Module 3: Section 1- Exchange and Transport Flashcards
1
Q
why do organisms need exchange surfaces?
A
- cells need to take in things like Oxygen and Glucose for aerobic respiration and other metabolic reactions
- They also need to secrete waste products from these reactions eg. urea and carbon dioxide
2
Q
SA:V ratio in smaller animals
A
- higher SA:V ratios
3
Q
Why do multicellular organisms need exchange surfaces
A
- diffusion across the outer membrane is too slow because:
~some cells are deep within the body (big distance between them and outside environment)
~larger animals have lower SA:V ratio- difficult to exchange enough substances to supply large volume of animal
~multicellular organisms have a higher metabolic rate than single celled organisms so use up O2 and glucose faster
4
Q
Why do single celled organisms not need exchange surfaces?
A
- the diffusion rate is quick due to the shorter distance the substances have to travel
- substances can diffuse directly into (or out of) the cell across the cell-surface membrane
5
Q
Specialised Exchange surfaces features
A
- Large SA: eg root hair cells, increases rate of absorption of water (by osmosis) and mineral ions (by active transport) from the soil
- Thin: eg alveoli, thin alveolar epithelium helps decrease the distance over which O2 and CO2 diffusion takes place
- Good Blood Supply and/or Ventilation: eg alveoli + fish gills, helps maintain concentration gradients of O2 and/or CO2
6
Q
Gaseous exchange in the lungs
A
- air enters trachea
- trachea splits into 2 bronchi- one bronchus leading to each lung
-each bronchus branches off into smaller tubes called bronchioles - bronchioles end up in small ‘air sacs’ called alveoli where gases are exchanged
- The ribcage, intercostal muscles and diaphragm all work together to move air in and out
7
Q
Goblet cells
A
- (lining the airways) secret mucus
- the mucus traps microorganisms and dust particles in the inhaled air, stopping them from reaching the alveoli
8
Q
Cilia
A
- on the surface of cells lining the airways
- beat the mucus
- moves the mucus upwards away from the alveoli towards the throat, where it’s swallowed. This prevents lung infections
9
Q
Elastic fibres
A
- in walls of trachea, bronchi, bronchioles and alveoli
- help the process of breathing out
- on breathing in, lungs inflate and elastic fibres are stretched
- fibres then recoil to help push the air out when exhaling
10
Q
Smoot muscle
A
- in walls of the trachea, bronchi and bronchioles
- allows their diameter to be controlled
-during exercise, smooth muscle relaxes, making tubes wider - less resistance to airflow and air can move in+out of lungs easily
11
Q
Rings of cartilage
A
- in walls of the trachea and bronchi to provide support
- strong but flexible- stops trachea and bronchi collapsing when you breathe in and pressure drops
12
Q
Trachea
A
cartilage: large C-shaped pieces
-smooth muscle, elastic fibres, goblet cells
- ciliated epithelium
13
Q
Bronchi
A
cartilage: smaller pieces
-smooth muscle, elastic fibres, goblet cells
- ciliated epithelium
14
Q
larger bronchiole
A
cartilage: none
-smooth muscle, elastic fibres, goblet cells
-ciliated epithelium
15
Q
Alveoli
A
cartilage: none
- elastic fibres
no cilia
no goblet cells or smooth muscle
16
Q
Inspiration
A
- external intercostal and diaphragm muscles contract
- causes ribcage to move upwards and outwards and the diaphragm to flatten, increasing the volume of the thorax
- As volume of thorax increases, the lung pressure decreases (below atmospheric pressure)
- This causes air to flow into the lungs
- Inspiration is an active process- requires energy
17
Q
Expiration
A
- External intercostal and diaphragm muscles relax
- rib cage moves downwards and inwards and the diaphragm becomes curved again
- The thorax volume decreases, causing the air pressure to increase ( above atmospheric pressure)
- Air is forced out of the lungs
- Normal expiration is a passive process- doesn’t require energy
18
Q
Forced expiration
A
- intercostal muscles contract, to pull the ribcage down and in
19
Q
Tidal volume
A
-volume of air in each breath (usually about 0.4 dm3)
20
Q
Vital capacity
A
- maximum volume of air that can be breathed in or out
21
Q
Breathing rate
A
-how many breaths are taken , usually in a minute
22
Q
Oxygen consumption or oxygen uptake
A
- rate at which an organism uses up oxygen
23
Q
Spirometer method
A
- spirometer has oxygen-filled chamber with a movable lid
- person breathes through tube connected to oxygen chamber
- as person breathes in and out, lid of the chamber moves up and down
- These movements can be recorded by a pen attached to the lid of chamber, writes on a rotating drum, creating a spirometer trace or hooked to motion sensor + data logger
- soda lime in the tube the subject breathes into, absorbs CO2
24
Q
Fish gas exchange
A
- water enters mouth and passes out through gills
- Each gill made up of lots of thin branches called gill filaments or primary lamellae. gill filaments= covered in tiny structures called gill plates/ secondary lamellae, which increase SA even more. each gill- supported by gill arch
- Gill plates have lots of blood capillaries and thin surface layer of cells to speed up diffusion
25
Fish gas exchange Part 2
- Blood flow through gill plates in one direction and water flows over in the opposite direction
(counter-current system)
- maintains a large concentration gradient between water and blood
- conc of oxygen in water is always higher than that in blood, so as much oxygen as possible diffuses from water into the blood
26
How fish gills are ventilated
1) fish opens mouth, lowers floor of buccal cavity. Volume of the buccal cavity increases, decreasing pressure inside the cavity, water sucked in
2) Fish closes mouth, floor of buccal cavity is raised again. Volume inside cavity decreases, pressure increases and water is forced out of cavity across gill filaments
3) Each gill is covered by a bony flap called the operculum (protects the gill). The increase in pressure forces the operculum on each side of the head to open, allowing water to leave the gills
