The Respiratory System Flashcards
Why do large multicellular organisms require a respiratory systems?
•small SA/V ratio
•diffusion insufficient to provide all cells with the required oxygen and to remove all carbon dioxide.
• large organisms are more active than smaller organisms.
Why do some multicellular organisms (e.g. trees) not require specialised exchange surfaces?
Trees have a larger number of leaves which provide a large SA/V ratio for diffusion.
Describe the pathway of gas through the respiratory system
Nose—> trachea—> bronchi—> bronchioles—> alveoli—> capillaries
What is the function of mucus in the respiratory system?
It traps harmful substances and organisms,preventing entry into the lungs.
Where are the ciliated epithelial cells found?
Found lining the surface of the respiratory tract
Describe the function of ciliated epithelial cells lining the airways
Move in synchronised waves to best mucus(containing dirt and pathogens) up to the back of the throat where it is swallowed
What are the lungs?
A pair of organs consisting of the bronchioles, alveoli and surrounding tissue
What is the thorax?
•Area between neck and abdomen
• includes organs found within the chest and lungs
What is ventilation?
The movement of fresh air into the lungs and stale air out of the lungs via inhalation and exhalation
What does ventilation require?
•rib cage
• intercostal muscles
•diaphragm
What is inspiration?
Breathing in
Describe the process of inspiration
•rib cage moves up and out
•diaphragm contracts and flattens
•volume of thorax increases
•pressure in thorax decreases below air pressure
•air moves into the trachea
What is expiration?
Breathing out
Describe the process of expiration
•ribs move down and in
•diaphragm relaxes and reverts to dome shape.
•volume of throat decreases.
•pressure in thorax increases above air pressure
•air moves out of the trachea
How is ventilation modelled?
Using the bell jar model
What are the alveoli?
A cluster of air sacs in the lungs where gas exchange occurs
Describe the process of gas exchange at the alveoli
•oxygen diffuses from air in the alveoli into blood into the capillaries
•carbon dioxide diffuses from blood in the capillaries into air in the alveoli.
How are alveoli adapted for gaseous exchange? (5)
•large surface area
•surrounded by a network of capillaries giving a good blood supply
•rapid blood flow maintains a steep concentration gradient
•thin wall (one cell thick) giving a short diffusion distance
•walls covered by a thin, moist film, enabling gases to dissolve and increasing the rate of diffusion.
What is the chemical test for carbon dioxide?
• bubble gas through lime water
•CO2 turns lime water milky
What chemicals found in tobacco smoke damage the lungs?
•carcinogens
•tar
•nicotine
•carbon monoxide
What is a carcinogen?
A chemical that causes cancer
How does tar affect the airways?
•sticky substance deposited in the airways
• stimulates mucus production
•paralyses the cilia, preventing mucus from being swept away. Muscus containing microorganisms and dirt builds.
•leads to smokers cough
Describe the effects of nicotine on the body
•increases heart rate
•addictive
•damages lungs
What effect does carbon monoxide have on the body?
•binds with haemoglobin in red blood cells irreversibly.
•reduces oxygen - carrying capacity of the blood
