exchange and transport Flashcards
(44 cards)
how are substances exchanged in single-celled organisms
substances diffuse directly into / out of cell
diffusion is quick due to small distance
why do multi cellular organisms need transport systems
- large distance between cells
- large distance between cells and outside environment
- low surface area to volume ratio
- higher metabolic rate so use oxygen / glucose fast
Describe structure and function of root hair cell
Absorbs water (osmosis) and mineral (nitrate) ions (active transport) Millions of microscopic hairs on a single branch to increase surface area - increase rate of absorption
what are alveolus made from?
single layer of thin flat cells : alveolar epithelium
Describe gas exchange in the alveoli
Oxygen diffuses out of alveolar space into blood
Carbon dioxide diffuses into alveolar space
Describe the blood supply to each alveoli
Each alveoli has its own blood supply due to the surrounding capillary network
Describe blood supply / ventilation of fish gills
- fish gills contain large network of capillaries to keep blood supply high
- well ventilated (fresh water constantly passing)
Both help maintain concentration gradient of oxygen
Describe the where air goes when you breath in (4)
- air enters trachea
- trachea splits into two bronchi
- each bronchus branches off into bronchioles (small tubes)
- bronchioles end in alveoli (gas exchanged)
name the 3 things that work together to move air in/out
- rib cage
- intercostal muscles
- diaphragm
what is a goblet cell ?
cell in the lungs that secretes mucus
why is mucus needed in the lungs ?
traps microorganisms and dust particles in air, preventing them from reaching alveoli
what does cilia do in the lungs?
moves mucus upward towards the throat, where its swallowed - this helps prevent lung infections
what do elastic fibres in the lungs do ?
help with the process of breathing out - elastic fibres stretch when breathing in, then the fibres recoil, pushing air out
what does smooth muscle do in the lungs?
controls diameter of tubes (e.g. trachea) - during exercise they relax, widening the tubes, meaning less resistance to airflow
why are there rings of cartilage in the walls of the trachea and brochi ?
provides support (strong and flexible) so that they don’t collapse when breathe in and pressure drops
describe cartilage in trachea
large C - shaped pieces
describe cartilage in bronchi
smaller pieces
Describe inspiration (6)
- external intercostal and diaphragm contract
- rib cage moves up and out
- diaphragm flattens
- = volume of thorax is increased
5 lung pressure decreases - air flows into lungs
why does inspiration require energy and expiration doesn’t ?
inspiration is an active process, respiration is a passive process
Describe expiration
- external intercostal and diaphragm relax
- rib cage moves down and in
- diaphragm becomes curved
- = volume of thorax decreases
- air pressure increases
- air forced out of lungs
how can expiration be forced ?
internal intercostal muscles contract, pulling rib cage down and in
what is tidal volume ?
vol of air in each breath at rest - usually 0.4dm3
what is vital capacity ?
max vol of air that can breathed in / out
what is breathing rate ?
breaths per (time) - usually bpm
