Exchange And Transport

Front 1

what do organisms need to keep them alive?

Back 1

- oxygen for aerobic respiration

- glucose as a source of energy

- proteins for growth and repair

- fats to make membranes and to be a store of energy

- water

-minerals to maintain the water potential and to help enzyme action and other aspects of metabolism.

Front 2

how do single cells/small organisms exchange gases, nutrients and waste?

Back 2

across their outer surface, they have a large surface area to volume ratio

Front 3

what are the features that good gas exchange surfaces have?

Back 3

- large surface area to provide more space for molecules to pass through (folding walls and membranes)

-thin barrier - reduce diffusion distance

- fresh supply of molecules on one side to keep concentration high

- removal of required molecules on the other side to keep the concentration low

Front 4

what are some examples of exchange surfaces in living organisms?

Back 4

- small intestine - where nutrients are absorbed

- liver - levels of sugars in blood adjusted

- root hairs of plants - water/minerals absorbed

- hyphae of fungi - nutrients absorbed

Front 5

explain why large active organisms need special surfaces for exchange?

Back 5

large active organisms need lots of oxygen for respiration, they cannot supply enough through their skin surface, as their surface area to volume ratio is too low. a special surface exchange gives a greater area so more oxygen can be absorbed and more carbon dioxide can be removed.

Front 6

how is a plant root adapted for taking in water and mineral ions?

Back 6

the tip of a plant root has specialised epithelial cells, these are called root hair cells, the root hair cells have a long extension which increases their surface area. the wall and membrane are permeable to water and minerals.

Front 7

how does gas exchange occur in the lungs?

Back 7

gases pass both ways through the thin walls of the alveoli. oxygen passes from the air in the alveoli to the blood in the capillaries. carbon dioxide passes from the blood to the air in the alveoli.

Front 8

how does a large surface area help exchange in the lungs?

Back 8

it provides more space for molecules to pass through. - the alveoli are small and in a large quantity so the total surface area of the lungs is large.

Front 9

how does a permeable barrier help exchange in the lungs?

Back 9

the plasma membranes that surround the thin cytoplasm of the cells form the barrier to exchange - these readily allow the diffusion of oxygen and carbon dioxide.

Front 10

what adaptations in the lung help reduce the distance the gases have to diffuse?

Back 10

- alveoulus wall/capillary wall - one cell thick

- walls consist of squamous cells

-capillaries close to alveolus walls

- narrow capillaries - RBC squeezed against capillary wall

- total barrier to diffusion only two flattened cells thick

Front 11

what is meant by a steep diffusion gradient?

Back 11

this means having a high concentration of molecules on the supply side of the exchange surface and a low concentration on the demand side

Front 12

what is the blood transport system?

Back 12

- blood brings CO2 from the tissues to lungs (concentration of co2 in blood higher than air of alveoli)

- heart pumps blood along pulmonary artery to lungs, in lungs the artery divides up to form finer vessels

- these carry blood to the capillaries which lie over the surface of the alveoli

Front 13

how does ventilation in the lung help maintain the diffusion gradient?

Back 13

breathing movement replace used air with fresh air. bringing more oxygen into lungs and ensuring concentration of oxygen in alveolus is higher than in blood

- ventilation also removes air containing CO2 from alveoli. (concentration of CO2 in alveolus lower than blood)

-constant supply of gas to one side of exchange surface and removal from other ensures that diffusion/exchange can continue.

Front 14

when you breathe in (inspiration) what happens?

Back 14

intercostal muscles contract

rib cage moves upwards/outwards

diaphragm muscles contract

diaphragm becomes flatter

volume of thorax is higher

pressure in thorax is lower

Front 15

when you breathe out (expiration) what happens?

Back 15

intercostal muscles relax

rib cage moves downwards/inwards

diaphragm muscles relax

diaphragm becomes more curved

volume of thorax is lower

pressure in thorax is higher

Front 16

what are the similarities of the trachea and bronchi?

Back 16

- they both have relatively thick walls that have several layers of tissue.

- walls consist of cartilage

- cartilage in form of incomplete rings

- layer of glandular tissue, connective tissue, elastic fibres, smooth muscle and blood vessels. (loose tissue)

- epithelium layer - cilia/goblet cells

Front 17

what are the bronchioles?

Back 17

- narrower than bronchi

- large bronchioles have cartilage/small ones dont

- wall made of smooth muscle and elastic fibres

- smallest bronchioles have clusters of alveoli (air sacs) at their ends

Front 18

what is the role of cartilage?

Back 18

- supports trachea/bronchi holding them open

-prevents collapse when air pressure is low

- does not form complete ring so is flexible so you can move neck without crushing airways

- allows oesophagus to expand during swallowing.

Front 19

what is the role of smooth muscle?

Back 19

- can contract

-it constricts airway making lumen of airway narrower - restricts flow of air to and from alveoli

- controlling the flow of air to alveoli may be important if there is harmful substances in air

(causes of asthma)

Front 20

what is the role of elastic fibres?

Back 20

- when smooth muscle contracts - diameter of lumen reduces. and the smooth muscle cannot reverse this effect. the elastic fibres get deformed when this happens and so can recoil to their original shape widening the airway.

Front 21

what is the role of the ciliated epithelium?

Back 21

- consists of ciliated cells taht have tiny hair like structures on them (cilia)

- the cilia move in synchronised pattern to waft the mucus up the airway to the back of the throat. one there the mucus is swallowed and the acidity in the stomach will kill any bacteria

Front 22

what does antagonistic mean?

Back 22

that they wok against each other

Front 23

what is tidal volume?

Back 23

the volume of air moved in and out of the lungs with each breath when you are at rest

(approx 0.5dm^3)

Front 24

what is vital capacity?

Back 24

the largest volume of air that can be moved into and out of he lungs in any one breath

(approx 5dm^3) regular exercise increases vital capacity.

Front 25

what is residual volume?

Back 25

the volume of air that always remains in the lungs even after biggest possible exhalation

(about 1.5dm^3)

Front 26

what is a spirometer and what does it do?

Back 26

measures lung volume - consists of chamber filled with oxygen that floats on tank of water. person breathes from disposable mouthpiece attached to tube connected to chamber of oxygen. breathing out pushes air into chamber which floats up. movements of chamber recorded using a datalogger so that spirometer trace can be produced.

Front 27

if someone breathes in and out of spirometer for a long time the level of carbon dioxide will increase dangerously. how is this avoided?

Back 27

- soda lime is used to absorb the carbon dioxide that is exhaled - the total volume of gas in spirometer will go down because volume of CO2 breathed out is same as volume of oxygen breathed in - as the carbon is removed this total reduction is equal to volume of oxygen used up by the person breathing in/out.

Front 28

what process is responsible for oxygen moving into the blood from the alveoli?

Back 28

diffusion

Front 29

suggest how a spirometer trace from a trained athlete would differ from a spirometer trace from an untrained individual?

Back 29

larger tidal volume and more breaths per minute

Front 30

why do small animals not need a seperate transport system?

Back 30

because all their cells are surrounded by the environment in which they live. diffusion will supply enough oxygen and nutrients to keep the cell alive.

Front 31

what affects the need for a transport system?

Back 31

- size

- surface area to volume ratio

- level of activity

Front 32

how does size affect the transport system?

Back 32

once an animal has several layers of alls, any oxygen or nutrients diffusing in from the outside will be used up by the outer layer of cells. the oxygen and nutrients will not reach the cells deeper within the body.

Front 33

surface area to volume ratio...

Back 33

- small animals - large surface area to volume ratio.

- large animals - small surface area to volume ratio

Front 34

level of activity...

Back 34

animals need energy from food so that they can move around. releasing energy from food by respiration requires oxygen

- the more active the animal - cells need good supply of nutrients/oxygen to supply the energy for movement.

Front 35

what are the features of a good transport system?

Back 35

includes:

- a fluid or medium to carry nutrients/oxygen around the body (blood)

- pump to create pressure pushing fluid around body (heart)

- exchange surfaces that enable oxygen/nutrients to enter/leave blood

(also tubes/vessels/two circuits)

Front 36

what is a single circulatory system?

Back 36

fish have a single circulatory system

- the blood flows from the heart to the gills and then on to the body before returning to the heart again

Front 37

what is a double circulatory system?

Back 37

- mammals have a double circulatory system - one circuit carries blood to the lungs to pick up oxygen (pulmonary circulation). the other circuit carries oxygen/nutrients throughout body to the tissues (systematic circulation)

(heart~body~heart~lungs~heart)

Front 38

explain why a double circulatory system is more efficient than a single circulatory system.

Back 38

- in a double circulatory system the blood returns to the heart after being oxygenated. it is possible to boost the pressure of the blood after it has been oxygenated. this means blood can flow faster and deliver more oxygen to the tissues.

- in a single circulatory system blood does not return straight to the heart after oxygenation - it loses pressure in the organ of gas exchange - it leaves at low pressure/travels more slowly to tissues. so it cannot deliver as much oxygen to the tissues.

Front 39

describe three features of a fish gas exchange system that facilitate gas exchange

Back 39

- greatly folded surface of gills (high surface area)

- water flow across gill surface opposite to the blood flow in gill capillaries , (countercurrent)

- gills supported and kept apart from eachother by the gas exchange medium (water)

Front 40

why do fish need to ventilate their gills?

Back 40

it prevents stagnation of the water at gills surface and maintains the concentration gradient necessary for continued gas exchange

Front 41

how do bony fish achieve adequate ventillation of the gills through:

- pumping (mouth and operculum)

- continuous swimming (mouth open)

Back 41

- operculum acts as a pump drawing water through the mouth and past the gill filaments.

- produces a constant flow of water over gill filaments

Front 42

describe countercurrent flow

Back 42

- oxygen rich water flows over gill filaments in the opposite direction to blood flow through gill filaments. blood in the capillaries always encounters water with a higher oxygen concentration gradient for diffusion into the blood is maintained across the entire gill.

Front 43

how does the countercurrent system in fish gills increase the efficiency of oxygen extraction from the water?

Back 43

- as blood flows through the gill capillaries (gaining oxygen) it encounters blood of increasing oxygen content. this maintains the diffusion gradient across the entire gill surface.

Front 44

explain why parallel flow would not achieve the same rates of oxygen extraction.

Back 44

in parallel flow the oxygen concentration in the blood and the water would quickly equalise and diffusion into the blood would stop.

Front 45

in terms of the amount of oxygen available in the water explain why fish are very sensitive to increases in water temperature or suspended organic material in the water.

Back 45

oxygen availability in water is low anyway so anything that lowers this still further (high temp or decomposition of organic material) increases the vulnerability of fish to oxygen deprivation. this is especially so for fish with high oxygen requirements such as trout and salmon

Front 46

what are the similarities of insect and mammal gas exchange?

Back 46

- oxygen and carbon dioxide use same system

- tube system

- cartilage line material to keep tubes open

- large surface area

- oxygen dissolving into water before blood

- same air drawing system (breathing movement)

Front 47

what are the differences of insect and mammal gas exchange?

Back 47

- insects dont usually have blood pigments that can carry oxygen

- can reduce water loss by closing spiracles

- insects have small air holes in body

- tiny tracheoles - large surface area for exchange (insects)

- insects have trachial fluid which increases oxygen delivery

-insects have chitin

Front 48

how does gas exchange take place in insects?

Back 48

Insects have no transport system so gases need to be transported directly to the respiring tissues. Spiracles in contact with individual cells, contain fluid in which the gases are dissolved. Fluid is drawn into muscle tissue during exercise which increases the surface area of air in contact with the cells. The spiracles can be closed by valves and may be surrounded by tiny hairs. These help keep humidity around the opening, ensure there is a lower concentration gradient of water vapour, and so less is lost from the insect by evaporation.

Front 49

what are alternative methods of increasing the level of gas exchange? (insects)

Back 49

- mechanical ventilation of the tracheal system - air pumped into system by muscular pumping movements of thorax/abdomen changing the volume of body/pressure in tracheae and tracheoles.

-collapsible enlarged tracheae or air sacs - increase the amount of air moved through gas exchange system - inflated/deflated from ventilating movements of thorax/abdomen.