2: organisation

• What is a tissue?

  A group of cells with a similar structure and function
• What is an organ?

  A group of tissues performing specific function
• Organs are organised into...?

  Organ systems
• What is the digestive system?

  An organ system which works to digest food and absorb the nutrients into the bloodstream.
• 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)
• Amylase:

  -Where is it produced?

  -What does it do?

  -Where is it produced? Salivary glands, pancreas

  -What does it do? Breaks starch down into simple sugars
• Protease:

  -Where is it produced?

  -What does it do?

  - Produced in the stomach and small intestine

  - Breaks down proteins into amino acids
• Lipase:

  -Where is it produced?

  -What does it do?


  - Produced in the small intestine

  -Breaks down lipids (fats) into fatty acids and glycerol
• What are the products of digestion used for?

  To build new carbohydrates, lipids and proteins

  
  

  Some glucose is used in respiration
• What is bile?

  -Emulsifies fat to form small droplets (increases SA)

  -Alkaline to neutralise HCl from stomach

  -Made in the liver

  -Stored in the gall bladder

  -Increases the rate that lipase can break down fat
• What is the test for reducing sugars?

  Benedict's reagent

  -Heat in water bath

  -Positive will show colour change from blue to orange/brick red
• What is the test for starch?

  Iodine

  -Drop some onto the sample

  -Positive will show colour change from orange/brown to blue/black
• What is the test for protein?

  Biuret solution

  -Drop some into the sample

  -Positive will show colour change from blue to purple
• What is the emulsion test for lipids?

  Emulsion test

  -Mix food sample with 2cm³ ethanol and shake

  -Add to an equal volume of cold water

  -Positive result - cloudy emulsion forms
• What is the heart?

  An organ that pumps blood around the body in a double circulatory system.
• What is the pathway of blood through the heart/body?


  Body > vena cava > right atrium > right ventricle > pulmonary artery > lung > pulmonary vein > left atrium > left ventricle > aotra > body
• What is a valve?


  Found in the heart and in veins, prevent the backflow of blood.

  
• How is resting heart rate controlled?

  Cells in the right atrium that act as a pacemaker.
• What is an artificial pacemaker?

  An electrical device that is used to correct irregularities in heart rate.
• What are the three types of blood vessel?

  arteries, capillaries, veins
• How does the structure of an artery relate to its function?

  - Thick, elastic walls, thin lumen > to withstand pressure of blood

  
  

  - No valves > high pressure, they are not needed
• How does the structure of an vein relate to its function?

  - Thin walls, large lumen

  - Valves > blood returns through the veins at a lower pressure, need valves to ensure blood is flowing in the correct direction
• How does the structure of a capillary relate to its function?

  -One cell thick walls > very thin, reduces diffusion distance

  -Many spread out in a network > large SA for exchange
• What are the four components of blood?

  -White blood cells

  -Red blood cells

  -Platelets

  -Plasma
• What do white blood cells do?

  Fight infection, eg by phagocytosis

  
• What do red blood cells do?

  Carry oxygen, which attaches to haemoglobin molecules in the cells

  
• What do platelets do?

  -They are small fragments of cells that have no nucleus

  -They help the blood to clot at a wound - stops blood pouring out and microbes getting into your bloodstream

  
• What does plasma do?

  -Plasma is the liquid part of the blood

  -It carries the blood cells through the blood vessels

  -It contains many dissolved substances, such as carbon dioxide and glucose

  
• What happens in coronary heart disease?

  -Layers of fatty material build up inside the coronary arteries and narrow them.

  (Coronary arteries - arteries in the heart)

  -Reduces flow of blood, lack of oxygen to the heart muscle

  
• What are statins?

  Drugs that reduce cholesterol in the blood

  Slows down the rate of fatty material deposit

  
• What is a stent?

  A stent keeps coronary arteries open

  A stent is inserted using a balloon. The balloon inflates, opening the stent. The balloon can then be removed, leaving the stent in place

  
• What happens if there is a faulty valve?

  The valve may not open/close fully - blood may either not be able to move through, or the valve might leak.

  
  

  Can be replaced by mechanical or biological valves
• What is a transplant?

  A donor heart is used to replace a patient's heart (or lungs, etc)

  
  

  Artificial hearts are occasionally used to keep patients alive whilst waiting for a heart transplant, or to allow the heart to rest as an aid to recovery.
• What is health?

  A state of complete physical and mental well-being
• What are factors (other than disease) that can cause ill health?

  Diet

  Stress

  Life situations
• How can diseases interact?

  Eg:

  -Defects in the immune system mean someone is more likely to suffer from infectious disease

  -Viruses in cells can trigger cancers

  -Immune reactions caused by pathogens can trigger allergies, eg skin rashes and asthma

  -Severe physical ill health can lead to depression and other mental illnesses
• What is a risk factor?


  Anything that increases the likelihood of injury, disease, or other health problems. They can be:

  -Aspects of lifestyle

  -Substances in the body or environment
• What risk factors do we know of and what diseases do they link to?

  -Diet/smoking/exercise > cardiovascular disease

  -Obesity > type 2 diabetes

  -Alcohol > liver and brain function

  -Smoking > lung disease and lung cancer

  -Smoking and alcohol > effects on unborn babies

  -Carcinogens, eg ionising radiation > cancers
• What is cancer?

  The result of changes in cells that lead to uncontrolled growth and division
• What are benign tumours?

  Growths of abnormal cells which are contained in one area, usually within a membrane. They do not invade other parts of the body