Transcript learning ppt john

IB OPTION D: HUMAN PHYSIOLOGY
D1 HUMAN NUTRITION
A balanced diet is essential to human health
Syllabus
Syllabus
Understandings
Human Health
WHO definition of Health
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)
Understandings
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.
Understandings
Essential nutrients
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 doses.
Understandings
Essential nutrients
Categories of essential nutrient include:
•Essential fatty acids
•Essential amino acids
•Vitamins
•Dietary minerals
Understandings
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
Understandings
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.
Applications
Amino acids – Phenylketonuria (PKU)
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
Understandings
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
Understandings
Dietary minerals – known elements
https://openparachute.wordpress.com/2013/06/16/is-fluoride-an-essential-dietary-mineral/ (from Wikipedia ‘Dietary Minerals’)
Understandings
Dietary minerals – major functions
http://scienceineverydayterms.blogspot.com/2012_10_01_archive.html
Applications
Dietary minerals – deficiency diseases
Syllabus
requires
you to
refer to
calcium
and rickets
http://www.biologydiscussion.com/essay/essay-on-nutritional-deficiency-diseases/2378
Understandings
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-phpapp02/95/vitamins-3-638.jpg?cb=1411469178
Understandings
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
Understandings
Vitamins – water soluble
http://image.slidesharecdn.com/watersolublevitaminanditsclasses-131211103833-phpapp01/95/water-soluble-vitamins-1-638.jpg?cb=1386758444
Understandings
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
Understandings
Vitamins – fat soluble
http://www.mindfulbody.com/media/24151/screen%20shot%202011-04-10%20at%204.20.20%20pm_550x324.jpg
Applications
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 Science
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 13th C). Yet a complete understanding of the
disease and its relationship with Vitamin C and ascorbic acid was not shown known until the 20th 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 mindedness
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
Understandings
Malnutrition
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.
Understandings
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.
Understandings
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://s3.amazonaws.com/files.digication.com/M8dbc16dfdd591359f08c1b77bcc0b702.png
Understandings
Starvation
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 can 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
Applications
Anorexia nervosa
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
Understandings
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/m2).
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.
Understandings
The obesity epidemic
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
http://www.heartspring.net/images/obesity_stats_by_country673.jpg
Understandings
The obesity epidemic
ToK: 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.
Understandings
The obesity epidemic – health problems
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
Understandings
The obesity epidemic – health problems
http://www.parashospitals.com/wp-content/uploads/2015/10/Obesity.jpg
Understandings
The obesity epidemic – health problems
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
Applications
Obesity and heart disease
Applications
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
Applications
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_calorimete
r.jpg
http://www2.vernier.com/sample_labs/CHEM-I-06energy_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/FileRepository/frg/i
mages//energy%20values%20of%20f
ood.JPG
Skills
Measuring energy content of food
http://health.gov/dietaryguidelines/dga2000/document/images/build_figure3.jpg
Skills
Nutrient content of food - databases
http://www.sugar.ca/getmedia/a9a44ac7-4932-430f-b461-3229d10283c1/NFTcomparison.aspx?width=630&height=400
http://www.fda.gov/ucm/groups/fdagovpublic/documents/image/ucm387542.png
Reading these labels requires a great deal of care!
Understandings
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 Science
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.
Understandings
Control of appetite – hormones and hypothalamus
Appetite control is a function of the hypothalamus. This is a small area lying between the
thalamus 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%20and%20weight%20control%20nov06%20v2.htm)
IB OPTION D: HUMAN PHYSIOLOGY
D1 HUMAN NUTRITION
A balanced diet is essential to human health
John Osborne, March 2016