3.1 - Exchange And Transport Flashcards
Why do small organisms not need a specialised gas exchange system?
They don’t need one because they have a large SA:Volume ratio so oxygen is able to easily reach the centre of the organism so it can rely on simple diffusion
Why do large organisms require a specialised gas exchange system?
They have a small SA:Volume ration and multiple cells so oxygen is not able to reach all of the cell in the organism. So it requires a specialised system to do it
What are the features of an efficient gas exchange system?
- A short diffusion pathway
- A large surface area
- Steep concentration gradient
- Good blood supply
- Moist
- Well ventilated
What are the features of the mammalian gas exchange system?
- Trachea
- Lungs
- Intercostal muscles
- Ribs
- Diaphragm
- Bronchi
- Bronchioles
- Alveoli
What tissues are in the respiratory system?
- Cartilage
- Smooth muscle
- Elastic fibres
- Epithelial tissue
How is the cartilage in the trachea specialised?
They have c shaped rings of cartilage to make the trachea stronger but also give the oesophagus room to expand
What is the tidal volume?
The volume of air breathed in and out in one breath
What is breathing rate?
The number of breathes taken in one minute
How do you work out breathing rate?
Count the number of full breathes in 60 seconds
How do you work out the tidal volume?
- Draw 2 line one above and one below the trace
- Measure 3 volumes between the lines
- Work out the mean
How do you work out vital capacity?
- Measure the height of the vital capacity (height of deep breathe out)
- Convert the volume using the axis
Why is soda lime used in a spirometry machine?
To absorb the carbon dioxide that the person releases
How do humans inhale?
- The diaphragm contracts causing it to move it down
- External intercostal muscles contract to raise the ribs
- The volume of the thorax increases
- Pressure decreases below atmospheric pressure
- Air moves into the lungs
How do humans exhale?
- Diaphragm relaxes causing it to move up
- External intercostal muscles relax and the ribs fall (intercostal muscles can contract to form more force)
- Volume of the chest cavity decreases
How do insects breathe?
- Oxygen goes through the spiracles that are on the thorax and abdomen
- It then goes through the trachea
- Goes into the tracheoles
How is the trachea adapted for its function?
- C-shaped cartilage rings for support
- Smooth muscle which can contract and the lumen constricts reducing air flow when there are harmful substance in the air
- Elastic fibres allow the lumen to stretch and recoil
- Ciliated epithelium with goblet cells so that anything harmful will get stuck in the mucus
How are the bronchi and the bronchioles adapted?
Cartilage within the walls for structural support
What is alveoli the site of?
Gas exchange
What happens in the alveoli?
Oxygen diffuses from the alveoli into the capillaries and carbon dioxide diffuses from the blood to the alveoli
How is the alveoli adapted?
- Large SA - lots of alveoli in a small space
- Short diffusion distance - walls are single cell thick (squamous epithelial)
- Maintains a concentration gradient - surrounded by a network of capillaries to move the gases quickly
What is ventilation?
The action of breathing
What do you use to measure the volume of air inhaled and exhaled?
Spirometer
How do you work out ventilation rate?
Tidal volume x breathing rate
What happens during exercise?
Oxygen uptake increases and ventilation rate decreases
How do fish breathe?
- The mouth opens and the bucal cavity is lowered
- Volume of the bucal cavity increases and the pressure decreases
- The opercular valve closes and the opercular cavity expands
- The bucal cavity raises and forces the water over the gills
- The opercular valve opens
How are gills adapted?
4 layers of gill filaments and gill lamellae to increase SA and make a short diffusion pathway
How does the counter current system work?
The water flows over the gill filaments in the opposite direction that the blood flows to ensure a diffusion gradient is maintained
What are spiracles and where are they found?
Ring shaped openings on the thorax
Who are spiricles adapted and why?
They have sphincters to open and close the spiracles to stop gases from entering or leaving
What are the trachea in insects?
Hard tubes leading from the spiracles
How is the trachea adapted and why (insects)?
Lined with chitin so that the tube don’t collapse
What are tracheoles in insects?
Single called, elongated tubes that go to individual cells
How are tracheoles adapted?
Permeable single cell walls for gas exchange and tracheole fluid to allow oxygen to dissolve in
How is the nasal cavity adapted?
- Large surface area and good blood supply to warm air to body temperature
- Hairy lining that secretes mucus to trap dust and microorganisms
- Moist surface that increases humidity to reduce evaporation
What is the function of goblet cells
Secrete mucus to trap microorganisms and dust to stop then from reaching alveoli
What is the function of cillia?
Hair like structure to beat mucus upwards to prevent it going into the alveoli
What is the function of elastic fibres?
Stretch and recoil whilst breathing in and out
What is the function of smooth muscle?
Helps control the diameter of the trachea, bronchi and bronchioles by making them wider which means there is less resistance of airflow
