2.5 Elements in biological molecules

recall the chemical elements present in carbohydrates, proteins and lipids (fats and oils)

Screen_shot_2011-10-27_at_12

Carbohydrates

 

  • Elements present in carbohydrates are carbon hydrogen and oxygen
  • Carbohydrates include simple sugars and the larger molecules are polysaccharides such as starch

Proteins

  • Elements present in proteins are carbon hydrogen oxygen and nitrogen
  • Protiens simple molecules are amino acids and the larger molecules are the proteins  (as both amino acids and proteins have 'n's in it it is an easier way to remember that nitrogen is a element in protein)

Lipids

  • Elements present in lipids are carbon hydrogen and oxygen (as you can see they are the same as carbohydrates however the structure and formula are very different)
  • Lipids can be divided in to two groups: the fat (animals) and the oils(plants) 

 

 

2.31 Villi structure and function

Explain how the structure of a villus helps absorption of the products of digestion in the small intestine

Screen_shot_2011-10-24_at_10
Screen_shot_2011-10-24_at_10


  • The whole inside wall of the small intestine is folded ( it is folded to increase surface area)
  • The structure in the Villi is called the lacteal
  • The Villi is surrounded by glucose molecules amino acid molecules and fatty acids
  • In the space around the Villi the space is in high concentration.
  • The Villi increases the surface area for absorption,and it also has a small diffusion distance(occurs fasst) 
  • The concentration gradient of the Vili is maintained by blood flow

2.30 Bile

recall that bile is produced by the liver and stored in the gall bladder, and understand the role of bile in neutralising stomach acid and emulsifying lipids

  • Screen_shot_2011-10-24_at_10
    The PH of the stomach is 3 due to the presence of Hydrochloric Acid
  • The Pancreas produced digestive enzymes
  • The liver is responsible for the production of a substance called bile. and the bile is stored in the galf bladder
  • When food is realised from the stomach in to the small intestine the PH is about 3. This makes the bile come out from the galf bladder through the bile duct
  • The bile joins the pancreatic duct which mixes with the digestive enzymes
  • The bile has two effect on meeting the partially digestive contents of the stomach the first effect is to neutralize the stomach acid and to create the PH of about 7.The second effect of the bile is that fat molecules are broken down in the small droplets
  • When fat molecules are broken down in to small droplets it is called emulsification (this is not an enzyme action) - the reason of this is to increase the surface area of lipids

2.29 Digestive Enzymes

understand the role of disgestive enzymes to include the digestion of startch to glucose by amylase and maltase the digestion protein to amino acids by proteases and the digestion of lipids to fatty acids and glycerol by lipases

  • Digestive enzymes turn insoluble food that humans disgest in to soluble molecules which is then absorbered in to the blood steam. This happens in the small intestine
  • There are 3 types of this process. The first one includes starch uses the enzymes amylase startch them which become broken up maltose
  • Maltose is then broken which becomes glucose which is soluble, it then breaks down of proteins its broken down my enzymes called proteases which then turn in to amino acid
  • The third type of digestion is when lipids are broken down by lipase which then becomes glycerol and fatty acids

2.28 Peristalsis

explain how and why food is moved through the gut by peristalsis

Screen_shot_2011-10-23_at_3

  • The gut wall is composed of muscle tissues, when the muscles contracts the diametre decreases
  • The food enters the gut and stretches the walls of the gut causing reflect behind the bolus. The contration pushes the bolus downwards and stretches the gut wall which then contrats and sqeezes the bolus downwards again

 

2.27 Stages of Digestion

understand the processes of ingestion, absorption, assimilation and egestion

Screen_shot_2011-10-24_at_10
Stage 1 - Ingestion Location: Mouth, Teeth, Salivary Glans Outline: Mastication ( chewing) Creates a ball of food for swallowing. Salivary glanes add lubricant for swallowing and also add salivary aminase.

Stage 2 - Digestion Location: Intestine, Stomach Outline: Stage where insoluble food particles are digested to become soluble by enzymes

Stage 3 - Absorption Location: Small intestine Outline: Small intestine are structure such as the villi and micro villi which will sbsorb food. Soluble food absorbs in to blood vessels

Stage 4 - Assimilation Location: Tissues and Organs Outline: Digestive food difuses in to cells. Molecules which been absorbed in the blood stream pass to cells to be used

Stage 5 - Egestion Location: Rectum/Anus Large intestine Outline: Removal of undisgested food

2.26 The human alimentary canal

recongnise the structure of the human alimentary canal and describe outline the functions of the mouth oesonhagus stomach, small intestine, large intestine and pancreas

DIGESTIVE SYSTEM


Screen_shot_2011-10-24_at_10
ood is introduced by ingestion. The teeth breaks down food, as the mucus is used for lubrication so it can slide down the digestive system. Salivary amilas is an enzyme that digest carbohydrates. The aphosogus is a tube that carries food to the stomach ( no digestion) which the food moves down the tube by peristolsis. Foos is then stored in the stomach. In the stomach there is an acid which kills bacteria, also there is a group of enzymes called proteases which is a digestion of the protien. As the food passes the stomach it goes to the small intestines. In addition from the pancreas of the digestive enzyme these enzyme complete the break down of the food so then it can be absorbed in to small parts ( small intestines abosorb blood)

2.25 Energy and Diet

understand that energy requirements vary with activity levels, age and pregnancy

Screen_shot_2011-10-23_at_12

  • As we get older we require more energy, expect when you get to the 'elderly stage'
  • The higher line shows the energy required for people who do sports or work in manual labour
  • Women who are pregenant also require more energy as their fetus grows

2.24b Vitamins and Minerals

recall sources and describe functions of carbohydrates proteins, lipids(fats and oils) vitamin A,C,D and the mineral ions, calcium and iron, water and dietry fibre as xomponents of the diet

Vitamin A's functions are that they let us humans see in the dark ( light sensitive pigment in the eye) The source is from fish liver oil and liver. The dificiency disease is night blindness

Vitamin C's functions are to connect tissues which helps cells stick to each other. The source of Vitamin C are citrus fruits like oranges. The dificiency disease is scurvy. Scurvy causes bleeding in gums

Vitamin D's functions are to absorm calcium from food. The sources are sunshine, fat, eggs and fish. The dificiency disease is Richets, which causes bending in bones

Minerals are calcium and iron. The function of calcium is to strengthen bones. A source for calcium is milk. If humans lack in calcium they get Richets (bending in bones)

Fibres are from plants, when you lack fibre it causes you to have constipation

Water creates solutions(chemistry of life), they are obtained by drinking water or are from food. If you lack water you get dehydrated

 

2.24a Sources of Food

recall sources and descrive functions of carbohydrates, protiens, lipid, Vitamin A,C,D and the minerals ions calcium and iron. Water and dietry divre as components of the diet

Carbohydrates

  • Grass form seeds, which provides Carbohydrates ( Rice, Wheat)
  • Root Tubers of potatoes is good carbohydrates
  • Carbohydrates provide energy through respiration
    Screen_shot_2011-10-24_at_10

Protien

  • Animals like fish provide protein
  • Plants like beans provide protein
  • Protein provides growth, particulary grown on muscles
    Screen_shot_2011-10-24_at_10

Lipids

  • Animals provide fat
  • Fish provide oils
  • Plants provide oils like palm oil and sunflower oil
  • Lipids store energy and is an insulator
    Screen_shot_2011-10-24_at_10

About