Organisation Flashcards
what do glands do ?
produce digestive juices
what does the small intestine do ?
digests food and absorbs food molecules
what does the liver do ?
produces bile
what does the stomach do ?
digests food
what does the large intestine do ?
absorbs water molecules from the remaining undigested food
what is an organism ?
the highest level of organisation in a multicellular organism
what is an organelle ?
Organelle A specialised unit within a cell which performs a specific function
what is a cell ?
Cell The basic building block of all living organisms
what is a tissue ?
Tissue A group of cells working together to perform a shared function, and often with similar structure
what is an organ ?
Organ A structure made up of groups of different tissues, working together to perform specific functions
what is an organ system ?
Organ system A group of organs with related functions, working together to perform certain functions within the body
Surface area effect on gas exchange
The size of their surface, or surface area, defines how quickly they can absorb substances. The size of their volume defines how much of these substances they need.
Name two blood supply adaptations
the network of blood capillaries that surrounds each alveolus in the lungs
the network of blood capillaries in each villus in the small intestine
Effective gas exchange in lungs
The moving blood and ventilated surfaces mean that a steep concentration gradient can be maintained. This increases effective exchange.
The human lungs provide an exchange surface adapted for:
absorbing oxygen – needed for respiration – into the blood from the air
transferring carbon dioxide – produced by respiration – from the blood into the lungs then the air
The structure of the respiratory system
The human respiratory system is adapted to allow air to pass in and out of the body, and for efficient gas exchange to happen.
The lungs are enclosed in the thorax, surrounded and protected by 12 pairs of ribs. The ribs are moved by two sets of intercostal muscles. There is a muscular diaphragm below the lungs. The lungs are sealed within two airtight pleural membranes. These wrap around the lungs and line the rib cage.
The trachea, or windpipe, branches into two bronchi – one bronchus to each lung. Rings of cartilage in the walls of the trachea help to keep it open as air is drawn in.
The bronchi split into smaller branches and then into smaller tubes called bronchioles. Each bronchiole ends in a cluster of microscopic air sacs called alveoli.
The alveoli are adapted to provide a very large surface area for gaseous exchange:
There is also a short diffusion path - the walls of blood capillaries and alveoli are just one cell thick.
The ventilation of the lungs and the blood flow through the surrounding capillaries mean gases are being removed continually, and steep concentration gradients are set up for gases to diffuse.
Carbohydrates
Source of energy, glucose is the main respiratory substrate
Starch: potatoes, rice and wheat products, bread, cereals and pasta.
Sugars: fruit, smoothies, fizzy drinks, chocolate and sweets
Proteins
Proteins
Growth and repair
Meat, eggs, cheese, beans, nuts and seeds
Lipids
Lipids
Energy, make up part of cell membranes so essential for normal growth
Butter and margarine, meat and processed meat, plant oils, oily fish, nuts and seeds
Once absorbed by the body, glucose molecules are transported to cells and:
used for respiration
reassembled into the storage form of carbohydrate in animals - glycogen
Starch is a polymer of glucose.
It must be broken down into glucose molecules – it is too large to pass through the gut.
what are proteins made from
Proteins are made up of amino acids.
they are re assembled in the body through protein synthesis
Lipid molecules are too large to pass through the gut wall and must be digested first.
n the body’s cells, they are reassembled into the lipids the cell needs, for instance, for the cell membranes.
The human digestive system has two functions:
breaks down complex food substances
provides the very large surface area for maximum absorption of food
Mouth
Mouth Begins the digestion of carbohydrates
Stomach
Stomach Begins the digestion of protein; small molecules such as alcohol absorbed
Large intestine
Large intestine Absorption of water; egestion of undigested food
How do enzymes work ?
In an organism, the active site of each enzyme is a different shape. It is a perfect match to the shape of the substrate molecule, or molecules. This is essential to the enzyme being able to work. One enzyme is therefore specific to one substrate’s chemical reaction, or type of chemical reaction.
Low temperatures and enzymes
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 and enzymes
Higher temperatures disrupt the shape of the active site, which will reduce its activity, or prevent it from working. The enzyme will have been denatured.
pH and enzymes
Enzymes are also sensitive to pH. Changing the pH of its surroundings will also change the shape of the active site of an enzyme.
carbohydrates are broken down into …..
carbohydrate = simple sugars
lipids are broken down into …..
lipids = fatty acids + glycerol
proteins are broken down into …..
protein = amino acids
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.
Contains sodium hydrogencarbonate, which is an alkali.
It neutralises stomach acid and produces the optimum pH for pancreatic enzymes.
Is produced in the liver, but stored and concentrated in the gall bladder.
