Science test ( diffusion and diseases )

• diffusion is the movement of dissolved particles from areas of high concentration to low concentration without energy being involved
• when a type of movement does not need energy ( ex. diffusion ) we say it is a type of passive transport
• diffusion happens in cells
• these cells have a partially permeable membrane so they only allow certain molecules to pass through
• we say a movement is selective when it only allows certain molecules to pass through ( ex. partially permeable membrane )
• There are 3 factors affecting diffusion:

  1. concentration gradient ( the larger the concentration or the difference in number of particles the faster diffusion is )
  2. temperature ( higher temperatures gives the particles more energy to move so the rate of diffusion increases )
  3. surface area ( larger surface area where particles can pass so diffusion becomes faster )
• osmosis: the movement of water molecules across a partially permeable membrane from an area of higher concentration to an area of low concentration
• if we have a cell with two sides ( inside and outside ) diffusion will move from high to low concentration but molecules from both sides will move but the higher concentration will have more molecules that are moving
• there are 2 types of transport:

  1. passive transport ( without energy ) like diffusion and osmosis
  2. active transport ( needs energy )
• active transport moves from low to high concentration
• there is a molecule called ATP that gives energy to the carrier protein ( gate between the cell ) to open and let the molecules pass from low to high concentration but without energy this gate remains closed
• active transport: the movement of dissolved molecules into or out of a cell membrane, from an area of low to high concentration
• the particles is active transport go against a concentration gradient and require energy
• a communicable disease is an infectious disease that is transmitted from one person to another, it is caused by pathogens
• pathogen: an organism that causes a disease
• how to reduce or prevent the spread of disease:

  1. being hygienic
  2. destroying vectors
  3. isolating infected individuals
  4. vaccination
• a vector is an organism that carries a disease to another organism but it is not sick from that disease
• if the amount of energy you get from your food is different from the amount of energy you need your diet is imbalanced
• an unbalanced diet is when you eat more or less food than what your body needs
• a deficiency is when your body doesn't get enough of a particular nutrient
• there are 2 main types of white blood cells:

  1. phagocytes
  2. lymphocytes
• the most important part of your immune system is the white blood cells, when they come across a microbe they have 2 lines of attack:

  1. consuming them ( phagocytes )
  2. producing antibodies ( lymphocytes )
• the phagocytes are the first cells that act to fight a pathogen
• phagocytes can ingest microorganisms, the cells surrounds the microbe and once the pathogen is in the cell it is broken down and destroyed by digestive enzymes
• then the lymphocytes makes a specialised cell called the antibody that holds the pathogen in place
• then the body makes a different white blood cell that goes and gives chemicals that break down and destroy the pathogen
• it takes 7-14 days to make the right antibody to stick to the antigen then the body makes a memory cell of the pathogen and antibody so when that same pathogen comes again it takes less than 7-14 days to make the right antibody, it takes less
• different types of diseases:

  1. communicable
  2. non-communicable
  3. deficiency
  4. lifestyle
  5. inherited
  6. auto-immune
• a drug is a substance that affects how a body works
• a medicine is a drug that helps treat or prevent a disease
• types of drugs:

  1. painkillers ( panadol )
  2. antibiotic ( penicillin )
• painkillers relieve pain but they don't kill the pathogen
• antibiotics kills and stops the growth of bacteria only not viruses
• nervous system: is the organ system that helps us to sense changes in our surroundings and inside our bodies
• the nervous system allows our bodies to respond rapidly to those changes. the organs of the central nervous system ( CNS ) are the brain and spinal cord
• the CNS is linked to the body by organs called nerves
• stimulus ------> sensory neuron -----> brain/spinal cord ( coordinate system ) -----> motor neuron ------> effector -------> response
• changes that we sense are called stimulus, and they are detected by receptor cells ( eyes, nose, ears )
• when a stimulus is detected a receptor cell produces electrical signals called impulses that travel along the nerves usually to the brain or spinal cord
• the brain processes the information and sends impulses back out along the nerves to effectors ( muscles and glands )