Biology P1

• Cells


  Basic building blocks of all living organisms
• Tissue


  Group of cells with similar structure and function
• Organs


  Groups of tissues that work together to perform a specific function
• Organ systems


  A group of organs that work together in performing vital body functions to form an organism
• Example of organ system


  Digestive system- several organs work together to digest and absorb food.

  Nervous system
• Mouth


  Where food enters the alimentary canal and digestion begins
• Salivary glands


  Produce saliva containing amylase
• Oesophagus


  Muscular tube which moves ingested food to the stomach
• Stomach


  Large muscular organ that continues the mechanical and chemical digestion of food
• Pancreas


  produces digestive enzymes and insulin
• Liver


  Produces bile, which emulsifies fat and neutralises stomach acid
• Gall bladder


  Stores bile before releasing it into the duodenum
• Small intestine (duodenum)


  Where food is mixed with digestive enzymes and bile
• Small intestine (ileum)


  Where digested food is absorbed into the blood and lymph
• Large intestine (colon)


  Where water is reabsorbed
• Large intestine (rectum)


  Where faeces are stored
• Large intestine (anus)


  Where faeces leave the alimentary canal
• Catalyst


  substance that speeds up the rate of a chemical reaction
• Enzyme


  Biological catalysts that speed up the rate of chemical reactions in biological processes. Enzymes are necessary to all living organisms as they maintain reaction speeds of all metabolic reactions at a rate that can sustain life
• Bile


  A substance which made in the liver and stored in the gall bladder. It is alkaline to neutralise hydrochloric acid from the stomach. It also emulsifies fat to form small droplets which increases the surface area. The alkaline conditions and large surface area increase the rate of fat breakdown by lipase
• Nature of enzyme molecules (temperature)


  Enzymes work fastest at their 'optimum temperature' so heating to high temperatures (beyond the optimum) will break the bonds that hold the enzyme together and it will lose its shape. This is known as denaturation. Substrates cannot fit into denatured enzymes as the shape of their active site has been lost. Increasing the temperature towards the optimum increases the activity of enzymes as the more kinetic energy the molecules have the faster they move and the number of collisions with the substrate molecules increases, leading to a faster rate of reaction. This means that low temperatures do not denature enzymes, they just make them work more slowly due to a lack of kinetic energy
• Nature of enzyme molecules (pH changes)

  If the pH is too high or too low, the bonds that hold the amino acid chain together to make up the protein can be disrupted/destroyed

  This will change the shape of the active site, so the substrate can no longer fit into it, reducing the rate of activity

  Moving too far away from the optimum pH will cause the enzyme to denature and activity will stop
• Catalysing reactions


  Enzymes catalyse specific reactions in living organisms due to the shape of their active site.
• Lock and key theory

  All enzymes have an active site which is where it can bind to a substrate (substance involved in the reaction).

  Enzymes and their active sites have very specific shapes. The specific shape of each active site means only certain substrates can bind to it and form enzyme-substrate complexes. This means each enzyme can only catalyse one specific type of reaction and therefore produce the products.

  The 'lock and key' model is a simplified version of how enzymes work. It states that the active site of an enzyme fits the substrate perfectly like a lock and a key, they are complementary.
• Where is protease produced?

  Stomach

  pancreas

  small intestine
• Where is amylase produced


  Salivary glands pancreas

  small intestine
• Where is lipase produced

  Pancreas

  small intestine
• Protease


  Breaks down proteins into amino acids
• Amylase (a type of carbohydrase)


  Breaks down starch into maltose
• Lipase


  Breaks down lipids into fatty acids and glycerol
• Carbohydrase


  Breaks down carbohydrates into simple sugars
• What do digestive enzymes do

  Convert food into small soluble molecules that can be absorbed into the bloodstream.
• Digestion products use


  They are used to build new carbohydrates, lipids and proteins. Some glucose is used in respiration
• Structure of the heart

  has four chambers (right and left atriums, right and left ventricles)
• Structure of the lungs

  - air enters trachea

  - trachea splits into bronchi (one bronchus to each lung)

  - bronchus branches off into bronchioles

  - bronchioles end in alveoli

  - ribcage, intercostal muscles and diaphragm work together to move air in and out
• Heart


  An organ that pumps blood around the body in a double circulatory system. The right ventricle pumps blood to the lungs where gas exchange takes place. The left ventricle pumps blood around the rest of the body

  
• Pathway of blood


  Vena Cava - Right Atria - Right Ventricle - Pulmonary Artery - Lungs - Pulmonary Vein - Left Atria - Left Ventricle - Aorta - Body
• Pathway of air to bloodstream

  Nose/Mouth - Trachea - Bronchi - Bronchioles- Alveoli - Capillary
• Resting heart rate


  The natural resting heart rate is controlled by a group of cells located in the right atrium that act as a pacemaker. Artificial pacemakers are electrical devices used to correct irregularities in the heart rate.
• Types of blood vessels

  Veins

  Arteries

  Capillaries