Biology 1

Keeping Healthy
1. Diet and exercise
  1. Metabolic rate it the chemical recation that allows cells to release energy
    1. After exercise your metabolic rate stay high for a while
  2. A feature of LDLs is they carry cholesterol from the liver to the cells of the body
  3. It is best to have a high proportion of HDL compared to LDL for a healthy heart.
2. Defending against infections
  1. Bacteria are living cells and, in warm, moist conditions, can multiply rapidly. Once inside the body, they release poisons or toxins that make us feel ill
  2. Viruses are much smaller than bacteria cells and can only reproduce inside host cells and they damage them. The viruses are then passed out in the bloodstream, the airways, or by other routes
  3. White blood cells can: ingest pathogens and destroy them, produce antibodies to destroy particular pathogens, produce antitoxins that counteract the toxins released by pathogens
    1. the pathogens are not the disease - they cause the disease. White blood cells do not eat the pathogens - they ingest them. Antibodies and antitoxins are not living things - they are specialised proteins.
    2. Antibodies bind to pathogens and damage or destroy them. Also clumping them together so that they are easily ingested by white blood cells called phagocytes.
      1. Each lymphocyte produces a specific type of antibody which is a chemical fit to a certain antigen
    3. When weak or in active forms of pathogens are injected into the body, they stimulate white blood cells to produce antibodies against the pathogen. If the person does get infected by the pathogen later, their body can respond in the same way as if they had had the disease before
      1. If a large proportion of the population is immune to a particular pathogen, the risk of an epidemic or pandemic is reduced
  4. Antibiotics are substances that kill bacteria or stop their growth. Painkillers helps to relieve the symptoms of an infectious disease
    1. This types of medication do not work against viruses because they live and reproduce inside cells. It is difficult to develop drugs that kill viruses without also damaging the body’s tissues.
  5. Antibiotics kill individual pathogens of the non-resistant strain resistant then individual pathogens survive and reproduce allowing the population of the resistant pathogens increases.
  6. To cultivate bacteria you need sterile conditions involving: the Petri dishes, nutrient agar jelly and other culture media must be sterilised, the inoculating loops used to transfer microorganisms must be sterilised (usually by passing the metal loop through a Bunsen burner flame), and seeling the lid of the Petri dish is sealed with sticky tape to stop microorganisms from the air getting in and contaminating the culture.
Nerves and Hormones
1. Receptors are groups of specialised cells that can detect changes in the environment called stimuli. Receptors are often located in the sense organs
  1. Eyes respond to light. Ears respond to sound, Tongue responds to taste, Noise responds to smell, Skin responds to touch
2. Sensory neurones carry an impulse from receptors to the spinal cord and brain, where the brain translates it then relay neurones carrys from one part of the CNS to another motor neurones carry signals from the CNS to effectors.
  1. The synapse is where two neurones meet. The signals cross this gap using chemicals. One neurone releases the chemical into the gap. The chemical diffuses across the gap and makes the next neurone transmit an electrical signal.
3. In reflex actions a receptor detects a stimulus, a change in the environment, then the sensory neurone sends impulses to relay neurone that's when motor neurone sends impulses to effector effector produces a response.
4. Hormones are chemical substances that regulate processes in the body
  1. To control water concentration our body uses; the lungs - when we exhale the skin - through sweating passing urine - produced by the kidneys
  2. Blood sugar levels are controlled to provide cells with a constant supply of energy. Blood sugar level is controlled by the release and storage of glucose controlled by insulin
  3. Body temperature is controlled by sweating, shivering, and controlling blood flow to the skin
5. TO BE CONTINUED

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Biology 1

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	Created by Hannah Somerfield almost 10 years ago