Flashcards in 3.1 - Exchange Surfaces and Breathing Deck (38)
What four things need to be interchanged between an organism and its environment?
Respiratory gases (O2 and CO2)
Nutrients (glucose, fatty acids, amino acids, vitamins and minerals)
Waste products (urea and CO2)
In what two ways can exchange occur?
Passively (no energy required) - diffusion and osmosis
Actively (energy required) - active transport
In what way are small organisms able to exchange efficiently?
Large surface area to volume ratio. Surface area is large enough compared to their volume.
How are organisms adapted to exchange if diffusion is the only transport method?
Flat shape so that no cell is ever far from the surface. Specialised exchange surfaces with large surface areas to increase SA:V ratio.
What are the features of a specialised exchange surface?
Large surface area
Short diffusion distance
Steep concentration gradient maintained
Define simple diffusion.
The net movement of molecules from an area of high concentration to an area of low concentration.
What is the equation for Fick's law?
Rate of diffusion = (surface area x concentration gradient) divided by diffusion distance
Describe the changes when you inspire (breathe in).
External intercostal muscles contract, internal intercostal muscles relax.
Ribs move up and out.
Diaphragm contracts (flattens).
Volume of the thorax increases.
Air pressure in the lungs decreases.
Describe the changes when you expire (breathe out).
External intercostal muscles relax, internal intercostal muscles contract.
Ribs move down and in.
Diaphragm relaxes (domed).
Volume of the thorax decreases.
Air pressure in the lungs increases.
Describe the structure and function of the trachea.
Flexible airway made of rings of cartilage.
Cartilage stops collapsing when air pressure changes.
Walls made up of ciliated epithelia and goblet cells.
Goblet cells produce mucus that traps dirt particles and bacteria from air breathed in.
Cilia move dirty mucus up to throat where it passes down oesophagus into stomach.
Describe the structure and function of the bronchi.
Two divisions of the trachea, each leading to one lung.
Similar function to the trachea (mucus moved up).
Describe the structure and function of the bronchioles.
Branching subdivisions of the bronchi, muscle walls lined with epithelial cells.
Muscle allows for constriction to control air flow in and out of the alveoli.
Describe the structure and function of the alveoli.
Minute air sacs at the end of bronchioles, contain elastic fibres and are lined with epithelial cells.
Elastic fibres allow for stretching and recoil when breathing in and out.
Why is diffusion from alveoli to blood rapid?
Walls of alveoli and capillaries are very thin, and red blood cells are squeezed flat against capillary walls - short diffusion pathway.
What are the causes, effects and symptoms of asthma?
Smooth muscle walls of bronchi/bronchioles contract and secrete more mucus.
Constriction and inflammation decreases the diameter of the airways.
Air flow in and out reduced, reducing the amount of oxygen to the alveoli.
Lower concentration gradient so lower rate of diffusion.
What is the function of the squamous epithelium?
Provides short diffusion distance.
What is the function of the ciliated epithelium?
Cilia waft mucus along airway.
What is the function of the glandular tissue?
What is the function of the cartilage?
Supports the airway.
What is the function of the smooth muscle?
Constricts the airway.
What is the function of the elastic tissue?
Recoils to dilate airways or to help expel air from the alveoli.
What is the function of the blood?
What is the function of the nervous tissue?
Carries messages to coordinate action.
What is the function of the connective tissue?
Holds other tissues together.
What machine is used to measure the air into and out of the lungs?
What does tidal volume mean?
Volume of air inhaled or exhaled in one breath during normal breathing.
What does vital capacity mean?
The maximum volume of air that can be moved by the lungs in one breath.
What does residual volume mean?
Volume of air that remains in the lungs even after forced expiration.
What does total lung capacity mean?
Vital capacity + residual volume.