B2: Organisation Paper1 Flashcards
What is a cell
The basic building block of a living organism
What is a tissue
A group of cells with similar structure and function working together. Eg muscular tissue contracts to bring about movement
What is an organ
A collection of tissues working together to perform a specific function eg the stomach contains glandular, muscular and epithelial tissues
What is an organ system
A group of organs working together to perform specific functions eg the digestive system contains organs such as the stomach the small and large intestine
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
Produces hydrochloric acid- which kills any bacteria present and provides the optimum acidic pH for the protease enzyme to 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 (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 starch
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
Increasing temp increases enzyme action, as molecules have higher kinetic energy. Above certain temp, the shape of the active site is altered and the enzyme becomes denatured, so it can no longer catalyse the reaction, the optimum temp is around 37 degrees
How does pH affect enzyme function
The optimum pH for most enzymes is 7 (apart from proteases in stomach) if pH is too extreme the shape of active site may be altered and 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 change 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 eg 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 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
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 right atrium via vena cava, and left atrium via 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.
How can an abnormal heart rhythm be treated
Irregular heart rhythms can be treated using an artificial pacemaker, which sends out electrical signals to correct the hearts rhythm.
What are the three types of blood vessel in the body
Arteries
Veins
Capillaries
How are arteries adapted for their function
Function: carry blood away from the heart
Thick muscle layer- adds strength to resist high pressure
Thick elastic layer- allows arteries to stretch and recoil- in order to withstand high pressure.
How are veins adapted for their function
Function: carry blood towards the heart
Wide lumen: enables low pressure
Valves- prevent backflow of blood
How are capillaries adapted for their function
Function: enable transfer of substances between the blood and tissues
Walls are one cell thick- short diffusion path
Permeable walls- substances can diffuse across.
Narrow lumen- blood moves slowly- more time for diffusion.
