Body mass can be measured by
simply standing on a set of weighing scales, unfortunately this only gives you
a numeric figure of how heavy your body is. It doesn’t differentiate between
fat mass and muscle mass, so the overall accuracy of body mass can be misunderstood.
When the body mass index was introduced in the 1830s by Lambert Adolphe and
Jacque Quetelet it was designed to estimate a healthy weight by a simple
calculation (Daniel Bubnis, 2017).
3.2 Measuring Body Mass
Nutrient
Age 65+
Protein
53g
Iron
9mg
Zinc
9.5mg
Vitamin A
700mg
Folate
200mg
Vitamin C
40mcg
Salt
6g
With only a small change from
an adult, older adults again will need to adjust their daily calorie intake in
line with the level of activity that they are doing. Generally, as adults
become older and into their frail years, they establish a more sedentary
lifestyle. Unless there are any other significant ill heath, older adults tend
to continue to eat in the way in which they always have, usually 3 main meals
per day, to include a good amount of meat and vegetables, and a lower number of
sugary snacks.
Older
Adults Aged 65+
The consequences of an adults
eating the wrong foods can have a serious impact on their health. According to
results from Health Survey England 2013, 41% men and 33% of women are
overweight. Being overweight/obese can cause Cardiovascular Disease, Type 2 Diabetes,
Stroke, High blood Pressure and hypertension. Pressure is also put on joints
and limbs. Many of these chronic diseases can be prevented by maintaining a
healthy weight and lifestyle.
Nutrients important for women
are Iron, Calcium and Folate, whereas men need to concentrate on Selenium
(mineral for immune system) and Lycopene (Found in watermelon, Red grapefruit
& tomato products) for protecting against prostate cancer. Excess Protein
in the body can put systems in the body under pressure and can cause toxic
ketones if protein make up 30% of your calorie intake. Keytosis uses the
proteins and converts it into sugars. Excess keytones leads to loss and sodium
from the body.
Nutrient
Aged19-65
Protein
55g
Iron
14.8mg
Zinc
9.5mg
Vitamin A
700mcg
Folate
200mcg
Vitamin C
40mcg
Salt
6g
The requirement in adulthood
doesn’t change from an older adolescent, except in pregnancy and increased
activity level. An adult diet provides enough of most nutrients, but still has a
low intake of vitamins, and energy from fatty acid is higher than the
recommended as is salt and fibre intake. (FSA nutrient and food based
guidelines for UK institutions, 2007)
Adulthood
Aged 18-65
Unfortunately, this age group
is also a high risk of developing eating disorders Eg Anorexia Nervosa, Bulimia
Nervosa, Binge and Emotional Eating. In 2013 34% of boys and 35% were
overweight. Anorexia Nervosa peaks between the ages of 15-19, mainly in girls
but 11% are male.
Nutrient
Age 11-14
Age 15-18
Protein
42g
55g
Iron
14.8mg
14.8mg
Zinc
9mg
9.5mg
Vitamin A
600mg
700mg
Folate
200mcg
200mcg
Vitamin C
35mg
40mg
Salt
6g
6g
More Iron is needed to grow
and for muscle development. Once a girl starts menstruation she will require
more iron than a boy of the same age. – A lack of Iron can lead to anaemia.
More calcium is needed for increase in bone mass. It is recommended that boys
have 1000mg and girls have 800mg per day to ensure continued healthy, strong
bones. Failure to have the recommended amount of calcium could cause future
bone health problems and a higher risk of fractures.
As adolescents continue to
grow they require more energy, protein and calcium to allow growth and
development, but also for the increase in activity. Many in this age group have
a low intake of vitamins especially Vitamin A, Iron, Calcium, Zinc and Iodine.
Adolescents
Aged 11-18
Ensuring that children are
getting the required amount, ensures they are getting all the nutrients they
need. Failing to get these nutrients can lead to health problems Eg Kwashiorkor
– Disease caused by lack of protein. It
causes muscle wasting, water retention (Oedema) Hair and skin lose colour and
skin becomes scaly. Marasmus is caused by lack of calories and protein, causing
the body to waste away. Children are noticeably skinny rather that swollen like
Kwashiorkor.
It was recently reported that
children aged 4-10 are still exceeding the daily recommended allowance of
sugar, currently making up 13% of their diet, over double the advised amount of
5% (Gov.uk, 2016).
Nutrient
Age 4-6
Age 7-10
Protein
20g
28g
Iron
6mg
9mg
Zinc
6.5mg
7mg
Vitamin A
400mcg
500mcg
Folate
100mcg
150mcg
Vitamin C
30mg
30mf
Salt
3g
5g
It is recommended that
children should eat the following guideline amount of food per day (FSA
nutrient and food based guidelines for UK institutions, 2007).
Children grow rapidly and are
very active. Their diet needs to provide energy and the right nutrients to
ensure correct growth and a healthy body weight. Snacks like crisps, biscuits
and sweets should be eaten in moderation, and foods such as yoghurt, milk and
fruit/raw vegetables should be offered instead of the sugary snacks.
Children
Aged 3-10
Vitamins
–
Essential for the functioning of the body, including cell function, growth and
development. There are 13 essential vitamins that can only come from a wide
varied diet.
Fats – We
can not live without fat, we need it to help prevent disease. Too much fat can
cause obesity, heart problems, high blood & cholesterol levels.
Protein
– An essential nutrient of the body, without it
the body would be unable to repair muscle or tissue.
Carbohydrate – When
our diet is low in carbohydrate, our body uses its fat reserve as a fuel
source.
To maintain a healthy body, a
healthy balanced diet is required, by consuming the correct amount of nutrients
and eating a varied diet.
3.1
Dietary requirements at Key life stages
Food Group
What do we use them for
What food we find them in
Picture
Carbohydrate
Functioning
of the immune system. Provide energy. Required for physical activity, brain
function and for our organs to operate
Bread,
Pasta, Potatoes
Protein
Builds
up muscle & bone tissue. Plays a very important role in the growth and
repair of the muscle and tissues.
Meat
& Fish
Eggs,
cheese
Milk,
yoghurt
Beans,
Lentils & Peas
Fats
Our
bodies require a small amount of fats, to give us energy. We cannot live
without them. Good fats help our bodies functions, and prevent disease
Biscuits,
Cakes, palm oil, Fatty cuts of meat, butter, ghee, Hard Cheese.
Healthy
Fats: Avocado, Nuts, Chia Seeds, Dark Chocolate
Vitamins – Fat Soluble
Don’t Need to Eat Everyday
Vitamin A
Vital
for Vision & healthy skin.
Chicken,
Eggs, Fish, Apple, Melon, Carrots, Broccoli, Cheese, Milk & Butter.
Vitamin D
Healthy
bones & teeth. Absorbs and maintains the calcium levels. Promotes the
calcification of bones & teeth.
Salmon,
Fish Oils, Peppers, Liver & Dairy products
Vitamin E (Known as
Tocopherol)
Antioxidant.
Helps in the production of red blood cells.
Olive
Oil, Avocado, nuts, Whole cereal, Eggs, Sprouts, Milk & Butter.
Vitamin K
Main
role is clotting of blood, maintenance of strong bones
Liver,
leafy green vegetables
Vitamins – Water Soluble
Don’t Store in the Body,
Need to Eat Everyday
Vitamin C (ascorbic Acid)
Boosts
the immune system. Associated with protein metabolism.
Oranges,
Blackcurrants, Spinach, Green & Red Peppers, Seafood & Strawberries
Vitamin B6 (Pyridoxine)
Associated
with amino acid metabolism
Egg
Yolk, Beans, Yeast, White Fish & Peanuts
Vitamin B12 (Cobalamin)
DNA
syntheses, Formation of myelin
Found
in almost foods of animal origin
Folic Acid (Folate)
Liver,
Leafy Green Vegetables, Brown Rice, Nuts & milk
Minerals
Calcium
Healthy
bones & teeth
Cheese,
Eggs, Milk & Sardines
Iron
Formation
of haemoglobin in red blood cells
Liver,
Red Meat, Dried Fruit, Pulses
Potassium
Needed
for muscle contraction, heart function. Turns carbohydrates into energy.
Fruit
& vegetables
Zinc
Needed
for metabolism. Growth in pregnancies, children & adolescence.
Water
All
our cells, organs and tissues use water to regulate temperature. Water is
used to transport nutrients. Our body loses water through breathing, sweating
and digestion. Very important to keep the body hydrated. Makes up 83% of
blood & 75% of our brain.
Drinking
Water, Juice, Milk, Tea, Coffee, Soup. Fruit & vegetable
2.1
Constituent food groups of a balanced diet
Mouth
Digestion
begins when food is put in the mouth (Ingestion)…The food is chewed and
broken down by the teeth and mixed with salivary amylase formed in the salary
glands, to form a bolus. This is Mechanical digestion. At this stage the
salivary amylase starts to digest starch.
Salivary
Glands
Saliva
helps to lubricate the food and the mouth. Also used to clean the mouth.
Saliva is made up of 99.4% of water, whilst the rest is salivary amylase and
Lysozyme.
The
salivary amylase is natural to slightly alkaline. It starts to break down
complex sugars and starches.
Lysozyme
is responsible for keeping the bacteria at a suitable level.
Stomach
J-
Shaped – Salivary amylase stops
working due to the acidic environment.
3
Areas
Fundus
– Top,
Body
– Main Working Area
Pylorus
– Bottom.
The
Mucosa is arranged in folds (Rugae) this continues to break the bolus up into
small pieces. – Mechanical Digestion. The Rugae folds increases the surface
area to release more gastric juices. The bolus mixes with gastric juices and
produces Chyme, through Chemical Digestion.
Within Deep pits, Oxyntic/Parietal cells
produce hydrochloric acid lowering the pH to 2.0-3.0. This enables the right
pH for pepsin to work, to digest protein, and rennin is produced to curdle
Milk.
Pepsin
breaks down the peptide bonds in the protein chains into polypeptides.
Exopeptidase enzymes break polypeptides into amino acids by breaking down the
chains from the ends.
Mucous
cells secretes a mucus (Alkaline buffer) to protect the stomach lining from
the acid, to stop it from digesting itself!
The
stomach is temporary storage, allowing digestive enzymes i.e Pepsin to work.
Chemical
digestion – Allowing for the pepsins to break down the protein into
polypeptides
Mechanical
digestion – Stomach acts as a churn to mix the bolus with gastric juices.
‘Churning effect’ created by the Gastric Muscle.
Limited
absorption of simple chemicals ie Water, Salts & Simple sugars.
Ghrelin
– Hormone released by the stomach that tells the brain when we are hungry or
not, when food is eaten and the stomach is stretched, it then tells the brain
we are full
Small
Intestine
Small Intestine – 3
Main Areas ( Duodenum, Jejunum & Illeum).
Key
role in Absorption.
Internal
structure is increased by circular folds called Villi, this provides more
surface area for absorption of nutrients. Each individual Villi has
microvilli attached to them as this further increases the surface area to
break down the chime and absorb nutients.
The
chyme enters the small intestine where it mixes with Pancreatic Juices, Bile
and intestinal juice. Chemical digestion of Protein, carbohydrates and fat
takes place.
Pancreatic
juices are secreted into the duodenum (which are alkaline pH 8) by the
endocrine cells in the wall of the duodenum, along with Bile this continue
digestion.
The
Pancreatic juices contain several enzymes. – The Alkaline intestinal juice
raises the pH of the contents.
Endopeptidase enzymes –
Trypsin & Chymotrypsin (inactive enzymes) Continue the digestion of
Protein, cutting the chain of amino acids into shorter sections – Convert
polypepsides to tripeptides, and amino acides. – Only activated upon their
arrival in the Duodenum, this would otherwise digest the Pancreas.
Exopeptidase enzymes –
Completes the digestion of protein by breaking the amino acid chains at the
end. Starts at the ends, breaks off one by one, so that it can be absorbed
through the Villi into the blood stream – Assists with the Growth &
repair of tissues.
The
pancreatic juices neutralises the chyme (Making it alkaline) to enable the
pancreatic enzymes to work. Once neutralised Pepsin stops working.
The
pancreatic enzymes continue to digest protein, cutting the chains of amino
acids into shorter chains.
The
enzymes produced by the lining complete the digestive process.
Pancreatic Enzymes. –
Breaks down Carbohydrates, Starches & Sugars.
The
Pancreatic Alpha Amylase (Normal Level is 0-137 U/L) – Converts starch to
maltose.
Maltase
breaks down Maltose to Glucose.
Sucrase
– Converts sucrose to glucose and Fructose (Fruit Sugars)
Lactase
– Converts lactose to glucose and galactose (Milk Sugars)
Pancreatic
Lipase – Converts fats & oils to
fatty acids and Glycerol – These are too big and have to be broken apart.
Lipase breaks down the bonds.
This
completes the chemical digestion of food.
Bile -Yellow /Brown substance. Not an enzyme.
Secreted by the liver and stored in the Gall Bladder The. pH is around 8.
Bile is made up of water, mineral salts, mucus, bile salts, bile pigments
& cholesterol. Enters via the bile duct from the liver. Emulsifies fats
& neutralising the stomach acid. Allows excretion of cholesterol and bile
pigments – helps bind cholesterol.
Large
Intestine
Loops
around the small intestine. Main Function is the reabsorption of water and
the formation of solid faeces. Small amount of minerals, vitamins & salt
are absorbed.
Normally
harmless bacteria synthesise Vitamin K and Folic Acid. Can become pathogenic
when entering another part of the body.
4
Sections –
Ascending Colon –
Extends upwards, curves to become the Transverse
Colon – Extends across the duodenum, to by the spleen, forms the Splenic
Flexure and curves to the …
Descending Colon –
Down the left-hand side of the abdominal cavity, leading to the
Sigmoid Colon – S
Shaped curve, continues to become the rectum.
Peristalsis
doesn’t continuously run in the colon, but there are ‘waves’ of strong
contractions, called mass movement (Approx. every 2 hours), to move the
faeces along ready for elimination.
Rectum
Usually
empty until faecal matter arrives from the colon. Defaecation occurs by a reflex action which
is involuntary in small children, but becomes a learned response by the
brain, so that we defaecate when convenient.
Anus
Defaecation
occurs from the anus. Involuntary contraction of the muscle in the rectum,
and relaxation of the Internal Anal Sphincter (Involuntary) moves the faeces
along the small anal canal, the
External
Anal Sphincter (Voluntary) allows defaecation to take place conveniently
1.1
Structure and function of the Digestive System
