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
The distance from the gas supply to their cells is too large
Gases can’t diffuse fast enough for the animal to survive
Explain why villi make good exchange surfaces
Large surface area to volume ratio
Thin layers - distance is small
Good blood supply - bigger the concentration, the faster the diffusion
Ventilation to maintain diffusion gradient
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
To allow 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 Similar in structure to trachea Contain cartilage rings -Smaller -Complete rings
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 changes the amount of air reaching lungs
Lined with thin flatterned epithelium, making gaseous exchange possible
what are the features in alveoli?
Pulmonary capillary Blood plasma Red blood cell compressed against capillary wall Endothelial cell of capillary Cavity of alveolus Alveolar duct Epithelial cell of alveolus Moist alveolar surface
how are alveoli adapted for gas exchange?
large surface area
thin layers - diffusion distance is small
good blood supply - millions of capillaries surround the alveoli which makes a constant flow of blood which brings oxygen and takes away carbon dioxide
good ventilation - maintains steep diffusion gradients for oxygen and carbon dioxide
alveoli is covered in a solution of water, salts and lung surfactant which makes the alveoli remain inflated.
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
air drawn through nasal passages, trachea, bronchi and bronchioles into lungs
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
air moves out of lungs until pressure in = pressure out
what’s a peak flow meter
measures the rate air is expelled from the lungs
what are vitalographs
more sophisticated than a PFM. patient breathes out as fast as possible, produces a graph of the amount of air they breathe out and how quickly.
define spirometer
used to measure different aspects of the lung volume or breathing patterns
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 breathed in or out in 1 breath, about 5dm cubed but varies in men and women and fitness
what’s tidal volume
the volume of gas that moves in and out of lungs in each resting breath, about 0.5dm cubed
what’s total lung capacity
total volume of the lungs
what’s residual volume
the volume of air that is left in the lungs, even after the biggest possible exhalation, about 1.5dm cubed
what is inspiratory reserve volume
maximum volume of air breathed in 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 and what does it mean
breath in - volume of gas in spirometer decreases
this is because oxygen is used up in respiration, carbon dioxide is released in respiration and carbon dioxide is absorbed by soda lime
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?
Each gill is made from lots of thin plates called gill filaments (primary lamellae)
Each gill filament is covered in lots of tiny structures called gill plates (secondary lamellae) which increase the surface area for exchange
The gill is supported by a gill arch which contains lots of capillaries.
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
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 water in the tracheoles muscles 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, or forced out, as 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
