M3, C7 Exchange Surfaces and Breathing Flashcards
What does surface area to volume ratio mean?
This compares how big the surface area is compared to the volume inside
Why can’t large and active animals rely on diffusion of substances across their body to survive?
They have a small SA:V
Long diffusion distance
High Metabolic rate
Diffusion too slow to rely on
Explain why single celled organisms don’t need specialised exchange surfaces
Metabolic activity relatively low
So relatively low oxygen needed or co2 produced
SA:V is large
Diffusion distances are small
What are all the features in the human gaseous exchange system?
nasal cavity nostril mouth trachea bronchus bronchioles intercostal muscles ribs diaphragm abdominal cavity alveoli
what are the features of the nasal cavity?
Large surface area with a good blood supply, warms the air to body temperature
Hairy lining, secretes mucus to trap dust and bacteria, protecting delicate lung tissue from irritation and infection
Moist surface, increases humidity of incoming air, reducing evaporation
what are the features of the trachea?
A wide tube supported by incomplete rings of strong, flexible cartilage –
Stops the trachea collapsing and allows food to move easily down the oesophagus
Lined by ciliated epithelium with goblet cells between them
Goblet cells – secrete mucus onto lining to trap dust and microorganisms
Cilia epithelium – cilia beat and move the mucus/trapped dirt and microorganisms away from lungs
Most of it goes into the throat is swallowed and digested
what are the features of bronchus?
In the chest cavity the trachea divides to form the left and right bronchus, leading to left and right lung
CIliated Epithelial cells
Smaller complete rings of cartilage
what are the features of bronchioles?
In the lungs the bronchi divides to form many smaller bronchioles. (less than 1mm diameter)
Contain no cartilage
Walls contain smooth muscle
-when contracts, causes the bronchioles to constrict (close up)
-when relax, causes the bronchioles to dilate (open up)
This controls the amount of air reaching lungs
Lined with squamous epithelium
What are the adaptations in alveoli?
Made of squamous epithelium cells- one cell thick
Contains collagen and elastic fibres allowing them to stretch during inhalation and recoil during exhalation to force air out
Surrounded by many capillaires- good blood supply
Contain lung surfactant which keeps them inflated
Moist surfaces reduce evaporation of water
what are some details in inspiration
energy using (active)
diaphragm contracts - flat and low
external intercostal muscles contract - ribs up and out
volume thorax increases, pressure decreases - below atmospheric pressure
air drawn through nasal passages, trachea, bronchi and bronchioles into lungs, down pressure gradient
what are some details about expiration
passive process
diaphragm relaxes - domed and moves up
external intercostal muscles relax - ribs down and in
elastic fibres in alveoli return to normal length
volume of thorax decreases, pressure increases to above atmospheric pressure
air moves out of lungs until pressure it equals atmospheric pressure again
what’s a peak flow meter
measures the rate air is expelled from the lungs
what are vitalographs
A graph that shows the rate at which air can be expelled from the lungs
define spirometer
A piece of equipment used to measure breathing patterns or lung volume
how does a spirometer work
it has a oxygen-filled chamber with a movable lid
the person breathes through a tube connected to the oxygen chamber
as the person breathes in or out, the lid of the chamber moves up or down
these movements are recorded by a pen attached to the lid of the chamber, this writes on a rotary drum
the soda lime in the tube the subject breathes into absorbs carbon dioxide
the person wears a nose clip to ensure that air cannot enter or leave the body except via the apparatus
what’s vital capacity
The maximum volume of air that can be inhaled or exhaled in one breath
what’s tidal volume
The volume of air that is inhaled/exhaled during regular breathing
what’s total lung capacity
total volume of the lungs
what’s residual volume
Volume of air left in your lungs after the deepest possible exhalation
what is inspiratory reserve volume
volume of air that can be inhaled over and above normal inhalation
what is expiratory reserve volume
extra amount of air you can force out over and above normal exhalation
what’s the equation for ventilation rate
VR = tidal volume X breathing rate
on a spirometer trace, what does it mean when the line goes up
breath out - volume of gas in spirometer increases
on a spirometer trace, what does it mean when the line goes down
breath in - volume of gas in spirometer decreases
How do gills work in fish?
Water, containing oxygen, enters the fish through its mouth and passes out through the gills.
As water passes over of the gills, oxygen diffuses into the fish gills and into the blood, whilst carbon dioxide passes out of the fish blood in the gills back into the water.
How are fish gills ventilated?
Open mouth = increase volume of buccal cavity (the space inside the mouth) and decreases pressure so water drawn in.
Closed mouth = decreases volume of buccal cavity and increases pressure so causes water to go back through the gills and so O2 diffuses out of the water into gills
What is the structure of a gill?
The gill is supported by the gill arch
The gill arch branches out into many gill filaments stacked on top of one another
On top of the gill filaments are many gill lamellae which increase the SA of the gill
What is the counter current system?
Blood in the gills flows in the opposite direction to water flow.
This means water with a high oxygen concentration always flows next to blood with a low oxygen concentration
Maintains steep conc gradient
how do gases enter and leave an insect
Along the thorax and abdomen of insects are small openings, called spiracles.
Air and water can enter and leave through these
In order to minimise water loss, the spiracles can be closed, by the spiracle sphincter muscles contracting
When the animal is particularly active, more spiracles open to ensure sufficient oxygen enters the insect
what body fluid do insects have instead of blood
haemolymph
which is yellowy-green and transports hormones, nutrients and waste around the body
What type of insects needs more oxygen?
Larger and more active ones, such as bees, locusts and grasshoppers
why can’t gases diffuse through an insect’s skin
because they have a tough exoskeleton
how do insects limit water loss
they have spiracle sphincters which are kept closed for as much as possible
what is the route for gases entering an insect
spiracle tracheae tracheoles Tracheole fluid body cell
what are tracheae (insects)
largest tubes of an insects respiratory system
carry air into the body
lined with spiral of chitin
why do insects need chitin in their tracheae
keeps them open if they are bent or pressed
relatively impermeable to gases and so little gas exchange takes place in the trachea
what are tracheoles
single, greatly elongated cell
no chitin lining so are freely permeable to gases
spread throughout the tissues of an insect
this is wear most gas exchange takes place between the air and respiring cells
what is tracheal fluid
towards the end of the tracheoles
limits the penetration of air for diffusion
what is mechanical ventilation of the tracheole system
air is actively pumped into the system by muscular pumping movements of the thorax and/or abdomen.
These movements change the volume of the body and this changes the pressure in the tracheae and tracheoles, so air is forced in or out depending on the pressure changes
why do bigger insects need collapsible enlarged tracheae or air sacs
used to increase the amount of air moved through the gas exchange system. they are usually inflated and deflated by the ventilating movements of the thorax and abdomen
What happens to the tracheal fluid in the trachea during times of high metabolic activity in an insect
During times of high metabolic activity the tracheal fluid diffuses into surrounding muscles from the tracheole, where oxygen can diffuse directly from the fluid into the cell and CO2 out of the cell
The removal of the tracheal fluid from the tracheole is advantageous as it increases the SA of the traceoles so more gas exchange can take place AND also increases the volume of the tracheoles, decreasing their pressure (to below atmospheric) so more air moves into the tracheoles down the pressure gradient
