Chapter 7 Exchange And Transport Flashcards
Explain why single celled organisms do not need specialised exchange surfaces
The metabolic demands of single celled organisms are relatively low
They have a large surface area to volume ratio
Why do multicellular organisms need specialised exchange systems?
-They have a higher metabolic demand
-The diffusion distance is much greater
-They have small surface areas to volume ratios
What are the features of specialised exchange systems?
-Large surface area to volume ratio
-Thin
-Moist
-Good blood supply
-Ventilation to maintain the diffusion gradient
-Permeable
Describe how a large surface area to volume ratio provides an effective exchange surface area?
Provides an area where exchange can happen fast within large organisms
Describe how a thin surface provides an effective exchange surface?
Diffusion distances are much shorter, therefore making the process fast and efficient.
Describe how a good blood supply provides an effective exchange surface?
A good blood supply ensures that substances are constantly delivered to and removed from the exchange surface, this provides a steep concentration gradient for diffusion.
Describe how a moist surface provides an effective exchange surface
Moisture increases surface tension, making it easier and more efficient for gases to diffuse across the surface.
Describe how ventilation provides an effective exchange surface
The ventilation system helps to maintain a concentration gradient for gases and makes the process more efficient.
Identify the key structures of the mammalian gaseous exchange system
Nasal cavity
Trachea
Bronchus
Bronchioles
Alveoli
Describe the structure of the trachea
A wide tube supported by ‘C’ shaped rings of cartilage which stop the trachea from collapsing.
The trachea is lined with Ciliated epithelium, containing goblet cells.
The trachea is also composed of smooth muscles and elastic fibres.
What are the components that make up the trachea?
Cartilage
Goblet cells
Ciliated epithelium
Smooth muscle
Elastic fibres
What is the function of Goblet cells?
Goblet cells line the airways, secreting a mucus onto the lining of the trachea to trap dust and microorganisms.
What is the function of the Ciliated epithelium?
Ciliated epithelium contains cilia which are hair like projections on the end of cells.
The cilia beat and move the mucus, along with dust and microorganisms up and away from the lungs. It is then swallowed and digested in the stomach.
Describe the structure of Bronchi
Bronchi have irregular small rings of cartilage
Composed of smooth muscle, elastic fibres and lined with Ciliated epithelium cells
Describe the structure of Bronchioles
Bronchioles have no cartilage, larger bronchiole walls contain smooth muscle and elastic fibres.
The bronchioles are lined with a thin layer of Ciliated epithelium.
Describe the structure of Alveoli
Alveoli are tiny air sacs, consisting of a layer of thin squamous epithelial cells along with collagen and elastic fibres.
What is the function of Elastic fibres?
Stretch and recoil to aid the process of exhalation.
What is the function of Smooth muscle?
Controls the involuntary contraction and relaxation of muscles.
How does Smooth muscle aid the process of gaseous exchange ?
Contraction of smooth muscle restricts air flow into lungs, while the relaxation of smooth muscles opens up air flow into the lungs.
During exercise, smooth muscle is able to expand.
What is the function of Cartilage?
Providing structural support by holding the airways open during inhalation preventing it from collapsing when air pressure is low.
How do Elastic fibres aid the process of gaseous exchange?
During inhalation, the airways constrict and the elastic fibres stretch, the elastic fibres will then recoil to their original size during exhalation to dilate the airway.
What are the adaptions of alveoli for efficient gas exchange?
-Large surface area
-Thin- one epithelial cell thick so diffusion distances between the alveoli and capillaries is short
-Good blood supply- the capillaries bring a constant flow of carbon dioxide and then carries off oxygen, maintaining a steep concentration gradient.
-Good ventilation- air is moved in and out of the alveoli maintaining a diffusion gradient for oxygen and carbon dioxide between the blood and air in lungs.
How can surface: volume ratio be calculated?
Ratio= surface area / volume
Describe the process of inspiration
External intercostal muscles contract
Internal intercostal muscles relax
Ribcage moves up and out
Diaphragm flattens and contracts
Volume of the thorax increases
Pressure in the thorax is reduced, so air is drawn into the lungs.
Describe the process of expiration
External intercostal muscles relax
Internal intercostal muscles contract
Ribs move down and in
Diaphragm relaxes and domes
Volume of thorax decreases
Pressure of the thorax increases, so air moves out of lungs.
What type of process if expiration?
Passive
What type of process is inspiration?
Active
How can the process of expiration become active?
Exhaling forcibly uses energy,
the internal intercostal muscles contract pulling the ribs down hard and fast
The abdominal muscles contract forcing the diaphragm up to increase pressure in the lungs rapidly, so air is forced out
Why does air flow into the lungs during inspiration?
Oxygen moves into the lungs down a pressure gradient, this is because there is a higher pressure outside the lungs and a lower pressure inside the lungs.
How can the capacity of the lungs be measured?
Peak flow meter
Vitalograph
Spirometer