Unit 1

• Oxygen diffuse from alveoli to the blood capillary during inhalation.
• Oxygen from the alveoli diffuses into the blood capillaries surrounding the alveoli during inhalation.
• The oxygen combines with the haemoglobin in the red blood cells, producing oxyhaemoglobin.
• Oxyhaemoglobin  oxygen + haemoglobin during inhalation.
• This carbon dioxide is expelled from the alveoli during exhalation.
• The heart pumps the oxygenated blood out to the body cells during inhalation.
• The deoxygenated blood is finally carried back to the heart and then to the blood capillaries surrounding the alveoli in the lungs during inhalation.
• At the same time, higher concentration of carbon dioxide in the blood capillaries causes carbon dioxide to diffuse from the blood capillaries into the alveoli.
• Oxygen from the oxyhaemoglobin diffuses out of the blood capillaries into the body cell during inhalation.
• Inhalation: External intercostal muscles contract, External intercostal muscles relax, Rib cage moves upwards and outwards, Rib cage moves downwards and inwards, The diaphragm contracts and flattens, The diaphragm relaxes and curves upwards, The volume of the thoracic cavity increases, The volume of the thoracic cavity decreases, The air pressure in the thoracic cavity decreases, The air pressure in the thoracic cavity increases, Air enters the lungs, Air is forced out of the lungs.
• Carbon dioxide diffuse from blood capillary to the alveoli during exhalation.
• Balloons contract during gas exchange.
• Gaseous exchange takes place in the lungs by diffusion.
• The deoxygenated blood releases carbon dioxide to the alveoli and absorbs oxygen, forming oxygenated blood again during inhalation.
• Balloons expand when rubber sheet is pulled upwards, air pressure inside bell jar increased.
• When rubber sheet is pulled downwards, air pressure inside bell jar is lowered.
• Cell respiration takes place in all living cells.
• Diffusion: the movement of gas molecules from higher concentration to lower concentration.
• Red blood cells transport oxygen to the cells that need it for aerobic respiration.
• Red blood cells have a permeable membrane so oxygen can diffuse in and out.
• Red blood cells are full of haemoglobin, a special protein which binds to and releases oxygen.
• Red blood cells have no nucleus to maximise space for lots of haemoglobin.
• Red blood cells have a biconcave disc shape which maximises surface area to maximise the rate of diffusion of oxygen.
• The lack of a nucleus in red blood cells allows them to be flexible so they can squeeze through narrow capillaries like those around alveoli.
• White blood cells fight infections like sore throats and chicken pox.
• Plasma is a straw coloured liquid that carries oxygen and nutrients to the body’s cells, removes waste products, and protects the body against infection.
• Platelets stop bleeding if you cut yourself and form a scab to prevent entry of microorganisms.
• Blood is a mixture of different types of cells suspended in a straw coloured liquid called plasma.
• The main function of blood is to carry oxygen and nutrients to the body’s cells, remove waste products, and protect the body against infection.
• Different components of the blood carry out different roles.
• The smallest blood cell is a type of white blood cell called a granulocyte.
• A component of blood can be a cell, a liquid, a fragment, or a combination of these.
• Sickle cell anemia affects the type of blood cell called a red blood cell.
• Sickle cell anemia causes symptoms such as tiredness caused by a lack of oxygen getting to the muscles.
• Sickle cell anemia is more prevalent in African people due to a genetic mutation.