Exchange Surfaces Flashcards
Features of specialised exchange ssytem
Increased surface area- Provides area needed for exchange and overcomes limitations of SA:V ratio of larger organisms e.g. root hair
Thin layers- DIstances for diffusion are ashort, making the process fast and efficient
Good blood supply- Steeper concentration gradeint, faster diffusion rate= substances contstly removd from surface
Ventilation to maintain diffusion gradient- Gases, helps maintain concentration gradeints adn makes process more efficient
Why do humans have to have a specialized gaseous exchange system
Need to take in lots of o2 and therefore§ remove co2
High metabolic rate because they ate active and maintain body temp
Relatively big
Small sa:V ratio
Key structures in human gaseous exchange system
Nasal cavity Trachea Bronchus Bronchioles Alveoli
Nasal cavity
Large surface area with good blood supply, warm air to body temp
Hairy lining, secretes mucus and traps dust
Moist surfaces increase humidity of incoming air reducing evaporation
Trachea
The main airway carrying clean warm and moist air from the nose down teh chest
Wide tube supported by incomplete rings of strong flexible cartidifge , stopping it from collapsing( incomplete so food can easily move down oesphagus)
Lucid with ciliated epithelium
Bronchus
In the chest cavity, trachea divides to form left bronchus = left lung and right bronchus leading to right lung
Similar structure to trachea
Small supporting rings on cartilage
Bronchi oles
In the lungs bronchi divide to form bronchi oles
Smaller bronchioles( 1mm) have no cardilidge
The walls of the broncholes contain smooth muscle, When the smooth muscle contracts, bronchioles constrict
When it relaxes, the bornchioles dilate( open up), this changes the amount of air reaching teh lungs.
Lined with thin layer of flattened epithelium
Alevoli
Tiny air sacs, main gas exchange surfaces of bod
Diameter of 200-300 um
Layer of thin, flattered epithelial cells+ some collagen and elastic fibers
Elastic tissues allow alveloi to stretch as air is drawn in and return to their resting size= squeeze air out
= ELASTIC RECOIL
Adaptations of alveoli
Large surface area( 300-500 per lung, 50-75km2)
Thin layers- 1 cell thick
Good blood supply- Constant flow
Good ventilation- Breathing moves air in and out of the alveoli, helping maintain steep diffusion gradients of co2 and o2 between blood and air lungs
Lung surfacant
Inner surface of alveoli
Makes it possible for alveolar to remain inflated, o2 dissolved in water before diffusing into the blood
The lungs - why is air moved into and out
Pressure exhanges in teh thorax brought by breathing movements
What is ventilation?
Movement of air
What is the thorax?
Chest cavity
Lined by pleural membranes
Where are the intercoastal and external muscles found
Between ribs
What is inspiration?
Taking in air
Uses energy
Steps for inspiration
Diaphragm( dome shaped), contracts, flatterning and lowering
The external intercostal muscles contract,moving the ribs upwards and outwards
The volume of thorax increases= pressure reduced
Lower pressure than that of atmospheric air, so drawn in
Steps for expiration
Muscles in diaphragm relax
Moves up into resting domed shape
External intercostal muscles relax, ribs move down and inwards under gravity
Elastic fibers in the alveoli of lungs return to normal length
Decrease volume of throax
Pressure inside the thorax greater than atmospheric air, air moves out of lungs
Peak flow meter
Used to measure rate at which air can be expelled q
Vitalographs
Sophisticated version of peak flow meter, the patient breathes as quickly as tehy can = graph of the anout of air and how fast its breathed out
Spirometer
Measure aspects of lung volume or breathing
Features of a spirometer
Soda lime absorbs co2 from exhaled air Enough air/oxygen and sterile medical grade Nose clip check helath All seals secure Not too mcuh water
TIdal volume
Volume of air that moves into and out of lungs with each resting breath
Vital capacity
Volume of air that can be breathed in whne the strognest possible exhalation is followed by deepest breath
Inspiratory reverse volume
Max volume of air you can breathe in over adn above normal inhalation = EXTRA
Expiratory reserve volume
Extra air you can force out of lungs aboce normal tidal volume you can breathe out
Residual volume
Air left in lungs when exhaled hard
Total lung capacity
Residual volume + vital capacity
Breathing rate
Breaths per minute
Ventilation rate
Total volume of air inhaled in 1 minute ( tidal * breathing rate per minute
