3.1 Flashcards
Exchange surface
Place that substances move across membranes into an organism
Squamous tissue
Single layer of flat cells in contact with one of the two layers of the basement membrane
Epithelium
Thin tissue forming the outer layer of bodies surface and lining the alimentary canal and other hollow structures
Villi
Can be found in small intestines and increase its surface area to help more nutrients enter blood stream
Concentration gradient
Difference in the concentration of a substance between two areas
Surfactant
A substance which tends to reduce the surface tension of a liquid in which it is dissolved
Inspiration
Breathing in / inhaling
Expiration
Exhaling from lungs
Diffusion
Net movement of particles down a concentration gradient, it is passive
Surface area to volume ratio
Surface area of organism divided by its volume expressed as a ratio
What are alveoli?
Tiny folds of the lung epithelium to increase SA
What are bronchi and bronchioles
Smaller airways leading into lungs
What is a diaphragm
Layer of muscle beneath lungs
Intercostal muscle
Muscles between the ribs
Contraction of external intercostal muscles raises rib cage
What is trachea
Main airway leading from back of mouth to lungs
Ventilation
Refreshing of air in lungs so there is higher oxygen concentration than in blood and lower carbon dioxide concentration
Cartilage
Form of connective tissue
Ciliated epithelium
A layer of cells that have many cilia
Elastic fibres
Protein fibres that can deform and recoil to their original size
Goblet cells
Cells that secrete mucus
Smooth muscle
Involuntary muscle that contracts without need of conscious thought
Exchange surface
Place that substances move across membranes in an organism
Squamous tissue
Single layer of flat cells in contact with one of the two layers of basement membrane
Epithelium
Thin tissue forming the outer layer of a body’s surface and lining alimentary canal and other hollow structures
Villi
Can be found in small intestines and increase their SA to help more nutrients into blood
Surfactant
A substance which tends to reduce surface tension of a liquid in which it is dissolved
Concentration gradient
Difference in concentration in a substance between two areas
Inspiration
Inhaling breathing in
Exhalation
Exhaling from lungs
Breathing rate
Number of breaths per minute
Oxygen uptake
Volume of oxygen absorbed by lungs in one minute
Tidal volume
Volume of air inhaled or exhaled in one breath at rest
Spirometer
Device which can measure movement if air in and out of lungs
Vital capacity
Greatest volume of air that can be expelled from the lungs after taking deepest breath possible
Buccal cavity
The mouth
Countercurrent flow
Where two fluids flow in opposite directions
Filaments
Slender branches of tissue that make up gill. Often called primary lamellae
Lamellae
Secondary lamellae, folds the filament to increase surface area, so are called gill plates
Operculum
A bony flap that covers and protects the gills
Spiracle
An external opening or pore that allows air in or out of tracheae
Tracheal fluid
Fluid found at end of tracheoles in tracheal system
Tracheal system
A system of air filled tubes in insects
How do singles felled organisms (amoeba, bacteria, Protozoa) and small organisms (flat worms) exchange materials across their membranes
By diffusion
What do single felled organisms have to ensure exchange surface is adequate for diffusion
Large SA:V ratio
Do smaller or larger organisms have larger SA:V ratio
Smaller, the bigger the organism the smaller the SA:V ratio
Why can’t large organisms get nutrients via diffusion
Nutrients and gases have a greater distance to travel and outer surface isn’t sufficient for nutrients and gases to enter body fast enough to keep cells alive
What materials and toxic waste to large organisms need and expel
Heat-large number of cells undergoing metabolism,
Waste must be rapidly removed to prevent enzymes denaturing,
Cells are distant from external environment and have to cross many barriers and travel long distances
Why do large organisms need intestines and lungs and circulatory system
Materials can’t diffuse quick enough so need specialised surfaces, intestines absorb digested nutrients, alveoli in lungs for gas exchange
Why is large SA necessary for exchange surface
allows more molecules to pass through, often achieved by folding walls and membranes involved, many spherical alveoli in lungs
How are thin walls designed for exchange surfaces
One cell thick which reduces diffusion distance between source and destination, eg, wall of alveoli one cell thick squamous epithelium cells
Epithelium cells have adapted in the body by
Certain ones have cilia which removed foreign substances
Why steep concentration gradient is necessary for diffusion
Constant supply of materials being exchanged on one side and constant removal on the other, ensuring rapid diffusion
How is small intestine adapted as special exchange surface
Villi and microvilli increase SA for absorption of soluble nutrients which are removed and transported to cells via circulatory system
How is root hair adapted for exchange
Large SA for absorption of water and minerals
How are alveoli in lungs adapted for exchange
Large SA for oxygen and carbon dioxide exchange
How is hyphae in fungi adapted for exchange
Large SA to absorb nutrients
How do we breathe?
Gaseous exchange in mammals consists of air flowing in&out of lungs and airways
What happens when we breathe
Lungs in chest cavity, air passes into them via nose, air goes along the trachea, bronchi & bronchioles before reaching alveoli where gas exchange happens
What protects the lungs and helps ventilation
Lungs protected by rib cage which is protected by intercostal muscles which with the diaphragm help produce breathing movement (ventilation)
What happens at the alveoli in gas exchange
Gases pass by diffusion through alveoli thin walls, oxygen passes to blood capillaries and carbon dioxide diffuses from blood to air in alveoli, lungs must maintain a steep concentration gradient for this to happen
Which part of the lungs have to largest surface area
Alveoli (small about 100-300um across), so many that SA of lungs in half tennis court
What is lined on the alveoli that evaporates when we breathe out
Small layer of moisture called surfactant which coats internal surface of alveoli and reduces cohesive force between water molecules to prevent alveoli collapsing
Why is the barrier to exchange In alveoli and blood capillaries permeable
Made of squamous epithelium cells and allows oxygen and CO2 through as the are small and non-polar
How have thin walls at alveoli and blood capillaries adapted
Capillaries and alveolus both one cell thick of squamous cells, capillaries are in close contact with alveolar wall, capillaries are narrow so RBC squeezed against wall reducing rate of flow and closer to air in alveoli, total diffusion barrier is two cells think (1um)
How is good blood supply useful in exchange
Maintains and concentration gradient, transports CO2 from tissues to lungs and transports oxygen away from lungs—> maintains gradient for diffusion to happen
Why is moisture lining alveoli useful
Let’s gassed dissolve to ease diffusion
Why do lungs produce surfactant
To reduce cohesive forces between water molecules so alveoli do not collapse
What is the purpose of ventilation
Replace used air with new air
Does the concentration of oxygen in alveoli remain higher or lower than in blood(inhalation)
Higher
Does carbon dioxide concentration remain higher or lower in alveoli than in blood (exhalation)
Lower
What happens to diaphragm when we inhale
Contracts and moves downwards and becomes flatter (moves digestive organs downwards)
What happens to external intercostal muscles when we inhale
They contract to raise the ribs
In inhalation does the chest cavity volume increase or decrease
Increase
In inhalation does the chest cavity pressure go higher or lower than the atmospheric pressure
Lower than atmospheric pressure
Does air move in or out of lungs in inhalation
Air moves into lungs
What happens to diaphragm when you exhale
It relaxes and pushed up the displaced organs underneath
What happen to external and internal intercostal muscles when we exhale
External relax and ribs fall but internal can contract to push more air out
Give example or when internal intercostal muscles will contract
Exercise, sneezing, coughing
Does volume of chest cavity increase or decrease in exhalation
Decrease
Does the lung pressure increase or decrease compared to atmospheric pressure in expiration
Increase
Does are go in or out of lungs in expiration
Air moves out of lungs
What are alveoli comprised or and surrounded by and what does this create
Comprised of squamous epithelium cells and surrounded by blood capillaries creating a short diffusion distance
What do alveolus walls contain and what is their purpose
Elastic fibres that stretch in inhalation and recoil pushing air out in expiration
Can alveolus walls be seen under a light microscope
There so thin they can’t be seen with light microscope
Why is the lungs airway large
To allow air flow without obstruction
Why does the trachea divide into smaller airways
To deliver air to all the alveoli
Why must the airway be strong
So it won’t collapse in low pressure
What are 2 key features of the lungs airways
Must be flexible and stretch and recoil
What is the airway lined with that hero’s lungs healthy
Ciliates epithelium cells
How does goblet cells and ciliates epithelium work
Goblet cells in epithelium secret mucus to trap pathogens cilia then woft musics to back of the mouth where it is swallowed
What other tissue also produces mucus
Glandular tissue in loose tissue
Is trachea or bronchi narrower
Bronchi
In the trachea and bronchi what prevents them from collapsing in inspiration
Walls consist of cartilage
What is the structure of cartilage and what is its function
C-shaped rings of cartilage which allows more flexibility than complete ring so there is space for food to pass down oesophagus
What is on the inside surface of Cartilage and give examples
Layers of loose tissue for example glandular, connective tissue and elastic fibres, Smooth muscle, blood vessels
What is the inner lining of trachea
Epithelium layer(goblet and cilia cells)
What is space on the inside of a hollow tube inside the human body called
Lumen
Are bronchi or bronchioles more narrow
Bronchioles
Do bronchioles have cartilage
Larger ones do but smaller don’t
What is bronchioles wall mostly consist of
Smooth muscle and elastic fibres
What do the smallest bronchioles have at the end of them
Alveoli
What are the functions of cartilage
Support trachea and bronchi holding them open, prevents collapse under low pressure in inhalation, not a complete ring so flexible, can move neck without constricting airway and allows oesophagus to expand during swallowing
Function of smooth muscle
Can contract and restrict airway, makes lumen much narrower, restricted airway good if harmful substances in the air (not voluntary) and allergic reactions or asthma can cause it to contract
Function of elastic fibres
When smooth muscle contracts it cannot reverse the lumen constriction, elastic fibres are deformed when airway constricts but when smooth muscle relaxes elastic fibres recoil to original shape and size causing airway to dialate
Function of goblet cells and glandular tissue
Under epithelium they secret mucus which traps tiny particles of dust to reduce risk of infection
Function of ciliates epithelium
Epithelium consists of epithelium cells which have many hair like structures projecting form membrane called cilia, they move in synchronised wave motion to waft mucus up airway to back of mouth where can be swallowed and acidity kills bacteria
What does a spirometer measure
Lung volume, movement of are in and out of lungs as a person breathes
What is the structure of spirometer
Float chamber consists of air or oxygen floating on a tank of water, when inhale air drawn from chamber so lid moves down and in exhalation air returns to chamber lifting lid which is recorded on data logger, CO2 rich air passes through soda lime to absorb it so only oxygen consumption measured and a trace marker attached to the mobile upper half
Person using a spirometer should be….
Healthy and asthma free
What happens if soda like is not fresh and functioning
CO2 levels can come dangerously high as oxygen used in respiration is replaced with CO2
Why is it important there are no air leaks on a spirometer
Would give invalid results if it isn’t a closed system
Gives two precautions when using a spirometer
Mouthpiece sterilised and water chamber can’t be overfilled as water may enter tubes
Why are modern spirometer although easier not as good
Don’t measure oxygen consumption
What is the total lung volume equation
Vital capacity + residual volume
How is vital capacity measured
Taking deep breath and expelling as much air as possible from lungs
What does vital capacity results depend on and what is an average result
Depends on height, size, age, gender, level of regular exercise (higher in trained athletes) is usually 2.5-5dm^3
What is the average tidal volume and is it enough for whole body during exercise
0.5dm^3 and is enough oxygen for whole body at rest
What does breathing do
Gives o2 for respiration and removes CO2 produced in respiration
What happens in human body when person breathes from spirometer
Oxygen is absorbed by blood and replaced by carbon dioxide
On the trace it is constantly decreasing, why
CO2 absorbed by soda like so volume of air in spirometer decreases
Is the volume of CO2 released and absorbed by soda lime equal or different to volume of oxygen absorbed by blood
Equal
What is inspiratory reserve volume and when do we use it and on average what is it
How much extra air you can breathe in with forces inhalation, needed when exercising and usually 3dm^3
What is expiratory reserve volume and how would you work it out
How much extra air you can breathe out in forced exhalation, difference between tidal volume and vital capacity when you exhale
How to calculate rate of oxygen uptake
Find gradient if the decrease in volume on a graph
How to measure breathing rate from spirometer graph
Count number of peaks per minute, usually 12-14
When does oxygen intake increase and why
Increased demand like exercise as muscles are respiring more due to deeper breaths or higher breathing rate
How to calculate ventilation rate
Tidal volume x number of breathes per min
How to calculate vital capacity
Tidal volume + inspiratory and expiratory reserve volume
What do the normal vital capacity of normal person and an athlete
normal person=4-5L
Athlete=6L
What is another word for dead space and in L how much is there usually
Residual volume about 1.5L
Why is there a steep concentration gradient maintained between blood and alveoli
Blood reaching alveoli has lower partial pressure did oxygen and higher partial pressure of CO2 than the alveolar air
How are results of spirometer test recorded
Pen attached to moving lid draws on a revolving drum creating a graph
Why is a nose clip worn when using a spirometer
To keep a closed system between lungs and spirometer
How do you achieve the best diffusion rate
Large, thin, permeable respiratory area
What problem do land organisms have and what is there solution
If their cells exposed to air they will dehydrate so they have a waterproof cover (khitin, wax, keratin) however waterproof cover prevents diffusion so specialised structures developed for gas exchange (leaves, lungs, tracheae)
What are problems aquatic organisms have and how are the resolved
Much less oxygen in water so diffusion is much slower than air so they developed large and efficient structures to overcome this
How to bony fish respire
Use gills to absorb oxygen dissolved in water and release CO2 into water
How many pairs of gill arches do fish have
4-5
What is the operculum
Bony plate which covers the gills
How many rows of gill filaments are there on each arch
2
What are the filaments attached to the bony arch called
Primary lamellae
What are features of fish filaments
Very thin and surface is folded many times to create a large SA
What is the secondary lamellae
Surface of primary lamellae is folded many times and thus is called secondary lamellae
Where do the capillaries go in order to get more oxygen in fish
Close to the secondary lamellae
How does gas exchange work in a fish
Short diffusion distance for gas to cross, rich blood supply, water constantly pumped over gills to maintain concentration gradient, oxygen diffuses from water in gills and CO2 diffuses out of gills into water
What is countercurrent flow and how does it optimise o2 intake
Blood flows along Gill arch, out along filaments to secondary lamellae, blood then flows in opposite direction to the flow of water over lamellae(countercurrent flow)
When does gas exchange occur in fish
When water passes over the gills
What is the distance between water and blood in lamellae
5um
Give two features in fish for efficient gas exchange
Gills have extensive blood capillary network and haemoglobin used to carry oxygen, gills provide large surface area (filament and lamellae)
How do bony fish keep blood flowing over gills
Using buccal-opercular pump
Do bony fish actively or passively ventilation
Actively as is more Efficient
How do bony fish actively ventilate
Floor of mouth moves downwards drawing water into the buccal cavity, when floor lowers volume increases so pressure decreases and water flows in, then mouth is closed, floor is raised pushing the water through gills due to pressure increase, as water pushes up from buccal cavity operculum moves outwards to reduce pressure in opercular cavity helping water flow through gills
Why do fish die out of water
Without surrounding water gills stick together and there isn’t enough SA for fish to get oxygen in needs by diffusing through skin
Why don’t insects transport oxygen in blood
Have an open circulatory system where body fluids act as blood and tissue fluid , this is slow and can be affected by body movement
What animals have air filled tracheal systems
Insects
What does the air filled tracheal system do
Supplies air directly to all responding tissue
What is a spiracle
A pore in each segment of insect where air enters
What are tracheae and tracheoles
Tracheae Series of tubes found in insects that get smaller and smaller tubes called tracheoles which air is transported in
What is tracheal fluid and where’s it found
End of tracheoles are open and filled with this fluid
Where does gaseous exchange occur in insects
Between air in tracheole and tracheal fluid and some can occur across thin walls of tracheoles
What are the two segments of an insect
Thorax and abdomen
What supports the tracheae
Chitchin
What happen when insects are active and need a better blood supply
Tissues are active so tracheal fluids can be withdrawn into body fluids to increase SA of tracheole wall exposed to air so more oxygen can be absorbed
Why can’t there be gas exchange through insects covering
Too thick
What do insects have instead of lungs
Internal respiratory system with openings called spiracles which open when CO2 is needed
Where do spiracles lead to
System of tubes which run to insects cells (tracheal system)
Where does gas exchange occur in insects
Tracheoles
Why are tracheoles good for gas exchange
Freely permeable to gases, tracheal fluid makes them moist, air pumped in and out of them by insects to maintain concentration gradient
How do some insects ventilate using section of tracheal system
Sections of tracheal system expand and have flexible walls which act as air sacs which can be squeezed by action of flight muscle
How do some insects ventilate using wings
Thorax volume decreases so air in tracheal system is under pressure and pushed out of tracheal system, when volume of thorax increase pressure inside drops and outside air pushed into tracheal system
How do locusts ventilate
Can alter abdomen volume with breathing movement and coordinates with open and close valve on spiracles, as abdomen expand spiracle at front of body opens and air enters tracheal system and as abdomen reduces in volume spiracle at rear end of body opens and air leaves tracheal system
Give examples of bony fish
Cod , mackerel, trout, lungfish
How are insects body divided
Thorax, abdomen, head and 2 pairs of wings attached to thorax
Where are lungs situated
In thorax, walls of which formed by ribs, sternum and intercostal muscles and diaphragm floor
What directly surrounds the lungs and what does it do
A narrow pleural cavity lined by pleural membranes which has a thin layer of pleural fluid, lubricant, which allows pleural membranes to slide over each other when thorax expands and contracts
What happens when we breathe in
Sternum moves forwards, ribs move up and out due to contraction of intercostal muscles
What happens when we breathe out and what happens when we breathe out doing exercise
Passive process where elastic fibres recoil after being stretched or in exercise intercostal muscles contract to push more air out
What is the pressure gradient in the lungs when we are relaxing compared to the outside atmosphere
Resting pressure in lungs is almost the same as atmospheric pressure , but, lungs are elastic and often pull away from thorax, pressure in pleural cavity is less than atmospheric
What happen in inspiration and what happens in exhalation
Walls and floors of thorax move out and down, pleural pressure falls lowering lung pressure below atmospheric pressure so air enters lungs, this increases volume and returns to atmospheric pressure,, exact opposite in expiration
What is the structure of lungs
Spongy and consist of 2 bronchi, which become bronchioles which lead to a bunch of alveoli
When is gas exchange most efficient
When large amounts of alveoli are near extensive capillary system
What is the purpose of the alveolar epithelium being covered in a thin layer of fluid
It dissolved oxygen before diffusion so alveoli don’t collapse and expanding would be difficult but fluid has surfactant so this doesn’t happen
Wall of alveoli and capillaries both have squamous epithelium close to each other, why is this good
Diffusion distance only 2 cell thick so there is minimum resistance for gas diffusion
What is dead space or residual volume
When we breathe not all the air is exchanged some remains in trachea and bronchial tubes
What happens to blood o2 and CO2 levels when we exercise
Blood o2 decreases and blood CO2 will rise, if oxygen deprived for too long hypoxia occurs
What happens if we breath pure oxygen
Isn’t bad u less at high pressure like diving where it can interfere with cell respiration
What do the basement layer of epithelium cell
One side of epithelium is free and one has cells which support and control what passes through it to
Difference between epidermis and endothelium
Epidermis is our skin and endothelium lines inner cavities and tubes
How is epithelium protected from abrasion
Mucus acts as lubricant easing movement
What is mucus membrane and where is it found
Moist epithelium contains goblet cells and connective tissue found in gut lining and breathing track
What does connective tissue do
Fills gaps between organs and tissues, contains protein fibres and several other cells with similar composition to basement membrane
What is elastic tissue properties
Contains elastic fibres and cells and is strong but flexible
Cartilage properties
Cartilage is soft bone with collagen and elastic fibres, hayaline cartilage found in trachea walls to prevent them caving in
