Option D Human Physiology D 1 Human Nutrition

Option D: Human Physiology D. 1 Human Nutrition

D. 1 • Essential idea: A balanced diet is essential to human health.

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Components of the Human Diet Nutrients are chemical substances found in food that are used in the body Nutrition Information: Food energy: from carbohydrates, proteins, fats. Units: food calories (kcal) or kilojoules (1 kcal = 4. 18 k. J) daily needs vary by individual based on gender, age, size and activity. Fats (lipids) can be saturated or unsaturated. Trans fats are particularly unhealthy. Sodium (salt): keep it low. Carbohydrates are polymers of sugars (an energy source). Sugars are absorbed easily into the blood Dietary fiber (cellulose) cannot be digested (healthy). Proteins are polymers and sources of amino acids. They are used to build new proteins in cells. Vitamins are organic compounds that are essential in small amounts in the diet. Minerals are mineral ions (elements) that are also essential. http: //www. wolframalpha. com/input/? i=big+mac+nutrition

D. 1. U 1 Essential nutrients cannot be synthesized by the body, therefore they have to be included in the diet. Nutrient: a chemical substance found in foods that used in the body. Essential Nutrients Cannot be replaced or synthesized by the body, so must be taken in the diet. • • • Water Minerals Some vitamins Some unsaturated fatty acids Some amino acids Non-essential Nutrients Can be replaced or synthesized by the body, so are not necessary in the diet. • Carbohydrates/sugars (energy could come from proteins or fats) • Other minerals and some vitamins • Saturated fatty acids • Some amino acids. Dietary fiber is also necessary, though as it is not absorbed it is technically not a nutrient. Image: 'La Boqueria' http: //www. flickr. com/photos/9147703@N 03/280330584 0

Vitamins & Minerals D. 1. U 2 Dietary minerals are essential chemical elements. AND D. 1. U 3 Vitamins are chemically diverse carbon compounds that cannot be synthesized by the body. Minerals are inorganic elemental ions found in food. Vitamins are complex organic compounds (contain C, H and O). Some can be made by the body, but others are essential in the diet. http: //en. wikipedia. org/wiki/Vitamin_C http: //tinyurl. com/35 d 6 qyq

Eye function/vision, maintenance of epithelial tissues (hair, skin, lining of organs) Coenzymes (assist enzymes), digestion, red blood cell maturation, nervous system http: //whqlibdoc. who. int/publications/2004/9241546123. pdf

http: //www. youtube. com/watch? v=dcw 1 m 31 zu. TE Understanding Vitamin D http: //highered. mcgrawhill. com/sites/0072507470/student_view 0/chapter 25/animation __b_vitamins. html http: //www. youtube. com/watch? v=on. SPZ 0 a. BUKM

D. 1. A 1 Production of ascorbic acid by some mammals, but not others that need a dietary supply Vitamin C is a compound called ascorbic acid. Function: Immune system, healing (It is needed to synthesize collagen fibers that form part of many tissues in the body), antioxidant. Majority of plants and animals, including most mammals, can synthesize vitamin C. All cases studied so far show a mutation in GLO gene (codes for the enzyme L-gulono- -lactone oxidase) is responsible. This enzyme catalyzes the final reaction in synthesizing vitamin C.

D. 1. A 1 Production of ascorbic acid by some mammals, but not others that need a dietary supply The mutation in the GLO gene has occurred several times in evolutionary history. Those, including humans, that cannot synthesize vitamin C must consume it.

D. 1. U 6 Malnutrition may be caused by a deficiency, imbalance or excess of nutrients in the diet. Malnutrition can be the result of a poor diet: • Diets low in quantity – low protein and calorie content • Unbalanced diets – fail to provide essential nutrients or contain excess fats and refined carbs Behavioral and physiological disorders can also be a cause of malnutrition. A deficiency in vitamin C can cause a variety of symptoms that are collectively known as scurvy. Includes general weakness, anemia (vitamin C helps in the absorption of iron), gum disease, and skin hemorrhages. https: //www. nlm. nih. gov/medlineplus/ency/article/000355. htm

http: //whqlibdoc. who. int/publications/2004/9241546123_chap 7. pdf

Nature of Science – Falsification of theories with one theory being superseded by another It was thought that scurvy only affected humans because laboratory attempts to induce symptoms in mice and rats failed. This was disproven in 1907 when scientists, Holst and Frolisch, published their paper on scurvy in guinea pigs. This was somewhat unpopular with the scientific community as nutrient deficiencies were not yet known. They successfully developed an animal model by feeding guinea pigs a diet of whole grains. Having an animal model allowed for the study of the factors that led to scurvy as well as the preventative value of different foods. They cured the guinea pigs of scurvy by feeding them cabbage and lemon juice.

What are some of the examples of science denialism mentioned in the video? How do they relate to IB Biology topics we have studied so far? What do you think are reliable sources of information regarding health and nutrition? How would you evaluate evidence presented to you including some of the statements he made in this video? http: //www. ted. com/talks/michael_specter_the_danger_of_science_denial. html

D. 1. A 3 Lack of Vitamin D or calcium can affect bone mineralization and cause rickets or osteomalacia. Vitamin D can be synthesized in the skin. This can only occur when skin is exposed to ultraviolet light (290 -310 nm) http: //www. endocrinesurgery. net. au/vitamin-d/

D. 1. A 3 Lack of Vitamin D or calcium can affect bone mineralization and cause rickets or osteomalacia. Individuals with darker skin have good protection against UV radiation, but produce less vitamin D. A deficiency of vitamin D can lead to rickets in children • bones near growth plates do not mineralize properly • Leads to irregular, thick and wide bone growth • Children do not reach optimal height & legs are often bowed in or out at the knees A deficiency of vitamin D can lead to osteomalacia in adults • Means “soft bones” – bone matrix is weak http: //www. endocrinesurgery. net. au/vitamin-d/ http: //www. leeds. ac. uk/yawya/bioarchaeology/Deficienc

D. 1. U 4 Some fatty acids and some amino acids are essential. Fatty Acids • High-density energy storage • Usually solid at room temp • Animal products, palm and coconut oil • High contribution to coronary heart disease (CHD) Image: 'Ã�l 2' http: //www. flickr. com/photos/67499195@N 00/2071538655 Found on flickrcc. net CH 3(CH 2)n. COOH • Usually oils at room temp • Usually plant sources, e. g. olive oil • Lower contribution to CHD

Fatty Acids CH 3(CH 2)n. COOH High-density (efficient) energy storage Metabolism of fatty acids in cell respiration skips glycolysis. Coenzyme A* cuts off carbon atoms from the fatty acid in the link reaction and carries them to the Krebs cycle. Therefore: longer chains are a greater store of potential energy. *Coenzymes assist enzymes and are made using vitamins. It’s all connected!

Fatty Acids Important components of the plasma membrane http: //en. wikipedia. org/wiki/Cell_membrane

Fatty Acids CH 3(CH 2)n. COOH Have other diverse functions. g l y c e r o l Triglycerides are efficient energy stores. fatty acids saturated mono-unsaturated poly-unsaturated Lipid Hormones • Steroid hormones, such as testosterone and cortisol, are made using lipids. • Hormones are chemical messengers. http: //en. wikipedia. org/wiki/Triglyceride

D. 1. U 4 Some fatty acids and some amino acids are essential. Essential fatty acids: Two fatty acids, omega-3 and omega-6, are required in our diet because we lack the enzymes to make them. Omega-3 and omega-6 are needed throughout the body but are needed in larger quantities for brain and eye development.

D. 1. U 4 Some fatty acids and some amino acids are essential. phenylalanine hydroxylase

D. 1. U 4 Some fatty acids and some amino acids are essential. Essential amino acids: Histidine Isoleucine Lysine Methionine Phenylalanine Tryptophan Valine Threonine (only if phenylalanine is not in the diet) Arginine (required in the diet of infants)

D. 1. U 5 Lack of essential amino acids affects the production of proteins. Protein-deficiency malnutrition Kwashiorkor: “The disease of the first child when the second is born. ” https: //www. youtube. com/wat ch? v=GALb. Eobx. Esc Caused by a lack of essential amino acids as a result of extremely low protein intake (such as when breastfeeding ceases for one child and the diet switches to low-protein sources of energy). Essential amino acids are therefore not available to make new proteins enzymes, pumps, antibodies – that are necessary for normal cell function, growth and immunity. Edema (severe swelling) results as fluids gather in tissues and cannot be returned to the blood effectively. Growth is severely stunted and mental development can be impaired. Risk factors: • Extreme poverty, overpopulation, large family sizes • Drought, war, poor infrastructure http: //en. wikipedia. org/wiki/Kwashiorkor

D. 1. A 2 Cause and treatment of phenylketonuria (PKU). Phenylketonuria (PKU) Inherited, progressive, degenerative. Cause Autosomal recessive, disease-causing allele: mis-sense base-substitution mutation on the gene for the enzyme phenylalanine hydroxylase. Result Phenylalanine (Phe) cannot be metabolized into tyrosine. Phe builds up in the brain, and competes with other amino-acids related to transport. Effect Mental development is retarded. Detection http: //en. wikipedia. org/wiki/Phenylketonuria Heel-prick (Guthrie test) of newborns to test concentration of Phe and Phe: Tyr ratio.

Phenylketonuria (PKU) Inherited, progressive, degenerative. Detection Heel-prick (Guthrie test) of newborns to test concentration of Phe and Phe: Tyr ratio. https: //youtu. be/4 V 9 w. IWKs. Zw. E Treatment Strict low-Phe diet: no dairy, meat, breastmilk, nuts or aspartame (artificial sweetener). Tyrosine supplements may be needed. http: //en. wikipedia. org/wiki/Neonatal_heel_prick There is no cure for PKU. Genetic counseling would be sought by prospective parents who suffer from or are suspected carriers of the disease-causing PKU allele. http: //youtu. be/CEi. OYSYhnh. Y