09 science

• Endocrine glands release hormones into the bloodstream. This lets the hormones travel to cells in other parts of the body. The endocrine hormones help control mood, growth and development, the way our organs work, metabolism , and reproduction.
• PNS (peripheral Nervous System) - all the nerves outside the brain and spinal cord
• CNS (Central Nervous System) - the brain and spinal cord
• Name all primary endocrine glands

  Adrenal gland, pancreas, pituitary gland, thyroid, hypothalamus, thymus, ovaries, testes
• Adrenal Gland


  secretes adrenaline into your bloodstream, to increase energy levels
• Pancreas


  The pancreas is an organ of the endocrine and digestive system, the pancreas produces the hormone insulin which helps control sugar levels
• Thyroid

  The thyroid is a small butterfly-shaped gland at the base of your neck. The thyroid makes the main hormones such as thyroxine and triiodothyronine.
• Pituitary Gland


  A small pea-sized gland found at the base of your brain, it acts as a control-centre and tell the rest of the glands in the endocrine system what to do.
• Hypothalamus


  A structure deep in the brain, its main function is to keep the body stable. The hypothalamus produces many hormones such as dopamine and the growth releasing hormone.
• Ovaries

  The ovaries produce and release eggs into the female reproductive tract at the mid-point of each menstrual cycle. They also produce the female hormones oestrogen and progesterone and androgens.
• Testes


  The main hormone produced is testosterone is responsible for certain changes in puberty and regulating mood and various other things.
• What is a hormone?

  A hormone is a chemical substance that act as messengers to various glands or organs, they help how cells and organs do their work.
• What is the variable in homeostasis?

  The variable is the part of your internal environment that the body is controlling
• What is an example of a variable in homeostasis?

  body temperature, blood pressure, ion concentrations, glucose levels etc.
• What is the set point in homeostasis?

  The set point is the ideal value for a variable, e.g. the ideal temperature for a human body is a round 37 degrees celsius
• What is the reference range in homeostasis?

  The reference range is the acceptable range of values for a variable.
• What is a stimulus?

  A stimulus is anything your body senses, e.g. change in temperature, the sun shining in your eyes, or the smell of food
• Disease is defined as any condition in which the body cannot function properly
• Bacteria is one group of microorganisms that can cause disease is bacteria
• Bacteria


  Bacteria are microscopic unicellular organisms.
• Viruses


  Viruses are pathogens, they need a host and use it to make thousands of identical viruses. The host cell is damaged or destroyed when it releases new viruses that spread throughout the body infecting other cells.
• What are the differences between bacteria and viruses?

  Bacteria are living organisms and can be found everywhere in the world they act as decomposers, while viruses are non-living and need a host to reproduce, and infect cells through reproduction.
• pathogen - a bacterium, virus, or fungi that can cause disease.
• We are at constant risk of invasion by pathogens, such as bacteria and viruses. An infection occurs when pathogens manage to enter the body and multiply. The pathogens can damage the body's cells, causing symptoms such as a rash or fever. A person has a disease only when symptoms appear. This may be hours, days or weeks after infection.
• Diseases caused by pathogens are called infectious diseases. Examples include the common cold, the flu and hepatitis. Many infectious diseases can spread from person to person.
• Many diseases are not caused by pathogens. Instead, they may be caused by:

  • lifestyle factors, such as smoking
  • environmental factors, such as air pollution
  • genetic factors inherited from one's parents

  These are called non-infectious diseases.
• When an infectious disease can pass from one person to another it is called contagious. Pathogens can pass from person to person in different ways. Examples include shaking hands, sharing drinks and breathing in saliva droplets when an infected person coughs or sneezes.
• The immune system is the body system that prevents and fights disease. It is made up of many organs, tissues and cells working together. The immune system fights both infectious diseases, like measles, and non-infectious diseases, like cancer.
• The immune system can be described as having three lines of defence to protect the body against pathogens.
• The first line of defence is made up of barriers to prevent infection.
• The second line of defence is made up of responses to infection that apply generally to all pathogens.
• The third line of defence provides immunity against specific pathogens
• The skin is an effective barrier that covers most of the body. Cuts and grazes are possible sites of infection, which is why first aid is important. Other ways that pathogens can enter the body include the mouth, airways, eyes and urinary tract. Responses such as coughing and vomiting can remove pathogens from the airways or stomach.
• Skin - acts as an effective barrier against most pathogens, unless it is broken by a cut or graze.
• Tears, saliva, and mucus all act to trap pathogens so they can be flushed from the body or swallowed. These bodily fluids also contain chemical enzymes. They can kill many types of bacteria by breaking down their cell walls.
• Cilia are microscopic hairs on the cells that line airways. CIlia move back and forth pushing mucus and trapped pathogens out of airways.
• Urine flow - flushes pathogens out of the bladder and urethra
• • Physical barriers stop pathogens from entering the body by blocking or trapping them. Examples include skin and mucus. Some physical barriers, like cilia, actively push pathogens out. This is shown in the diagram.
• • Chemical barriers kill pathogens before they can enter the body. They include stomach acid as well as enzymes in tears, saliva and mucus.
• Fever is an increase in core body temp. above 38 degrees celsius, it is usually accompanied by sweating or shivering. A high temp. slows down or even kills some pathogens. It also speeds up processes that help the immune system deals with the threat.