Life Science term 1

• Structure of the digestive system:

  • Main components include the mouth, oesophagus, stomach, intestines, and liver
• The digestive system is made up of the mouth, esophagus, stomach, small intestine (duodenum, jejunum, ileum), large intestine (cecum, colon, rectum), liver, gallbladder, pancreas, salivary glands.
• Digestion begins with chewing food into smaller pieces to make it easier to swallow.
• Saliva contains enzymes that begin breaking down carbohydrates.
• Main processes in the digestive system:
• Ingestion:

  • The intake of food by biting, chewing and swallowing
• Digestion:

  • Mechanical and chemical processes that convert food into soluble nutrients
• Absorption:

  • Occurs when the soluble nutrients are taken up by the bloodstream in the intestines
• Egestion:

  • Occurs when undigested food materials, called faeces, are passed out of the body through the anus
• The circulatory system transports substances around the body
• Blood carries nutrients and oxygen to cells and removes carbon dioxide and other waste
• Raw materials and waste products are transported in the blood to excretory organs such as the lungs, kidneys, and skin
• The main components of the circulatory system are the heart, blood vessels, and blood
• The heart is a muscular organ that pumps blood around the body
• Humans have a closed blood system where blood flows contained in blood vessels
• Arteries transport blood away from the heart
• Arteries branch into tiny blood vessels called capillaries, which lie between the cells
• Capillaries have walls made up of a single layer of cells, allowing gases and nutrients to pass through easily
• Oxygen and nutrients pass from the blood across the capillary walls into the cells, while carbon dioxide and waste products pass from the cells back into the capillaries
• Capillaries join to form veins, which remove carbon dioxide and waste substances from the cells
• Veins are blood vessels that transport blood towards the heart
• The main processes of the circulatory system include circulating blood between the heart and the lungs
• Blood going from the heart to the lungs is low in oxygen but rich in carbon dioxide
• Blood returning to the heart is rich in oxygen
• The heart pumps oxygen-rich blood from the lungs to the body
• Arteries: blood vessels that transport blood away from the heart
• Capillaries: the smallest blood vessel in the circulatory system
• Veins: blood vessels that transport blood towards the heart
• High blood pressure:

  • Condition where blood is pushed against artery walls at abnormally high force
  • Arteries push back harder, walls become thicker, less space for blood flow
• Heart attack:

  • Occurs when a blood clot blocks blood flow to the heart muscle
  • Causes heart muscle to die or get damaged, often leading to death
• Stroke:

  • Blood flow to the brain is stopped
  • Happens when a blood vessel bursts or is blocked by a clot
  • Brain cells die due to lack of oxygen, may cause death
• The respiratory system supplies oxygen and removes carbon dioxide from living cells
• Respiration needs oxygen to take place and carbon dioxide is given off
• Main components of the respiratory system include:

  • Nose and mouth
  • Trachea and other air passageways
  • Lungs and blood
• The trachea is the tube through which air travels to the lungs
• The trachea splits into the left and right bronchi which branch to smaller tubes
• The smaller tubes eventually end in tiny hollow cavities called alveoli
• Main processes:

  • Breathing
  • Gaseous exchange
  • Respiration
• These processes are responsible for maintaining the correct levels of oxygen and carbon dioxide in the body
• Breathing consists of two processes:

  • Inhalation: muscles in the thorax contract and air is drawn into the lungs
  • Exhalation: muscles relax and air is forced out of the lungs