Exchange surfaces and breathing Flashcards
why do single celled organisms not require a specialised exchange surface?
- Large surface area to volume ratio. Surface area is
large enough compared to their volume. - Their central cells are closer to the outside
- Diffusion of gases is fast enough
- They have a low metabolic demand.The oxygen demand and carbon dioxide production of cells of cells are low
State the three main factors that affect the need for an exchange system
Size, SA:Vol ratio and level of activity (metabolic demand).
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)
Heat
What are the features of a specialised exchange surface?
Large surface area
Short diffusion distance (thin layers)
Steep concentration gradient maintained (good blood supply and good ventilation)
Why do large organisms need an specialised exchange surface?
- Small surface area to volume ratio.They have a large volume of cells.
- Their central cells are further away to the outside
- Diffusion of gases is not fast enough
- They have a high metabolic demand.The oxygen demand and carbon dioxide production of cells of cells are high.Large organisms are very active and have to maintain their body temperature.
Describe and explain three features of a good exchange surface
- Large SA (folded walls; provides more space
for relevant molecules to pass through) - thin, permeable barriers (reduces diffusion
distance) - good blood supply (keeps high concentration
gradients for rapid diffusion)
what are the features of the nasal cavity and there importance?
1.A large surface with good blood supply which
warms up the air to body temperature.
- Hairy lining which secretes mucus to trap dust and bacteria .This is important because it protects the lung tissue from irritation and infection.
- Moist surfaces which increases which increases the humidity of incoming air. This is important because it reduces evaporation from the exchange surface.
Describe the structure and function of the trachea.
- Flexible and strong airway made of incomplete rings of cartilage. Cartilage stops the trachea from collapsing .The incomplete rings allow food to move easily.
- Walls made up of ciliated epithelium and goblet cells.Goblet cells secretes mucus that traps dust and bacteria from air breathed in.
The cilia beat moves the mucus away from the lungs.
what effect does cigarette smoke has on the ciliated epithelium?
The smoke stops the cilia beatings .This leads to mucus building up in the trachea .
Describe the structure and function of the bronchioles.
The bronchi divides into many bronchioles .The bronchioles are made of smooth muscle.The smooth muscle contracts and relax.
Describe the structure and function of the alveoli.
The alveoli are tiny air sacs,which is the main gas exchange surface of the body and is 200-300 um wide.The alveolus consists of thin flattened epithelial cells ,collagen and elastic fibers.The elastic fibers allow the aveoli to stretch and return to the original size (elastic recoil).
What features allow the alveoli to be an effective gas exchange?
- large surface area
2.The alveoli and capillaries walls are one
cell thick so therefore it has a short diffusion
distance.
3.Good blood supply helps maintain a steep concentration gradient.
4.Good ventilation helps maintain an a steep
diffusion gradient
- The alveoli contains surfactants which the
alveoli remain inflated.
What features allow the alveoli to be an effective gas exchange?
- large surface area
2.The alveoli and capillaries walls are one
cell thick so therefore it has a short diffusion
distance.
3.Good blood supply helps maintain a steep concentration gradient.
4.Good ventilation helps maintain an a steep
diffusion gradient
- The alveoli contains surfactants which the
alveoli remain inflated and reduce
cohesive forces between water molecules,
preventing collapse .
Describe the mechanism of inspiration
Inspiration is breathing in.
- Diaphragm contracts ( lowering and flattening)
- External intercostal muscles contract, moving
the ribcage outwards and upwards.
3.The volume of thorax increased and the
pressure decreases below atmospheric
pressure and air dis drawn in through the nasal
passage to equalises the pressure.
Describe the mechanism of expiration
Expiration is breathing out
- Diaphragm relaxes moving up
- External intercostal muscles relax, moving
the ribcage inwards
3.The volume of thorax decreases and the
pressure increases is grater than atmospheric
pressure and air dis drawn out through the nasal
passage to equalises the pressure.
