Exchange And Transport Flashcards
Small and large organism in relation to SA:V ratio
- Smaller organisms=Larger SA:V ratio.
- Larger organisms=Smaller SA:V ratio.
How to single-celled organisms exchange substances?
- Substances can diffuse directly into the cell across the cell surface membrane.
- Diffusion rate is quick because of the short distances and because they tend to have a high SA:V ratio.
Why is gas exchange slow in multicellular organisms?
- Some cells are deep within the body. (Big distance between them and the outside environment).
- Large animals have low surface area to volume ratio.
- Multicellular organisms have a high metabolic rate, so they use up oxygen and glucose faster.
Special features on exchange surfaces
- A large surface area.
- Thin cell walls.
- Good blood supply.
How does a large surface area improve gas exchange efficiency?
- Provides the area needed for exchange.
- Overcomes the limitations of the SA:V ratio of larger organisms.
E.g root hair cells (branches are covered in hairs).
How do thin cell walls improve gas exchange efficiency?
- Provides a shorter pathway for diffusion.
- E.g alveoli in the lungs.
Good blood supply
- Ensures substances are constantly delivered to and removed from the exchange surface.
- Maintains a steep concentration gradient for diffusion.
- E.g alveoli in the lungs and gills of a fish.
What are the key feature of the gaseous exchange system?
- Cartilage.
- Ciliated epithelium.
- Goblet cells.
- Smooth muscle.
- Elastic fibres.
Cartilage function
- supports the trachea and bronchi
- prevents the lungs from collapsing in the event of pressure drop during exhalation
Where is the Ciliated epithelium found and what is its function?
- present in bronchi, bronchioles and trachea,
- moves mucus along to prevent lung infection by moving it towards the throat
Where are goblet cells found and what is their function?
- present in the trachea, bronchi and bronchioles
- involved in mucus secretion to trap bacteria and dust to reduce risk of infection with the help of lysozyme which digests bacteria
Smooth muscle function
- Constricts the airway.
- Controls the flow of air to and from alveoli.
Elastic fibres function
stretch when we inhale and recoil when we exhale thus controlling the flow of air
Which features are present in the trachea and in what form?
- Cartilage present (large C-shaped pieces).
- Smooth muscle present.
- Elastic fibres present
- Goblet cells present.
- Ciliated epithelium present.
Which features are present in the Bronchi and in what form?
- Cartilage present (smaller pieces).
- Smooth muscle present.
- Elastic fibres present.
- Goblet cells present.
- Ciliated Epithelium present.
Which features are present in the larger bronchiole and in what form?
- Cartilage not present.
- Smooth muscle present.
- Elastic fibres present.
- Goblet cells present.
- Ciliated epithelium present.
Which features are present in smaller bronchioles and in what form?
- Cartilage not present.
- Smooth muscle present.
- Elastic fibres present.
- Goblet cells not present.
- Ciliated epithelium present.
Which features are present in the smallest bronchioles and in what form?
- Cartilage not present.
- Smooth muscle not present.
- Elastic fibres present.
- Goblet cells not present.
- No Ciliated epithelium.
Which features are present in alveoli and in what form?
- Cartilage not present.
- Smooth muscle not present.
- Elastic fibres present.
- Goblet cells not present.
- No Ciliated epithelium.
What happens during inspiration?
- The external intercostal muscles and diaphragm muscles contract.
- This causes the ribcage to move upward and outward and the diaphragm to flatten, increases the volume of the thorax.
- As the volume of the thorax increase, the lung pressure decreases (to below atmospheric pressure).
- This causes air to flow into the lungs.
- Inspiration is an active process (requires energy).
What happens during expiration?
- The external intercostal muscles and diaphragm muscles relax.
- Ribcage moved downwards and inwards.
- Volume of thorax decrease, causing the air pressure to increase (to above atmospheric pressure).
- Air is forced out of the lungs.
- Expiration is a passive process (doesn’t require energy).
What does a spirometer give readings of?
- Tidal volume.
- Vital capacity.
- Breathing rate.
- Oxygen uptake.
What is tidal volume?
- The volume of air in each breath. (Usually about 0.4dm cubed).
What is vital capacity?
- The maximum volume of air that can be breathed in our out.
What is breathing rate?
- How many breaths are take per unit time. (Usually per minute).
What is oxygen uptake?
- The rate at which a person uses up oxygen.
How do you use a spirometer?
- A spirometer has an oxygen-filled chamber with a moveable lid.
- The person breathes through a tube connected to the oxygen chamber.
- As the person breathes in and out, the kid of the chamber moved up and down.
- These movement are recorded by a pen attached to the lid of the chamber.
- This creates a spirometer trace.
- The soda lime in the tube absorbs carbon dioxide so the person doesn’t breathe it back in.
Why is a counter-current exchange system important?
- Means that water with a high oxygen concentration always flows next to the blood with a low oxygen concentration.
- This means that a steep concentration gradient is maintained.
Fish adaptations
- Gill filaments give a big surface area for gas exchange.
- Gill filament are covered in Gill plated which increases the surface area even more.
How to fish ventilate?
- Fish opens its mouth, which lowers the floor of the buccal cavity.
- Volume of buccal cavity increases, deceasing the pressure inside the cavity.
- Water is sucked into the cavity.
- The fish closes its mouth and the floor of the buccal cavity is raised again.
- The volume inside the cavity decreases, and the pressure increases.
- Water is forced out of the cavity and across the Gill filaments.
- Each Gill is covered by a operculum.
- The Increase in pressure caused the operculum to open allow water to leave the gills.
How do insects exchange gases?
- Air moves into the trachea through spiracles.
- Oxygen travels down the concentration gradient toward the cells.
- Co2 from the cells move down its own concentration gradient toward the spiracles to be released.
- Trachea branches off into tracheoles which have thin permeable walls and go into individual cells.
- Tracheoles contain a fluid which oxygen dissolved in.
- Oxygen diffuses from the fluid into body cells.
- Co2 diffuses in the opposite direction.
- Insects use rhythmic abdominal movements to change the volume of their bodies and move air in and out of their spiracles.
How to dissect fish gills
- Place the fish on a cutting board.
- Push back the operculum and uses scissors to remove the gills.
- Cut each Gill arch through the bone at the top and bottom.
- Draw the Gill and label it.
- Wear an apron and gloves.
How to dissect an insect.
- Fix the legs to a dissecting board.
- Cut and remove a pieced of exoskeleton.
- Use a syringe to fill in the abdomen with saline solution.
- Mount the trachea on a wet mount microscope slide and examine it under a light microscope.
- Trachea will appear silver or grey because they are filled with air.
- Can also see rings of chitin in the walls of the trachea (used for support).
