ORGANISATION #2 Flashcards
The human digestive system has two functions:
breaks down complex food substances
provides the very large surface area for maximum absorption of food
digestion
Mouth
Begins the digestion of carbohydrates
Stomach
Begins the digestion of protein; small molecules such as alcohol absorbed
Small intestine
Continues the digestion of carbohydrate and protein; begins the digestion of lipids
Small intestine -
Completes the digestion of carbohydrates and proteins into single sugars and amino acids; absorption of single sugars, amino acids and fatty acids and glycerol
Large intestine
Absorption of water; egestion of undigested food
lock and key method
the active site- the protein has a complementary shape to the substrate- the molecule that is taking part in the reaction
the substrate collides with the active site of the enzyme and becomes attached
the enzyme then catylyes the breakdown of the substrate- the fit between the active site and the enzyme is perfect
products released from active site
enzyme can be reused
Factors affecting enzyme action temp
Temperature
At low temperatures, the number of successful collisions between the enzyme and substrate is reduced because their molecular movement decreases. The reaction is slow.
Higher temperatures break the forces that hold the enzyme together causing the enzyme to denature and the subtrate no longer fits
The effect of pH
Enzymes are also sensitive to pH. Changing the pH of its surroundings will also change the shape of the active site of an enzyme.
what breaks down carbohydrate
carbohydrase
Carbohydrases break down carbohydrates into
simple sugars
what breaks doen starch
amylase
amylase breaks starch into
glucose
what breaks down protein
protease
what does protease break the protein into
amino acids
what breaks down lipids
lipase
what do lipase break down lipids into
fatty acids+ glycerol
bile-
Emulsifies lipids, breaking them up physically into tiny droplets. Tiny droplets have a much larger surface area, over which lipases can work, than larger pieces, or drops of lipid.
Humans have a double circulatory system. The heart pumps blood through two circuits:
the pulmonary circulation
the systemic circulation
what does the pulmonary circuit do
The pulmonary circulation transports blood to the lungs. At the lungs:
oxygen diffuses into the blood from the alveoli - the blood becomes oxygenated
carbon dioxide diffuses from the blood into the lungs
The pulmonary circulation is under lower pressure, because:
blood is delivered to the lungs only, which are very close to the heart
in a healthy person, this lower pressure is optimum for the diffusion of gases
what does the systemic circuit do
The systemic circulation transports:
oxygen and nutrients to the body
carbon dioxide and other wastes away from cells
The systemic circulation is under high pressure - it has to deliver blood to the extremities of the body.
arteries
Always carry blood away from the heart
Carry oxygenated blood, except for the pulmonary artery
Carry blood under high pressure
Have thick muscular and elastic walls to pump and accommodate blood
A type of supporting tissue called connective tissue provides strength
The channel in the blood vessel that carries blood - the lumen - is narrow
Have a wide lumen
veins
Always carry blood to the heart
Always carry deoxygenated blood, except for the pulmonary vein
Carry blood under low or negative pressure
Have thin walls - have less muscular tissue than arteries
Have less connective tissue than arteries
Have a wide lumen
capillaries
The walls of capillaries are just one cell thick. Capillaries therefore allow the exchange of molecules between the blood and the body’s cells - molecules can diffuse across their walls. This exchange of molecules is not possible across the walls of other types of blood vessel.
whats in the blood
rbc
wbc
platelets
plasma
plasma
rbc
wbc
platelets
Plasma Transporting carbon dioxide, digested food molecules, urea and hormones; distributing heat Red blood cells Transporting oxygen White blood cells Ingesting pathogens and producing antibodies Platelets Involved in blood clotting
rbc
They have a biconcave shape - they are the shape of a disc that is curved inwards on both sides - to maximise their surface area for oxygen absorption.
They are thin, so there is only a short distance for the oxygen to diffuse to reach the centre of the cell.
wbc
have phagocytes Phagocytes engulf and destroy unwanted microorganisms that enter the blood
have lymphocytes- Lymphocytes produce soluble proteins called antibodies when a foreign body such as a microorganism enters the body.
