Chapter 4: Animal tissues, organs and organ systems Flashcards
What is digestion?
The breakdown of food into smaller molecules that can diffuse into the blood
What is the function of the salivary glands?
To produce saliva, especially when you’re hungry and sense food. Saliva acts as a lubricant, making it easier to swallow food. It also contains AMYLASE, an enzyme that breaks down starch (a carbohydrate) into glucose
What is the oesophagus?
The tube that connects the mouth to the stomach. It pushes boluses of food downwards using rhythmic contractions
What is the function of the stomach?
Produces PROTEASE, an enzyme that breaks down protein into amino acids. It also releases hydrochloric acid, which kills pathogens and reduces the pH of the stomach to the optimal level for protease to work
What is the function of the liver in the digestive system?
Produces bile, a non-enzyme that helps to break down lipids (fats). Bile is stored in the gall bladder before being released into the small intestine
What is the function of the pancreas?
Produces 3 types of enzymes found in the digestive system: CARBOHYDRASE enzymes, LIPASE enzymes and PROTEASE enzymes
What is the rule for enzymes?
_____-ose is broken down by the enzyme _____-ase
What is the function of the small intestine?
Absorbs the products of digestion into the blood. Longer and narrower than the large intestine
How is the small intestine adapted to its function?
It contains villi, which are microscopic finger-like projections which massively increase the surface area for absorption. It also contains muscles which contract rhythmically to push food along (peristalsis)
What is the function of the large intestine?
Absorbs water and salts from the remaining digested food
What is a substrate?
A molecule which an enzyme acts on
What is lipase?
An enzyme which breaks down lipids into 3 fatty acid molecules and 1 glycerol molecule
What is the function of bile?
Breaks down large globules of fat into small droplets (it acts as an emulsifier). It increases the surface area of the fat so the lipase enzymes can break it down more quickly. Bile is alkaline so neutralises HCl entering the small intestine, allowing the enzymes there to work optimally
How do enzymes work?
The substrate fits into the active site (unique to the substrate) and the enzyme breaks its bonds.
How are enzymes destroyed?
High temperatures and extreme pH values can permanently change the shape of the active site, meaning the substrate no longer fits.
When are enzymes most effective (highest enzyme activity)?
At their optimal temperature and pH. If the temperature gets too low, they won’t have enough energy to break the bonds and if it gets too high they’ll become denatured
What are synthesis enzymes?
Enzymes which make complex molecules from simpler substances. For example, the enzyme found in protein synthesis joins amino acids to make proteins
What is an artery?
A large blood vessel that takes blood AWAY from the heart. They have thick elastic walls which can stretch to cope with the high-pressure blood
What is a vein?
A large blood vessel that returns blood to the heart. They have thinner walls than arteries because the blood is at a lower pressure. They also have one-way valves to prevent blood flowing in the wrong direction
What are capillaries?
Tiny blood vessels that spread out into tissues and organs to deliver blood and oxygen to them. They have thin walls to maximise diffusion. They connect arteries to veins
How does the heart pump blood around the body?
It contains pacemaker cells, which regularly generate electrical impulses. These electrical impulses travel along neurons to the cardiac muscle, causing it to contract
What path does blood take around the body?
Lungs (gains oxygen) Pulmonary vein Left atrium Left ventricle Aorta Body (loses oxygen) Vena cava Right atrium Right ventricle Pulmonary artery Lungs
Atria = input, Ventricle = output
How is the heart adapted to its function?
It contains valves at the top of the atria to prevent blood from being pumped backwards and to force it into the ventricles. The walls of the left ventricle are thicker than in the right ventricle. This is because the left ventricle needs to pump blood further to the extremities of the body, while the right ventricle only needs to pump it to the lungs
What is double circulation?
When blood goes through the heart twice on every circulation
