Biology: Chapter 7: Human Diet and Digestion

gall bladder

STORES BILE TO RELEASE INTO DUODENUM AS REQUIRED

function of large intestine. colon and anus

WATER IS ABSORBED FROM REMAINING MATERIAL IN THE COLON TO PRODUCE FAECES FAECES IS STORED IN THE RECTUM AND REMOVED THROUGH THE ANUS

define the following ingestion digestion absorption assimilation egestion

(a) ingestion - the taking of substances, e.g. food and drink, into the body (b) digestion - the breakdown of food (c) absorption - the movement of nutrients from the intestines into the blood (d) assimilation - uptake and use of nutrients by cells (e) egestion - the removal of undigested food from the body as faeces

pancreas and pancreatic juice function

PRODUCES ALL THREE TYPES OF DIGESTIVE ENZYME: ANYLASE, PROTEASE AND LIPASE pancreatic juice also has sodium hydrogen carbonate which provides alkaline nature for enzymes and neutralises acidic food from stomach

Liver and bile functions

PRODUCES BILE. It breaks down large drops of fat into smaller ones. This is known as emulsification. The larger surface area allows lipase to chemically break down the lipid into glycerol and fatty acids faster It is alkaline to neutralise the hydrochloric acid which comes from the stomach AMINO ACIDS NOT USED TO MAKE PROTEINS BROKEN DOWN HERE DEAMINATION WHICH PRODUCES UREA

1. define physical digestion 2. what is its importance 3. where does it happen

- Physical digestion is the breakdown of food into smaller pieces without chemical change to the food molecules - The processes that take place during physical digestion help to increase the surface area of food for the action of enzymes during chemical digestion - It is mainly carried out by the chewing action of the teeth, the churning action of the stomach and the emulsification of fats by bile in the duodenum

what is absorption and where does it happen for nutrients [give names of nutrients]? where is water absorbed and where does most of it happens?

1. Absorption is the movement of digested food molecules from the digestive system into the blood (glucose and amino acids) and lymph (fatty acids and glycerol) Nutrients are absorbed in the small intestine. 2. Water is absorbed in both the small intestine and the colon, but most absorption of water (around 80%) happens in the small intestine

describe the function of the following enzymes and state where they are produced and secreted: amylase maltase lipase what do proteases do? pepsin trypsin

1. Amylases are produced in the mouth and the pancreas (secreted into the duodenum) Amylases digest starch into smaller sugars. Amylase is secreted into the alimentary canal in the mouth and the duodenum (from the pancreas) and digests starch to maltose (a disaccharide) 2. Maltose is digested by the enzyme maltase into glucose on the membranes of the epithelium lining the small intestine 3. Lipase enzymes are produced in the pancreas and secreted into the duodenum .They digest lipids into fatty acids and glycerol 4. Proteases are a group of enzymes that break down proteins into amino acids in the stomach and small intestine (with the enzymes in the small intestine having been produced in the pancreas) 5. Pepsin is produced in the stomach and breaks down protein in acidic conditions 6. Trypsin is produced in the pancreas and secreted into the duodenum where is breaks down protein in alkaline conditions

what are fluids of stomach collectively known as? what are functions of HCL

1. gastric juice 2. gives an acidic pH. The low pH kills bacteria in food that we have ingested as it denatures the enzymes in their cells, meaning they cannot carry out any cell reactions to maintain life Pepsin, produced in the stomach, is an example of an enzyme which has a very low optimum pH - around pH 2 The hydrochloric acid produced in the stomach ensures that conditions in the stomach remain within the optimum range for pepsin to work at its fastest rate

Describe what is meant the term 'balanced diet'?

A balanced diet consists of all of the food groups in the correct proportions

function of small intestine. duodenum and ileum

FIRST SECTION IS CALLED THE DUODENUM AND IS WHERE THE FOOD COMING OUT OF THE STOMACH FINISHES BEING DIGESTED BY ENZYMES PRODUCED HERE AND ALSO SECRETED FROM THE PANCREAS PH OF THE SMALL INTESTINE IS SLIGHTLY ALKALINE - AROUND PH8-9 SECOND SECTION IS CALLED THE ILEUM AND IS WHERE ABSORPTION OF DIGESTED FOOD MOLECULES TAKES PLACE THE ILEUM IS LONG AND LINED WITH VILLI TO INCREASE THE SURFACE AREA OVER WHICH ABSORPTION CAN TAKE PLACE

function of stomach

FOOD IS MECHANICALLY DIGESTED BY CHURNING ACTIONS WHILE PROTEASE ENZYMES START TO CHEMICALLY DIGEST PROTEINS HYDROCHLORIC ACID IS PRESENT TO KILL BACTERIA IN FOOD AND PROVIDE THE OPTIMUM PH FOR PROTEASE ENZYMES TO WORK

what is the function of bile?

It is alkaline to neutralise the hydrochloric acid which comes from the stomach The enzymes in the small intestine have a higher (more alkaline) optimum pH than those in the stomach It breaks down large globules of fat into smaller ones. This is known as emulsification. The larger surface area allows lipase to chemically break down the lipid into glycerol and fatty acids faster

describe the way in which the structure of a villus is related to its function

Microvilli on the surface of the villus further increase surface area for faster absorption of nutrients Wall of villus is one cell thick meaning that there is only a short distance for absorption to happen by diffusion and active transport have mitochondria for energy for active transport Well supplied with a network of blood capillaries that transport glucose and amino acids away from the small intestine in the blood Lacteal runs through the centre of the villus to transport fatty acids and glycerol away from the small intestine in the lymph which eventually enters blood stream

what kind of digestion takes place in mouth? what do teeth do? what does saliva and tongue do?

THE MOUTH IS WHERE MECHANICAL DIGESTION TAKES PLACE -TEETH CHEW FOOD TO BREAK IT INTO SMALLER PIECES AND INCREASE IT'S SURFACE AREA TO VOLUME RATIO AMYLASE ENZYMES IN SALIVA START DIGESTING STARCH INTO MALTOSE THE FOOD IS SHAPED INTO A BOLUS IBALL) BY THE TONGUE AND LUBRICATED IN SALIVA SO IT CAN BE SWALLOWED EASILY

function of oesophagus

TUBE THAT CONNECTS THE MOUTH TO THE STOMACH WHERE THE FOOD BOLUS GOES AFTER BEING SWALLOWED WAVE-LIKE CONTRACTIONS. THIS IS CALLED PERISTALSIS

how is the ileum adapted for absorption and how do these adaptations help?

The ileum is adapted for absorption as it is very long and has a highly folded surface with millions of villi (tiny, finger like projections) These adaptations massively increase the surface area of the ileum, allowing absorption to take place faster and more efficiently

State the principal dietary sources and describe the importance of: (a) carbohydrates (b) fats and oils [lipids] (c) proteins (d) vitamins, limited to C and D (e) mineral ions, limited to calcium and iron (f) fibre (roughage) (g) water

a. function: source of energy sources: bread cereal pasta rice potatoes b. function: insulation and energy storage sources: butter oil nuts c. function: growth and repair sources: meat fish eggs pulses and nuts d. function: needed in small quantities to maintain health sources: fruits and vegetables Vitamin C: forms and essential part of collagen protein which makes hair skin bones and gums. deficiency causes scurvy. found in strawberries, citrus fruits and green vegetables Vitamin D: helps body to absorb calcium better and is required of strong and teeth. found in oily fish, eggs, liver, dairy products and made naturally when body is exposed to sun e. function: needed in small quantities to maintain health sources: fruits vegetables meat and dairy products calcium: needed for strong bones and teeth and is involved in clotting of blood. deficiency can lead osteoporosis later in life. found in meat cheese and eggs iron: needed to make haemoglobin which is the red pigment in red blood cells that transport oxygen red meat liver and green leafy vegetables like spinach f. function: provides bulk [roughage] for the intestine to push food through sources: vegetables and whole grains g. function: needed for chemical reaction to take place in cells sources: water juice milk fruits and vegetables

define chemical digestion what is the role of chemical digestion

chemical digestion is the breakdown of large insoluble molecules into small soluble molecules. role of chemical digestion in producing small soluble molecules that can be absorbed

Describe the structure of human teeth Describe the functions of the types of human teeth in physical digestion of food how does stomach carry out physical digestion? what tissues in stomach?

enamel, dentine, pulp, nerves, blood vessels and cement, and understand that teeth are embedded in bone and the gums Incisors - chisel-shaped for biting and cutting Canines - pointed for tearing, holding and biting Premolars and molars - larger, flat surfaces with ridges at the edges for chewing and grinding up food the stomach lining contains muscles which contract to physically squeeze and mix the food with the strong digestive juices that are present Also known as "stomach churning". muscular, epithelial and glandular. These tissues work together to allow the stomach to carry out its role.