topic 2 bio

• Tissues in the stomach

  EPITHELIAL TISSUE - Covers outside and inside of stomach.

  MUSCULAR TISSUE - Contracts, causing stomach wall to move, churning contents.

  GLANDULAR TISSUE - Produces acid and enzymes which help digest food.
• What does the mouth do in digestion?

  chews food and mixes it with saliva, which contains enzymes that digests starch to sugar
• What does the liver do?

  It produces bile which neutralises stomach acid and emulsifies fat
• What does the stomach do?

  -It pummels the food with its muscular walls and thick layer of mucus

  -It produces pepsin

  -It produces hydrochloric acid to kill bacteria and give the right pH for pepsin to work
• What does the pancreas do?

  produces enzymes for digestion of the starch and protein digestion , it also starts the lipid digestion
• What does the small intestine do?

  absorbs soluble food molecules into the bloodstream by diffusion or active transport
• What does the large intestine do?

  It's where excess water is absorbed from the food
• What does the anus do in the digestive system?

  Sphincter at the end of the digestive tract. Controlled by yourself, if held to long control is lost.
• What are enzymes?


  Proteins that speed up chemical reactions
• What is the lock and key theory?

  A substrate is specific to one enzyme because of the specific shape of its active site (like a key fitting a lock)
• What is amylase and what does it do?

  Amylases is an enzyme that breaks down starch to sugar
• Where is amylase found?

  Salivary glands, pancreatic fluid
• What is lipase?


  a pancreatic enzyme that catalyses the breakdown of fats to fatty acids and glycerol or other alcohols.
• Where is lipase found?

  pancreatic fluid and small intestine
• What does protease do?

  breaks down proteins into amino acids
• Where is protease found?

  Stomach, pancreas, small intestine
• What is bile


  An alkaline which neutralises stomach acid and increases digestion
• why does lipase work least in acidic conditions

  acidic conditions would denature the lipase enzyme, which inhibits enzyme activity
• Where is it produced and stored?

  produced- liver

  stored- gall bladder
• how does bile increase lipid digestion

  bile emulsifies fats which gives the lipase a larger surface area to work on
• what does bile to do improve conditions for digestion

  bile makes conditions alkaline and gives optimum ph for lipase action
• Steps to take for any food test.

  -get food piece

  -transfer food to beaker with water

  -give mixture stir with glass rod

  -filter solution with funnel paper to remove solid food
• Sugar food test


  Benedict's solution

  
  

  -if it has sugar it will go blue to green, yellow or brick red
• Starch food test


  Iodine solution

  
  

  orange-red turns blue-black
• Protein food test


  Biuret reagent

  
  

  Blue to purple
• Where are the lungs located

  The upper part of the body (thorax).
• How do the lungs function as a ventilation system?

  Trachea, where air passes through to the lungs, contains rings of cartilage which prevent trachea collapsing,

  
  

  Trachea splits to two smaller tubes,

  
  

  Bronchi, each one is a bronchus, bronchi splits to bronchioles]

  
  

  Bronchioles end at small bags called alveoli
• How are alveoli adapted for gas exchange?

  • millions of alveoli mean large surface area

  • good blood supply

  • moist - dissolve gases

  
  

  THESE FACTORS ENSURE CO2 IS REMOVED RAPIDLY AND OXYGEN DIFFUSES INTO THE BLOOD
• Breathing


  -increases rate of diffusion

  -brings fresh oxygen in and takes out co2

  -makes concentration gradent
• fish circulation


  single loop, two chambers
• human circulatory system


  moves oxygenated blood throughout the body
• vena cava


  a large vein carrying deoxygenated blood into the heart
• pulmonary artery


  Carries deoxygentated blood from the heart to the lungs
• pulmonary veins


  Deliver oxygen rich blood from the lungs to the left atrium
• aorta


  oxygenated blood pumps from heart to body
• What different to the left one to the right one?

  has a thicker muscular wall than the right as it pumps blood around the body
• What does a pacemaker do?

  Controls resting heart rate by sending electrical impluses
• How does the heart work?

  Blood flows into the 2 atria from the vena cava and the pulmonary vein

  The atria contract, pushing the blood into the ventricles

  The venticles contract forcing blood into the pulmonary arteru and the aorta in and out of the heart

  The blood flows to the organs through arteries and returns through veins

  The atria fill again and the whole cycle starts over
• What are arteries?


  carry high pressure blood from heart to organs

  
  

  thick muscular walls to withstand high pressure

  elastic fibres to stretch when blood surges pass, they recoil
• What are capillaries?


  when blood passes capillaries, glucose and oxygen diffuse to cells.

  
  

  thin walls for short diffusion path between blood and cells, co2 diffuses from blood to cells