Exchange & Transport Flashcards
(55 cards)
Why is diffusion alone enough to supply the needs for single celled organisms
Metabolic activity is usually low so oxygen demands and CO2 production is low
Surface area to volume ratio is large
Problems bigger organisms face
Smaller SA:V ratio
Distance between the cells and where oxygen is needed and the supply of oxygen is too far for effective diffusion to take place.
Have high oxygen demand
What does an increased surface area do?
Gases can be exchanged quickly And in large amounts
What do thin layers do?
The distances that substances have to diffuse are short, making the process fast and efficient
What does a good blood supply do?
The steeper the concentration gradient, the faster diffusion takes place. Ensures substances are constantly delivered to and removed from the exchange surface. This maintains a steep concentration gradient for diffusion.
What does good ventilation do?
A ventilation system helps maintain a concentration gradient and makes the process more efficient.
What components do mammals have?
Small SA:V ratio
Large volume of cells
High metabolic rate as they are active and maintain body temp
Need lots of oxygen for cellular respiration.
What does the nasal cavity do
Large surface area with good blood supply, which warms the air
Hairy lining which secretes mucus to trap dust and bacteria
Moist surfaces which increases the humidity of the incoming air reducing evaporation
What is the trachea
The main airway carrying clean warm moist air from the nose to chest.
Wide tube made of incomplete rings of cartilage which stop it from collapsing
What do goblet cells do
Secrete mucus onto the lining of the trachea to trap dust that have escaped the nasal cavity
What do ciliated epithelial cell’s do?
The cilia beat and move the mucus away from the lungs.
Structure of bronchus
Trachea divides to form bronchus. Similar structure to trachea with same rings of cartilage but are smaller
What do bronchioles do
Bronchi divide into small bronchioles. Small ones have no cartilage rings. Walls of them contain smooth muscle.
Lined with thin layer of flattened epithelium
What happens when smooth muscle of bronchioles contract
Bronchioles constrict- changes amount of air reaching lungs
What happens when smooth muscle of bronchioles relax
The bronchioles dilate- which changes amount of air reaching lungs
What do the alveoli do
Tiny air sacs which are the main exchange surfaces of the body
Consist of a layer of thin flattened epithelial cells along with some collagen and elastic fibres. The elastic tissues allow the alveoli to stretch as air is drawn in- elastic recoil
What allows alveoli to remain inflated?
Lung surfactant
Define ventilation
Movement of air
In and out of the lungs
What happens during inspiration
Diaphragm contracts and flattens
External intercostal muscles contract, moving the ribs upwards and outwards
Volume of thorax increased so pressure reduces, and is now lower than atmospheric pressure so air is drawn in
What happens during expiration
Diaphragm relaxes and turns dome shaped
External intercostal muscles relax so ribs move down and inwards.
Pressure is greater than atmospheric pressure so air moves out of lungs
What happens when you exhale forcibly?
You use energy
Internal intercostal muscles contract pulling the ribs down hard and fast and the abdominal muscles contract forcing the diaphragm up to increase pressure rapidly
What is a peak flow meter
Measures the rate at which air can be expelled from the lungs
What are vitalographs
Produces a growth of the amount of air breathed out and how quickly it is done so
What is a spirometer
Measures lung volume/ ventilation
