Exchange Surfaces And Breathing Flashcards
(50 cards)
1
Q
Why can single celled organisms rely on diffusion alone for gas exchange
A
- low metabolic activity: low oxygen demand and carbon dioxide production
- large S.A.: V ratio: diffusion distances are small, making gas exchange efficient
2
Q
Why can’t larger organisms rely on diffusion alone for gas exchange
A
- higher metabolic activity: greater oxygen demand and carbon dioxide production
- smaller SA:V ratio: diffusion distances are too large and slow to meet the oxygen needs of deep tissues
3
Q
What are the four key features of efficient gas exchange surfaces
A
- Increased surface area for more areas for diffusion (e.g root hair cells for plants and villi for mammals)
- Thin layers: short diffusion distances, faster exchange (e.g alveoli in lungs, villi in the small intestine)
- Good blood supply to maintain a steep concentration gradient (e.g alveoli, fish gills, villi)
- Ventilation maintains the diffusion gradient (e.g alveoli for airflow and fish gills for water flow)
4
Q
How does a good blood supply improve the efficiency of exchange surfaces
A
It maintains a steep concentration gradient by continuously delivering oxygen and removing carbon dioxide
This ensures faster diffusion
5
Q
Why is ventilation important for gas exchange
A
It maintains concentration gradients of gases
- In fish gills: it ensures a constant flow of water with dissolved gases
- In alveoli: ventilation maintains a constant supply of oxygen and removal of carbon dioxide
6
Q
Why do land animals face a conflict between gaseous exchange and water conservation
A
- gaseous exchange surfaces are moist to allow oxygen to dissolve before diffusing into tissues
- however this moisture also makes them prone to water evaporation, creating conflict between gas exchange and water loss
7
Q
Why do mammals need efficient gas exchange systems
A
- Large size: small SA;V ratio - oxygen demands wouldn’t be met in time
- High metabolic rates: requires a lot of oxygen for respiration
- Constant temperature regulation: demands continuous energy production
8
Q
What is the function of the nasal cavity in the gaseous exhange system
A
- Large surface area + good blood supply (warms air to body temperature)
- Hairy lining + mucus (traps dust and bacteria, preventing lung irritation)
- Moist surfaces (increases humidity and reduces water loss from exchange surfaces)
9
Q
What is the function of trachea in the gaseous exchange system
A
- carriers air from they nasal cavity to the chest
- supported by incomplete rings of cartilage to prevent collapse but allows flexibility for food to pass down the oesophagus
- lined with ciliated epithelium and goblet cells
Goblet cells - secrete mucus to trap dust and microbes
Cilia - move mucus away from the lungs
10
Q
What is the function of the bronchi
A
- the trachea divides into two bronchi, leading to each lung
- similar structure to the trachea but smaller
- supported by rings of cartilage to prevent collapse
11
Q
What is the function of the bronchioles
A
- bronchi divide into smaller bronchioles
- No cartilage rings
- smooth muscle controls airflow:
Contracts - bronchioles constrict reducing airflow
Relaxes - bronchioles dilate, increasing airflow - lined with thin epithelium : some gas exchange occurs here
12
Q
What are alveoli and their role in gas exchange
A
- tiny air sacs (between 200-300 micrometre diameter) where gas exchange occurs
- surrounded by capillaries for efficient diffusion
Contains elastic fibres (elastin) which allows for stretching during inhalation and elastic recoil helps expel air during exhalations
13
Q
What are adaptions of alveoli for efficient gas exchange occurs
A
- large surface area - 300-500 million alveoli in adult lungs
(50-75m^2 surface area) - thin layers - alveolar and capillary walls are one cell thick, reducing diffusion distances
- good blood supply - dense capillary network maintains a steep concentration gradient
- good ventilation: breathing moves air in and out, maintaining diffusion gradients
- moist inner surface - dissolves gasses, aiding diffusion
14
Q
What is the role of the lung surfactant
A
- coats the alveoli with water, salts and phospholipids
- prevents alveolar collapse by reducing surface tension
- helps oxygen dissolve before diffusing into blood
15
Q
What is ventilation in the lungs
A
- the movement of air in and out of the lungs due to pressure changes in the thorax
- involves inspiration and expiration
16
Q
What happens during inspiration
(Inhalation)
A
- Diaphragm contracts - flattens and lowers
- External intercostal muscles contract - ribs moves up and out
- Thorax volumes increases - lowering pressure below atmospheric pressure
- Air is drawn into the lungs to equalise pressure
17
Q
What happens during expiration (exhalation)
A
- Diaphragm relaxes: moves up into a domed shape
- External intercostal muscles relax - ribs moves down and in
- Thorax volumes increases decreases - increasing pressure
- Air is forced out of lungs
18
Q
What happens during forced expiration
A
- It is an active process that uses energy
- Internal intercostal muscles contract - ribs are pulled down hard and fast
- Abdominal muscles contract - push the diaphragm rapidly increases lung pressure
- More air is expelled forcefully
19
Q
What happens during an asthma attack
A
- Histamines are released - cause of inflammation and swelling of bronchiole epithelial cells
- Goblet cells produce excess mucus
- Smooth muscle contracts narrowing the airway
- Airways fill with mucus, making breathing difficult
20
Q
What are the two main treatments asthma
A
- Relievers - immediate relief, similar to adrenaline, causing smooth muscle relaxation and airway dilation
- Preventers - steroids taken daily to reduce airway sensitivity and inflammation
21
Q
Why do premature babies struggle to breathe
A
- lung surfactant no produced until around the 30th week of pregnancy
- without surfactant, alveoli collapse after each breath, making it difficult for babies to breathe
- artificial lung surfactants can be sprayed into premature babies lungs to prevent alveolar collapse
22
Q
What is tidal volume
A
The volume of air that moves into and out of the lungs with each resting breath
23
Q
What is vital capacity
A
The maximum volume of air that can be exhaled after the deepest possible inhalation
24
Q
What is the inspiratorio reserve volume
A
The additional volume of air you can inhale beyond a normal breath
25
What is a expiratory reserve volume
The extra volume of air that can be expelled beyond the normal tidal volume
26
What’s residual volume
The volume of air left in the lungs after maximum exhalation; cannot be measured directly
27
What is ventilation rate and how is it calculated
The total volume of air inhaled in one minute
Ventilation = tidal volume x breathing rate
28
What does the peak flow meter measure
The rate at which air can be expelled from the lungs
29
What does a vitalograph measure
The forced expiratory volume in 1 second, shown on a graph
30
What is a spirometer used for
To measure different aspects of lung volume and investigate breathing patterns
31
What’s are spiracles
Small openings along the thorax and abdomen where air enters and leaves the insects body
32
What is the role of spiracle sphincters
They open and close the spiracles to minimise water loss and control gas exchange
33
What are the tracheae in insects
Large tubes (about 1mm diameter) that carry air into the body; lined with chitin to prevent collapse
34
What are tracheoles `
Narrow tubes (0.6-8 micrometre diameter) where most the gas exchange occurs; they lack chitin lining and are permeable to gases
35
What is the function of tracheal fluid in insects
It limits air penetration for diffusion, but during high oxygen demand, water moves out by osmosis, increasing the surface area for gas exchange
36
What is the mechanical ventilation in insects
Muscular pumping movements of the thorax and/or abdomen to actively move air through the tracheal system
37
What are air sacs in insects
Collapsible, enlarged tracheae that act as reservoirs to increase airflow during high oxygen demand
38
What is discontinuous gas exchange (DGC)
A breathing pattern with three phases
1. Closed : no gas exchange; oxygen diffuses from tracheae into cells
2. Fluttering: spiracles open and close rapidly, allowing some gas exchange while minimising water loss
3. Open: spiracles open widely to release carbon dioxide rapidly
39
What is the primary site of gas exchange in fish
Gills
40
What covers the gills and helps them maintain water flow
The operculum (a bony flap)
41
What are the gill lamellae and why are they important
Thin, vasculares structures with a large surface area where gas exchange occurs
42
What is counter current exchange in fish
Blood and water flow in opposite directions, maintaining a steep concentration gradient for efficient gas exchange
43
Why is countercurrent exchange more effective than parallel exchange
It prevents equilibrium from being reached allowing fish to extract up to 80% of the oxygen from water
44
How do overlapping gil filaments improve gas exchange in they increase resistance, slowing water flow and providing more time for diffusion
they increase resistance, slowing water flow and providing more time for diffusion
45
How do fish ventilate their gils when stationary
They use their buccal-opercular pump system
1. Mouth opens : buccal cavity expands, drawing water in
2. Mouth closes: operculum opens, forcing water over the gills
46
Why do multicellular animals need specialised transport systems
- high metabolic demands: more oxygen and nutrients are needed and more waste is produced
- SA:V ratio decreases : diffusion along is insufficient
- transport of molecules: hormones and enzymes produced in one location are needed elsewhere
- digested food: needs to be transported to cells for respiration
- waste removal : metabolic waste must be transported to excretory organs
47
What are the features of most circulatory systems
Transport medium: blood or haemolymph
Vessels: to carry the medium
Pumping mechanism: moves fluid around body
Mass transport: the bulk movement of fluis around the body
48
What is an open circulatory system and its process
blood isn’t always contained in vessels; it flows freely through body cavities
1. Heart pumps blood into haemocoel (open body cavity)
2. Blood is under low pressure and directly contacts tissues
3. Blood returns to heart via open-ended vessels
Example: insects
49
What is haemolymph
Insect blood that transports nutrients, nitrogenous waste products, immune cells (for disease defence)
DOES NOT transport oxygen or carbon dioxide (gaseous exchange system occurs in the tracheal system)
Blood flow cannot be varied to meet changing demands
50
What is a closed circulatory system and its process
Blood is enclosed in vessels and does not contact body cells directly
1. Heart pumps blood under pressure - faster flow and blood returns directly to heart
2. Substances exchange via diffusion through capillary walls
3. Blood flow cannot be varied be adjusted by narrowing or widening vessels
Most closed systems contain respiratory pigments (e.g haemoglobin) to carry gases
