7 Exchange surfaces and breathing Flashcards
(47 cards)
1
Q
Describe the exchange in microscopic organisms
A
- microscopic organisms such as bacteria have a large SA:V ratio
- substances exchanged directly with their surrounding environment
- this is possible as substances have a short distance to travel
2
Q
Describe the exchange in organisms with greater size
A
- SA:V ratio decreases
- less surface area for the absorption of nutrients and gases
- greater volume results in a longer diffusion distance
- BMR increases and therefore demand for nutrients and gases increase
- simple diffusion through surface is not enough
3
Q
Describe the exchange in plants
A
- large organisms have specialised exchange surface
- thin cell walls
- large surface area to volume ratio
- increase rate of water uptake and mineral absorption
4
Q
What makes an effective exchange surface?
A
- large surface area
- short diffusion distance
- good blood supply
- ventilation mechanism (alveoli)
5
Q
Describe “alveoli”
A
- small air sacs
- gas exchange takes place
- made of thin, flattened epithelial cells
- contain collagen and elastic tissue for it to stretch and recoil
- exchange of oxygen and carbon dioxide occurs between the alveoli and the capillaries via passive diffusion
- made of 2 types of cells
6
Q
Structure of the lungs?
A
- trachea
- bronchi
- bronchioles
- alveoli
- parietal pleura
- visceral pleura
- pleural cavity
- diaphragm
- ribs
- intercostal muscles
7
Q
Describe “trachea”
A
- channel which allows gas to travel in and out
- contains rings of C-shaped cartilage
8
Q
Describe “cartilage”
A
- strong and flexible tissue
- rings ensure trachea to stay open under low pressure and allow it to move and flex
9
Q
Describe “goblet cells”
A
Mucus producing cells which traps dust, bacteria and other microorganisms
10
Q
Describe “cilia”
A
Waft the mucus upwards away from lungs
11
Q
Describe “bronchi”
A
- similar structure to the trachea but have thinner walls
- cartilage rings are also present but are a full circle
12
Q
Describe “bronchioles”
A
- each one varies in size and structure, getting smaller as they get closer to the alveoli
- larger bronchioles contain elastic fibres and smooth muscle
- smallest bronchioles do not have smooth muscle but they do have elastic fibres for stretching and recoiling
13
Q
Describe “smooth muscle”
A
- found throughout the walls of the bronchi and larger bronchioles
- helps to regulate the flow of air into the lungs
- dilated when more air is needed
- constrict when less air is needed
14
Q
Describe “elastic fibres”
A
- present in all lung tissue
- enable lungs to stretch and recoil
- recoil allows exhalation to be passive
15
Q
Describe “type 1 pneumocytes”
A
- line the alveolar surface
- squamous and extremely thin
- cover about 95% of alveolar surface
- involved in gas exchange
16
Q
Describe “type 2 pneumocytes”
A
- granular and roughly cuboidal
- cover about 5% of alveolar surface
- secrete alveolar/pulmonary surfactant which reduces surface tension, stops alveoli collapsing during expiration and dissolves oxygen for ease of diffusion
17
Q
Describe “squamous epithelium”
A
- a single thin layer of flattened cells with irregular boundaries
- forms the structure of the alveolar wall
- very thin and permeable for easy diffusion
18
Q
Describe “pleural membrane”
A
- parietal pleura lines inside of chest cavity
- visceral pleura lines the lungs
19
Q
Describe “pleural cavity”
A
- pleural fluid is a lubrication fluid in the pleural cavity
- reduces friction on the surface of the lungs
20
Q
Steps of inspiration?
A
- External intercostal muscles between the ribs contract, moving them upwards and outwards
- The diaphragm muscle below the lungs contracts and flattens
- The thorax volume increases
- Thorax pressure is reduced below atmospheric pressure
- The outside air is drawn into the lungs
21
Q
Steps of expiration?
A
- The external intercostal muscles relax
- Ribs move inwards and downwards
- The diaphragm relaxes and becomes dome shaped
- The volume of thorax is reduced
- The thorax pressure increases above atmospheric pressure
- Air is forced outside the lungs
22
Q
Describe “measuring ventilation”
A
- measure lung function and investigating breathing
- changes in the amount of gas exchanged can happen normally due to physical activity or due to various diseases
- various instruments can be used to measure normal lung activity as well as diagnose lung disorders
23
Q
Describe “peak flow meter”
A
- simple measurement of how quickly you can blow air out of your lungs
- measuring how fast you’re able to breathe out
- your peak flow score can indicate whether your airways are narrowed
24
Q
Describe “vitalograph”
A
- used to measure the forced expiratory volume
- advanced version of a peak flow meter
- monitoring of lung function for respiratory conditions including chronic obstructive pulmonary disease (COPD), cystic fibrosis and post-transplant patient
25
Describe “spirometer”
- used to measure different aspects of lung volume
- used to diagnose asthma, COPD and other conditions that affect breathing
26
Define “tidal volume”
Volume of air which moves in and out of lungs with each resting breath
27
Define “inspiratory reserve volume”
Maximum volume of air which can be breathed in
28
Define “expiratory reserve volume”
Extra air which can be forced out of the lungs above normal tidal volume
29
Define “vital capacity”
The maximum volume of air a person can expel from the lungs after a maximum inhalation
30
Define “residual capacity”
Volume of air that remains in a person’s lungs after maximum exhalation
31
Define “forced expiratory volume (FEV)”
Measures how much air a person can exhale upon a forced breath
32
Define “breathing rate”
The number of breaths taken per minute
33
Define “ventilation rate”
The total volume of air inhaled in one minute
34
Describe “oxygen consumption”
- the volume of gas in the spirometer left at the end
- calculated by taking the average slope of the trace
35
Describe “gills”
- organs for gas exchange in bony fish with series of gills on each side of head
- large SA:V with good blood supply
- each gill arch is attached to two stacks of filaments
36
Describe “lamellae”
- microscopic
- full of capillaries
- increase the surface area of gills
37
Describe “counter-current flow”
- blood flows through the gill plates in one direction
- water flows in the other direction
- maintains a large concentration gradient
- makes gas exchange more efficient
38
Inspiration of bony fish?
1. Buccal cavity floor lowers
2. Mouth opens
3. Volume of buccal cavity increases
4. Pressure in buccal cavity decreases
5. Water flows into buccal cavity
39
Expiration of bony fish?
1. Buccal cavity floor moves upwards
2. Mouth closes
3. Volume of buccal cavity decreases
4. Pressure of buccal cavity increases
5. Water flows through the gills and operculum opens due to pressure
40
Describe the gas exchange in insects
- insects are metabolically active and have a high oxygen demand
- rigid exoskeleton made of chitin is impermeable to gases
- no blood present so gas exchange system (tracheal system) delivers oxygen directly to cells
41
Describe “spiracles”
- small openings which line the abdomen or thorax of the insect
- contain sphincter valves which can open and close the spiracle
- dependent on oxygen demand and other factors
42
Describe the insect respiratory system
- leading from the spiracle are trachea
- tracheae are tubes which lead to tracheoles
- rigid rings of chitin keep tracheae open
43
Describe how tracheoles are related to gas exchange
- a large number of tracheoles run between cells and into muscle fibres
- site of gas exchange
- tracheoles are composed of a single elongated cell
- freely permeable to gases
44
Describe “discontinuous gas exchange”
- **closed** spiracles recycle the oxygen in the tracheae which allows survival without constant breathing
- spiracles open and close rapidly during **fluttering** to replenish oxygen supplies
- spiracles **open** when CO2 levels are very high to allow rapid removal of CO2
45
Describe “abdominal pumping”
- mechanical ventilation in insects
- larger insects can not rely solely on passive diffusion
- air is moved in to the tracheal system using muscular **pumping movement** of the **thorax/abdomen**
- movements change the **volume** of the body cavity therefore changes the **pressure**
- allows air to move in and out of
46
Why can the trachea of an insect collapse or enlarge?
- used as a reservoir for some insects
- can be inflated or deflated depending on the need for oxygen
47
Adaptations for gas exchange in insects?
- tracheoles have thin walls so short diffusion distance to cells
- highly branched so large surface area
- tracheae are able to fill with air maintains concentration gradient
- fluid in the end of tracheoles that moves out allows faster diffusion
- abdominal pumping moves air which maintains concentration gradient
