IB OPTION D HUMAN PHYSIOLOGY D 1 HUMAN

IB OPTION D: HUMAN PHYSIOLOGY D 1 HUMAN NUTRITION A balanced diet is essential to human health

Syllabus

Syllabus

Understanding Human Health WHO definition of Health is a state of complete physical, mental and social well-being and not merely the absence of disease or infirmity. (http: //www. who. int/about/definition/en/print. html)

Understanding Balanced Diet A balanced diet consists of the proper quantities and proportions of foods needed to maintain health and growth. These foods include carbohydrates, fats, proteins, minerals, vitamins and water.

Understanding Essential nutrients are substances that are metabolically necessary but cannot be synthesized by the organism and are therefore obtained from a dietary source. Different species may have different essential nutrients. Many essential nutrients, especially minerals, may be toxic in large

Understanding Essential nutrients Categories of essential nutrient include: • Essential fatty acids • Essential amino acids • Vitamins • Dietary minerals

Understanding Essential nutrients – fatty acids Only two fatty acids are known to be essential for humans: alpha-linolenic acid (an omega-3 fatty acid) and linoleic acid (an omega-6 fatty acid). Some other fatty acids are sometimes classified as "conditionally essential, “ meaning that they can become essential under some developmental or disease conditions. With fatty acids, the body makes lipids. http: //justnaturalplease. weebly. com/uploads/4/9/1/9/49194565/6861742_orig. jpg

Understanding Essential nutrients – amino acids An essential amino acid is an amino acid that cannot be synthesized by an organism, and therefore must be supplied in the diet. The nine amino acids humans cannot synthesize are phenylalanine, valine, threonine, tryptophan, methionine, leucine, isoleucine, lysine and histidine. Amino acids are required in the body to make proteins.

Application Amino acids – Phenylketonuria (PKU) is a rare genetic condition that causes an amino acid called phenylalanine to build up in the body. Phenylalanine is an essential amino acid and is found in all proteins and some artificial sweeteners. Your body uses an enzyme called phenylalanine hydroxylase to convert phenylalanine into tyrosine, a nonessential amino acid. Your body needs tyrosine to create neurotransmitters, such as epinephrine, norepinephrine, and dopamine. PKU is caused by a defect in the PAH gene that helps create phenylalanine hydroxylase. When this enzyme is missing, the body is unable to break down phenylalanine. This causes a buildup of phenylalanine in the body. Early diagnosis and treatment can help relieve symptoms of PKU and prevent brain damage. Healthline: phenylketonuria

Understanding Dietary minerals Dietary elements (commonly known as dietary minerals or mineral nutrients) are the chemical elements required by living organisms, other than the four elements carbon, hydrogen, nitrogen, and oxygen present in common organic molecules and in some common inorganic molecules such as water and carbon dioxide. With vitamins, They are known as the micronutrients. http: //www. bellybytes. com/articles/images/minerals. jpg

Understanding Dietary minerals – known elements https: //openparachute. wordpress. com/2013/06/16/is-fluoride-an-essential-dietary-mineral/ (from Wikipedia ‘Dietary Minerals’)

Understanding Dietary minerals – major functions http: //scienceineverydayterms. blogspot. com/2012_10_01_archive. html

Application Dietary minerals – deficiency disea Syllabus requires you to refer to calcium and rickets http: //www. biologydiscussion. com/essay-on-nutritional-deficiency-diseases/2378

Understanding Vitamins • Organic compounds • Micro-nutrients • Cannot be synthesised in the body • Therefore are essential in the diet • Classified as either: • Water soluble • Fat soluble http: //image. slidesharecdn. com/vitamins-140923104530 -phpapp 02/95/vitamins-3 -638. jpg? cb=1411469178

Understanding Vitamins – water soluble • Hydrophilic molecules with polar or ionic regions • Short-term availability – absorbed directly into blood • Therefore must be consumed daily • Excess amounts usually excreted easily in urine • Kidney cannot handle mega-doses, which may therefore be toxic. B complex vitamin showing points which are attractive to water molecules

Understanding Vitamins – water soluble http: //image. slidesharecdn. com/watersolublevitaminanditsclasses-131211103833 -phpapp 01/95/water-soluble-vitamins-1 -638. jpg? cb=1386758444

Understanding Vitamins – fat soluble • Hydrophobic molecules with primarily non-polar hydrocarbons • Dissolve in fat – in foods, in lipids for absorption and in the body • Like fats, they can be stored in the body until required • Carried in the blood as lipo-protein complexes • Can accumulate in the body and become toxic

Understanding Vitamins – fat soluble http: //www. mindfulbody. com/media/24151/screen%20 shot%202011 -04 -10%20 at%204. 20%20 pm_550 x 324. jpg

Application Vitamin C – special case Question: What have humans, guinea pigs, bats and dry-nosed primates (monkeys, tarsiers and apes) in common? Answer: Unlike all other mammals, they cannot synthesise Ascorbic acid (Vitamin C). The reason seems to be the appearance 60 million years ago of a mutant version of a gene responsibile for the production of an enzyme crucial for the synthesis of ascorbic acid from glucose. The mutation was not selected against because, presumably like today, there was sufficient Vitamin C in the diet of those animals. Vitamin C is therefore an essential nutrient for humans. Without Vitamin C, humans succumb to scurvy. http: //mentalfloss. com/article/50697/4 -diseases-caused-lack-essential-vitamins-and-minerals

Nature of Scienc Vitamin C – progress of knowledge Scurvy is one of the oldest diseases known to humans. There are probable references in the Bible and clear identification in the early Middle Ages (Jaques de Vitry 13 th C). Yet a complete understanding of the disease and its relationship with Vitamin C and ascorbic acid was not shown known until the 20 th C. Late Middle Age seafarers suffered terribly until it was realised that citrus and other fruits and fresh foods, even potatoes, could cure the disease. The disease was variously thought to be caused by infection, food poisoning, protein or mineral deficiency, depending upon the state of knowledge at the time. Several attempts were made to experiment with different mammals and birds but it wasn’t until, quite fortuitously, experiments were conducted with guinea pigs, that it was realised most mammals produced their own ascorbic acid, unlike humans. Research was also hampered by the rapid decay of ascorbic acid over time or when it is heat treated (ie pasteurised for preservation). Ascorbic acid primarily works as a co-enzyme in the synthesis of the protein collagen in the body. Without ascorbic acid, much of the connective tissue containing collagen, is improperly formed, hence the wide range of symptoms of scurvy, seen as deteriorated skin, teeth, bones and almost any other tissue formed with collagen. New research constantly shows that Vitmain C is crucially important to many other metabolic activities in the body, including the absorption of haem-iron in the gut and wound healing. There is no reliable evidence to suggest that meg-doses of Vitamin C help cure the common cold. UNHCR Vitamin C research paper 1999

International mindedne VMNIS The Vitamin and Mineral Nutrition Information System (VMNIS), formerly known as the Micronutrient Deficiency Information System (MDIS), was established in 1991 following a request by the World Health Assembly to strengthen surveillance of micronutrient deficiencies at the global level. Part of WHO's mandate is to assess the micronutrient status of populations, monitor and evaluate the impact of strategies for the prevention and control of micronutrient malnutrition, and to track related trends over time. WHO: VMNIS

Understanding Malnutrition is a broad term which refers to both under-nutrition and over-nutrition. Malnutrition can be defined as the insufficient, excessive or imbalanced consumption of nutrients. Individuals are malnourished, or suffer from under-nutrition if their diet does not provide them with adequate calories and protein for maintenance and growth, or they cannot fully utilize the food they eat due to illness. People are also malnourished, or suffer from over-nutrition if they consume too many calories. According to the World Health Organization (WHO), malnutrition is the gravest single threat to global public health.

Understanding Under-nutrition – symptoms Symptoms might include: Pallor (pale skin), fatigue, weakness, trouble breathing, unusual food cravings, hair loss, periods of light-headedness, constipation, sleepiness, heart palpitations, feeling faint or fainting, depression, tingling and numbness of the joints, menstrual issues & poor concentration.

Understanding Under-nutrition – causes UNDER-NUTRITION results from the interaction of many possible causes, which may include: • Disease and infections • Unhealthy or unsupportive environment • Poverty • Lack of education • Natural disasters or war • Eating disorders • Social problems https: //s 3. amazonaws. com/files. digication. com/M 8 dbc 16 dfdd 591359 f 08 c 1 b 77 bcc 0 b 702. png

Understanding Starvation is a severe deficiency in caloric energy intake needed to maintain human life. Energy or growth needs are not balanced by energy or protein intake. It is the most extreme form of malnutrition. In humans, prolonged starvation cause permanent tissue breakdown, organ damage and eventually, death. The term inanition refers to the symptoms and effects of starvation. Starvation may also be used as a means of torture or execution. http: //www. leighpeele. com/wp-content/uploads/2013/08/starvation-mode. jpg Wikipedia: Starvation

Application Anorexia nervosa is a serious eating disorder with multiple causes and symptoms. The principle symptom and result is intentional and sometimes extreme weight loss. If anorexia nervosa is not treated, it can result in severe health problems, including problems with the heart and blood vessels – leading to poor circulation, an irregular heartbeat, low blood pressure, heart valve disease, heart failure and swelling in the feet, hands or face (oedema). There are so many resources available about anorexia nervosa and other eating disorders. Try these: http: //www. nhs. uk/Conditions/Anorexia-nervosa/Pages/Symptoms. aspx http: //www. nhs. uk/Conditions/Anorexia-nervosa/Pages/Complications. aspx

Understanding The obesity epidemic What are overweight and obesity? Overweight and obesity are defined as abnormal or excessive fat accumulation that may impair health. Body mass index (BMI) is a simple index of weight-for-height. For adults it is defined as a person's weight in kilograms divided by the square of his height in meters (kg/m 2). WHO determinants are: • BMI equal to or less than 18. 5 is underweight • BMI greater than or equal to 25 is overweight • BMI greater than or equal to 30 is obesity The fundamental cause of the obesity epidemic is Calorie intake being greater than Calorie expenditure. The energy budget does not balance.

Understanding The obesity epidemic http: //www. heartspring. net/images/obesity_stats_by_country 673. jpg Where Does Ecuador Stand? • 23% of children under the age of five are stunted and 6% are underweight. • There are roughly equivalent numbers of overweight and underweight children in Ecuador, and overweight is increasing. • 50% of those aged 15 and above are overweight, of which 14% are obese. • 10% of infants are born with a low birth weight. World Bank: Ecuador

Understanding The obesity epidemic To. K: A map such as this shows a problem but should be treated with caution. • Whole populations? • Adults only? • Males or females? • Children? • Year? WHO Report 2012. Adults in 2008.

Understanding The obesity epidemic – health problem If you're obese, you're more likely to develop a number of potentially serious health problems, including: • High triglycerides and low high-density lipoprotein (HDL) cholesterol • Type 2 diabetes • Hypertension (high blood pressure) • Metabolic syndrome — high blood sugar, high blood pressure, high triglycerides and low HDL cholesterol • Heart disease • Stroke • Cancer, including cancer of the uterus, cervix, endometrium, ovaries, breast, colon, rectum, esophagus, liver, gallbladder, pancreas, kidney and prostate • Breathing disorders, including sleep apnea, a potentially serious sleep disorder in which breathing repeatedly stops and starts • Gallbladder disease • Gynaecological problems, such as infertility and irregular periods • Erectile dysfunction and sexual health issues • Non-alcoholic fatty liver disease, a condition in which fat builds up in the liver and can cause inflammation or scarring • Osteoarthritis mayo clinic: health problems with obesity

Understanding The obesity epidemic – health problem http: //www. parashospitals. com/wp-content/uploads/2015/10/Obesity. jpg

Understanding The obesity epidemic – health problem Quality of life When you're obese, overall quality of life may be diminished – you may not be able to do things you used to do, such as participating in enjoyable activities. Obese people may even encounter discrimination. Other weight-related issues that may affect quality of life include: • Depression • Disability • Sexual problems • Shame and guilt • Social isolation • Lower work achievement mayo clinic: health problems with obesity

Application Obesity and heart disease

Application Cholesterol in the blood Cholesterol is made in the liver. It is fundamental to the structure and functioning of cell membranes, the production of some hormones and the passage of neural signals across synapses. Cholesterol is also consumed in excessive quantities in the human diet, most especially in foods containing animal fats. Because cholesterol is not soluble in blood plasma, it is transported by a protein carrier, forming a lipo-protein molecule in the blood. Excess LDL (low density lipo-protein) cholesterol in the blood is clearly linked to the formation of plaques (atherosclerosis) in blood vessels such as the coronary arteries. Plaques are a prime cause of heart disease. HDL cholesterol may not have the same effect. http: //www. vcharkarn. com/uploads/sites/6/2014/03/HDL_LDL. jpg

Application Atherosclerosis http: //healthyprotocols. com/images_atherosclerosis. jpg

The simplest formula for calculating the energy content is: A more reliable result should take into account the specific heat capacity of water http: //michigantoday. umich. edu/archive/2013/01/health_calorimeter. jpg http: //www 2. vernier. com/sample_labs/CHEM-I-06 energy_content_foods_open. pdf Foods, depending on their carbohydrate/fat/protein component, have different energy content which can be determined by measuring the heat released from their combustion. In its simplest form, a food such as a dried peanut is burnt beneath a known volume of water, which shows a temperature change. The investigation can be completed with much more attention paid to variables, and perhaps using data logging temperature sensors, such as Vernier. The investigation is properly done in a bomb calorimeter. http: //www. rsc. org/learnchemistry/Content/File. Repository/frg/i mages//energy%20 values%20 of%20 fo od. JPG Skills Measuring energy content of food

http: //health. gov/dietaryguidelines/dga 2000/document/images/build_figure 3. jpg Skills Nutrient content of food - database http: //www. sugar. ca/getmedia/a 9 a 44 ac 7 -4932 -430 f-b 461 -3229 d 10283 c 1/NFTcomparison. aspx? width=630&height=400 http: //www. fda. gov/ucm/groups/fdagovpublic/documents/image/ucm 387542. png Reading these labels requires a great deal of care

Understanding Control of appetite The brain detects alterations in energy stores and triggers metabolic and behavioural responses designed to maintain energy balance. Energy homeostasis is controlled mainly by neuronal circuits in the hypothalamus and brainstem, whereas reward and motivation aspects of eating behaviour are controlled by neurons in limbic regions and cerebral cortex. (The limbic system is the portion of the brain that deals with three key functions: emotions, memories and arousal (or stimulation). This system is composed of several parts, which are found above the brainstem and within the cerebrum. ) Check out this Khan Academy video: Hormone control of hunger

Nature of Scienc Control of appetite – theories The way in which the hypothalamus and the limbic areas of the brain control appetite is still far from understood. The ‘Dual Centre Hypothesis’ posited that the hypothalamus consisted of two centres: a hunger centre and a satiety centre. They worked in tandem, switching each other on or off, according to need. After some nasty little experiments on the brains and hypothalamus of dogs, the ‘Dual Centre Hypothesis’ has been replaced by the ‘Set Point Theory’ which suggests that the hypothalamus monitors deviations away from set points of fats, carbohydrates, etc. in the blood and tissues, and accordingly increases or decreases appetite.

Understanding Control of appetite – hormones and Appetite control is a function of the hypothalamus. This is a small area lying between the hypothalamus and pituitary, controlling the anterior segment of the pituitary and the many of the body's organs through vagus nerve stimulation. The hypothalamus contains several clusters of neurons, commonly designated as nuclei. Current research indicates that one of these, the arcuate nucleus, houses the appetite centre. Here we find sensors that monitor lipid and sugar levels in the circulation and others which respond to specific hormones. Ghrelin is a peptide hormone released from an empty stomach which thus stimulates the hypothalamus to stimulate appetite. Insulin (from the pancreas) and leptin (from fat cells in adipose tissue) dampen appetite. Not only does the arcuate nucleus measure metabolites and hormone levels, it also coordinates metabolism through adjustment of the activities of the liver, kidneys, intestine and adipose tissue. The hypothalamus controls appetite and coordinates this with energy utilization. It is, therefore, responsible for maintenance of body weight, carefully adjusting food intake to physical activity. Loss of sensitivity to hormones and metabolites in the arcuate nucleus can lead to unbalanced energy intake and use, resulting in overweight and obesity. (http: //www. medbio. info/horn/time%205/appetite%20 and%20 weight%20 control%20 nov 06%20 v 2. htm)

IB OPTION D: HUMAN PHYSIOLOGY D 1 HUMAN NUTRITION A balanced diet is essential to human health John Osborne, March 2016