Module 3 Flashcards
why are specialised exchange surfaces needed/not needed?
- Single celled organisms don’t need them as they have low metabolic activity so low demands for oxygen and CO2 exchange. Mammals use lots of energy on temperature regulation which they maintain independent of the environment.
- Also have high SA:Vol ratio
- Land mammals need water and gas exchange, but the conditions needed for gas exchange like moist lining are ideal for evaporation of water. Systems help minimise water loss.
- They have also developed a waterproof surface to minimis water loss stopping gases diffusing through
features of a good exchange surface:
- Large SA (folding walls and membranes)
- Thin barrier reducing diffusion distance
- Maintenance of diffusion gradient by good supply and removal (blood) so occurs faster
- Ventilation helps maintain gradient in gases eg. Flow of water in fish
- Active transport also used to increase rate
difference between respiration and breathing?
Respiration: a chemical reaction at cellular level
Breathing: exchange of gases in blood. CO2 is very important to remove as a build-up can dissolve in blood and is acidic, affecting pH and enzymes. Intercostal muscles move rib cage in and out during deeper breathing
We breathe so we can respire
Ficks law
rate of diffusion is directly proportional to SA x conc. gradient
/ diffusion distance
what surrounds the lungs and what does this do?
Lungs are surrounded by double membranes called pleural membranes which have fluid in the pleural cavity. This provides lubrication between lungs and rib cage
Nasal cavity features
- Has a large SA with good blood supply warming air to body temp
- Hair lining which secretes mucus to trap dust and bacteria protecting lung tissue from irritation and infection
- moist surfaces which increase humidity of incoming air reducing evaporation from exchange surfaces
trachea features
- tube is supported by incomplete rings of strong, flexible cartilage which prevent it collapsing. They are incomplete so food can move easily down oesophagus behind trachea, and in-between rings flexibility Is retained. Ends of cartilage rings are joined by smooth muscle and elastic fibres
- is lined with ciliated epithelium and goblet cells that trap dust and microorganisms that escaped the nose lining and are wafted back up to the throat to be swallowed and digested.
bronchus features
- in chest cavity trachea splits into left and right bronchus leading to each lung
- when in the lungs the bronchi divide to form many small bronchioles with smooth muscle and elastic fibres on walls. This muscle can contract and relax changing the amount of air entering the lungs, but the smallest bronchioles only have elastic fibres not muscle.
- They are lined with a thin layer of flattened epithelium making gas exchange possible
- Bronchi have full rings of cartilage as wont rub against oesophagus, but bronchioles have none. Smallest bronchioles have no goblet cells or cilia.
alveoli features
• Tiny air sacs which are main gas exchange surface. Walls have flattened epithelium cells, collagen and elastic fibres, helping it stretch as air is drawn in and squeeze air out- elastic recoil makes expiration a passive process.
what cells make the wall of the alveoli and capillary?
- Squamous epithelium cells make the wall of the alveoli
- Endothelial cells make the wall of the capillary
what is the function of the capillary network in lungs?
• is mostly pulmonary capillaries
• Forms a dense network around each alveolus
• Alveolar macrophages (type of phagocytic white blood cell)
digest any foreign particles (dust and pathogen) that have reached
the alveoli
what is the function of the epithelial cells in lungs?
- Squamous epithelial cells
- Type 1 and type 2 pneumocytes
- Type 1 are large and flat that make up most of cell wall
- Type 2 secrete surfactant which has antibacterial properties
connective tissue structure and function:
- Forms a supporting layer beneath the epithelium
- Consists of fine collagen and elastin fibres and fibroblast cells
- Allows stretch and recoil of lung tissue with breathing, preventing alveoli bursting. The recoil also helps expel air.
cartilage structure and function:
• Form a connective tissue composed of cells surrounded by a material consisting of mucopolysaccharides, which are complex polysaccharides containing amino groups.
support preventing collapse
What is surfactant and what does it do?
- A mixture of lipids and proteins which helps reduce surface tension of liquid lining the inner surface of alveoli
- Speeds up transport of gases between the air and liquid lining alveolus
- Kills bacteria
- Helps alveoli remain inflated and they stick together as you exhale
Location and function of structures in respiratory system: Cartilage smooth muscle elastic fibres goblet cells ciliated epithelium
trachea and bronchi
support preventing collapse
bronchioles
contracts to constrict airways to control airflow
bronchioles
as smooth muscle relaxes fibres recoil so airways dilate
trachea and bronchi
secrete mucus to trap particles in air
trachea and bronchi
waft mucus up the throat by synchronised beating
why do insects a need gas exchange system?
• They have a tough exoskeleton which doesn’t allow gas exchange and have no blood pigment to carry oxygen
How is the amount of air entering insects gas exchange system managed?
- Has small openings called spiracles along the thorax and abdomen which allow water and air to leave and also for water to escape. There are a pair of spiracles pre abdomen segment.
- Sphincters can open and close the spiracles, and they are kept closed as much as possible to reduce water loss, especially when inactive so oxygen demand is low and there is little CO2 (this is minimised by fluttering when they open and close v quick)
- In discontinuous gas exchange there are 3 stages: open, closed and fluttering . When the spiracles are closed CO2 diffuses into the bodily fluids and is held in the process buffering.
What happens to air after it enters through the spiracles?
- Tracheae lead away from the spiracles, running into and along the body and are the largest respiratory tubes at 1mm diameter.
- Tracheae are lined with chitin which keeps them open if they get bent or pressed. As its relatively impermeable to gases little gas exchange occurs in the trachea
- Tracheae branch into narrower tracheoles diameter 0.6-0.8 um, which are single elongated cells with no chitin lining, therefore are permeable to gases. As they are very small, they run through tissues and through individual respiring cells allowing gas exchange and provide a large SA.
- The movement of air occurs by diffusion usually, and oxygen dissolves in the moisture of the tracheole walls.
How is the supply of oxygen increased in insects?
What can happen if oxygen demand is too high?
• When there is a high oxygen demand (flying) then lactic acid builds up in the tissues causing water to osmose out of the tracheoles, exposing more SA for gas exchange
• Some larger insects like bees have high energy demands so have other methods of increasing gas exchange:
- Mechanical ventilation of the tracheal system is where muscular pumping of the thorax/abdomen actively pump air into the system, by changing the volume of the body, therefore changing the pressure in the tracheae and tracheoles, drawing air in or forcing it out. When the body expands air is sucked in.
- Collapsible enlarged tracheae or air sacs act as air reservoirs which are inflated or deflated by the contractions of the thorax and abdomen. They help increase the amount of air moved through the gas exchange system.
Why do bony fish need an exchange system?
• Although they don’t have to prevent water loss like insects, they have to overcome the viscosity of water (100x more than air)
• Also the lower oxygen content causing slow diffusion rates
large active fish like cod cannot rely on diffusion alone to reach the inner cells due to their small SA:Vol ratio
scaly outer surface doesn’t allow gas exchange
• It can also be hard to maintain a constant flow of water over the gills when the fish isn’t moving, and this water flow is necessary to keep the gill filaments apart, exposing their large SA.
What are the adaptations of the gills?
- Tips of adjacent gill filaments overlap, increasing the resistance to the flow of water over the gills slowing it down so more time for gas exchange
- filaments/lamellae increase SA
- rakers trap food and absorb it into the blood
- The water moving over the gills and the blood in the (gill filaments- where?) flows in different directions to maintain a steep concentration gradient so that the water always has higher concentration than water?? and a counter current exchange system is set up. Parallel/concurrent systems only extract 50% of oxygen flowing past as they reach equilibrium halfway through compared to 80% with bony fish
Where are the gills found and what are their features?
- They have gills in the gill cavity covered by a protective operculum (bony flap) which helps maintain flow of water over gills.
- The gills have a large SA- lamellae
- good blood supply
- thin layers
- a one-way flow of water across them to reduce the energy used to move the viscous water in and out of respiratory systems like lungs.
What method of ventilation do some primitive fish use and what do bony fish use?
- For some primitive cartilaginous fish like sharks when they stop moving the flow of water stops and the gills can’t be ventilated, as they rely solely on this- ram ventilation.
- Bony fish have another system: the mouth is opened and the floor of the buccal cavity (mouth) is lowered, increasing its volume and decreasing the pressure so that water moves in. Whilst this is happening the opercular valve is shut and the opercular cavity containing gills expands, lowering the pressure below the buccal cavity. The floor of the buccal cavity starts to move up increasing the pressure, so water moves out of it and over the gills.
- When the mouth closes the operculum opens and the sides of the opercular cavity move inwards. This increases pressure in the opercular cavity forcing water out the operculum. The floor of the buccal cavity is steadily moved up, so a steady flow of water is over the gills.
Process of inspiration
inspiratory centre in medulla oblongata of brain sends out nervous impulse
external intercostal muscles contract moving the rib cage up and out
internal intercostal muscles relax
increases volume of thorax/thoracic cavity
reduces pressure inside so draws air in from higher pressure outside
diaphragm contracts and flattens
lungs expand to reduce pressure activating stretch receptors so the inspiratory centre stops sending impulses
process of expiration
external intercostal muscles relax and ribs move in and down naturally due to gravity
internal intercostal muscles relax
decreases volume of thoracic cavity increasing pressure inside so air released
diaphragm involuntary muscles relaxes and curves in
elastic fibres in alveoli of lungs return to normal length due to elasticity and pressure on them
pressure inside and outside is now equal
stress receptors in lungs are deactivated
inhibition of respiratory centre stops
when do the internal intercostal muscles contract?
what else is needed?
when you cough or sneeze as there is a forced expiration so ribs move rapidly down and in
during this the external intercostals are relaxed
the abdominal muscles contract forcing diaphragm up to raptly increase pressure in lungs
what is the limitation of the bell jar?
doesn’t show ribs moving as glass jar cannot expand
what is a spirometer?
what is the trace of the volumes called?
What absorbs CO2?
What must the person do?
a device used to measure and record the volumes of air inspired and expired over time
spirograph/ kymograph
soda lime
block nose using clip
breathing rate
number of breaths per minute
tidal volume
volume of air inspired and expired in 1 breath usually measured at rest (500ml)/ (o.5dm3)
oxygen uptake
volume of oxygen absorbed by lungs in 1 minute
vital capacity
the greatest volume of air that can be expelled from the lungs after taking the deepest possible breath
pulmonary ventilation/ventilation rate
a measure of the volume of air that’s moved into lungs in 1 minute (dm3min-1)
tidal volume (dm3) x breathing rate (min-1)
What needs to be considered with spirometer measurements to make it a valid trial?
age, health, size
male have larger lung capacities
how do you use a float chamber spirometer?
the subject sits at rest a breaths NORMALLY
the spirometer chamber is filled with medical grade oxygen and float on water
as the subject inspires air is drawn in from the chamber and the lid moves down
during expiration the expired air is returned to the chamber and the lid moves up
these movements are recorded on the trace of a kymograph or spirograph
what precautions must be taken when using a spirometer?
healthy subject
wear nose peg
fresh soda lime to absorb co2
sterile mouthpiece
medical grade oxygen
no leaks to make results inaccurate/ invalid
water chamber not overfilled- inhale water
What do the lines mean if the y axis is lung volume?
what does the y axis mean if the y axis is spirometer volume?
up= inspire down= expire
up=expire
down= inspire
expiratory reserve volume
the volume of air that can be forced out after a normal tidal expiration
inspiratory reserve volume
the volume of air that can be inspired over and above a tidal inspiration
vital capacity
equation
affected by?
the greatest volume of air you can move into and out of your lungs in breath= IRV+ERV+TV
affected by age, sex, athleticism and posture
residual volume
What keeps alveoli open?
the volume of air that remains in the airways and alveoli after forced expiration (1.5dm3)
trachea and bronchi kept open by cartilage and surfactant strops alveoli collapsing
why are transport systems needed?
- To supply nutrients and oxygen like if food is digested in one organ system but needed in all others for respiration and metabolism
- To remove waste products from cells to excretory organs
- Temperature maintenance In birds and mammals
- Hormone circulation if made in one place and needed in another
- Circulation of cells involved in defence
mass flow
The bulk transport of materials from 1 point to another as a result of a pressure difference between the 2 points
What are the components of the circulatory system?
- Circulatory fluid
- Contractile pumping device (heart or modified blood vessel)
- Tubes through which fluid can circulate (blood vessels)
example of an open circulatory system: What is blood called? what is the heart like? where is blood pumped to? what is the main vessel called? How does blood move between the tissues? What are the valves to the heart called? when does exchange occur? How else can circulation be affected? what is carried? How is the body cavity split?
invertebrates like insects
haemolymph
in the abdomen and tubular
haemocoel
dorsal vessel
slowly under low pressure due to low diffusion gradient and can’t be controlled
ostia
when the transport medium comes into contact with the cells
by body movements like muscle pump in insects and fish
not oxygen or carbon dioxide- trachea, but food and nitrogenous waste products and cells involved in defence against disease
a membrane and the heart extends along the length of the thorax and abdomen
example of a closed circulatory system:
Where does blood stay?
What pumps the blood and how is it pumped?
How is blood distributed?
How do things enter and leave?
what carries respiratory gases?
Describe blood vessels in invertebrates like earthworms:
Echinoderms, annelids and vertebrates: (fish and mammals)
blood stays in blood vessels pumped by heart rapidly under high pressure
adjusted on demand bu vasodilation/constriction to different tissues/organs
through capillary walls by diffusion
blood pigment
have the dorsal (upper) and ventral (lower) blood vessels connected by lateral vessels in every segment. The dorsal vessel receives blood from the lateral vessels and carries it towards the head. The ventral vessel carries blood to the segmental vessels. The dorsal vessel is the main method of propelling blood as its contractile, but there are also several contractile aortic arches (hearts) which propel blood.
Describe the single circulation system in fish:
How are active fish adapted?
- 2 chambered heart near gills
- Blood first travels to gills where it passes through capillaries, picking up oxygen but loosing pressure. It continues to travel around the body, back to the heart more slowly
- Efficiency of gas exchange is limited so activity levels are usually low, except in fish which have an efficient one. They have counter current gaseous exchange mechanisms in gills that allows them to take in oxygen from the water. They don’t regulate their own temperature as its determined by water temperature, and their body weight is supported by the water so metabolic demands are reduced.
Double circulation system :
why is it high pressure?
what does exchange occur between?
Why is it needed to be efficient?
- 4 chambered heart
- Deoxygenated blood travels into the right-hand side of the heart and is pumped to the lungs where it picks up oxygen. Oxygenated blood, returns to the left side of the heart which gives it a boost so that it can reach all other parts of the body quickly.
- Oxygenated blood that travels to an organ travels directly back to the heart, not another organ, apart from blood going to the gut, which then goes onto the liver via the hepatic portal vein before returning to the heart
- High pressure as only flows through one capillary network per circuit, so steep concentration, gradient and more efficient exchange
- Exchange occurs between blood and tissue fluid surrounding the cells of your body
- Very active, especially land mammals that maintain their own body temperature
pulmonary circulation
systemic circualtion
myogenic
right hand side of heart pumps blood to lungs only
the left side of the heart pumps blood to the rest of the body
contractions originate from the muscle tissue not nerve impulses to preserve resources
biozone pink
what do the valves do?
the atrioventricular valves prevent back flow of blood into atria when ventricles contract
the semi lunar valves prevent back flow of blood into ventricles when they relax
What separates the sides of the heart?
what is a hole in the heart?
septum
• The development of the septum isn’t complete until after birth, and the foetus; blood is oxygenated in the placenta so the blood in the heart is very similar and mixes freely.
• The gap closes in the days after birth, but if it doesn’t its called a hole in the heart and is heart as a murmur.
• Large holes may need surgery
What is the cardiac cycle?
what are the phases?
a sequence of events in 1 heartbeat
diastole
atrial systole
ventricular systole
What happens in diastole?
What happens in atrial systole?
What happens in ventricular systole?
Diastole:
• The atria and ventricles relax and blood flows into the atria of the heart from the veins at low pressure
• At the beginning of diastole the AV valves are closed but as pressure builds in the atria to higher that in the ventricles, they are forced open so blood can flow into the ventricles
Atrial systole:
• Both atrial walls contract pushing remaining blood into ventricles, so they are empty
• The sphincters where the vena cava and pulmonary veins enter the atria close to prevent backflow
• Once the ventricles are full of blood ventricular systole begins
Ventricular systole:
• As the ventricular walls start to contract pressure builds up to a point where it forces the AV valves closed
• As pressure continues to build the semi lunar valves will open when it higher than pulmonary arteries and aorta
• (de/oxygenated) blood flows into the arteries (names) which have elastic walls so can stretch to accommodate blood. The contraction or aorta walls helps valves prevent backflow of blood