4.2.2 Animal tissues, organs and organ systems Flashcards
What is the main function of the digestive system?
To digest food and absorb nutrients obtained from digestion.
What is the role of the pancreas and the salivary gland in the digestive system?
The pancreas and the salivary gland are glands which produce digestive juices containing enzymes.
What is the role of the stomach in the digestive system?
Produce hydrochloric acid - which kills any bacteria present and provides the optimum acidic pH for the protease enzyme function.
What is the role of the small intestine in the digestive system?
The small intestine 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 (stored in the gallbladder) which emulsifies lipids and allows the lipase enzyme to work more efficiently.
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?
Enzymes act as biological catalysts which speed up the rate of biological reactions (the breakdown of food) without being used up.
How does the shape of an enzyme affect its function?
Enzymes have a specific active site which is complementary to their substrate.
What is metabolism?
The sum of all the reactions in a cell or an organism.
What types of metabolic reactions do enzymes catalyse?
- Building larger molecules from smaller molecules eg. Glucose to starcg
- changing one molecule to another eg. Glucose to fructose.
- Breaking down larger molecules into smaller molecules eg. Carbohydrates to glucose.
What is the lock and key hypothesis of enzyme function?
The shape of the enzyme 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 action, as molecules have a higher kinetic energy. Above a certain temperature, the shape of the active site is altered and the enzyme becomes denatured, so it can no longer catalyse the reaction. The optimum temperature is around 37 degree Celsius
How does pH affect enzyme function?
The optimum pH for most enzymes is 7 (apart from proteases in the stomach). If the pH is too extreme, the shape of the active site may be altered and the enzyme may no longer work.
Where are carbohydrases, proteases and lipases produced in the body?
- Carbohydrases: amylase - salivary gland and pancreas; Maltase - small intestine.
- Proteases: pepsin - stomach; others - pancreas and small intestine.
- Lipases: pancreas and small intestine.
What is the role of carbohydrases in the digestive system?
Carbohydrases break down carbohydrates into monosaccharides and disaccharides. Amylase breaks down starch into maltose, and maltase breaks down maltose into glucose.
What is the role of proteases in the digestive system?
Proteases break down proteins into amino acids
What is the role of lipases in the digestive system?
Lipases break 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.
Where is bile made and stored in the body?
Bile is made by the liver and stored in the gallbladder
What is the role of bile in the digestive system?
- Bile is an alkaline substance which neutralises the hydrochloric acid secreted by the stomach.
- Bile emulsifies lipids to form droplets - this increases 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 the lungs - where the gaseous exchange of oxygen and carbon dioxide takes place
- One pathway carries blood from the heart to the tissues.
Where does blood pumped by the right ventricle go?
The lungs
Where does blood pumped by the left ventricle go?
Body tissues
Why is the double circulatory system important?
It makes the circulatory system more efficient - 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 - 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 4 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
What is the purpose of valves in the heart?
Prevent the backflow of blood
What is the purpose of coronary arteries?
Coronary arteries supply the heart muscle with oxygenated blood.
Describe the process of blood flow through the heart
- Blood enters the right atrium via the vena cava, and the left atrium via the pulmonary vein.
- The atria contract, forcing blood into the ventricles and 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 ventricle enters the aorta (to the body)
What is the approximate value of the natural resting heart rate?
70 beats per minute
How is the heart rate controlled?
Heart rate is controlled by a group of cells in the right atrium which act as a pacemaker. They release waves of electrical activity which cause the heart muscle to contract.
