Organisms Exchange Substances With Their Environment Flashcards
Describe the relationship between size and surface area to volume ratio
Increase size results in a decrease in surface area to volume ratio
List the four organisms that gas exchange occurs in
Fish
Insects
Humans
Plants
Describe the gas exchange in single celled organisms.
Occurs in the tracheal system
Spiracles- opening in exoskeleton with valves to allow air to enter
Trachea- tubes that lead to tracheoles
Tracheoles- extend to organs which deliver the oxygen
What is the order of the tracheal system and how does it work?
Spiracles- opening in exoskeleton that allows air to enter
Trachea-tubes that extend to tracheoles
Describe the adaptations of fish for gas exchange
Gill arch attached to gill filaments to increase surface area
Rows of lamellae to also increase surface and form network of capillaries
What is the counter current principle in fish?
Water flows in opposite direction to blood to ensure a favourable concentration gradient
Describe the adaptations of plants for gas exchange
Waxy cuticle- prevents water loss
Palisade mesophyll- layers of elongated cells with chloroplast which speeds up photosynthesis
Stomata- pores on underside which allows air to enter and leave
Guard cells- control the opening and closing of stomata
Explain the differences between gas exchange in terrestrial insects and xerophytic plants
Insects:
Air enters through spiracles and moves down trachea into tracheoles.
Rhythmic abdominal movements causes the air to move in and out of the spiracles
Plants:
Air enters through stomata and diffuses through the air spaces within the sponges mesophyll allowing co2 to diffuse rapidly
List the gross structure of the human gas exchange system
Nose
Trachea
Lungs
Bronchi
Bronchioles
Alveoli
Describe the structure and function of the alveoli
Tiny sacs with thin walls to enable sufficient gas exchange (short diffusion pathway)
It is the main site of gas exchange in the lungs
Describe the structure and function of the bronchioles
Narrow tubes which carry air from bronchi to alveoli
Describe the structure and function of the bronchi
Bronchi lead to bronchioles
Describe the structure and function of the trachea
Airway that leads from mouth to nose then to bronchi.
Lined with mucus-and cilla which sweeps the mucus away.
Describe the structure and function of the lungs
Central part of the respiratory system where gas exchange takes place
What are the features of the alveolar epithelium?
Large number of alveoli- increases surface area for co2 and o2 to diffuse
Thin walls- short diffusion pathway
Extensive capillary network- constant flow of blood
Describe inhalation in the human body
Volume of thorax increases
Air pressure decreases
Diaphragm flattens and contracts
External intercostal muscles contract
Ribcage moves up and down
Describe exhalation in the human body
Volume of thorax decreases
Air pressure increases
Diaphragm becomes domed
External intercostal muscles relax
Internal intercostal muscles contract
Ribcage moves down and back