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 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 contains organs such as the stomach, the small intestine and the large intestine.
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 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 (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 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?
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°.
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
Pmonosaccharides 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 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 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.
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
heart’s 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.