Animal tissues, organs and organ systems

• What are enzymes?


  • A protein that increases the rate of reactions in the body
  • Called biological catalysts
• What is the active site of an enzyme?


  The part of the enzyme that binds to a specific substrate
• Can you describe the lock and key theory?


  • The active site is like the lock while the substrate is the key
  • Like there is only one key for every lock, there is only one substrate for each active site
• What does it mean if an enzyme has denatured?


  The shape of the active site has been altered and can no longer fit with it's complementary substrate, therefore can no longer catalyse the reaction
• Rate of reaction = Amount of product produced / time taken for reaction
• What are factors that affect rate of reaction?


  • pH
  • Enzymes have an optimum pH
  • If the pH strays away from the optimum pH, the rate may decrease or enzymes may denature
  • Temperature
  • Increasing temperature initially increases the rate
  • Once it strays past the optimum temperature, enzymes denature
• What is the purpose of the digestive system?


  The food you eat is large and insoluble and needs to be broken down in order for it to be absorbed into cells
• What organs are in the digestive system?


  • Glands (salivary glands and pancreas)
  • Produce enzymes to chemically break down food
  • Stomach
  • Produced hydrochloric acid to kill bacteria and provide an optimum pH for protease to work
  • Small intestine
  • Soluble molecules are absorbed into blood
  • Liver
  • Produces bile which helps digest lipids
  • Gall bladder
  • Stores bile
  • Large intestine
  • Absorbs water and undigested food to produces faeces
  • Rectum
  • Remains are excreted
• What are the enzymes involved in digestion?


  • Carbohydrases converts carbohydrates into simple sugars
  • --> Amylase turns starch into maltose
  • Produced in salivary glands, pancreas, small intestine
  • Proteases converts proteins into amino acids
  • --> Pepsin
  • Produced in stomach, pancreas, small intestine
  • Lipases converts lipids into fatty acids and glycerol
  • Produced in pancreas and small intestine
• What are the reagents used to test for biological molecules?


  • Benedict's test for reduced sugars
  • Turns blue to brick red/orange/yellow (depending on concentration of sugar)
  • Iodine test for starch
  • Turns orange to blue/black
  • Biuret test for proteins
  • Turns blue to purple
  • Sudan III test for lipids
  • Red layer will form on top
  • Ethanol for lipids
  • Cloudy layer will form on top
• What are the roles of bile?


  • It is alkaline to neutralise the hydrochloric acid in the stomach
  • Emulsifies lipids (breaks down large droplets into smaller ones)
• What is the purpose of the circulatory system?


  Carries oxygen around the body and removes waste products
• Heart pumps blood around the body in a double circulatory system
• What are the two circuits in the double circulatory system?


  1. Between the lungs and the heart
  2. Between the heart and the rest of the body
• What are the structures of the heart?


  • Four chambers
  • Right and left atria
  • Right and left ventricles (left ventricle is thicker as blood is at a higher pressure there)
  • Valves prevent blood flowing backwards
  • Coronary arteries to supply the heart with oxygenated blood
• What is the process of blood flowing through the body?


  1. Deoxygenated blood flows from the body to the heart (right atrium) through the vena cava
  2. Deoxygenated blood flows from the heart (left ventricle) to the lungs through the pulmonary artery
  3. Oxygenated blood flows from the lungs to the heart (left atrium) through the pulmonary vein
  4. Oxygenated blood flows from the heart (left ventricle) to the rest of the body through the aorta
• Pacemaker cells in the right atrium control our natural resting heart rate with small electrical impulses
• What can be used if an individual has an irregular heartbeat?

  Artificial pacemaker (electrical device)
• What are the types of blood vessels?


  • Arteries carry blood away from the heart
  • Veins carry blood towards the heart
  • Capillaries carry blood between the bloodstream and body cells
• What are the adaptations of arteries?


  • Layers of muscle to make them strong
  • Elastic fibres to allow them to stretch
  • Narrow lumen
  • Helps to withstand high pressure
• What are the adaptations of veins?


  • Wide lumen allows blood to flow through with low pressure
  • Valves to prevent blood flowing backwards
• What are the adaptations of capillaries?


  • One cell thick for short diffusion pathway
  • Permeable walls to allow the movement of substances
• How do you calculate rate of blood flow?


  Rate of blood flow = Volume of blood / Number of minutes
• What does the gas exchange system consist of?


  • Trachea (windpipe)
  • Intercostal muscles (contract and relax for ventilation)
  • Bronchi (separates into each lung)
  • Bronchioles (split from bronchi)
  • Alveoli (air sacs)
  • Diaphragm (separates from digestive organs)
• How do we inhale?


  • Ribcage moves up and out and the diaphragm moves down to increase volume
  • This causes lower pressure
  • Air is drawn to chest
• How are alveoli adapted for gas exchange?


  • Large number means large surface area
  • One cell thick creates shorter diffusion distance
  • Surrounded by a network of capillaries which maintains concentration gradient
• How do you calculate breathing rate?


  Number of breaths / number of minutes
• What are the different components of blood?


  • Plasma
  • Red blood cells
  • White blood cells
  • Platelets
• What is the function of plasma?


  • Carries the rest of the components of the blood
  • Carries glucose, amino acids, carbon dioxide, urea, hormones, proteins, antibodies and antitoxins
• What is the function of red blood cells?


  • Carry oxygen from lungs to the rest of the body
  • Biconcave disc increases surface area
  • No nucleus to carry more oxygen
  • Oxygen is binded to haemoglobin
• What is the function of white blood cells?


  • Part of the immune system
  • They do have a nucleus
  • Three types: antibodies, antitoxins, phagocytes
• What is the function of platelets?


  • Help blood clot
  • Clot dries to form a scab which prevents microorganisms from entering
  • Small fragments of cells
• What is coronary heart disease?


  • Coronary arteries blocked by fatty deposits
  • This decreases blood flow, so decreases oxygen
  • This may lead to a heart attack
• Is coronary heart disease communicable or non-communicable?


  Non-communicable
• What are two solutions for CHD?


  • Statins
  • Stents
• In what ways can diseases interact with each other?

  • Diseases that affect the immune system like HIV can make people more susceptible to diseases
  • Viruses can bring more cancers
  • Physical diseases can affect mental health
  • Allergies can be triggered by immune reactions
• What are some examples of risk factors?


  • Poor diet, lack of exercise, and smoking can lead to cardiovascular diseases
  • Obesity can lead to Type 2 diabetes
  • Excessive alcohol intake can cause liver and brain damage
  • Smoking can lead to lung diseases
  • Ionising radiation can lead to cancer
  • Smoking during pregnancy can lead to low birth weight
• What are stents (mechanical devices)?


  Metal mesh tubes in the arteries that keep them open
• What are the advantages of stents (mechanical devices)?


  • Lowers risk of heart attack
  • Recovery time for surgery is quick
  • Can be used when donor organs are not available
• What are the disadvantages of stents (mechanical devices)?


  • Risk of heart attack during procedure
  • Risk of infections
  • May need to be replaced
  • Scar tissue may be built up