C7- Exchange surfaces and Breathing Flashcards by Eva Morrill

2 reasons why simple diffusion alone is enough to supply the needs of a single celled organism

The metabolic activity of a single celled organism is usually low, so oxygen demands and CO2 production of the cell are usually low

The surface area to volume ratio of the organism is large

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4 common features of specialised exchange surfaces

Increased surface area

Thin layers

Good blood supply

Ventilation to maintain diffusion gradient

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Why do specialised exchange surfaces have an increased surface area?

Provides area needed for exchanges

Overcome limitations provided by lowered SA:V in larger organisms

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Why do specialised exchange surfaces have thin layers

Shortens the diffusion pathway

This makes the process fast and efficient

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Why do specialised exchanged surfaces have a good blood supply and ventialtion

Maintains concentration gradient for diffusion

Makes the process of exchange more efficient

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Adaptations of the nasal cavity

Moist – reduces evaporation from
exchange surfaces

Good blood supply – warms the air

Hairs – traps bacteria and dust

Mucus – traps bacteria and dust

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Adaptations of the trachea

Carries warm moist air
- Greater kinetic energy of particles in air then increases rate of diffusion

C-shaped rings of cartilage
– prevents collapse

Lined with:
Ciliated epithelial cells
Goblet cells

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Adaptations of Bronchus

Rings of cartilage in the walls of the bronchi provide support

It is strong but flexible

It stops the trachea and bronchi collapsing when pressure drops

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Adaptations of bronchioles

Small (1mm)

No cartilage

Thin layer of epithelial cells – some
gaseous exchange

Walls contain smooth muscle so can
constrict and dilate

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Adaptations of alveoli

Good ventilation- Oxygen and carbon dioxide are moved efficiently into and out of the alveoli so that concentration gradients are maintained

Thin layers –single cell thick Less distance for oxygen to diffuse across

Large surface area- Greater efficiency of diffusion

Good blood supply –Takes oxygen away quickly so maintains a high concentration gradient

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Ventilation

definition

Breathing

where air is constantly moving in and out of the lungs

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Inspiration

Inhalation

occurs when air pressure in the atmosphere is greater than that of the lungs

forcing air into the alveoli

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Expiration

exhalation

occurs when air pressure in the lungs is greater than the air pressure in the atmosphere

Forcing air out of the alveoli

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2 sets of muscles involved in ventialltion

Diaphragm

Intercostal muscles

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2 types of intercostal muscles

effects of contraction

internal = contraction leads to expiration

external= contraction leads to inspiration

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antagonistic pair of muscles

definition

One muscle of the pair contracts to move the body part, the other muscle in the pair then contracts to return the body part back to the original position

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Boyles law

P1V1= P2V2

Decreasing volume increases collisions, increasing pressure

Inspiration process

External intercostal muscles contract, internal relax

diaphragm contracts

Air pressure in thorax decreases

lung volume increases

air moves in

Expiration process

Internal intercostal muscles contract, external relax

Diaphragm relaxes

Air pressure in thorax increases

Lung volume decreases

Air moves out

Adaptation of gills

Large surface area

Gill filaments overlap – so resist water
flow (slows water down for more
efficient oxygen uptake)

Counter-current exchange – allows 80%
of oxygen to be taken up (cartilaginous
fish have a parallel system which only
allows 50% uptake)

Fish gills

Operculum

Skin flap over the gills

Protects gills

Directs flow of water

Fish Gills

Counter current system

Water flows against the direction of blood

Means there is always a concentration gradient

Blood can be more oxygenated at the gills than parallel system

The water with the lowest oxygen concentration is found adjacent to the most deoxygenated blood

Why will fish die if left for a long time out of the water

In air gill filaments all stick together

SA for gas exchange is greatly reduced and so fish dies from lack of oxygen

Structure of gills in fish

Series of gills on each side of the head

Each gill arch is attached to two stacks of filaments

On the surface of each filament, there are rows of lamellae

The lamellae surface consists of a single layer of flattened cells that cover a vast network of capillaries

Ventilation mechanism in fish Inspiration of water

The ventilation mechanism in fish constantly pushes water over the surface of the gills and ensures they are constantly supplied with water rich in oxygen (maintaining the concentration gradient) When the fish open their mouth they lower the floor of the buccal cavity. This causes the volume inside the buccal cavity to increase, which causes a decrease in pressure within the cavity The pressure is higher outside the mouth of the fish and so water flows into the buccal cavity

Ventilation mechanism in fish expiration of water

The fish then raises the floor of the buccal cavity to close its mouth, increasing the pressure within the buccal cavity Water flows from the buccal cavity (high pressure) into the gill cavity (low pressure) As water enters pressure begins to build up in the gill cavity and causes the operculum (a flap of tissue covering the gills) to be forced open and water to exit the fish The operculum is pulled shut when the floor of the buccal cavity is lowered at the start of the next cycle

Function of gill rakers in fish

Gill rakers' primary function is to guard the fragile respiratory surfaces of the gill filaments from potential damage by particulates within the water taken into the buccal cavity during respiration

Gas exchange in insects spiracles

There are tiny holes called spiracles along the side of the insect. The spiracles are the openings of larger tubes called tracheae. The spiracles allow oxygen to diffuse in and carbon dioxide to diffuse out of the tracheae.

Gas exchange in insects tracheae and tracheoles

The spiracles are the openings of larger tubes called tracheae. The finest branches of the tubes are called tracheoles, these extend to the surface of nearly every cell At the cell surface gas is exchanged by diffusion across the moist epithelium that lines the terminal ends of the tracheal system.

Gas exchange in insects Mechanism of tracheal fluid

when oxygen demand build up, lactic acid concentrations increase in the tissues Water moves out of tracheoles to the tissues by osmosis Exposing more surface area for gas exchange

Extra adaptations for gas exchange in large insects

Mechanical ventilation of the tracheal system --> air is mechanically pumped in by muscles in abdomen and thorax, creates volume and pressure changes forcing air in and out collapsible trachea which act as air reservoirs --> increase volume of air moved through the gas exchange system

ventilation rate

tidal volume x breathes per minute

Methods to test capacity of lungs 3

peak flow meter vitalograph spirometer

Tidal volume

volume of air that moves in and out of lungs with each resting breath

Vital capacity

volume of air that can be breathed in with largest possible exhalation followed by largest possible inhalation

residual volume

volume of air left in lungs after you have exhaled as hard as possible

inspiratory and expiratory reserve volumes

maximum volume of air you can breathe in or out over and above normal inhalation or exhalation

total lung capacity

sum of vital capacity and residual volume

What is insect exoskeleton made out of

Chitin

Spirometer

measure lung volume and breathing pattern

Peak flow meter and vitalograph

peak flow meter- rate of expulsion of air form lungs fastest rate of air flow from lungs--> indication of lung function vitalograph- digital peak flow

Why is inhalation an active process but exhalation passive

for inhalation diaphragm contracts requires, ATP / energy for exhalation elastic recoil of lungs;