Organisation

• What is a cell?

  The basic building black of a living organism
• What is a tissue?

  A group of cells with a similar structure and function working together. For example, muscular tissue contracts to bring about movement
• What is an organ?

  A collection of tissues working together to perform a specific function. For example, the stomach contains glandular, muscular and epithelial tissues.
• What is an organ system?

  A group of organs working together to perform specific functions. For example, the digestive system contains organs such as the stomach, the small intestine and the large intestine.
• What is the main function of the digestive system?

  To digest food and absorb the nutrients obtained from them
• What is the role of the pancreas and salivary gland in the digestive system?

  They produce digestive juices containing enzymes
• What is the role of the stomach in the digestive system?

  Produces hydrochloric acid- which kills any bacteria present and provides the optimum acidic pH for the pro tease enzyme to function
• What is the role of the small intestine in the digestive system?

  The site where soluble foods molecules are absorbed into the blood stream
• What is the role of the liver in the digestive system?

  Produces bile (stored in gallbaldder) which emulsifies lipids and allows the lipase enzyme to work more efficiently
• What is the role of the large intestine in the digestive system?

  Absorbs water from undigested food, producing faeces.
• What is the role of enzymes in the digestive system?

  They act as biological catalysts which speed up the rate of biological reactions (break down of food) without being used up.
• How does the shape of the enzyme affect its function?

  Enzymes have a specific active site which is complementary to their substrate
• What type of metabolic reactions do enzymes catalyse?

  • Building larger molecules from smaller molecules eg. glucose to starch
  • Changing one molecule to another eg. glucose to fructose
  • Breaking down larger molecules into smaller molecules eg carbohydrates to glucose
• What is the lock and key hypothesis of enzyme function ?

  The shape of the enzyme active site and the substrate are complementary, so can bind together to form an enzyme-substrate complex.
• How does temperature affect enzyme action?

  Up to a certain point, increasing temperature increases enzyme action, as molecules have a higher kinetic energy. Above a certain temperature, the shape of the active site is altered and the enzyme becomes denatured, so it can no longer catalyse the reaction. The optimum temperature is around 37°.
• How does pH affect enzyme function?

  The optimum pH for most enzymes is 7 (apart from proteases in the stomach). If the pH is too extreme, the shape of the active site may be altered and the enzyme may no longer work.
• Where are carbohydrases, proteases and lipases produced in the body?

  ● Carbohydrases: amylase - salivary gland and pancreas; maltase - small intestine.

  ● Proteases: pepsin - stomach; others - pancreas and small intestine.

  ● Lipases: pancreas and small intestine.
• What is the role of carbohydrases in the digestive system?

  Carbohydrases breaks down carbohydrates into monosaccharides and disaccharides. Amylase breaks down starch into maltose.
• What is the role of pro tease in the digestive system?

  Breaks down proteins into amino acids
• What is the role of lipase in the digestive system?

  Breaks down lipids into fatty acids and glycerol
• How are the products of digestion used?

  They are used to build up bigger molecules such as carbohydrates and proteins. Glucose is used as a substrate in respiration
• Where is bile made and stored in the body?

  Bile is made in the liver and stored in the gallbladder.
• What is the role of bile in the digestive system?

  ● Bile is an alkaline substance which neutralises the hydrochloric acid secreted by the stomach.

  ● Bile emulsifies lipids to form droplets - this increases the surface area for the lipase enzyme to work on.
• What is the heart?

  An organ that pumps blood around the body
• What is the purpose of the circulatory system?

  Carries oxygen and other useful substances to bodily tissues and removes waste substances
• How does the double circulatory system work?

  • One pathway carries blood from the heart to the lungs- where the gaseous exchange of oxygen and carbon dioxide takes place.
  • One pathway carries blood from the heart to the tissues
• Where does pumped by the right ventricle go?

  The lungs
• Where does blood pumped by the left ventricle go?

  Body tissues
• Why is the double circulatory system important?

  It makes the circulatory system more efficient - for example, oxygenated blood can be pumped around the body at a higher pressure by the left ventricle.
• How much chamber does the heart have and what are they called?

  4- right atrium, right ventricle, left atrium, left ventricle.
• Why is the wall of the left ventricle thicker?

  It has to pump blood at a higher pressure around the whole body
• What are the 4 maid blood vessels associated with heart?

  ● Aorta (left) - carries oxygenated blood from the heart to the body.

  ● Pulmonary vein (left) - carries oxygenated blood from the lungs to the heart.

  ● Vena cava (right) - carries deoxygenated blood from the body to the heart. ● Pulmonary artery (right) - carries deoxygenated blood from the heart to the lungs.
• What is the purpose valves in the heart?

  Prevent backflow of the blood
• What is the purpose of coronary arteries?

  They supply the heart muscle with oxygenated blood
• Describe the process of blood flow through the heart?

  • Blood enters the right atrium via the vena cava, and the left atrium via pulmonary vein
  • The atria contract, forcing blood into the ventricles and causing valves to shut
  • After the ventricle contract, blood in the right ventricle enters the pulmonary artery (to the lungs) and blood in the left ventricle enters the aorta (to the body)
• What is the approximate value of the natural resting heart rate?

  70 beats per minute
• How is the heart rate controlled?

  Heart rate is controlled by a group of cells in the right atrium which act as a pacemaker. They release waves of electrical activity which cause the heart muscle to contract.
• How can an abnormal heart rate rhythm be treated?

  Using an artificial peacemaker, which sends out electrical signals to correct the hearts rhythm
• What are the three types of blood vessels in the body?

  • Arteries
  • Veins
  • capillaries
• How are arteries adapted for their function?

  ● Function: carry blood away from the heart.

  ● Thick muscle layer - adds strength to resist high pressure.

  ● Thick elastic layer - allows arteries to stretch and recoil - in order to withstand high pressure