gas exchange 1

The atmosphere is a mix of gases, primarily made up of _____, followed by oxygen, carbon dioxide, and water vapor.

nitrogen

These gases are constantly cycling through the _____ and oxygen/carbon dioxide cycles.

carbon cycle; water cycle

Atmospheric pressure is the _____of a column of air over a standard unit of area.

weight

The weight of air pushing down on the Earth's surface creates_____ pressure.

air (or atmospheric)

At sea level, the standard air pressure is defined as_____ atm.

1

Air pressure is greater _____in the atmosphere, where more gas particles are present.

lower (closer to the ground)

Atmospheric pressure can be measured using a device called a _____.

barometer

A barometer typically uses a column of _____to measure pressure.

mercury (Hg)

At standard pressure, the mercury column in a barometer rises to a height of_____ mm.

760

Air pressure pushes mercury into a vacuum tube. The _____the air pressure, the higher the mercury rises.

greater

The total pressure exerted by the atmosphere can be broken down into _____pressures.

partial

Partial pressure is based on the________of each gas in the atmosphere.

percentage (or proportion)

For example, if nitrogen makes up ~70% of air, then nitrogen’s partial pressure is about _____ mm Hg at sea level.

532 (or 70% of 760)

While the percentage of gases in the atmosphere stays the same, their partial pressures change with _____ .

altitude

At higher elevations, air pressure is _____ , which makes it harder to breathe.

lower

Molecules move from an area of high concentration to low concentration through a process called _____.

diffusion

Diffusion is a _____process, meaning it does not require energy input.

passive

The greater the difference in concentration or pressure between two points, the_____ the rate of diffusion.

faster

At higher altitudes, it is harder to breathe because the partial pressure of oxygen is much_____ than at sea level.

lower

The partial pressure difference between air and blood is smaller at high altitudes, so oxygen enters the blood more _____ .

slowly

One reason diffusion slows at high altitudes is that the_____ between air and blood pO₂ is reduced.

pressure differential

The rate of diffusion depends on factors like distance, area, pressure gradient, and _____of the molecule.

size

The _____the membrane thickness, the slower the rate of diffusion.

greater

The larger the surface area available for gas transfer, the_____ the rate of diffusion.

faster

The thinner the diffusion surface (less thickness), the _____the rate of gas transfer.

faster

Gas diffusion is enhanced when the gas has _____solubility and _____molecular weight.

higher; lower

The mathematical model that calculates diffusion rate is called_____ Law.

Fick’s

Primitive animals that are only a few cell layers thick can rely on_____ of gases across membranes.

passive diffusion

In simple animals, no blood vessels or carriers are needed because_____ can freely diffuse in and_____ out.

oxygen; carbon dioxide

Some _____have capillaries close to the skin and permeable skin tissue, allowing them to exchange gases directly across their skin.

amphibians

Amphibians with permeable skin and surface capillaries can remain submerged for extended periods even though they normally breathe with _____.

lungs

A limitation of diffusion is that as_____ increases, diffusion becomes non-viable due to obstructed gas movement.

body thickness

Insects do not have _____, but instead rely on a system of air tubes called_____ for gas exchange.

lungs; trachea

The small holes in an insect's exoskeleton that allow air to enter the body are called _____.

spiracles

Spiracles connect to chitin-lined tubes called _____, which branch into finer tubes called_____ .

tracheae; tracheoles

The _____contain a small volume of liquid that improves gas exchange at the cellular level.

tracheoles

Spiracles are controlled by_____ valves, allowing the insect to open or close them to conserve water.

muscular

Insects use their tracheal system to deliver oxygen directly to their _____without needing a circulatory system to carry gases.

tissues

Larger insects can enhance gas exchange by expanding and contracting parts of their_____ , creating a sort of pump that increases circulation.

exoskeleton

The accordion-like motion of the exoskeleton in large insects acts like a_____ to assist in air movement and gas exchange.

pump

Gills function like a_____ to maximize surface area for gas exchange.

radiator

The goal of gill function is to maximize the difference in_____ of oxygen between water and blood.

partial pressure

_____refers to how much water is flowing over the gills from the outside.

Ventilation

_____refers to how much blood is being pumped through the blood vessels within the gills.

Perfusion

Without sufficient ventilation and perfusion, the gradient of gases will even out and _____transfer efficiency.

decrease

Gills contain structures called_____ , which are stacked wafers of tissue that maximize surface area.

lamellae

Sea water flows across the_____ , exposing lamellae on both sides to external oxygen.

gill filaments

The blood in the gill lamellae flows in the _____direction of the water.

opposite (countercurrent)

Countercurrent exchange ensures that O₂ in water is always_____ than in blood, enabling constant gas exchange.

higher

The epithelial tissue in the gill capillaries is _____enough to enable efficient gas diffusion.

thin

Modified limbs in horseshoe crabs that are used for gas exchange are called_____ .

book gills

If internal, these flap-like gas exchange structures are called _____ .

book lungs

Each book gill or book lung contains about _____ thin lamellae to increase surface area.

100

Movements of the book gills help propel _____ through the lamellae while also circulating seawater around them.

hemolymph

Book gills and book lungs function similarly to fish gills by maximizing _____from the environment.

oxygen extraction

Terrestrial vertebrates rely on internal respiratory organs called_____ .

lungs

An advantage of breathing air is that it has a higher_____ rate compared to water.

diffusion

Air contains a _____oxygen content than water.

greater

Ventilating air requires _____energy than ventilating water.

less

A major disadvantage of breathing air is the loss of_____ due to evaporation across moist surfaces.

water

To reduce water loss, terrestrial animals have _____respiratory structures like lungs.

internalized

Air enters through the _____or_____ cavity.

nasal; oral

The _____is a cartilage-ringed tube that prevents airway collapse.

trachea

The trachea splits into two tubes called the left and right_____ .

bronchi

Bronchi branch repeatedly into smaller tubes called_____ .

bronchioles

Bronchioles are lined with _____muscle, capable of contraction.

smooth

Bronchioles terminate in clusters of air-filled sacs called _____.

alveoli

Alveoli are covered with a dense network of _____to maximize gas exchange.

capillaries

The alveoli consist of two types of cells: _____and _____.

Type I; Type II

The alveolar cell type responsible for gas exchange is the_____ cell.

Type I

The alveolar cell type that repairs other cells and secretes surfactant is the_____ cell.

Type II

_____ is a gel-like mixture of proteins and amphipathic lipids secreted by Type II cells.

Surfactant

Surfactant helps reduce_____ tension in the alveolar sacs, aiding in gas exchange.

surface

The thickening of alveolar tissue that decreases gas exchange efficiency is called _____.

pulmonary fibrosis

In _____, alveoli fill with fluid, reducing the amount of air that can interact with the alveolar surface.

cystic fibrosis

_____is a lung infection where alveoli fill with fluid, preventing proper gas exchange.

pneumonia

_____ involves the destruction of alveolar sacs, reducing surface area and capillary interaction.

emphysema

_____is a condition where bronchioles contract excessively, narrowing the airways.

asthma

Humans breathe by creating a vacuum inside the lungs in a process called _____breathing.

negative pressure

In negative pressure breathing, air is drawn in due to a drop in _____inside the lungs.

pressure

The primary muscle responsible for breathing is the_____ .

diaphragm

During inhalation, the diaphragm_____ and the rib cage expands, increasing lung volume.

contracts

The increase in lung volume during inhalation creates a _____ that pulls air in.

vacuum (or negative pressure)

During exhalation, the diaphragm and rib cage_____ , causing lung volume to decrease.

relax

The decrease in lung volume during exhalation creates_____ pressure, forcing air out.

positive

Air taken in through inhalation is at _____temperature and _____ humidity.

ambient; ambient

Air inside the lungs must be warmed to_____ temperature and brought to_____ humidity.

body; 100%

Each exhalation leads to a loss of _____ and_____ .

heat; moisture

The approximate daily water loss from breathing is about _____cup.

1

The brain region that sets the basic rhythm for breathing is the _____ .

medulla

The cerebral cortex can_____ influence breathing rate, but the medulla controls _____regulation.

consciously; automatic

Breathing rate is influenced by negative feedback from _____receptors in the aorta and carotid arteries.

chemoreceptors

Stretch receptors in the _____ also help regulate breathing rate.

bronchioles

The two types of ventilation patterns in vertebrates are_____ breathing and _____flow.

tidal; unidirectional

Tidal breathing, as seen in mammals, involves air entering and exiting through the_____ path.

same

Birds and crocodiles use_____ airflow, in which air flows in _____direction(s) through the respiratory system.

unidirectional; one

In unidirectional flow, air first enters the _____air sacs before flowing into the lungs.

posterior

On exhalation in birds and crocodiles, air moves from the air sacs into the_____ .

lungs

On the next inhalation, air moves from the lungs to the air sacs, and is then exhaled out.

anterior

Birds and crocodiles always have _____in their lungs, which makes gas exchange more efficient.

air