Module 3.1.1 - Exchange surfaces Flashcards
What size cells have a larger SA:V ratio?
Smaller cells
What size cells have a smaller SA:V ratio?
Larger cells
What have larger organisms developed a range of?
Different adaptations to increase the ratio at their exchange surfaces
How do you work out the SA of a sphere?
4πr^2
How do you work out the volume of a sphere?
4/3πr^3
What does the alveoli in the lungs increasing the SA:V ratio allow?
For more effective exchange of oxygen and carbon dioxide between the alveoli and the blood capillaries
How many alveoli does an adult lung contain?
About 480 million which provides a SA of about 70m^2
What does the lateral extension on the root hair cell of a plant do?
Increases the SA of the cell which increases the rate of absorption of nutrients from the soil
What is Fick’s Law?
Rate of diffusion ∝ (surface area x con c difference) ÷ thickness of membrane
What is the trachea surrounded by?
16-20 rings of hyaline cartilage which are c shaped
What does the cartilage surrounding the trachea do?
Supports it to help it from collapsing
Why is the cartilage surrounding the trachea c-shaped?
To allow the trachea to expand when breathing
What do ligaments connect together?
Rings around the trachea and a smooth muscle called trachealis muscle
What does the trachealis muscle do?
Bridges the gap of the cartilage ends
What is the trachea lined with?
Ciliated pseudostratified columnar epithelium
Where are goblet cells located?
In between CPCE
What do goblet cells do?
Release mucus to trap pathogens. Cilia then wafts the pathogens back up to the mouth where they are swallowed and killed by HCL acid in the stomach
What does the 4th thoracic vertebra do?
Branches into left and right main bronchi (primary bronchi)
How do the bronchi branch of into each section?
The primary bronchi enters the lungs at a point called the hilum and branch into secondary bronchi, which in turn branch into tertiary bronchi
What happens to the airways as the bronchi divides?
They get narrower
What does the tertiary bronchi do?
Divides into 4th, 5th and 6th order tertiary bronchi and once the airways become too narrow to be supported by cartilage, they become bronchioles
What are bronchioles?
Formed when tertiary bronchi become too narrow to be supported by cartilage
What is the structure of bronchioles?
Their walls don’t have hyaline cartilage so rely on elastic fibres that are attached to surrounding lung tissues for support
What happens as bronchioles get smaller?
They divide into terminal bronchioles which finally divide into respiratory bronchioles and this marks the start of the respiratory zone where air is delivered to the alveoli for gas exchange
What is the respiratory zone?
Where air is delivered to the alveoli for gas exchange
What is the epithelium?
At the start of the bronchioles is simple ciliated columnar epithelium and changes to simple cuboidal epithelium as the size decreases
What is the average surface area of an alveoli?
70cm^2
What does the alveoli have?
A moist lining that gases will dissolve in, before moving across the membrane by simple diffusion
What does the surfactant do to the alveoli?
Keeps alveoli inflated and has a liquid inside of the alveoli
What is the structure of the epithelial cells lining the alveoli?
Thin and flattened (squamous), can fit closely together to form tissues
What is each lung enclosed within?
A pleural sac
What does the pleural sac contain?
Pleural fluid to allow the inner and outer walls to slide over each other during the act of breathing, with a little friction
Following the phrenic nerve, what happens to the diaphagm?
It contracts and moves in the downwards direction
Where is the intercostal muscle?
Between the ribs
What is the external intercostal muscle responsible for?
Elevation of ribs and bending them more open by contracting
What is the intercostal muscle responsible for?
Depression of the ribs and bending them inwards by relaxing
Which intercostal muscle is used in inhalation?
External intercostal muscle which moves the ribcage up and out. This increases the volume of the thoracic cavity and decreases the pressure
Which intercostal muscle is used in exhalation?
Internal intercostal muscle which relax to move the ribcage down and in. This decreases the volume of the thoracic cavity and increases the pressure.
What is Boyle’s Law?
Pressure ∝ volume of a gas
(if the temp is kept constant within a closed system)
What is the pressure like between the thoracic cavity and the atmosphere during inhalation?
The pressure inside the thoracic cavity needs to be lower than the atmospheric pressure outside the body
What is creating between the atmosphere and the alveolus when inhaling?
A pressure gradient which generates a flow of air from a higher pressure in the atmosphere and into the gas exchange system through the nose or mouth
How does air enter the lungs?
It flows along the trachea, the bronchi and the bronchioles before reaching the alveoli for gas exchange
What interaction happens between the internal and external intercostal muscles during inhalation?
Antagonistic interaction.
When one is contracting (agonist), the antagonist muscle is doing the opposite/relaxing
External - agonist
Internal - antagonist
What affects gaseous exchange?
Level of activity
Size of organism
What can you use to measure lung capacity?
- peak flow meter
- spirometer
- vitalographs
What is a peak flow meter?
Small, hand-held device that measures how quickly you can blow air out of your lungs, blow as hard and fast as you can into it, asthmatic people use it often to anticipate an attack
What is a spirometer?
Static lower half of tank is full of water, mobile upper half is full of oxygen, breath out into tank and upper half will rise, breath in from tank and upper half will fall, trace maker is attached to upper half to record results
How do u measure ventilation rate?
Tidal volume X breathing rate (per minute)
What is tidal volume?
The volume of air that moves in and out of the lungs with each resting breath
What is vital capacity?
Volume of air that can be exhaled when the deepest possible intake of breath is followed by the strongest possible exhalation
What is inspiratory reserve volume?
Max volume of air you can breath in over and above a normal inhalation
What is expiratory reserve volume?
Extra amount of air you can force out of your lungs over and above the normal tidal volume or air you breathe out
What is residual volume?
Volume of air that is left in your lungs when you have exhaled as hard as possible, can’t be measured directly
What is total lung capacity?
Sum of vital capacity and residual volume
What is breathing rate?
Number of breaths taken per minute
What is ventilation rate?
Total volume of air inhales in one minute
What type of system do fish have?
Single circulatory system/ closed
What covers the 5 pairs of gills in a fish?
Operculum - bony plate
Where is deoxygenated blood pumped towards by the heart?
Towards the 5 pairs of gills covered by the operculum
What flows through the gill arch in a fish?
Blood
What parts does the gill arch have attached?
Primary lamellae which is very thin and folded into secondary lamellae
Why is the secondary lamellae folded?
Increases surface area for gas exchange between capillaries in lamellae and the water
What does counter current mean?
Fluids flow in opposite directions to each other
How can diffusion happen in gills?
Because of the counter current, all gills are used as higher conc of oxygen in water than in the capillaries in the lamellae to maximise the absorption of oxygen
Where is the buccal cavity in fish?
The mouth
What is the operculum cavity?
Space under the operculum
What is the buccal-operculum pump?
Changes in the volume of the buccal and operculum cavity create the pump which keeps oxygenated water flowing over the gills
What is the process of water entering the buccal cavity and then leaving the gills?
The floor of the mouth moves downwards, increasing the volume of the buccal cavity and this draws water into the mouth. The mouth closes and the floor raises which pushes water towards the gills. The movement of the operculum outwards decreases the pressure in the opercular cavity, and the oxygenated water flows with the pressure gradient through the gills.
What type of system do insects have?
Open circulatory
What does an open circulatory mean?
Haemolymph (blood and tissue fluid) bathes organs in the body
What is a spiracle?
A respiratory opening in the exoskeleton of the thorax and the abdomen of an insect
How does air enter the insect?
Though pores that are found in each segment and known as spiracles
What happens to the trachea in insects?
Given support by a polysaccharide called chitin
How do you get from the spiracle to the tracheal fluid?
Spiracle - trachea - tracheoles - tracheal fluid
What does the trachea divide into?
Trachea divides into smaller tubes called tracheoles and the end of these tubes are open and filled with tracheal fluid
What happens when an insect is active?
Tracheal fluid moves out of tracheoles, exposing more surface area for diffusion.
What does gas exchange occur between?
Between the air that’s in the tracheole and the respiring cells
How does the tracheal system stay ventilated?
Tracheoles found surrounding the flight muscles are flexible and act like air sacs. The are squeezed when the muscles contract and expand when muscles relax. The repetitive expansion and contraction of these sacs ventilate the tracheal system.
