3: Organisms Exchange Surfaces Flashcards
1
Q
Why do we have exchange surfaces?
A
- all living things need to exchange with their environment
- Cells need oxygen and nutrients from surroundings for aerobic respiration
- We need to secrete waste, carbon dioxide and urea
- Heat needs to be exchanged, many living things need to stay around the same temperature
- The ease of exchange depends on SA: Vr
2
Q
How does single celled organisms exchange?
A
- living things need to supply all the cells with substances and remove waste products at a rate enabling them to survive
- In single celled organisms substances can diffuse directly across the cell surface membrane
- As distance needed to travel a small diffusion rate is fast (short diffusion pathway)
3
Q
How do multicellular organisms exchange?
A
- the rates of diffusion is slow as some cells are deep within the body which means the larger distance between cells and environments (small SA:Vr)
- To survive we’ve developed efficient specialised exchange (mass transport) systems for efficient exchange
4
Q
How and why do we exchange heat?
A
- metabolic activity inside cells generate heat
- Organisms need to maintain a constant temperature to ensure metabolic processes can still take place
- Heat also needs to be exchanged between organisms and the environment
- The ease /rate heat is exchanged depends on their size and shape
5
Q
How does size affect heat exchange?
A
- the rate heat is lost depends on SA:Vr
- larger organism, smaller SA: Vr, harder to lose heat
- as smaller organisins have larger, SA:Vr, they lose heat easily
- organisms need high metabolic rate to generate heat (stay warm) -> smaller organisms
6
Q
How does shape affect heat exchange?
A
- have animals in warmer climate will have features with a high SA:Vr such as large extremities (ears/ legs) to increase rate of heat loss
- Animals in cooler climates will have features that reduce SA:Vr such as smaller extremities to reduce the rate of heat loss
7
Q
What are adaptations of animals with a large SA:Vr?
A
- animals with large SA:Vr lose more water as it evaporates from the service
- Small desert animals have kidney structure adaptations to allow them to produce less urine
- thick fur and Blubber to hibernate when cold
- In cold climates they eat food (like nuts and seeds) high in energy to support high metabolic rate
8
Q
What are adaptations of animals with a small SA:Vr in hot climates?
A
- animals with small SA:Vr that live in hot climates find it hard to lose heat easily
- Elephants have developed large flat ears which increase surface area through which heat can be lost
- Hippo spend the most of day in water to keep cool by warming water
9
Q
Ventilation
What is an epithelium and endithelium?
A
Epithelium wall seperating internal & external environment
Endothelium- walls seperating internal environment
10
Q
What is ventilation?
A
- the movement of air in and out of something
- our cells need oxygen during respiration
- For this to happen oxygen leads to diffuse into blood to be carried around the body to cells
- our respiring cells also produce carbon dioxide as a byproduct which needs to be removed from the body
- This happens in body through breathing
11
Q
What are the features of the respiratory system?
A
- air enters body through nasal cavity to the trachea (aka windpipe)
- Larynx (voice box) has rings of cartilage for stability
- This branches off into two pipes called bronchi to enter each lung
- The bronci branch into bronchioles with alveoli (gas exchange surface of humans)
- Surrounding the lungs is the ribcage which have intercostal muscles between each rib
- Below the lungs separating thorax (upper parts of the body) from the abdomen is the diaphragm (rib and diaphragm move in ventilation)
12
Q
What is the layout of the intercostal muscles?
A
found between ribs
External i.c.- involved in normal inspiration (inhale) and expiration (exhale)
Internal i.c.- intercostal muscles are involved in forced expiration (more air out)
13
Q
What are the steps of inspiration (inhale)?
A
- when we inhale, intercostal muscles between ribs contract causing the rib cage to move up and out
- diaphragm contracts and flattens moving down
- these movements increase the volume in a thoratic cavity (thorax)
- increase in volume decreases pressure in the lungs so to below the atmosphere (atmospheric pressure)
- as a result of this air (not just oxygen) rushes into the lungs down the pressure gradient
Inspiration is an active process as muscles require energy to contract
14
Q
What are the steps of expiration (exhale)?
A
- when we exhale external intercostal muscles relax causing the rib cage to move down and in
- diaphragm relaxes becomes dome shaped and curves up again
- this decreases volume in the thoratic cavity (thorax)
- decreases in volume in thoracic cavity results and increase in pressure in the lungs to above atmospheric pressure
- this causes air to be forced down the pressure gradient as it exits the lungs
Expiration is a passive process as it doesn’t require energy
15
Q
What happens in forced expiration?
A
- external intercostal muscles relax and internal intercostal muscles contracts pulling rib cage further down and in
- This makes them antagonistic as they both do the opposite
16
Q
What are adaptations of the alveoli?
A
- Large surface area-600 million to increase diffusion rate
- Short diffusion pathway- walls of alveoli only one cell thick, made of flat cells (alveolar epithelium) surrounded by capillary endothelium
- Moist- help gases dissolve on moisture help pass gas across permeable membrane
17
Q
How does the diffusion of gas occur?
A
- when we inhale there’s a higher concentration of oxygen in the alveoli then the blood so oxygen diffusers across the alveolar epithelium and capillary endothelium into the haemoglobin in the blood
- This is then carried by the blood around the body to respiring cells
- There is a higher concentration of carbon dioxide in the blood than the alveoli (as our bodies make CO2) so carbon dioxide diffuses across the capillary endothelium and aviola epithelium to get exhale
- This is then exhale through the nasal cavity
18
Q
What is a spirometer?
A
- A machine doctors used to measure lung volume (Can diagnose lung disease)
- The spirometer has a chamber with oxygen in it
- Lid of chamber moves up and down with each breath
- Person breathes in chamber through mouthpiece removing oxygen from the chamber
- Exhaling high CO2 levels into the chain that can be dangerous
- Soda lime in spirometer absorbs CO2 exhaled
- Exhaling high CO2 levels into the chain that can be dangerous
- attached to spirometer is a pen
- As person breathes in and out, lid moves up and down recording movement on rotating drum (making spirometer trace)
19
Q
How do you measure lung capacity on a graph?
measured with spirometer
A
tidal volume- the volume of air taken in each breath (length of regular waves)
forced expiration volume(FEV1)- maximum volume of air that can be exhaled in one second (not including tidal)
forced vital capacity (FVC)- maximum volume of air that can be breathered out or in forcefully after deep breath in
residual volume- volume of air that always remains in lungs (even after forced expiration)
total lung capacity- maximum volume of air that can be inspired into lungs (highest wave peak from y is zero)
ventillation rate- number of breaths per minute
up is exhale, down is inhale
20
Q
How are insects adapted for gas exchange?
A
- Insects that live on land (terrestrial) have microscopic air-filled pipes called tracheae which they use for gas exchange.
- Air moves into the tracheae through tiny pores called spiracles.
- Each of the tracheae branch off into smaller trachioles, which have thin permeable walls and go to individual cells.
- Carbon dioxide from these respiring cells move down its own concentration gradient in the opposite direction towards the spiracles to be released into the atmosphere.
- As the insect’s circulatory system does not transport the oxygen (and carbon dioxide) around the body, the insect uses rhythmic abdominal movements to move air in and out of the spiracles.
21
Q
How do insects control water loss?
A
- Exchanging gases with the atmosphere can also result in the loss of water vapour.
- If an insect is losing too much water they will use their muscles to close their spiracles.
- To reduce the amount of water evaporating they are also covered with a waterproof waxy cuticle and have tiny hairs around the spiracles.
22
Q
Why do fish need specialised gas exchange surfaces?
A
- fish have a smaller SA: Vr
- to increase the rate of diffusion of gases to and from respiring cells, they have developed specialised gds exchange surfaces
- fish have gills as an exchange system
23
Q
How are fish gills adapted to gas exchange?
A
- water (containing oxygen) passes along gills
- each gill is made up of thin plates (gill fillaments) attatched to a gill arch
- these gill fillaments increase the s.a. for gas exchange to occur, increasing the diffusion rate
- on each gill fillament are tiny structures (lamellae) which further increase the s.a. over which gas exchange occurs
- each lamellae has lots of blood cappillaries and a thin cell layer
- this also helps to increase the rate of difusion of gases (oxygen and carbon dioxide) between the blood of the fish and the water
24
Q
What is the counter-current mechanism?
A
- the blood flowing through lamellae in the gills flows in one direction, the water flows over lamellae in the opposite direction
- the water has a higher conc. of oxygen compared to the blood, which has a lower oxygen conc.
- the counter-current mechanism creates a steep conc. gradient between the water and the blood which is maintained over the entire gill fillament length
- this ensures that as much oxygen possible diffuses from the water into the blood
25
Q
What is the structre of the leaf?
A
- waxy cutivle
- upper epidermis
- palisade mesophyll
- xylem and phloem
- spongy mesophyll
- stomata
- guard cell
- lower epidemis
26
Q
Why do plants need specialised gas exchange surfaces?
A
- plants need CO2 for photosynthesis and produces O2 as waste
- however, they need O2 for respiration when there’s no sunlight and produce CO2 as waste
- the main gas exchange surgave is the surface of the mesophyll cells in the leaf (they’re well adapted for their function due to large surface area)
- mesophyll cells inside the leaf, gases move in and out the leaf through stoma in epidermis
- stomata open to allow gas exchange and close if the plant loses too much water
- guard cells control opening and closing of the stomata
- the higher the temp., the more water loss through transpiration
27
Q
How do the guard cells work?
A
- when water enters the guard cells, it makes them turgid, going swell opening the stomatal pores
- if the plant starts to become dehydrated, the guard cells lose water and become flaccid, closing stomatal pores
28
Q
What is a xerophyte?
A
WHAT: plants adapted to survive in warm, dry, windy habitats (this means water loss through the stomata is more of a problem)
- they have adaptations to help to redue water loss through stomata (transpiration/ evaporation)
29
Q
What are adaptions of xerophytes?
A
- waxy cuticle- reduces water loss, the hotter te climate, the thicker the waxy cuticle to reduce water loss.
- sunken stomata- when air moves across the lower epidermis of the leaf, water coming out of the stomata will evaporate. suken stomata allows moist air to be trapped around them reducing the w.p. gradient between the air and leaf and the amount of water diffusing out of the leaf.
- hairs on epidermis- hairs trap moist air around the stomata reducing the w.p. gradient between the air and leaf and the amount of water diffusing out of the leaf.
- fewer stomata- less places in the leaf for water to lose air through
- curled leaves- stomata located on the inside of the leaf, protects stomata from wind so less water is lost/ drawn out of the plant by transpiration as the wind blows over.
30
Q
What is the circulatory system?
A
- responsible for transporting raw materials and waste products around mamalian bodies
- large multicellular organisms need the circulatory system as a specialised exchange (mass transport system)
- made up of the heart and blood vessels
- heart pumps blood through vessels and carried through the body
- transports respiratory gases, products of digestion, metabolic waste and hormones around the body
31
Q
Why is the circulatory system a double circulatory system?
A
- there’s 2 circuits with blood circulating around the body
- one circuit from the heart to the lungs, the other from the heart to the rest of the body
- blood passes through the heart 2x in one full circuit of the body
32
Q
What are the main blood vessels in the circulatory system?
A
- vena cava- deoxygenated blood from body -> heart
- aorta- oxygenated blood from heart -> body
- pulmonary artery- deoxygenated blood from heart -> lungs
- pulmonary vein- oxygenated blood from lungs -> heart
- renal artery- oxygenated blood from heart -> kidney
- renal vein- deoxygenated blood from lungs -> heart
- coronary arteries- blod flows through to supply the heart with blood
33
Q
What are the 3 types of blood vessels?
A
- veins- thin outer wall, large lumen
- capillaries- thinnest wall
- arteries (+arterioles)- elastic, rigid wall, small lumen, thick wall
34
Q
What is the role of arteries?
A
- carry oxygented blood away from the heart to the body (except pulmonary artery)
- carries blood at high pressure with thick, muscular walls
- have elastic tissue so artery can stretch/ recoil as the heart beats
- inner lining (endothelium) is folded so artery can stretch
- helps artery to cope with high pressure
- large lumer
35
Q
What are arterioles?
A
- arteries divide into smaller vessels (arterioles)
- form network around the body, blood directed to body parts in need
- this is controlled by muscles in arterioles,
- contract restricts blood flow and relaxes to allow full blood flow
