Digestive System PDF

BODY SYSTEMS Digestive System ​ process of breaking down food to make its nutrients available ​ transforms food into usable energy ​ digestive system ○​ mouth, oesophagus, stomach, small intestine, large intestine, rectum, anus → part of digestive tract ○...

BODY SYSTEMS Digestive System ​ process of breaking down food to make its nutrients available ​ transforms food into usable energy ​ digestive system ○​ mouth, oesophagus, stomach, small intestine, large intestine, rectum, anus → part of digestive tract ○​ gallbladder, pancreas, liver, appendix → organs on the side of digestive tract, produce a series of chemical to help digest ​ digestive tract - pathway that food takes 1.​ mouth 2.​ oesophagus 3.​ stomach 4.​ small intestine 5.​ large intestine 6.​ rectum 7.​ anus Types of digestion ​ mechanical → food is broken down into smaller pieces → physical change because no new chemicals are formed → tear and chew food ​ chemical → large complex substances broken down into simpler chemical the body can digest → chemical change because new chemicals are formed → e.g. saliva and gastric juices break down food Digestive processes ​ ingestion → food is taken into the mouth ​ digestion → enzymes break large insoluble substance into small soluble ones ​ absorption → products of digestion are absorbed through the lining of the small intestine ​ egestion → removal of faeces (containing undigested food, bacteria, enzymes, cells from the intestine lining) Chemical components 1.​ chemical food groups ○​ carbohydrates  ○​ fats/lipids ○​ proteins ○​ vitamins/minerals ○​ fibre 2.​ enzymes ○​ chemicals made and used by our bodies to breakdown food into smaller components Mouth ​ starts with teeth ○​ incisors - bite off small pieces to chew ○​ premolars & molars - grind food into smaller pieces as you chew ○​ canine - not used in humans but animals use to hold onto food ​ food is mixed with saliva as it is being caused ​ saliva is a watery liquid produced by salivary glands ○​ contains chemicals that change starch (complex) to glucose (simple, easily absorbed) ○​ moistens food so it is easy to swallow ​ tongue rolls food into ball (bolus) Swallowing ​ oesophagus → long muscular tube with mouth and stomach at each end, muscles push bolus ​ peristalsis → process of rhythmic contraction and relaxing of muscles in the oesophagus that keeps food moving ​ epiglottis → flap that closes windpipe so food doesn't go into lungs (otherwise choking) ​ sphincter → esophageal sphincter - separates oesophagus from stomach, opens when food passes, closes so food/stomach juices don’t go back up ​ → pyloric sphincter - separates stomach from small intestine, controls release of digested food Stomach ​ shaped like a bag ​ food is stored for 1-6 hrs ​ muscular walls contract and relax to digest - churning to mix with gastric juices ​ includes HCl (hydrochloric acid) which kills bacteria ​ include thick layer of mucus which stops the stomach from digesting itself ​ pepsin converts proteins into amino acids Small intestine ​ very long narrow tube → 6m long, 3 cm diameter ​ duodenum → first part  → two tubes carry chemicals important for digestion (come from pancreas & liver) → walls are muscular - churns food - changes into usable forms ​ ileum → second part → food passes into ileum from duodenum (very tiny particles) → food is absorbed → inner lining are villi (greatly increase the surface area through which nutrients are absorbed Large intestine ​ 1.5m long, 6-7 cm diameter ​ water is reabsorbed from what is left of food and remaining nutrients ​ any waste forms lumps of faeces called stools - expelled through anus Rectum ​ lower part of large intestine ​ end of colon and anal canal ​ holds faeces and absorbs excess water Anus ​ sphincter muscle at the end of digestive tract ​ releases waste (faeces) Organs not part of digestive tract ​ produce chemical to help in digestion ​ pancreas → produces pancreatic juice - contains chemical to help digest carbs, fats, proteins ​ liver → produces bile (greenish liquid, works like detergent) - mechanically digests fats - large pieces of fat broken into tiny pieces ​ appendix → blind-ended tube attached to large intestine - helps with immune system coz it has useful bacteria ​ gallbladder → stores bile - when food is eaten it releases bile into digestive tract Digestive disorders ​ vomiting → stress/infections cause muscular wall of stomach & small intestine to contract - sphincters open - contents are forced out from oesophagus mixed with acid and bile ​ diarrhoea → bacteria and viruses cause lining of small intestine to be inflamed - no longer absorb water from faeces ​ heartburn → peristalsis pushes food down oesophagus to stomach - pressure causes to move back up - burning sensation is acid attacking lining of oesophagus  ​ appendicitis → when opening of appendix is blocked - inflamed, filled with mucus, swollen - treat by removing before it bursts and creates infection Respiratory System ​ series of chemical changes in cells to release energy ​ takes in air to extract oxygen → passed into bloodstream and distributed to cells for respiration Where the air goes ​ air is warmed in the nasal cavity ​ mucus + cilia (tiny hairs) →large dust particles are filtered out ​ warm, moist air travels down the trachea (windpipe) to the lungs ○​ cartilage keeps trachea from collapsing ​ trachea divides into 2 bronchi (bronchus), divide into bronchioles, ends in alveoli (alveolus) which is a cluster of sacs ​ alveoli help for gas exchange Gas exchange ​ alveoli walls are only one cell thick, surrounded by capillaries ​ oxygen dissolves in alveolus then moves (diffusion) to the blood  ​ oxygen enters red blood cells → carries oxygen to the cells where it is needed ○​ blood from the lungs in red coz it has oxygen ​ cells use oxygen to release energy from food ○​ carbon dioxide is produced in the process → waste product ○​ CO2 moves from cells to blood to alveoli and then breathed out Breathing ​ air in alveoli is constantly replaced as you breathe ​ breathing is involuntary → something you do without thinking ​ as you breathe in, muscles in ribs contract → rib cage moves up and out ​ diaphragm (sheet of muscle that separated abdomen and chest) contracts and flattens, and lungs expand ​ air is sucked through to fill up extra space ​ when you breathe out, all muscles relax Process of respiration ​ respiration begins when oxygen and glucose are together in the cells → react together ​ products - carbon dioxide, water and energy ​ oxygen + glucose → carbon dioxide + water + energy ​ the more energy, the faster the process, the more glucose and oxygen needed Circulatory System ​ heart, blood vessels, blood ​ heart pumps to keep blood moving → carries materials needed for the body Blood vessels ​ Arteries ○​ carry blood away from the heart ○​ when heart beats, blood moves to the arteries under pressure → tough elastic walls to withstand pressure, bounce back into shape ○​ regular expansion and contraction in some places → pulse ​ Capillaries ○​ arteries branch into smaller blood vessels → finest nes are called capillaries ○​ reach nearly every cell ○​ one cell thick → allow dissolved materials to pass through - materials needed pass into the cells, waste materials pass into the capillaries ​ Veins  ○​ capillaries join back together to form veins ○​ carry blood back to heart ○​ don’t need thick walls → pressure of heartbeat is lost when blood goes back ○​ pushed back up by contraction of muscles pressing against veins ○​ valves along veins to make sure blood is only flowing one way → open when blood is flowing towards heart, close it not ○​ if you sit still for too long, veins blood can pool and form dangerous clots called a thrombosis ​ Bruises ○​ capillaries near the skin burst and leak into surrounding tissues ○​ first it is red, then purple and yellow and the blood is being cleaned away by the body