Level 1 Semester 2 Module (Blood and Immune) PDF

Level 1 Semester 2 Module (Blood and Immune)  Basal Metabolic Rate Prof. Ahmed Abdalfattah Professor of Medical Physiology  The Basal Metabolic Rate Energy output (Expenditure)/ square meter of body surface area(m2)/Hour under the following basal conditions: Complete physic...

Level 1 Semester 2 Module (Blood and Immune)  Basal Metabolic Rate Prof. Ahmed Abdalfattah Professor of Medical Physiology  The Basal Metabolic Rate Energy output (Expenditure)/ square meter of body surface area(m2)/Hour under the following basal conditions: Complete physical and mental rest Post absorptive state (12-14 hour after the last meal) Comfortable environment (room temperature 20-24 degree when the person is dressed N.B.  The absorption of energy carriers from the intestine is not continuous; it rises to high levels over a 4-hour period following each meal (the absorptive state) and tapers toward zero between meals, after each absorptive state has ended (the postabsorptive, or fasting, state)  Method of determination  By indirect calorimetry  Under basal conditions  The energy output is calculated/ hour and then subdivided on the surface area and expressed as C/meter square/Hour  Surface area can be obtained from DuBois chart  Significance of BMR It investigates the metabolic rate in absence of the major factors that affect it (muscular activity, emotions, food intake, environmental temperature) Judging the metabolic rate of the individual relative to the standard of the same age and sex. BMR in young adult males= 40 C/M /hour And represents the unavoidable cost of life i.e energy expenditure liberated as a result of the vital activities of the body as heart beating, respiratory movements……….  Clinical expression of BMR  BMR is expressed as the percentage of increase or decrease from the normal slandered value. 2  If BMR = 60 C/ M /h meaning it is +50%  BMR is considered normal if ± 15% of the slandered What's meant by BMR as +? 50% this means that It exceeds the normal standard value by 20C  BMR of an individual is 60C/m2/hour Measurement of BMR A. Direct Calorimetry B. Indirect calorimetry: Direct Calorimetry Indirect calorimetry Factors affecting the BMR: A) Physiological factors B) Pathological factors C) Chemical factors  A. Physiological factors 1-Age: Newborn 1.5—2 times as the adult Adult 40 C/Meter square/Hour Slight rise at the age of puberty Then decline1C every 10 years  A. Physiological factors -2 Sex: BMR is lower in females than males by.7% This difference is not due to endocrine differences because, it is present in children. It may be due to greater stores of fat in females (fat has little metabolic activity) 3- Race: Orientals and Africans have lower BMR than Europeans. 4- Dietetic Habits: The habit of eating protein rich diet for long periods increases BMR by 10 % more than eating carbohydrates. 5- Physical Activity: Athletes have higher 10% BMR than ordinary persons due to their muscle bulk and small store of fat. 6- Climate : BMR is higher 10% in cold zones (e.g. Europeans& Eskimos) than in hot zones. 7- Pregnancy: BMR gradually increases during pregnancy till doubled (100%) by its end and return normal after delivery due to: a) Increase thyroxin secretion. b) Added metabolism of fetus. -8Anxiety and tension: BMR increased due to increase epinephrine secretion and increased muscle tone  B. Pathological factors BMR increased in: 1 Hyperthyroidism (BMR increases up to.)100% 2 Hyperfunction of adrenal medulla (pheochromocytoma.) 3 Hyperfunction of adrenal cortex (Cushing's disease.) 4 Hyperpituatrism. 5 Fevers (BMR increases 10-14% for each 1.0°C rise in body temperature.) 6 Certain diseases: e.g:. Diabetes insipidius. Heart failure. Blood diseases  e.g. (leukemia & polycythemia.)  BMR decreased in 1. Hypothyroidism: cretinism & myxedema. 2. Hypopituatrism. 3. Hypofunction of adrenal cortex(Addison's disease.) 4. Hypothermia (a drop of body temperature by 1.0°C  decrease BMR by 10-.14% 5. Certain diseases:  e.g. shock & nephrotic syndrome. 6. Starvation.  C. Chemical factors  Factors increase BMR 1. Thyroxin: It increases BMR for long period. 2. Adrenaline: It increases BMR rapidly and for short period..3Sympathomimetic drugs  The specific dynamic action (SDA) obligatory increase in the metabolic rate that occurs after recent ingestion of food. Or, it is the power of food to stimulate metabolic rate  It starts about 1 hour following food intake. It reaches maximum within 4-5 hours. It decreases to basal level in 12-14 hours  Factors affecting SDA 1. Type of food ingested 2. Amount of food 3. External (environmental) temperature  1. Type of food ingested Proteins: increase the metabolic rate by about :30% Low biological value proteins & high biological value proteins produce the same SDA. So, SDA is not related to the biological value of proteins. Carbohydrates: increase it by.6% Fat: increases it by.4% Mixed diet: increases it by about.10%  2. Amount of food SDA is directly proportionate to the amount of food  3. External (environmental) temperature The excess heat produced as a result of SDA is completely lost fom the body at atmospheric temperature about 33oC Decrease body temperatre,, causes (SDA retained in the body to maintain the body temperature constant) At environmental temperature of 5°C SDA disappears because, in this condition, all the released heat is used to maintain body temperature, and the SDA= zero  Causes of SDA.1 The SDA of protein may be due to: a) The metabolic processes of amino acids in the liver (particularly the process of deamination & urea formation) (SDA of proteins disappear after hepatectomy). b) Direct stimulating effect of amino acids on the metabolic process in the tissues. 2. The SDA of carbohydrates may be due to: The metabolic processes that occur to them in the liver e.g. glycogenesis. 3.The SDA of fats may be due to: A direct stimulating effect of fatty acids on the metabolic processes in the tissues.  Also, the SDA is probably caused by: an increased sympathetic activity after good ingestion  Uses of SDA The heat of the SDA is a waste heat. It is not used by the body except in: 1. Cold climate: SDA of proteins is used to maintain body temperature constant. 2. Muscular exercise: SDA of carbohydrates is used Q2/: About SDA, what its value for protein diet& At which environmental temperature disappear? Q3: What does this equation estimate& mention 2 factors affecting it?