Exchange Surfaces and Breathing Flashcards
What is SA:V?
This is an important concept- the surface area of an organism divided by its volume, expressed as a ration.
Why do multicellular organisms need a specialised exchange system?
Multicellular organisms are so large so have a small SA:Vol.
Active, so metabolic rate means a higher demand for oxygen. Cells and tissues are too deep in the body.
Diffusion alone is too slow to supply enough oxygen and remove carbon dioxide.
What are features of a good exchange system?
Large surface area- to provide more spaces for molecules to diffuse through
Thin barrier- to reduce diffusion distance
Good blood supply- maintains a steep concentration gradient.
How are the alveoli adapted?
Large numbers of alveoli provide a large surface area.
Alveoli are small in size to provide a small surface area to volume ration.
Alveolar cells secrete surfactant to maintain surface area and prevent collapse.
Squamous epithelial cells are one cell thick so provide a short diffusion distance.
Elastic fibres recoil to help ventilation.
Ventilation maintains a steep concentration gradient.
What is inspiration?
The diaphragm contracts, flattens and moves down.
External intercostals contacts and the ribs rise.
Volume of the thorax increases.
Pressure in thorax drops below atmospheric pressure.
Air moves into lungs down a pressure gradient.
What is expiration?
The diaphragm relaxes, curves up and moves into the chest cavity.
External intercostal muscles relax and ribs fall.
Volume of the thorax decreases.
Pressure in thorax rises above atmospheric pressure.
Air moves out of the lungs down a pressure gradient
Alveoli:
Squamous epithelium
Elastic fibres that stretch during inspiration and recoil to expel air during expiration
What is the trachea composed of?
Large C-shaped pieces of cartilage Smooth muscle Elastic fibres Goblet cells Ciliated Epithelium
What is the bronchi composed of?
Small pieces of cartilage Smooth muscle Elastic fibres Goblet cells Ciliated Epithelium
What are the Bronchioles composed of?
No cartilage Elastic fibres Smooth muscle Goblet cells Ciliated Epithelium
What is Smooth muscle?
Involuntary muscle that contracts without the need for conscious thought. E.g. in an allergic reaction
What is a method for a spirometer?
- Subject wears nose clip to not breathe through the nose
- Subject breathes regularly
- During inspiration, air is drawn from the chamber and the lid moves down.
- The movement of the lid is recorded by a data logger
- CO2 rich air is passed through a chamber of soda lime, absorbing the CO2, allowing the measurement of O2 consumption.
What precautions need to be taken before using a spirometer?
Check the health of the volunteer e.g. asthma
Soda lime should be fresh and functioning
No leaks in the apparatus
Mouthpiece should be sterilised
Water levels is not too high
Medical grade oxygen used
What is the equation for total lung volume?
Total Lung Volume= Vital Capacity+Residual Volume
What does vital capacity depend on?
Age
Gender
Level of regular exercise
Height of a person
What is vital capacity?
The maximum volume of air inhaled and exhaled in one breath
What is residual volume?
The volume of air that remains in the lungs even after forced expiration.
Why is there residual volume?
Thorax can not be completely compressed. Trachea and bronchi are held open by cartilage. Bronchioles and alveoli are held by elastic fibres.
What is tidal volume?
The volume of air inhaled or exhales in one breath at rest.
Gaseous Exchange in bony fish
Gills are the exchange surface
Each fill consists of two rows of primary lamellar attached to a fill arch so large surface area. Primary lamellae folded into secondary lamellae so larger surface area. Primary lamellae are thin so shorter diffusion distance.
What is countercurrent flow?
Where two fluids flow in opposite directions.
What is ventilation of a bony fish?
Mouth opens, floor of buccal cavity lowers. Volume of the buccaneers cavity increases, pressure drops and water moves in.
Mouth closes, floor of buffalo cavity raises.
Volume of the buccal cavity decreases, pressure increases.
Opercular valves open.
Water is pushed through the gills.
Gaseous exchange in insects:
Open circulatory system- oxygen is not transported in the blood
Air-filled tracheal system supplies air directly to all respiring tissues. Air enters via a spiracle, is transported through trachea, then tracheole.
Ends of tracheoles are open and filled with fluid called tracheal fluid.
It occurs between the air in the tracheoles and the tracheal fluid.
Gilbert cells and Ciliated epithelium:
Goblet cells secrete mucus to trap dust, bacteria, pollen. Cilia waft mucus away from the lungs, up the airways to be swallowed.
Cartilage
Allows flexibility and holds airways open to prevent collapse
Elastic fibres
Recoil to help expel air during ventilation
Which two types of epithelial tissue found in lungs are?
Squamous and Ciliated
