Organisms Exchange Substances With Their Environment Flashcards
Gas exchange in single called organisms.
Have a large surface area to volume ratio.
Oxygen is absorbed by diffusion across the cell surface membrane.
The same way co2 diffuses out.
How to calculate rate of diffusion.
(Surface area x difference in concentration)/length of diffusion pathway.
Describe gas exchange in insects.
They have a internal network of tubes called tracheae.
This is supported by strengthened rings to prevent them from collapsing.
They then divide into smaller dead end tubes called tracheoles.
This moves along a diffusion gradient.
The contraction of muscles can enable movement.
The end of tracheoles are filled with water.
Air moves in through pores called spiricals.
Describe gas exchange in fish.
Fish have gills located at the back of their head.
These are made up of gill filaments which are stacked up in a pile at right angles to gill lamellae which increase surface area.
Water is taken in through the mouth and forced over the gills and out through openings in the head.
Water and blood flow in opposite directions this is called counter current flow.
Describe gas exchange in the leaf of a plant.
Many small pores called stomata take in air.
It then travels through numerous interconnecting airspaces that occur throughout the mesophyll so gas can readily come into connect with the mesophyll cells.
Describe the structure and function of stomata.
Surrounded by guard cells which open and close the pore.
Can control the rate of gas exchange.
Prevents water loss.
How do insects limit water loss?
Small surface area to volume.
Waterproof covering.
Spiracles.
Limiting water loss in plants.
Thick cuticle. Rolling up leaves. Hairy leaves. Embedded stomata. Reduced surface area to volume ratio.
Describe the structure of the ventilation system.
Nostril Nasal cavity Trachea Bronchus Bronchiole Alveoli Lungs
Describe the structure of lungs.
Pair of lobed structures made up of a series of branched tubules called bronchioles which end in tiny air sacs alveoli.
Describe the structure of the trachea.
Flexible airway that is supported by rings of cartilage which prevents it from collapsing when pressure inside falls when breathing in.
Tracheal walls are made up of muscle lined with ciliates epithelium and goblet cells.
Describe the structure of bronchi.
Two divisions of trachea each leading to one lung.
Produce mucus to trap dirt.
Have cilia to move dirt up to throat.
Supported by cartilage.
Describe the structure of bronchioles.
A series of branching subdivisions of the bronchi.
Their walls are made up of muscle lined with epithelial cells.
This allows them to constrict air flow in and out of the alveoli.
Describe the structure of the alveoli.
Small air sacs with the diameter 100um-300um at the end of the bronchioles.
Between them there is some collagen and elastic fibres.
The elastic fibres allow the alveoli to expand then spring back during breathing.
Describe the process of inspiration.
The external intercostal muscles contract muscles contract while the internal intercostal muscles relax.
The ribs are pulled upwards and outwards increasing the volume of the thorax.
Diaphragm contracts.
The increased volume of the thorax results in a reduction of pressure in the lungs.
Atmospheric pressure is now greater than pulmonary pressure so air is forced into the lungs.
Describe the process of expiration.
The external intercostal muscles relax muscles contract while the internal intercostal muscles contract.
The ribs are pulled downwards and inwards decreasing the volume of the thorax.
The diaphragm muscles relax.
The decreased volume of the thorax results in a increase of pressure in the lungs.
Atmospheric pressure is now smaller than pulmonary pressure so air is forced out the lungs.
Pulmonary ventilation rate? (Dm3/min)
Tidal volume (dm3) x breathing rate (min-1)
Describe gas exchange in the alveoli.
Red blood cells are slowed as they pass through the pulmonary capillaries allowing more time for diffusion.
The distance before the alveolar air and red blood cells is reduced as the red blood cells are flattened against the capillary walls.
Air moves across the very short diffusion pathway constantly due to the constant movement of blood.
Describe the structure of the digestive system.
Mouth Salivary glands Oesophagus Liver Gall bladder Stomach Pancreas Small intestine Large intestine Rectum Anus
Describe the roles of the oesophagus.
Carries food from the mouth to the stomach.
Describe the structure and role of the stomach.
Muscular sac with an inner layer that produces enzymes.
Stores and digests food, especially proteins.
Describe the structure and role of ileum (small intestine).
Long muscular tube.
Food is further digested by the enzymes produced in its walls.
The walls are folded giving them a larger surface area.
Here the products or digestion are moved into the blood stream.
Describe the role of the large intestine.
Absorbs water from faeces.
Describe the role of the rectum.
Faces stored here until being removed through the anus by egestion.
The role of the salivary glands.
Situated near the mouth.
They pass they’re secretion via a duct in the mouth.
These contain amylase which hydrolyses starch into maltose.
Describe the pancreas.
Large glad situated bellow the stomach.
Produces pancreatic juice.
This contains protease to hydrolyse proteins, lipase to hydrolyse lipids and amylase to hydrolyse starch.
What is digestion?
The break down of large molecules into small soluble molecules.
This occurs through a physical and a chemical breakdown.
Structure of haemoglobin.
Primary structure, sequence of amino acids in polypeptide chains.
Secondary structure, each chain coiled into helix.
Tertiary structure, each chain folded into precise shape.
Quaternary structure, all 4 chains are joined together to form a spherical molecule. Each chain is associated with a haem group which contains a Fe2+ ion which can carry a single o2 molecule.
