B2 Flashcards
What is the order in which food passes through the digestive system?
Mouth, oesophagus, stomach, small intestine, large intestine, rectum, anus
What is the function of the mouth in digestion?
To mechanically break up food into smaller pieces to increase surface area
What is the function of stomach acid?
To kill potentially pathogenic microorganisms in food
What is the function of the small intestine?
To absorb carbohydrates, lipids amino acids,vitamins and mineral ions from digested food
Give an adaptation of the small intestine to aid absorption of digested molecules.
Has structures called villi which increase surface area
Give an adaptation of the cells lining the small intestine to aid absorption of digested molecules.
Epithelial cells lining the villi have microvilli on their surface which further increase surface area
What is the function of the large intestine?
To absorb water from digested foods
What is the function of liver in digestion?
To produce bile, an emulsifying and neutralising substance
What is the function of the gall bladder?
To store bile until it can be released into the small intestine
What is the function of the rectum?
To store undigested material before excretion
What is an enzyme?
A protein which can catalyse a reaction without being used up itself
What is a substrate?
A molecule or an atom which is acted upon by an enzyme
How does an enzyme ‘recognise’ its specific substrate?
A complementary shaped ‘active site’ - A region on the enzyme which fits the substrate
Name two environmental conditions that can change an enzyme’s active sight.
pH (either higher or lower than optimum)
Higher than optimum temperature
What do carbohydrases break down and what do they produce?
Carbohydrates to simple sugar (e.g. amylase to simple sugars)
What do proteases break down and what do they produce?
Proteins to Amino Acids
What do lipases break down and what is produced?
Lipids (fats) to fatty acids and glycerol
How does bile help the action of lipase?
- Provides alkaline conditions by neutralising acid from the stomach
- Emulsifies fat to form small droplets with a larger surface area
Which system transports substances around the body?
Circulatory system
Which are the upper chambers of the heart?
Atria
Which are the lower chambers of the heart?
Ventricles
What is the job of the heart valves?
To prevent back flow of blood in the heart
Name two key adaptations of capillaries.
- Very thin (only one cell thick) to reduce distance diffusion has to occur across
- very narrow to reduce distance diffusion has to occur across
Where is the natural pacemaker of the heart?
The right atrium
What gas diffuses into the bloodstream from the lungs?
Oxygen
What gas diffuses out of the bloodstream to the lungs?
Carbon dioxide
Describe 4 adaptations alveoli have to make them an efficient gas exchange surface.
- Thin walls (one cell thick)
- Extensive capillary network covering the surface of each alveolus
- Efficient movement of blood through capillaries to maintain a concentration gradient for diffusion of oxygen and carbon dioxide
- Folded inner surface to give a large surface area
What is blood?
A tissue
What is the liquid part of blood called?
Plasma
What are the three main cell types found in blood?
Red blood cells, white blood cells, platelets
What does blood plasma transport from the organs to the lungs?
Carbon dioxide
What do red blood cells transport?
Oxygen
What do red blood cells lack?
A nucleus
What do red blood cells contain?
Haemoglobin
What do platelets do?
Help clot the blood at wound sites
