin is always low and anaemia is common.