B2-Organisation

• what is a tissue?

  a group of similar cells that work together to carry out a particular function
• examples of tissues in mammals

  -muscular tissue contracts to move whatever its attached to

  -glandular tissue makes and secretes chemicals like enzymes and hormones

  -epithelial tissue covers parts of the body
• what is an organ?

  a group of different tissues working together to perform a certain function
• what tissues is the stomach made of?

  -muscular tissue moves the stomach wall to churn food

  -glandular tissue makes digestive juices

  -epithelial tissue covers the outside and inside of the stomach
• what is an organ system?

  a group of organs working together to perform a particular function
• what organs make up the digestive system?

  -glands produce digestive juices

  -stomach and small intestine digest food

  -liver produces bile

  -small intestine absorbs soluble food molecules

  -large intestine absorbs water
• what is a catalyst?

  a substance which increases the speed of a reaction without being used up
• what are enzymes?

  large proteins which are made up of chains of amino acids
• what does the lock and key diagram show?

  The substrate binds to the enzymes active site but if the enzyme becomes denatured the active site changes shape so the substrate can't bind to the active site
• how does temperature denature the enzyme?

  higher temperature increases the rate of reaction but if its too hot the bonds break which changes the shape of the active site so the substrate can no longer fit
• rate of reaction formula

  rate = 1000/time
• what are examples of big molecules?

  starch

  proteins

  fats
• why are big molecules broken down to smaller molecules?

  to pass through the walls of the digestive system and be absorbed into the blood
• what are examples of smaller soluble molecules?

  sugars

  amino acids

  glycerol

  fatty acids
• what is amylase?

  a carbohydrase
• what does amylase break down?

  starch into glucose
• where is amylase made?

  salivary glands

  pancreas

  small intestine
• what does protease convert?

  proteins into amino acids
• where are proteases made?

  stomach

  pancreas

  small intestine
• what do lipases convert?

  lipids into glycerol and fatty acids
• where are lipases made?

  pancreas

  small intestine
• what does bile do?

  neutralises stomach acid

  emulsifies fats to make digestion faster
• where is bile made?

  liver
• where is bile stored?

  gallbladder
• what happens at the alveoli?

  oxygen diffuses out of the alveoli into the blood

  carbon dioxide diffuses out of the blood into the alveoli
• how to calculate breathing rate

  breaths per minute = number of breaths / number of minutes
• what happens in the first circuit of the heart?

  right ventricle pumps deoxygenated blood to the lungs to get oxygen and then returns to the heart
• what happens in the second circuit of the heart?

  the left ventricle pumps oxygenated blood around other organs in the body. the body gives up the oxygen at the cells and the deoxygenated blood returns to the heart to be pumped to the lungs
• what do valves do?

  prevent backwards blood flow
• how does the heart pump blood?

  blood flows into the atriums from the vena cava and the pulmonary vein

  the atriums contract and pump blood into the ventricles

  ventricles contract and force the blood into the pulmonary artery and the aorta and out of the heart

  blood flows to the organs through arteries and returns through veins
• what do pacemakers do?

  produce electric impulses to muscle cells causing them to contract
• what does an artificial pacemaker do?

  produces an electrical current to keep the heart beating regularly
• what are types of blood vessels?

  arteries

  capillaries

  veins
• what do arteries do?

  carry blood away from the heart
• what do capillaries do?

  involved in the exchange of material at the tissues
• what do veins do?

  carry blood to the heart
• features of arteries

  strong elastic walls to deal with high pressure blood

  thick layers of muscle to make them strong

  elastic fibres to stretch and spring back
• features of capillaries

  permeable walls for substances to diffuse across

  thin walls (1 cell thick) to increase rate of diffusion

  supply food and oxygen

  take away carbon dioxide
• features of veins

  big lumen for blood to flow through

  valves

  elastic and muscle in walls
• how to calculate rate of blood flow

  rate of blood flow = volume of blood / number of minutes