3.3 Organisms exchange substance with their environment Flashcards
what are lungs
a pair of lobed structures
what is the trachea
Flexible airway that is supported by rings of cartilage
Prevents collapse as air pressure falls
Walls are made of muscle, lined with ciliated epithelium and goblet cells
what is bronchi
2 trachea divisions
Also makes mucus to trap dust and have cilia that moves dirt laden mucus to the throat
what are bronchioles
Series of branching sub-divisions of bronchi
Walls are muscle lined with epithelial cells
Muscle allows constriction so air flow can be controlled
what is the alveoli
About 1 cell thick
Between them, there are collagen
Lined with epithelium
Elastic fibres allow stretching
what are the 2 types of ventilation
expiration
inspiration
how does expiration work
Expiration:
Breathing out
External intercostal muscles relax. Internal intercostal muscles contract.
Ribs are pulled in and down ( flatten) so the volume of the thorax decreases
Diaphragm relaxes
decrease of thorax volume causes an increase in pressure.
Atmospheric pressure is lower than pulmonary pressure so air is forced out the lungs
how does inspiration work
Breathing in
External intercostal muscles contract. Internal intercostal muscles relax.
Ribs are pulled up and out ( raise) and so the volume of the thorax increases
Diaphragm flattens/contracts.
Increase of thorax volume causes a decrease in pressure.
Atmospheric pressure is greater than pulmonary pressure so air is forced into the lungs
what is the pulmonary ventilation rate equation
PVR = tidal volume × breathing rate
what is pulmonary ventilation rate
volume of air re-entering or leaving the lungs per minute
what is tidal volume
volume of air breath in/out the lungs per breath
what is breathing rate
number of breaths per minute
what is pulmonary ventilation rate
volume of air re-entering or leaving the lungs per minute
what is the movement of gas in gas exchange
Oxygen moves around the body down a concentration gradient
Carbon dioxide moves down its own diffusion gradient and pressure gradient but in the opposite direction
Trachea -> Bronchi -> Bronchioles -> Alveoli -> Blood -> body
what is the process of starch digestion
Begins in mouth- amylase
( starch → maltose)
Then small intestine duodenum (1st part)- amylase
( starch → maltose )
Then ileum ( last part of small intestine)- maltase
( maltose → α- glucose )
Maltase- membrane-bound disaccharidase
what is the entire process of starch digestion
Mouth (I)- chewed food increases the surface area, smaller pieces are easier to swallow Mouth (II) – saliva made in salivary gland contains amylase which breaks down starch. Mineral ions help maintain optimum pH of amylase Stomach (I)- acidic conditions. Makes salivary amylase acidic which denatures and prevents further hydrolysis of starch Small intestine (I)- pancreas releases pancreatic juice containing amylase, protease and lipase into the small intestine. This will break down any remaining starch Small intestine (II)- alkaline salts produced by the pancreas and intestine wall will maintain the pH Small intestine (III)- disaccharides found are maltase, sucrase and lactase. Maltase breaks maltose down into α- glucose.
what is protease
Breaks down large insoluble proteins to small soluble amino acids
Produced- stomach, pancreas, small intestine.
what is the process of protein digestion
Starts in the stomach and the small intestine ends it.
Endopeptidase- breaks large polypeptides into smaller polypeptides and hydrolases internal peptide bond
Exopeptidases- splits off 1 amino acid at a time working from the end of a polypeptide.
Dipeptidase- hydrolyse small peptides only 2/3 amino acids long. Located on the cell-surface membrane of epithelial cells in small intestine. The products enter cells of the lining of the small intestine.
why cant glucose diffuse
In the mammalian ileum, the concentration of glucose is to low for glucose to diffuse out into the blood.
what is the process of co-transport
Step 1- sodium ions are actively transported out of the epithelial cells into the ileum, into the blood via the sodium-potassium pump. This creates a concentration gradient
Step 2- this causes sodium ion to diffuse from the lumen of the ileum into the epithelial cell, down their concentration gradient. They do this via a sodium-glucose co-transporter proteins. The co-transporter carries glucose into the cell with sodium. As a result, the concentration of glucose inside the cell increases.
Step 3- glucose diffuses out of the cell into the blood, down its concentration gradient through a protein channel through facilitated diffusion
what is bile
Made in the liver, stored in gall bladder. Binds to fat droplets and breaks down into smaller fat droplets emulsification- increases surface area for lipase digestion.
what is lipase
Breaks down large insoluble lipids, fats and oils into small, soluble fatty acids and glycerol.
Produced- pancreas, small intestine
what is a micelle
Made from glycerol, fatty acid, monoglyceride and bile salts to form mixed micelles.
Hydrophobic groups on the inside, hydrophobic groups on the outside.
what is the process of blood flow
Superior vena cava brings blood back
Pulmonary artery takes blood to the lungs for oxygenation
Returns to the heart via pulmonary vein
Leaves heart by aorta
Blood goes around the body
The left ventricle has a thicker more muscular wall to allow more powerful pumping to pump blood around the body.
what do veins do
Take deoxygenated blood back to the heart under low pressure.
Wider lumen with little elastic/muscle tissue.
Has valves to stop backflow
Blood flow is helped by the contraction of surrounding body muscles.
what does arteries do
Carries blood from the heart to the rest of the body
Thick muscular walls
Has elastic tissue to stretch ( maintains high pressure)
Inner lining- endothelium- is folded, allowing the artery to stretch
All carries oxygenated blood apart from the pulmonary artery which
carries deoxygenated blood
what do arterioles do
Arteries divide into small vessels called arterioles that form a network throughout the body
Blood is directed to different parts of demand by muscles which contract to restrict blood or relax to allow full blood flow
Arterioles branch into capillaries
what do capillaries do
Are found close to cells in exchange tissues ( short diffusion pathway) as substances are exchanged.
Walls are 1 cell thick to have a short diffusion pathway
what do valves do
Only open one way. Opening and closing depends on relative pressure of heart chambers
Open- higher pressure behind, forces it to open
Closed- higher pressure in front forces it to close
Blood flow is unidirectional
Atrioventricular valve- links the atria to ventricle
Semilunar valve- links ventricle to pulmonary artery and aorta.
what is the cardiac output equation
Cardiac output = stroke volume × heart rate
what is cardiac output
Volume of blood pumped by the heart per minute
what is stroke volume
volume of blood pumped out the left ventricle during 1 cardiac cycle
what is atrial systole in the cardiac cycle
Ventricles are relaxed. Atria contract, decreasing the volume of chambers and increasing pressure. It forces blood into the ventricles. Slight increase in ventricular pressure and chamber volume as ventricles received rejected blood from contracting atria
what is ventricle systole in the cardiac cycle
The atria relax. Ventricles contract, increasing their pressure. The pressure in the ventricles ˃ pressure in atria. Forces AV valves shut. Pressure in ventricles ˃ pressure in aorta/ pulmonary artery. Forces SI valves open
what is diastole in the cardiac cycle
Ventricles and atria relax. SI valves close. Blood returns to the heart. Atria fills due to high pressure in vena cava/ pulmonary artery. Increases pressure. As ventricles relax, their pressure falls which opens AV valves.
how are plants adapted for efficient gas exchange
Leaves have many small holes called stomata which allow gases to enter and exit the leaves.
The large number of these means no cell is far from the stomata, reducing the diffusion distance.
Leaves also possess air spaces to allow gases to move around the leaf and easily come into contact with photosynthesising mesophyll cells.
how are single-celled organisms adapted for efficient gas exchange
Single celled organisms are small so they have a large surface area to volume ratio.
Oxygen is absorbed by diffusion across their body surfacewhich is covered only by a cell- surface membrane.
In the same way, carbon dioxide from respiration diffuses out across their body surface.
Cell walls are completely permeable
Gas exchange occurs by diffusion across their membranes.
Has a short diffusion pathway. No need for a specialised gas exchange system.
what are fish’s characteristics that means they have to have a specialised exchange surface
Have a waterproof, and therefore gas-tight outer covering. relatively large, so they also have a small surface area to volume ratio, therefore not adequate to supply and remove their respiratory. Specialized exchange surface- gills
what are gills structure
within the body of the fish, behind the head. Made up of gill filament (thin plates) which give it a large surface area. The gill filaments are stacked up in a pile. At right angles to the filaments are gill lamellae which increase the surface area of the gills. Filamentare covered in theses tiny structures. Water is taken in through the mouth and forced out the gills and out through an opening in each side of the body.
what is the counter-current system and how does it allow an efficient gas exchange system
blood and the water flow over the gill lamellae in opposite directions. Means water with a relatively high concentration of oxygen always flows next to blood This arrangement means that:
Blood with little oxygen in it meets water which has most, so diffusion of oxygen from the water to blood takes place.
Means a steep concentration is maintained between water and the blood- so as much oxygen as possible diffuses from water into the blood
why do insects need direct transport of gas
Insects do not possess a transport system therefore oxygen needs to be transported directly to tissues undergoing respiration.
how do insects get a direct transfer of gas
This is achieved with the help of spiracles, small openings of tubes, either bigger trachea or smaller tracheoles, which run into the body of an insect and supply it with the required gases.
Gases move in and out through diffusion, mass transport as a result of muscle contraction and as a result of volume changes in the tracheoles. Network of tubes- trachea and tracheoles.
Spiracles- can be opened and closed and compromise between gas exchange and water loss.
how do gases move in and out of the tracheal system along the diffusion gradient
- When cells are respiring, oxygen is used up in so it’s concentration towards the end of thetracheolesfalls.
- creates a diffusion gradient that causes oxygen to diffuse from the atmosphere to tracheae and tracheoles to the cells.
- Carbon dioxide is produced by cells during respiration- creates a diffusion gradient in the opposite direction, causing carbon dioxide to diffuse along the tracheoles and trachea into the atmosphere.
- diffusion in air is more rapid than in water, so respiratory gases are exchanged quickly by this method.
how do gases move in and out of insects using mass transport
The contraction of muscles in insects can squeeze the trachea enabling mass movements of air in and out.
this further speeds up the exchange
how do gases move in and out of insects using water at the end of tracheoles
- ends of the tracheoles are filled with water.
During periods of major activity, the muscle cells around the tracheoles respire carry out some anaerobic respiration, produces lactate, which is soluble and lowers the water potential of the muscle cells, so water moves into cells from the tracheoles by osmosis. The water in the ends of tracheoles decreases in volume and so draws air further into them. This means the final diffusion pathway is a gas rather than a liquid phase and therefore diffusion is more rapid.
