A Level Biology : Module 3 - Exchange and Transport Flashcards
1
Q
What happens to the SA : V ratio as an organism increases in size?
A
- SA : V ration decreases
- Greater volume means a longer diffusion distance to cells and tissues of the organism
2
Q
Why do we need a gas exchange system?
A
- To supply oxygen (which through aerobic respiration produces ATP)
- To remove CO2 (toxic waste produce of aerobic respiration which alters pH of cells)
3
Q
What do effective exchange surfaces have
A
- Large surface area
- Thin diffusion distance
- Good ventilation mechanism
- Good blood supply
4
Q
What are root hair cells
A
- Specialised cells found in roots of plants.
- They play an important role in the absorption of water and mineral ions from the soil
- Presence of root hairs increases the surface area
- So the water update by osmosis is greater
5
Q
What are alveoli and how do they work
A
- Small air sacs in the lungs where gaseous exchange happens with the capillaries
- Alveoli has a high concentration of O2, and a low concentration of CO2
- Capillaries have a low concentration of O2 and a high concentration of CO2
- Diffusion occurs across this concentration gradient (high to low) and exchange of gases occurs
6
Q
Features of Alveoli
A
- Thin walls (cells are flattened and walls are one cell thick, creating a small diffusion distance)
- Lots of alveoli (higher SA)
- Lots of capillaries (maintains high concentration gradient via constant blood flow) (capillaries are also 1 cell thick)
- Liquid surfactant in alveoli reduces surface tension between alveolar walls and gases. prevents atelectasis
7
Q
Features Fish Gills
A
- Lots of capillaries
- There is a counter current system (blood flow is opposite to water flow, ensuring the concentration gradient is maintained along the whole length of the capillary)
- Each gill arch contains gill filaments, with lamellae on them. increasing surface area for which O2 can diffuse across
8
Q
Cartilage
A
- Strong and flexible tissue
- Seen in rings around the trachea (tracheal rings)
- Helps to support trachea, ensuring it stays open while allowing it to move and flex while breathing
- In Bronchi, they are full circles of cartilage (rather than C shaped)
9
Q
Ciliated Epithelium
A
- Found in trachea, down to the bronchi
- Each cell has small projections called cilia
- Cilia sweeps mucus, dust and bacteria up the throat and away from the lungs
10
Q
Goblet Cells
A
- Found in ciliated epithelium and trachea
- PRODUCE MUCUS, (mucus traps dust and prevents them from reaching lungs)
- Mucus swept by cilia upwards where it is swallowed, then mucus and microbes are destroyed by the acid in the stomach
11
Q
Squamous Epithelium
A
- Makes up wall of alveoli
- Thin, allowing smaller diffusion distance
12
Q
Smooth Muscle
A
- Found throughout walls of bronchi and bronchioles
- Regulates flow of air
- Dilates when air is needed, constricts when air is less needed
13
Q
Elastic Fibres
A
- Present in all lung tissue
- Allow lungs to stretch and recoil, and the ability to recoil makes expiration a passive process
14
Q
mucus glands
A
- Works with goblet cells to secrete mucus
15
Q
Passage of air in the human body
A
- nose / mouth
- Trachea (windpipe)
- Bronchi
- Bronchioles
- Alveoli
16
Q
What happens as we inhale?
A
- Diaphragm contracts and flattens
- Increasing chest volume
- Decreasing pressure in lungs below atmospheric pressure
- Drawing air in down the pressure gradient
DURING EXERCISE
- External intercostal muscles contract, moving ribcage upwards and outwards, increasing thoracic cavity
17
Q
What happens when we breathe out?
A
At Rest
- Breathing out occurs due to reoil of lungs after being stretched
- Diaphragm relaxes (becoming dome shaped)
- Decreasing volume of chest
- Increasing pressure
- Forcing air out
WHEN EXERCISING
- Internal intercostal muscles contract to pull the ribs down and back
- Abdominal muscles contract to push organs upwards against diaphragm, decreasing volume in lungs, increasing pressure and this forcing exhalation
18
Q
What are the 4 main ways to measure breathing
A
- Vital Capacity
- Tidal Volume
- Breathing rate
- Oxygen Uptake
19
Q
Vital Capacity
A
- Maximum volume of air that can be breathed in or out in 1 breath
20
Q
Tidal Volume
A
- Normal volume of air breathed in or out of the lungs at normal breathing rate
21
Q
Breathing Rate
A
- Breaths per minute
22
Q
Oxygen Uptake
A
- Volume of oxygen used up by someone in a given time
23
Q
How does a Spirometer Work?
A
- Breathe into a tube
- CO2 is absorbed from exhaled air by soda lime (stops concentration of CO2 being too high, coz it will cause respiratory distress)
- Trace is drawn as person breathes into tube (rotating drum of paper or a graph is formed digitally)
- From the trace, tidal volume, vital capacity and breathing rate can be calculated
- Oxygen uptake can be measured by observing change in volume from total volume and CO2 removed
24
Q
Tracheal System of Insect
A
- Rigid exoskeleton, waxy coating IMPERMEABLE to gases
- Spiracles are openings to exoskeleton, (they have valves, allows air to enter and flow into tracheal system
- Trachea are tubes, which lead to tracheoles (held open by RIGID RINGS OF CARTILAGE)
- Lots of tracheoles run between cells and muscle fibres, which is where gas exchange takes place
- This works for smaller insects (provides sufficient oxygen)
- Tracheal fluid at the end of tracheoles allows O2 to dissolve and then diffuse into cells
25
Q
Ventilation mechanism in Insects
A
Whilst Flying
- They create a mass flow of air into tracheal system
- By closing their spiracles
- Using abdominal muscles creating a pumping movement for ventilation
- During flight, tracheal fluid is drawn into respiring muscle so gas diffuses across quicker (because of a shorter diffusion distance)
26
Q
Structure of Fish Gills
A
- Gills either side of head
- Gill arch attached to 2 stacks of filaments
- Each filament has lamellae in rows lined on the surface
27
Q
Counter Current Flow
A
- Capillary system in lamellae ensures blood flows in the opposite direction to water (COUNTER CURRENT FLOW)
- Counter Current flow ensures concentration gradient is maintained along the whole length of the capillary
28
Q
Ventilation Mechanism in Fish
A
- Constantly pushes water over surface of gills, ensures supply of oxygen rich water (concentration gradient maintained)
- Fish opens mouth
- Buccal cavity floor lowers
- Increasing volume of buccal cavity
- Decreasing pressure within cavity
- Drawing water in (because pressure outside mouth is greater, so water flows into buccal cavity)
- Fish raises floor of buccal cavity to close mouth, increasing pressure in buccal cavity
- Water flows from buccal cavity into gill cavity (across pressure gradient)
- As water enters, pressure begins to build up in gill cavity, causing operculum (a flap of tissue covering gills) to be forced open and allowing water to exit the fish
- Operculum is pulled shut when fish next opens its mouth
