Module 3: Exchange and Transport Flashcards
Describe the surface area to volume ratio for a small organism
They have very large surface areas to volume ratio.
This means that it has a big surface area and a shorter distance from the outside of the organism to the middle of it.
Therefore simple diffusion is needed.
Describe the surface area to volume ratio for a large organism.
They have small surface area to volume ratio as the distance from the centre of the organism to the outside is large.
Large organisms will have a higher metabolic rate.
How do single-cellular organisms exchange substances?
They can diffuse directly into or out of the cell across the cell-surface membrane.
The diffusion rate is quick due to the short distances that the substances have to travel.
They also have a high surface area to volume ratio.
How do multi-cellular organisms exchange substances?
They need specialised exchange surfaces due to diffusion being too slow. this is due to the following:
Multi-celled organisms have a large diffusion pathway.
They have a small surface area to volume ratio.
They have a large metabolic rate meaning they use up glucose and oxygen faster.
What are three features of Exchange surfaces?
They have a large surface area to increase efficiency.
They are thin to decrease the distance that the substances being exchanged have to travel over, and so to improve efficiency.
They have a good supply/good ventilation.
Describe the gas exchange surface in mammals.
In mammals the gas exchange surface is the lungs.
They help to get oxygen into the blood , for respiration, and to get rid of carbon dioxide, made by respiring cells, from the body.
When you breathe in, air enters the lungs via the trachea, windpipe. Then the Trachea spilts into 2 Bronchi, 1 Bronchus leading to each lung.
Each Bronchus then branches off into smaller tubes called Bronchioles which end in small air sacs called Alveoli.
This is where the gases are exchanged, and there are a lot of Alveoli in the lungs to provide a large surface area for diffusion.
Name the key features of the gaseous exchange system.
Goblet cells
Cilla
Elastic fibres
Smooth muscle
Cartilage
What is the structure and function of Cilla?
They are hair-like structures on the surface of epithelial cells that line the airways.
They beat the mucus secreted by the goblet cells and move it upwards away from the alveoli towards the throat where it is swallowed.
What is the structure and function of Goblet cells?
They are found in the ciliated epithelium where they secrete mucus.
The mucus traps microorganisms + dust particles in the inhaled air and stops them from reaching the Alveoli.
What is the structure and function of Elastic fibres?
Found in the walls of the trachea, bronchi and bronchioles and alveoli and helps with the process of breathing in and out.
When the lungs inflate, the elastic fibres are stretched, which then causes the elastic fibres to recoil to help push the air out of the lungs when exhaling.
What is the structure and function of smooth muscle?
They are found in the walls of the trachea, bronchi and bronchioles and allows the diameter to be controlled.
During exercise, smooth muscle relaxes, allowing the tubes to become wider, which means there is less resistance to airflow and air can move in and out of the lungs more easily.
What is the structure and function of Cartilage?
Found in rings on the walls of the trachea and bronchi.
Provides supports as it is strong and flexible.
It prevents the trachea and bronchi from collapsing when you breathe in and the pressure drops.
What are the main components of the Gas exchange system?
Trachea
Bronchi
Bronchioles
Alveoli
Lungs
Bronchus
What is found in the trachea?
Elastic fibres
Smooth muscle
Cartilage
Ciliated epithelium containing goblet cells.
What is found in the Bronchus?
Smooth muscle
Small cartilage pieces
Elastic fibres
Ciliated epithelium containing goblet cells
What is found in the Bronchiole?
Smooth muscle
Elastic fibres
Ciliated epithelium with goblet cells
What is found in the Alveolus?
Elastic Fibres
Alveolar Epithelium
Capillary
What does Ventilation in mammals consist of?
Ventilation consists of Inspiration (breathing in) and Expiration (breathing out) controlled by the movement of the diaphragm, intercostals muscles and ribcage.
Describe the process of Inspiration.
The external intercostal muscle and diaphragm contracts.
This causes the ribcage to move up and out and the diaphragm to flatten and move downwards
The volume of the thorax (the space where the lungs are) increases. this means that the pressure in the lungs decreases tom below atmospheric pressure
This causes air to flow into the lungs, it is an active process as it requires energy.
Describe the process of Expiration.
The external intercostal muscles and the ribcage relax.
This causes the ribcage to move down and in and the diaphragm become curved again.
The thorax volume decreases causing the pressure to increase above atmospheric pressure
It is a passive process and does not require energy.
What is a spirometer and what are its components?
A spirometer is a machine that can be used to investigate breathing
The components include:
Oxygen chamber
inhaled air
Pen that writes the spirometer trace
a rotating drum
soda lime
mouth piece
valve that makes inhaled air and exhaled air go in different directions
Define Total volume (TV)
The volume of air in each breath. This is usually about 0.4 dm3
Define Total Capacity
This is the maximum volume of air that can be breathed in or out.
Define breathing rate.
How many breaths are taken per unit time (usually per minute)
