Chapter 46 Gas exchange

What is the advantages ventilating in the air

There is a 30x higher concentration of air then in water
O2 diffuse faster
Air is less viscous than water

How is air being less viscous than water a benefit

we require less energy to ventilate

What is the disadvantage of using air to breather rather than water

Requires secretion to keep surface moist and allow for gas exchange

What is the requirement of gases to go through gas exchange

Gases must be soluable in liquids (in all respiratory surfaces (gills, book lungs, lungs, etc.)

What is the advantage of using water to breathe

The surface of the repository tract is always wet

What is the disadvantages of using water to breathe

Water and ion movement
Gas solubility
Gas concentration

How is Water and ion movement a disadvantage

There are things dissolved in the liquid which impacts how much things can dissolve in water, this also impacts tonicity and osmotic pressure

How is Gas solubility a disadvantage

There is more CO2 than O2 in the water

How is Gas concentration a disadvantage in water breathing

There is less O2 around

What is true about water solubility with oxygen and temperature

The warmer the water the less oxygen is in that water

What is positive pressure ventillation

forcing water/air across respiratory surface

Where do we see positive pressure

frogs, toads, and fishes

What animals has lost it’s reparatory muscles and uses ram ventilation

sharks and tuna

What is ram ventilation

swimming with an open mouth to rub water across gills

What is negative pressure ventilation

Increasing in volume to drop pressure and allow air to come in.

What animals have negative pressure ventilation

animals with a diaphragm (all mammals)

How do small animals with thin skin breathe

they breathe through the surface

What is the requirement for a small animal

animals have a high surface area:volume ratio and a low metabolic rat

What is the requirement for all respiratory surfaces

moist surface (all)
blood supply (most)
ventilation (most)

What kind of animals breathe through their surface

nudibranch mollusks, most annelids (earthworms), and amphibians

What is important to know about amphibians breathing

In the surface lungs/gills will be their way of breathing
In water they breathe through their skin

these are toads/frogs

What is the spiracel

opening of the body surface to the outside to allow air to get into trachea, seen in insects

What is the tracheal tube

air passage way you can find this in insects

What is the tracheole tube

a branched segment of trachea and it’s fluid filled and contacts the alveoli cells

How do we, insects, and some other arthropods ventilate

Movement: Just by moving it causes pressure change to move air into tubes
Muscle Contraction: Changing the diameter of tubules
Mini explosions: A build up of bicarbonate which results in mini explosions to cause a vacuum

What are gills and lungs made up of

epithelium

What are the 3 different type of gills

External
Internal
dermal

What has external gills

some annelids (polychaeta)

What has internal gills

aquatic mollusks, crustaceans, fishes, and amphibians

What has dermal gills

echinoderm

What is the characteristics of epithelium

it’s moist and thin

Outer gills are exposed too…

water

inner gills are exposed too…

blood vessels

What are dermal gills

The dermis is extending upward from the body surface, this is not epithelium but it’s covered via epithelium

What is the disadventage of going concurrent vs counter

there is an equilibrium in concurrent

How does lung form

invagination

Do fishes have internal or external gills

internal, they have an operculum

What is counter current exchange

When blood flows in opposite direction of another mediym
(seen in fish)

What is the benefit of counter current exchange in gills

maximize o2 concentration between blood

When do we humans have the highest concentration of oxygen in the blood

Exactly after gas exchange happens at the site of gas exchange

How is countercurrent set up in fishes

their gills are thin and rich in capillaries,

How is the air move in birds when breathing

it’s a one way flow through the lungs and associated structures

How is the movement of air in humans

mixing of incoming and outgoing air

How does the lung surface areas of an animal with very low activity look like

it has low surface area, like a salamander

How does surface areas of an animal with very high activity look like

there is multiple invagination/air sacs, to increase number of gas exchange

What are the air sacs of birds

very large invaginations of the lungs

What are the three/four important structures of the bird respiratory structure

posterior/anterior lungs, lungs, parabronchi

What is an air sacs

extension of lung, they contract and relax to force air in and out

What is parabronchi

equivlent of aveoli they hold the air for gas exchange to happen within the capiallries

Where does gas exchange happen in birds

parabronuhi

What is the flow of birds

First inhalation→first exhalation→second inhalation→second inhalation
(2 cycles of breathing)

What is first inspiration

Air goes through trachea→posterior sacs and partly into the lungs

What is first exhalation

posterior sacs→lungs

What is secondary inhalation

they breathe in air which goes to the posterior sac, and the air they already have goes to the anterior sacs

What is the secondary exhalation

the air which has been moved all around is breathed out and the air they breathed in again goes to the lungs from the posterior sac

How is current in birds (blood flow to air flow)

Crosscurrent exchange

What is crosscurrent exchange

There is a large vessel which branches out and each branches cross over the medium

What is the ranking of the types of currents (based on oxygen concentration after we do gas change)

1 Counter current
2 Cross curent
3 Con current

What is the flow of air in humans

Nostrails→nasal cavity→ pharynx→larynx→trachea→bronchial→bronchioles→aveoli

Where does gas exchange happens in humans

In the aveoli

What is the conducting zone in humans made up of

trachea→bronchial tree→bronchioles→terminal bronchioles

What is the respiratory zone in humans made up of

Respiratory bronchioles→avlevoli

What is conducting zone

just moving air, NO EXCHANGE POSSIBLE

What is respiratory zone

where gas exchange happens

Thoracic cavity is a closed or open space

closed

What is pleural cavity

fluid filled sac where lungs reside

What is the parietal pleural membrane

the membrane which wraps the walls of the thoracic cavity

What is the visceral pleural membrane

a SEROUS membrane which surrounds the lungs, it decreases friction when breathing

What is an alveolus made up of

simple squamous epithelium

What proportionality should I remember

👆 volume= 👇 pressure
(increase in volume, decreases pressure)

What kind of cells are there in alveoli (cells involved in gas exchange)

type 1, type 2, and macrophage

What does type 1 cells do

gas exchange

What does type 2 cells do

it produces and secretes surfactants

What do macrophages do

clear the air of any invaders via phagocytosis

All gases must cross…

lung surface: (((respiratory membrane→ epithelium of type 1 cell)))→interstitum:(((basement membrane of blood vessel→ and then endothelial cells of capillary)))

What are the pressures involved in ventilation

atmospheric pressure, intrapleural pressure, transpulmonary pressure, and intraalveolar pressure

What is intrapleural pressure

Pressure within the pleural cavity

What is transpulmonary pressure

the pressure difference from pleural sac and pressure within the lungs (alveoli)

What is intraalveolar pressure

The pressure within the alveoli pocket.

What is the pressure that inflates the lung

increases transpulmonary pressure

What is the mechanism of inspiration

Diaphragm contracts and thoracic cavity increases and intrapleural pressure decreases, which increases transpulmonary pressure and the lung inflate, and intraalvelolar pressure drops below atm so air enter lungs

What are the properties of lung

elasticity, distensibility, and compliance,

What is distensiability

increase with in width

What is elasticity

able to return to original size after being inflated

What is compliance

how easily a lungs can increase it’s volume (stretch) due to pressure

What is compliance equation

∆V/∆P
but as volume increases we need more and more pressure to increase the volume by the same unit (not linear)

What happens when lungs are to compliance

pressure increases volume of the lungs a lot, so it’s easy to inflate and hard to deflate

What happens when lungs are not compliate

it’s easy to deflate and hard to inflate

As we get older what lung property changes

decrease in elasticity, so we get lower compliance

What does surfactant do

Add’s surfactant between water molecule, because without surfactant the alveoli will collapse due to high water tension (makes it hard in inflate)

(water molecules pull each other in=collapse)

what is surfactant made up of

a protein and lipid mixture

Lung capacity chart (Memorize it)

total lung capacity= 6,000
the rest memorize okay

What is dalton’s law of partial pressure

total pressure is the sum of each gas pressure

P_total=P₁+P₂+P₃

What is Fick’s law of diffusion

Amount of gas that diffuses is due to:
partial pressure (NOT CONCENTRATION)
total surface area

What is tidal volume

Amount of air move into and out of the lungs with normal resting breathing

What is expiratory reserve volume

how much we can breathe out AFTER tidal volume

What is inspiratory reserve volume

how much we can breathe in AFTER tidal volume

What is residual volume

volume of air remaining in lungs at the end of maximal expiration,
(it’s always there (except death))

What is vital capacity

The maximum amount of air a person can exhale and inhale

What is functional residual capacity

the amount of air we start with during tidal volume