Master this deck with 60 terms through effective study methods.
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- Small surface area to volume ratio - Diffusion distances are too large - Diffusion alone is not efficient enough - Transport substances all around the organism - High metabolic demands
unicellular organisms have a large surface area to volume ratio. allowing them to be able to acquire the substances they need, as well as expel waste through diffusion alone, as they have low metabolic demands.
surface area / volume
2πr
πr²
2(bh + bl + hl)
length x width x height
2πrh + 2πr²
πr²h
4πr²
4/3πr^3
Gases and substances can diffuse directly into or our of the cell across the cell membrane because they have a large surface area compared to their volume so enough substances can be exchanged to supply the volume of the cell - there's a larger diffusion area compared to the actual volume.
Specialised exchange organs i.e Lungs, and mass transport i.e circulatory system.
- large surface area - thin - good blood supply
- Millions of long hairs on each root - Increases surface area - Increases the rate of absorption of water by osmosis - Increases the rate of mineral ion uptake by active transport.
- Each alveolus is made from a single thin layer of alveolar epithelium - Oxygen and carbon dioxide diffuse out of the alveolar space and into the blood and vice versa. - Thin walls reduce the diffusion distance for respiratory gases. -Hence increases rate of diffusion for efficient gas exchange.
- Alveoli are surrounded by a dense capillary network - Each alveolus has its own blood supply - Blood constantly takes oxygen away and delivers carbon dioxide - This maintains a steep concentration gradient as air in the lungs is ventilated.
- Mouth / nose / sinuses (air enters and exits) - Trachea - Bronchus (bronchi plural) - Bronchiole - Alveolus (gas exchange)
an epithelial tissue that secretes mucus and that lines many body cavities and tubular organs including the gut and respiratory passages.
- Goblet cells - Ciliated epithelial cells
A mucus-secreting epithelial cell. Mucus traps microorganisms and dust contained within inhaled air, stopping them from reaching the alveoli.
Hair-like structures on the surface of ciliated epithelial cells. They use microtubules to beat in a motion. This wafts mucus upwards towards the mouth and nose, away from the from the alveoli. This prevents lung infections.
Aid the process of breathing out. On breaithing in, th elungs inflate and the elastic fibres are stretched. Then the fibres recoil to help push air outwards when relaxing.
- Cartilage is strong but flexible - Prevents trachea and bronchi from collapsing when the pressure drops
Allow diameter of trachea, bronchi and bronchioles to be controlled. E.g. they relax during exercise to make them wider to make airflow easier.
- C-shaped hyaline cartilage rings on the anterior side - posterior wall contains smooth muscle - walls contain elastic fibres - Ciliated epithelium and goblet cells (mucous membrane)
- small pieces of cartilage - contains smooth muscle - contains elastic fibres - has goblet cells and Ciliated epithelium.
- NO cartilage - Sometimes contains some smooth muscle - Always contains elastic fibres - Sometimes contains goblet cells and Ciliated epithelium
- NO cartilage - no smooth muscle - no ciliated epithelium or goblet cells - contains elastic fibres
the process of inspiration and expiration of air through the pulmonary airways.
- Diaphragm - Intercostal muscles - Ribcage
- External intercostal muscles contract - Diaphragm contracts - Ribcage moves upwards and outwards - Volume of thorax increases - Thorax pressure decreases below atmospheric pressure - Air moves into the lungs down a pressure gradient (Active process - requires ATP)
- External intercostal muscles relax - Diaphragm relaxes - Ribcage moves downwards and inwards - Volume of thorax decreases - Thorax pressure increases above atmospheric pressure - Air moves out of the lungs down a pressure gradient - Passive process (no ATP required)
- Internal intercostal muscles contract - Ribcage moves abruptly downwards and inwards - Volume of thorax suddenly decreases -Pressure of thorax abruptly increases - Air violently moves out of lungs rapidly down a pressure gradient - Active process requiring ATP.
The amount of air inhaled or exhaled during normal breathing.
The maximum volume of air that can be breathed in or out in one breath
Number of breaths taken per minute.
The rate at which a person uses up oxygen
A spirometer has an oxygen filled chamber with a removable lid. The person breathes through a tube connected to the oxygen chamber. As the person breathes in and out, the lid of the chamber moves up and down. These movements can be recorded by a pen attached to the lid of the chamber - this writes on a rotating drum, creating a spirometer trace. The spirometer can also be linked to a motion sensor picked up by a data logger. The soda lime in the tube the patient breathes through absorbs CO2.
Because the air that's breathed out is a mixture of oxygen and carbon dioxide. The carbon dioxide is absorbed by the soda lime - so there's only oxygen in the chamber which the subject inhales from. As this oxygen gets used up by respiration, the total volume decreases.
To ensure they can only breathe air in and out through the tube.
The range of the largest peak to trough on the spirometer trace
Count the number of peaks, NOT including the vital capacity, in the trace in a minute
The range of the normal sized peak to trough on the spirometer trace
Use the peaks/troughs of the tidal volumes. Draw a straight line and calculate the gradient.
- Thin plates called gill filaments / primary lamellae - Gill filaments are covered in small structures called gill plates / secondary lamellae. - Each gill is supported by a gill arch.
- Gill filaments and lamellae are very thin - providing a short diffusion distance - Many gill filaments and lamellae provide a large surface area. - Countercurrent exchange system maintains a concentration gradient
- Blood flows through gill plates in one direction - Water flows in the opposite direction - This ensures water with a high concentration of oxygen always flows alongside blood with low oxygen concentration. - This means there is always a steepness concentration gradient maintained between the water and blood.
- Fish opens the mouth - The base of the buccal cavity lowers - The volume of the buccal cavity increases - Buccal pressure decreases - Water is sucked in down a pressure gradient
- Mouth closes - Base of buccal cavity lifts - Volume of buccal cavity decreases - Buccal pressure increases - Water sucked out of buccal cavity over the gills - Pressure forces the operculum open, and water leaves the gills into the surrounding environment.
protect gills
- Spiracles - Trachae - Tracheoles - Tracheal fluid
Openings in the body cavity where the trachea are exposed to outside air.
Microscopic air-filled pipes in insects
- An insect pumps its abdomen in and out, causing the pressure to rise and fall - Air is drawn in and out of the spiracles and the system by the changing pressure - Air moves into the tracheoles and arrives directly at muscle tissue Vice versa
1. Place chosen fish in a dissection tray or a cutting board 2. Push back the operculum and use scissors to carefully remove the gills. 3. Cut each gill arch through the bone at the top and bottom. 4. You should be able to see gill filaments upon close examination 5. Draw and label the gill using appropriate biological methodology
1. Fix the insect to a dissecting board by placing dissecting pins through its legs. 2. To examine the trachae, carefully cut and remove a piece of exoskeleton from along the length of the insect's abdomen. 3. Use a syringe to fill the abdomen with saline solution. 4. A network of thin, silver/grey tubes should be visible - these are trachae. 5. You can mount the trachae on a wet mount microscope slide and examine further with a light microscope. 6. Rings of chitin should be visible around the trachae.
- Scalpel: very sharp detachable blade used for fine cuts - Dissecting scissors: used for precise cutting - Dissecting pins: used with a wax-filled dissection tray for holding a specimen in place - Tweezers: for manipulating smaller parts of the specimen
To ensure cuts are precise To prevent injuries, blunt tools can be dangerous
- cut away from you to prevent cuts - wear gloves to prevent contamination - wear goggles to prevent eye irritation