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biology igcse > animal nutrition > Flashcards

animal nutrition Flashcards

1
Q

What does a balanced diet provide?

A

an adequate intake of the biological molecules and energy needed to sustain the body and ensure good health and growth
It contains: carbohydrates, proteins, fats, vitamins, minerals,water and fibre
These provide energy, growth and repair, and to regulate the body’s metabolism

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2
Q

What is basal metabolic rate

A

Energy required for body functions, even if you lie down and do very little you still need it lolzies
It varies from person to person but on average an adult needs 7000kj/day

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3
Q

Why can fat be bad for us

A

Saturated fats increase blood cholesterol which is linked to narrowing of the arteries and heart disease.
Cholesterol is a chem made in liver

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4
Q

Carbohydrates as a source of nutrients

A

sugar and starches
Ready source of energy that is easily respired.
Simple sugars area absorbed by the stomach into the blood almost immediately . Energy released as a result of respiration

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5
Q

Proteins as a source of nutrients

A

Growth and development.
You digest proteins into amino acids and then use these to make your own proteins
If protein isn’t used for growth and repair it may be respired to provide energy

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6
Q

Fats as a source of nutrients

A

Important as long term energy store. Fat is stored under the skin and around fat and organs. One gram of fat releases more than twice the energy than one gram of carbs or protein

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7
Q

Water as a source of nutrients

A

Makes up two thirds of your body mass.

Needed for chemical reactions to take place in solution.

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8
Q

Vitamins and minerals

A

VitC tissue repair- scurvy
VitD-strengthens bones and teeth-rickets and osteomalacia
Iron-formation of hemoglobin in red blood cells-anaemia
Calcium-Same as vitD

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9
Q

Fibre

A

Can’t be digested, adds bulk to food, helps movement of food in alimentary canal by peristalsis.
Fibre absorbs poisonous wastes from bacteria in our gut

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10
Q

What is energy output

A

Energy your body uses in a day. If energy input is greater than output, fat is stored in the body and body mass increases. We may run the risk of becoming overweight or obese

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11
Q

Major causes of obesity

A

High intake of fatty foods and refined foods containing a lot of added sugar
Too little exercise
Social and emotional stress leading to comfort eating

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12
Q

Problems with obesity and identifying obesity

A

More likely to have health problems like heart disease, high blood pressure, diabetes caused by high blood sugar and arthritis

Ppl who are 20% above the recommended weight for their height
Having a BMI greater than 30
BMI=body mass/kg divided by height/meters^2

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13
Q

What causes constipation

A

A diet lacking in roughage/fibre

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14
Q

What happens to the body during starvation

A

Draws upon stores of carbs, fat and protein for energy
bMR is reduced
The body uses stored fat and then breaks down muscle wasting and an emaciated appearance

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15
Q

What is protein energy malnutrition(PEM)

A

Caused by lack of dietary energy and protein
And lead to kwashiorkor or marasmur two different ways in body responds to lack of food
in both feeding should involve frequent servings of small quantities of food as PEM causes cells in the pancreas and intestines to die so fewer digestive enzymes are secreted

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16
Q

Symptoms of kwashiorkor

A

Oedema, swelling of abdomen and legs
Sparse dry hair
Flaky skin
Fat accumulation in the liver

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17
Q

Symptoms of marasmus

A

Very low body mass
Thin arms and legs
Little muscle or fat
Wizened/old looking face

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18
Q

Ingestion

A

Taking of substances into the body through the mouth

19
Q

Digestion

A

The breaking down of large insoluble molecules into small soluble molecules so that they can pass through the gut wall into the blood

20
Q

Absorption

A

The movement of small food molecules and ions through the wall of the intestine into the blood

21
Q

Assimilation

A

Movement of digestive food molecules into the cells of the body where they are used, becoming part of the cells

22
Q

Egestion

A

The passing out of food that has not been digested or absorbed, as faeces through the anus

23
Q

Mechanical digestion

A

The breakdown of large pieces of food into smaller pieces of food without changing food molecules
eg: chewing, muscle contractions in the stomach, small intestine large globules of fat broken into smaller globules by emulsification by bile

24
Q

Chemical digestion

A

The breakdown of large insoluble food molecules into smaller soluble molecules by the action of enzymes.
Occurs in mouth stomach and small intestines
Enzymes in alimentary canal: proteases, carbohydrases and lipases

25
Q

Proteases

A

Protein molecule made up of many different amino acids
|
protease enzymes break down protein molecules
|
amino acids

26
Q

Carbohydrase

A

Carbohydrase enzyme that breaks down starch is amylase

Starch molecules made up of many glucose molecules
|
Amylase enzyme breaks down starch to maltose(a sugar)
|
Glucose

27
Q

Lipase

A 
Fat molecule made up of fatty acid and glycerol molecule 
|
Lipase breaks down fat molecule 
|
fatty acids + glycerol
28
Q

Teeth, function and them all

A

Carry out mechanical digestion, 32teeth, increase surface area making it easier for enzymes to catalyze the reactions needed for chem digestion
Incisors: chisel-shaped for biting and cutting
Canines pointed for piercing and tearing
Premolars: have uneven cusps for grinding and chewing
Molars like premolars for chewing food

29
Q

Anatomy of a tooth

A

Divided into crown and root
Enamel forms hard outer layer, part above gum
Inside is the softer dentine, more like bone structure
A layer of cement fixes root into bony socket in jaw
Pulp cavity is space in tooth containing nerves and blood vessels

30
Q

What is tooth decay caused by

A

Bacteria mixes with saliva to form plaque, changes sugar to acid that attacks the enamel and dentine of the tooth

31
Q

How can tooth decay be avoided

A

By regular brushing with a good toothbrush, avoiding sugary foods, and visiting the dentist regularly

32
Q

What does saliva contain

A

Made in the salivary glands
Mucus; slimy substance that lubricates passage of food bolus down the throat
Amylase; enzyme that catalyses the breakdown of starch to maltose

33
Q

How does food pass down the oesophagus

A

Oesophagus has circular and longitudinal muscles in its wall
Food passes down by a wave of muscular contractions called peristalsis
The circular muscles contract and longitudinal muscles relax behind the food bolus to pass it along

34
Q

How is digestion carried out in the stomach

A

Stomach is a muscular bag that holds about 1l of food When food reaches the stomach…
Walls of stomach make gastric juice contains protease pepsin starts digestion of proteins into smaller molecules called polypeptides
Also contains hydrochloric acid:
-Kills bacteria in food, low ph denatures the enzymes in any harmful microorganisms in the food
-acid ph of 1.5-2 gives optimum conditions for the action of pepsin
Mixture of all this is called Chyme, muscular walls churn up the food to mix it well, takes 2-3hrs , contents now a runny liquid
Ring of muscle (pyloric sphincter) opens to let food pass into the duodenum

35
Q

What does pancreatic juice contain

A

Amylase
Trypsin-protease that breaks down protein and polypeptides to Peptides
Lipase-breaks down fats to fatty acids and glycerol
Sodium hydrogencarbonate an alkali that neutralizes the acidic food

36
Q

What enters the duodenum

A

By the pancreatic duct, pancreatic juice

By bile duct, bile (yellow-green fluid made liver and stored in the gallbladder)

37
Q

What is bile and what does it do

A

Bile is alkali and also neutralizes the acid given to the food in the stomach, gives the best ph for enzymes in the small intestine to work
Bile emulsifies fats by breaking down large gobules of fats into smaller globules. These have a larger surface area over which lipase can act to break fat down

38
Q

What is the function of the cells lining the ileum

A

They make enzymes that complete digestion of food
Proteases- peptides to amino acids
Sucrase which breaks down sucrose to glucose and fructose
Then maltose is broken down by maltase to glucose on the membranes of the epithelium lining the small intestine

39
Q

How is the small intestine adapted for absorption

A 
very large surface area of 9 square meters 
-possible as its v long and has folded inner lining w/ millions of villi, and the epithelial cells have microscopic projections called microvilli these vastly increase absorptive area 
Thin lining (one cell thick) so digested food can easily cross the wall into the blood and lymph
40
Q

Absorption in the small intestine

A

Digested food(simple sugars, amino acids, fatty acids and glycerol) pass through the wall of the small intestine by diffusion/active transport

Digested food reaches the capillaries and lacteals in villi. Absorbed food molecules are quickly transported to the live by the hepatic portal vein
Fatty acids and glycerol are transported in the lymph

41
Q

What happens when food gets to the colon

A

There is not much useful food left, mainly fibre, dead cells, bacteria and water
The solid waste is stored in the rectum, eventually are excreted as faeces through the anus, this is egestion

42
Q

What is cholera

A

Water-borne disease caused by bacterium vibro cholerae
Main symptom is diarrhoea as a result of dehydration
Tends to occur in areas where there is lack of proper sanitation or unclean water supply
Cholera is transmitted by ingestion of water or food that is contaminated by faecal matter containing the bacteria

43
Q

Effects of cholera on the body

A

Almost all bacteria killed in stomach but some reach small intestine and burrow thru the mucous lining the wall of the intestine and produce a toxin
Molecules of this toxin enter epithelial cells of intestinal wall, disrupting functioning of cell surface membrane of ep cells. Chloride ions pass out of the cells into intestinal lumen. This creates a water potential gradient. Water flows by osmosis from cells and body into lumen.
Movement of ions and water from blood into the lumen cause dehydration and diarrhoea

44
Q

What is oral rehydration therapy

A

A solution that contains:
Water to rehydrate the blood and other tissues
Sodium ions to replace ions lost from blood and tissue fluid
Glucose to provide energy for the active uptake of sodium ions from the intestine
Other ions such as potassium and chloride to replace lost ions

Water Alone isn’t enough as it isn’t absorbed by intestine and doesn’t contain ions Lost

biology igcse (3 decks)

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