D.1 Human nutrition Flashcards
The 6 types of Nutrients
- Carbohydrates
- Protein
- Fat
- Vitamin
- Mineral
- Water
Dietary minerals
Essential elements that are gained through our diet
Amino acids
- Essential amino acids cannot be produced by the body and must be present in the diet
- Non-essential amino acids can be produced by the body and are therefore not required as part of the diet
- A shortage of one or more essential amino acids in the diet will prevent the production of specific proteins
- Lack of amino acids = no production of proteins
The 9 essential amino acids
- phenylalanine
- valine
- threonine
- tryptophan
- methionine
- leucine
- isoleucine
- lysine
- histidine
Conditionally essential amino acids
amino acids can be produced by the body, but at rates lower than certain conditional requirements (e.g. during pregnancy or infancy) – they are essential at certain times only
malnutrition causes
is a health condition caused by a deficiency, imbalance or excess of nutrients in the diet
caused by an improper dietary intake of nutrients (too much or too little)
OR
inadequate utilisation of nutrients by the body (sickness)
Hypertension
Overweight ppl more likely to have
= Blood psi above normal
Caused by plaque build up in arteries (CHD)
- if fully block –> stroke or heart attack
Atherosclerosis
Forms when saturated fatty acids are deposited into arteries and combine with choleterole.
(Hardening of the arteries)
Type 2 Diabetes
- occurs when fat, liver and muscle cells become unresponsive to insulin
- results from a diet rich in sugars causing the progressive overstimulation of these cells by insulin
Causes:
- high sugar
- high fat but low fibre
- genetics
- lack of exercise
Appetite control
Hypothalamus
- Controlled by Appetite control centre in hypothalamus
- controlled by hormones produced in the pancreas, stomach, intestines and adipose tissue
Ghreline released from stomach when stomach empty
When food is digested:
Leptin released from adipose tissue + Peptide PYY3-36 from small intestine + insuline from pancreas
Forms negative feedback loop
Appetite control centre
(8 Mark Q.)
- Negative feedback loop
- Hypothalamus contains ACC
(To stimulate appettie) When stomach empty –> Ghrelin released to hypothalamus
(To inhibit appetite) When full –> Ghrelin stops, intestine releases PYY3-36, pancreas release insuline, addipose tissue release leptin
starvation
The most extreme form of malnutrition is starvation
The body uses its own glycogen stores, lipids, then muscle for energy
Anorexia
=> lack of appetite
Anorexia nervosa is an eating disorder in which individuals severely limit the amount of food they intake
Blood flow is reduced and blood pressure may drop as heart tissue begins to starve
vitamin C
- involved in the synthesis of collagen
- internally by most mammals from monosaccharides – but it is not produced by humans
- Mus be in diet
- deficiency in vitamin C levels will lead to the development of scurvy
Phenylketonuria (PKU)
autosomal recessive disease (not sex linked) caused by a mutation to the gene encoding the enzyme phenylalanine hydroxylase
Untreated PKU can lead to brain damage and mental retardation
PKU is treated by enforcing a strict diet that restricts the intake of phenylalanine to prevent its build up within the body
This low-protein diet should include certain types of fruits, grains, vegetables and special formula milk
Vitamin D
in the absence oif vitamin D, the body cannot absorb calcium and phosphorus, it is excreeded in faeces
This can lead to the onset of diseases such as osteomalacia (where bones soften) or rickets (where bones are deformed)
Vitamin D can be naturally synthesised by the body when a chemical precursor is exposed to UV light
vitamin D may be stored by the liver for when levels are low (e.g. during winter when sun exposure is reduced)
Individuals with darker skin pigmentation produce vitamin D more slowly and hence require greater sun exposure
- is fat soluble
- found in oily fish, liver, and dairy products
Cholesterol
needed for fluidity of cells in body
cannot dissolve in the bloodstream, so bind to proteins (to form lipoproteins) for transport
Low density lipoproteins (LDLs) carry cholesterol from the liver to the body raising blood cholestrol levels
High density lipoproteins (HDLs) carry excess cholesterol back to the liver for disposal lowering…
LDL builds up in arteries forming high cholersterole levels leading to CHD
Determining Energy Content of food
Energy (joules) = Mass of water (g) × 4.2 (J/gºC) × Temperature increase (ºC)
Determining Energy Content of food
Energy (joules) = Mass of water (g) × 4.2 (J/gºC) × Temperature increase (ºC)
Use of databases of nutritional content of foods to calculate intakes of essential nutrients from a daily diet
Joules = international units for energy
