d1 human nutrition Flashcards
1
Q
what are essential nutrients?
A
- biological molecules that cannot be synthesised directly and have to be consumed in that form
- essential nutrients cannot be synthesized by the body, therefore they have to be included in the diet
- many biological molecules in the human can be synthesised from other molecules
- e.g. testosterone is synthesised from cholesterol, and cholesterol can itself be synthesised carbohydrates
2
Q
what are the 4 main classes of essential nutrients?
A
- essential fatty acids
- essential amino acids
- essential vitamins
- essential minerals
3
Q
what are dietary minerals?
A
- essential chemical elements
- minerals: simple inorganic nutrients
- e.g.:
• calcium required in large amounts for bone synthesis
• phosphorous needed in large amounts (production of
phosphates)
• iodine required in making of thyroid hormones - as minerals are elements, there are no ways to produce them, and hence they must be obtained externally from the diet
- some important functions played by minerals:
• major constituents of structures such as teeth and bones (e.g. Ca, P, Mg)
• important components of body fluids (e.g. Na, K, Cl)
• cofactors for specific enzymes or components of proteins and hormones (e.g. Fe, P, I)
4
Q
what is the purpose of calcium in humans and where to obtain?
A
DIETARY SOURCES
- dairy products
- dark green vegetables
- legumes
FUNCTIONS IN THE BODY
- bone and tooth formation
- blood clotting
- nerve and muscle function
BONUS FUNCTION IN PLANTS
- important for plant root and shoot elongation
SYMPTOMS OF DEFICIENCY
- impaired growth
- loss of bone mass
5
Q
what is the purpose of phosphorus in humans and where to obtain?
A
DIETARY SOURCES
- dairy products
- meats
- grains
FUNCTIONS IN THE BODY
- bone and tooth formation
- acid-base balance
- nucleotide synthesis
SYMPTOMS OF DEFICIENCY
- weakness
- loss of minerals from bone
- calcium loss
6
Q
what is the purpose of sulfur in humans and where to obtain?
A
DIETARY SOURCEES
- proteins from many sources
FUNCTIONS IN THE BODY
- component of certain amino acids
SYMPTOMS OF DEFICIENCY
- impaired growth
- fatigue
- swelling
7
Q
what is the purpose of potassium in humans and where to obtain?
A
DIETARY SOURCES
- meats
- dairy products
- many fruits and vegetables
- grains
FUNCTIONS IN THE BODY
- acid-base balance
- water balance
- nerve function
BONUS FUNCTION IN PLANTS
- inorganic salt found within the sap of a plant (maintains water potential)
SYMPTOMS OF DEFICIENCY
- muscular weakness
- paralysis
- nausea
- heart failure
8
Q
what are vitamins?
A
- chemically diverse carbon compounds that cannot be synthesized by body
- vitamins are organic compounds (unlike minerals) needed in small quantities for efficient biological processes in human body
- essential vitamins refers to vitamins that cannot be naturally synthesised by human body, and needs to be absorbed from diet in their vitamin form
- some vitamins not technically essential, meaning that human body is capable of synthesising them (e.g. Vitamin D and Vitamin B7), but often not produced in sufficient amounts and hence need to be supplemented in diet
- vitamins are classified as fat soluble and water soluble vitamins
9
Q
why is vitamin c considered an essential nutrient for some but not for others?
A
- vitamin C can be produced by some mammals, and hence for these mammals Vitamin C is not considered an essential nutrient
- majority of mammals able to synthesise Vitamin C
- done through enzyme mediated steps to convert monosaccharides into ascorbic acid (Vitamin C)
- examples of mammals unable to synthesise include mammals from the primate suborder of Haplorrhini, which includes humans and tarsiers and many other monkeys and apes
- for these animals, a dietary supply of Vitamin C is needed
10
Q
what are the effects in lack of vitamin d and calcium?
A
- lack of Vitamin D or calcium can affect bone mineralization and cause rickets or osteomalacia
- in healthy production of bone tissues, osteocytes (bone cells) deposit calcium phosphate and calcium carbonate around them
- hence lack of calcium in diet will interfere with healthy production of bone tissues
- Vitamin D also needed to ensure efficient absorption of calcium in intestines
- deficiency in Vitamin D can also lead to a deficiency in calcium in the body
11
Q
what is rickets?
A
- disease that affects children, caused by low calcium levels in developing children (mainly due to low Vitamin D levels)
- results in bone tenderness (soft bones), and deformities as the bones develop
- main classic symptom is bow-leggedness, while irregular spine curvature may also develop
- other bones may also develop to be deformed as well
12
Q
what is osteomalacia?
A
- also results in bone softening due to a lack of calcium and/or Vitamin D in the diet
- technically rickets is a form of osteomalacia that occurs in children
- in adults, this can result in joint and bone pain, difficulty in walking, soft bones leading to easy fracturing and bending of bones
13
Q
what are the effects in lack of vitamin d and calcium?
A
- lack of Vitamin D or calcium can affect bone mineralization and cause rickets or osteomalacia
- in healthy production of bone tissues, osteocytes (bone cells) deposit calcium phosphate and calcium carbonate around them
- hence lack of calcium in diet will interfere with healthy production of bone tissues
- Vitamin D also needed to ensure efficient absorption of calcium in intestines
- deficiency in Vitamin D can also lead to a deficiency in calcium in the body
14
Q
how may cholesterol lead to coronary heart disease?
A
- cholesterol: organic molecule needed in body for formation of many other compounds (like steroid hormones) and in cell membrane
- hydrophobic, hence transported in form of lipoproteins in bloodstream
- 2 forms of lipoproteins: high density lipoproteins (HDL) and low density lipoproteins (LDL)
- HDL: in general removes fat molecules from cells back to liver for destruction or metabolism
- LDL: in general delivers fat molecules to cells, linked to atherosclerosis
- LDL: known as “bad cholesterol”, high levels of LDL leads to increased risks of atherosclerosis, where cholesterol and other fatty compounds deposited as plaque in arteries, and leads to hypertension
- when atherosclerosis occurs in the coronary arteries, they become blocked, leading to greatly reduced blood flow to heart muscles and hence coronary heart disease
15
Q
what is osteomalacia?
A
- also results in bone softening due to a lack of calcium and/or Vitamin D in the diet
- technically rickets is a form of osteomalacia that occurs in children
- in adults, this can result in joint and bone pain, difficulty in walking, soft bones leading to easy fracturing and bending of bones
16
Q
what is the cause of phenylketonuria? (pku)
how is phenylketonuria (pku) managed / treated?
A
- phenylketonuria (PKU): inherited disorder resulting in reduced capacity to metabolise phenylalanine
- gene responsible for creating enzymes involved in breaking down phenylalanine is such that metabolisation becomes very ineffective -> cannot break down to urea
- autosomal recessive disease
- caused by reduced production of enzyme
phenylalanine hydroxylase - end result is toxic buildup of phenylalanine in body, which can lead to intellectual disability, seizures, behavioural problems and other mental disorders in young children (during development)
- adults may also suffer from other similar neurological symptoms
TREATMENT / MANAGEMENT
- not a curable disease
- proper management to live normal life
- main form of management is great reduction in the amount of proteins consumed, especially in foods containing higher levels of phenylalanine
- individuals may end up with insufficient proteins in diet, may be supplemented with specially formulated supplements that have less phenylalanine
17
Q
how is malnutrition caused?
A
- caused by deficiency, imbalance or excess of nutrients in diet
- in absence of particular nutrient in diet will lead to deficiency diseases as body unable to function properly
- imbalances may also occur when regulatory systems (e.g. hormonal systems) are also malfunctioning
- 1 example would be diabetes where production or receptivity of insulin is affected, can lead to imbalance in glucose levels in bloodstream
- other hormonal problems may lead to imbalance in storage and utilising of fats and cholesterol (deposition)
- excess nutrients can also lead to diseases, especially those associated with obesity
18
Q
how is appetite controlled?
A
- appetite is controlled by centre in hypothalamus
- hypothalamus contains receptors that can be stimulated by particular hormones, and can also release hormones of their own, to control appetite
- hypothalamus can release hormones like neuropeptide Y that causes feeling of hunger, and hypothalamus can also release hormones that inhibit hunger
- other hormones stimulate hypothalamus to release necessary hormones to stimulate or suppress appetite
- stretch receptors in stomach send nerve impulses to brain when stomach is stretched (after feeding) to stimulate hypothalamus to suppress appetite
- adipose tissues release hormones (like leptin) that can lead to appetite suppression
- pancreas release hormones that respond to blood glucose levels (insulin and glucagon) that will stimulate the hypothalamus accordingly to modify appetite levels of a person
19
Q
what is the cause of phenylketonuria? (pku)
how is phenylketonuria (pku) managed / treated?
A
- phenylketonuria (PKU): inherited disorder resulting in reduced capacity to metabolise phenylalanine
- gene responsible for creating enzymes involved in breaking down phenylalanine is such that metabolisation becomes very ineffective -> cannot break down to urea
- autosomal recessive disease
- caused by reduced production of enzyme
phenylalanine hydroxylase - end result is toxic buildup of phenylalanine in body, which can lead to intellectual disability, seizures, behavioural problems and other mental disorders in young children (during development)
- adults may also suffer from other similar neurological symptoms
TREATMENT / MANAGEMENT
- not a curable disease
- proper management to live normal life
- main form of management is great reduction in the amount of proteins consumed, especially in foods containing higher levels of phenylalanine
- individuals may end up with insufficient proteins in diet, may be supplemented with specially formulated supplements that have less phenylalanine
20
Q
how is malnutrition caused?
A
- caused by deficiency, imbalance or excess of nutrients in diet
- in absence of particular nutrient in diet will lead to deficiency diseases as body unable to function properly
- imbalances may also occur when regulatory systems (e.g. hormonal systems) are also malfunctioning
- 1 example would be diabetes where production or receptivity of insulin is affected, can lead to imbalance in glucose levels in bloodstream
- other hormonal problems may lead to imbalance in storage and utilising of fats and cholesterol (deposition)
- excess nutrients can also lead to diseases, especially those associated with obesity
21
Q
how is appetite controlled?
A
- appetite is controlled by centre in hypothalamus
- hypothalamus contains receptors that can be stimulated by particular hormones, and can also release hormones of their own, to control appetite
- hypothalamus can release hormones like neuropeptide Y that causes feeling of hunger, and hypothalamus can also release hormones that inhibit hunger
- other hormones stimulate hypothalamus to release necessary hormones to stimulate or suppress appetite
- stretch receptors in stomach send nerve impulses to brain when stomach is stretched (after feeding) to stimulate hypothalamus to suppress appetite
- adipose tissues release hormones (like leptin) that can lead to appetite suppression
- pancreas release hormones that respond to blood glucose levels (insulin and glucagon) that will stimulate the hypothalamus accordingly to modify appetite levels of a person
22
Q
what are overweight individuals more likely to suffer from?
A
- hypertension and type II diabetes
- individuals can become overweight when over-nourished with excessive diet
- main cause for weight gain is storage of fats in adipose tissues in body
- many ways to determine if an individual is overweight, but 1 common method is to calculate the Body Mass Index (BMI), with individuals with a BMI of above 30 considered to be overweight
- hence, person who is overweight tends to have increased energy intake (big diet) and/or a reduced
energy expenditure (lack of exercise or sedentary lifestyle)
HYPERTENSION
- refers to symptom where a person has a much higher blood pressure than a normal person
- atherosclerosis, leading to narrowing of the blood vessels, is a leading cause of hypertension
• cholesterol and other fatty substances can form plaque on walls of arteries
• can be caused by a high cholesterol diet or genes
- usually 1st symptom of coronary heart
disease
- overweight individuals tend to have a high sugar, high fat diet that can lead to atherosclerosis
- lack of exercise in overweight individuals also may mean a weaker heart and circulatory system, and the heart might have to compensate by beating faster/harder
DIABETES MELLITUS TYPE II
- arises when cells in body no longer respond effectively to secretion of insulin, and this is known as “insulin resistance”
- e.g. liver normally stores excess glucose in form of glycogen, but as liver cells becomes desensitized to insulin, it no longer stores glucose and may instead release stored glucose
- usually consequence of high sugar diet, and cells become overstimulated by insulin and gradually becomes desensitized
- overweight individuals tend to have a high sugar diet, and hence are more likely to suffer from diabetes type II
23
Q
what is the impact of starvation on body tissue?
A
- starvation can lead to breakdown of body tissue
- arises when there is insufficient intake of nutrients into body
- to sustain life, body will start to breakdown tissues to obtain molecules to sustain life
- e.g. when starvation occurs, body will first break down storage tissues (mainly adipose tissues) to release energy
- when body runs out of fat reserves (adipose tissues), body will start to break down proteins in muscles for metabolism to release energy
- subsequently, other organs will be broken down for the same reasons, and this can lead or organ damage and ultimately loss of life
24
Q
what is the impact of anorexia on heart muscle?
A
- breakdown of heart muscle due to anorexia
- eating disorder, where individual greatly reduces food intake to point of self detriment or to obsessive level
- bodies may start to breakdown muscle tissue in order to release sufficient energy to support life
- may lead to decreased thickness of muscle walls in heart, leading to reduced blood pressure and insufficient flow of blood in the body
- heart may also suffer from arrhythmia, where the heartbeat becomes irregular
25
Q
how can energy content of food be determined?
A
- energy content of different foods can be estimated via combustion, and using the heat energy released to heat up water
- as specific heat capacity of water is known (4.18J per degree Celsius per gram of water), it is possible to calculate the amount of energy released
