Organisation Flashcards
What is a cell?
The basic building block of a living organism.
What is a tissue?
A group of cells with a similar structure and function working together. For example, muscular tissue contracts to bring about movement.
What is an organ?
A collection of tissues working together to perform a specific function. For example, the stomach contains the glandular, muscular and epithelial tissues.
What is an organ system?
A group of organs working together to perform specific functions. For example, the digestive system consists of the stomach, large intestine and small intestine working together.
What is the main function of the digestive system?
To digest food and absorb the nutrients obtained from digestion.
What is the role of the pancreas and salivary gland in the digestive system?
They produce digestive juices containing enzymes.
What is the role of the stomach in the digestive system?
Produces hydrochloric acid which kills bacteria and provides the optimum acidic pH for protease enzymes to function.
What is the role of the small intestine in the digestive system?
It is the site where soluble food molecules are absorbed into the bloodstream.
What is the role of the liver in the digestive system?
Produces bile (which is stored in the gall bladder).
What is the role of the large intestine in the digestive system?
Absorbs water from undigested food producing faeces.
What is the role of enzymes in the digestive system?
They act as biological catalysts which speed up the rate of biological reactions (the breakdown of food) without being used up in the process.
How does the shape of an enzyme affect its function?
They have a specific active site which is complementary to their substrate.
What types of metabolic reactions do enzymes catalyse?
Changing one molecule to another - e.g glucose to fructose.
Breaking down larger molecules into smaller molecules - e.g carbohydrates to glucose.
Building larger molecules from smaller molecules - e.g. glucose to starch.
What is the lock and key hypothesis of enzyme function?
The shape of an enzyme’s active site and the substrate are complementary so can bind together to form an enzyme-substrate complex.
How does temperature affect enzyme action?
Up to a certain point, increasing temperature increases enzyme reaction as molecules have a higher kinetic energy. Above a certain temperature the active site is altered and the enzyme becomes denatured so it can no longer catalyse the reaction. The optimum temperature is 37 degrees celsius.
How does pH affect enzyme function?
The optimum pH for most enzymes is 7 (apart from protease in the stomach). If the pH is too extreme, the shape of the active site may be altered and the enzyme will no longer work.
Where are carbohydrases, lipases and proteases found in the body?
Carbohydrase: amylase - salivary gland and pancreas; maltase - small intestine.
Protease: pepsin - stomach; others - pancreas and small intestine.
Lipases: pancreas and small intestine.
What is the role of carbohydrases and amylase in the digestive system?
Amylase breaks down starch into maltose and maltase breaks maltose into glucose.
Carbohydrases break down carbohydrates into simple sugars.
What is the role of protease in the digestive system?
Breaks down proteins into amino acids.
What is the role of lipase in the digestive system?
Lipase breaks down lipids into fatty acids and glycerol.
How are the products of digestion used?
They are used to build bigger molecules such as carbohydrates and proteins.
Glucose is used as a substrate in respiration.
What is the function of bile?
Neutralises the hydrochloric acid.
Emulsifies fats to form small droplets which increase the surface area for the lipase enzyme to work on.
What is the heart?
An organ that pumps blood around the body.
What is the purpose of the circulatory system?
Carries oxygen and other useful substances to bodily tissues and removes waste substances.
How does the double circulatory system work?
One pathway carries blood from the heart to tissues.
One pathway carries blood from the heart to the lungs where gaseous exchange of oxygen and carbon dioxide take place.
Where does the blood pumped by the right ventricle go to?
Lungs
Where does the blood pumped by the left ventricles go to?
Body tissues
Why is the double circulatory system important?
It makes the circulatory system more effective - for example oxygenated blood can be pumped around the body at a higher pressure by the left ventricle.
How many chambers does the heart have and what are they called?
4 chambers
Right atrium
Right ventricle
Left atrium
Left ventricle
Why is the wall of the left ventricle thicker?
The left ventricle has to pump blood at a higher pressure around the whole body.
What are the four main blood vessels associated with the heart?
Aorta (left) - carries oxygenated blood from the heart to the body.
Pulmonary vein (left) - carries oxygenated blood from the lungs to the heart
Vena cava (right) - carries deoxygenated blood from the body to the heart.
Pulmonary artery (right) - carries deoxygenated blood from the heart to the lungs.
Purpose of valves?
Prevents the backflow of blood.
Purpose of coronary arteries?
Supply the heart muscle with oxygenated blood.
Process of blood flow through the heart?
Blood enters the right atrium via the vena cava and the left ventricle via the pulmonary vein.
The aorta contract forcing blood into the ventricles causing valves to shut.
After the ventricles contract, blood in the right ventricle enters the pulmonary artery (to the lungs) and blood in the left ventricles enter the aorta (to the body).
How is the heart rate controlled?
A group of cells in the right atrium which act as pacemakers.
They release waves of electrical activity which cause the heart muscle to contract.
How can an abnormal heart rhythm be treated?
An artificial pacemaker which sends out electrical signals to correct the heart’s rhythm.
What are the three types of blood vessels in the body?
Arteries
Veins
Capillaries
How are arteries adapted to their function?
Function - carry blood away from the heart.
Thick muscle layer - adds strength to resist high temperatures.
Thick elastic layer - allows arteries to stretch and recoil to withstand high pressure.
How are veins adapted to their function?
Function - carry blood towards the heart.
Wide lumen - enables low pressure
Valves - prevent the backflow of blood.
How are capillaries adapted to their function?
Function - enables transfer of substances between the blood and tissues.
Walls are one cell thick - short diffusion pathway.
Permeable walls - substances can diffuse across.
Narrow lumen - blood moves slowly so there is more time for diffusion.
How can you calculate the rate of blood flow?
Volume of blood/number of minutes.
Where are the lungs found in the body?
Located in the thorax (within the chest). They are protected by the rib cage and are separated from the rest of the abdomen by the diaphragm.