15: Gas Exchange in Multi-Celled Animals Flashcards
Module 3, Lesson 4
In ____, gases diffuse directly in and out of the organism, so there is no need for a respiratory system.
Single-celled organisms
In ____, gases diffuse across the skin in highly vascular areas, which helps to supplement the action of the lungs.
Amphibians
____ use papillae to increase the surface area available for gas exchange.
Echinoderms
____ respire via extensive tracheal systems.
Insects
____ use gills for gas exchange.
Fish
In ____, an extensive system of alveoli in the lungs is used for gas exchange.
Mammals
True or false:
Gas exchange always takes place by diffusion across a plasma membrane.
True
____ are surrounded by water, so gas exchange is aqueous.
Plasma membranes
In terrestrial animals, respiratory structures are covered by…
A thin film of water
____ is a passive process dependent on concentration gradients.
Diffusion
The rate of diffusion is governed by…
Fick’s Law of Diffusion
According to Fick’s Law of Diffusion, the rate of diffusion is directly proportional to…
- The pressure/concentration difference
- The area over which diffusion occurs
According to Fick’s Law of Diffusion, the rate of diffusion is inversely proportional to…
The distance over which diffusion occurs
List the quantities involved in the equation for Fick’s Law of Diffusion.
- Pressure difference
- Area
- Distance
- Diffusion constant
How do evolutionary changes optimize the rate of diffusion?
(three ways)
- Increase surface area
- Decrease distance
- Increase concentration gradients
____ are specialized extensions of tissue that project into water to absorb oxygen.
Gills
Gills maximize ____ to extract as much oxygen as possible.
Surface area
____ are easily damaged and must be constantly moved to be in contact with oxygen-rich freshwater.
External gills
Bony fishes have ____, which are located between the buccal cavity and the opercular cavities.
Internal gills
Internal gills are covered by ____ for protection.
Operculum
The two ____ function as pumps, expanding to move water through the gills and out through the operculum.
Opercular cavities
Gills in bony fishes maximize diffusion rate by increasing the…
Pressure gradient
Gills have thin, membranous ____ that project into the water.
Lamellae
____ flow occurs when water and blood flow in opposite directions.
Countercurrent
____ ensures that the oxygen concentration in water is always higher than in the blood.
Countercurrent flow
Countercurrent flow increases oxygenation by…
Maximizing the oxygen gradient
Using countercurrent flow, up to ____% oxygenation can be achieved.
85
True or false:
Fish gills are the most efficient respiratory organs.
True
Why are gills poorly suited to a terrestrial environment?
(two reasons)
- Air is less supportive than water
- High surface area results in excess water loss
In ____, lungs are sac-like outpouchings of the gut with less surface area than other terrestrial animals.
Amphibians
Internal airways can remain open for gas exchange even on land because…
The body provides support
Amphibians use ____ breathing.
Positive pressure
In ____, air is forced into the lungs by filling the buccal cavity with air, closing the mouth, and squeezing the buccal cavity.
Positive pressure breathing
Most vertebrates, including humans, use ____ breathing.
Negative pressure
Bird lungs have one-directional airflow though tiny air vessels called….
Parabronchi
In bird lungs, gas exchange occurs in the…
Parabronchi
Bird lungs use ____ to ensure that old and new air do not mix in the lungs.
Anterior and posterior air sacs
In bird respiratory systems, the ____ hold newly-inhaled air.
Posterior sacs
In bird respiratory systems, the ____ are filled with air leaving the lungs.
Anterior sacs
True or false:
Birds have the least efficient respiratory system of all terrestrial vertebrates.
False
Theirs is the most efficient, enabling them to be active at high altitudes
List, in order, the structures that air passes through in the human respiratory system.
(seven)
- Nasal or oral cavity
- Pharynx
- Larynx
- Trachea
- Bronchi
- Bronchioles
- Alveoli
In humans, air that enters through the nasal cavity is filtered by ____ on the surface of the nasal epithelium.
Cilia
In humans, the airway and the food passageway cross in the…
Pharynx
The ____ contains the vocal cords.
Larynx
The passageway between the vocal cords is called the…
Glottis
The trachea is supported by c-shaped rings of ____ which are always open.
Cartilage
The trachea splits into two ____, and one enters each lung.
Bronchi
Bronchi branch into…
Bronchioles
Bronchioles terminate in small air sacs called…
Alveoli
The ____ provided by the millions of alveoli increases the rate of oxygen diffusion.
Surface area
True or false:
Alveoli and capillaries are both only one cell layer thick.
True
Alveoli are covered by a network of ____, which are the gas exchange areas in the lungs.
Capillaries
In humans, the heart and lungs are located in the…
Thoracic cavity
Epithelial cells that line the trachea, bronchi, and bronchioles secrete….
Mucus
The role of mucus is to…
Trap debris in inhaled air
The trachea and bronchi contain ____, which beath rhythmically to move mucus upwards through the airway.
Cilia
The action of the cilia in the trachea and bronchi is sometimes called a…
“mucus elevator”
The ____ is covered in a thin film of water and a surfactant to reduce surface tension.
Alveolar surface
____ engulf any particles that make it into the alveoli.
Alveolar macrophages
At sea level, the total air pressure is…
760 mm Hg
(1 atm)
____ are based on the percentage of a particular gas in dry air.
Partial pressures
The partial pressures of gases are responsible for creating a ____ in the lungs.
Pressure gradient
True or false:
The concentration of oxygen in the air decreases at higher altitudes.
False
Concentration remains the same, but partial pressure decreases.
Humans cannot survive above 6,000 meters because the ____ of oxygen is half what it is at sea level.
Partial pressure
The difference in oxygen partial pressure between the alveoli and the blood creates a gradient that favors…
Movement of oxygen into the blood
The difference in carbon dioxide partial pressure between the alveoli and the blood creates a gradient that favors…
Movement of carbon dioxide out of the blood
After oxygen diffuses into the capillaries, its partial pressure in the blood is about…
100 mm Hg
In ____, the partial pressure of oxygen is higher in the blood than in the tissues.
Peripheral tissues
In peripheral tissues, the partial pressures of oxygen and carbon dioxide favors…
Movement of oxygen into the extracellular fluid and the movement of carbon dioxide into the blood
Each breath is initiated by nerve impulses from the ____ in the medulla oblangata.
Respiratory control center
During inhalation, neurons stimulate the ____ and ____ to contract.
Diaphragm and external intercostal muscles
The ____ is a sheet of skeletal muscle that separates the thoracic and abdominal cavities.
Diaphragm
When the diaphragm contracts, it…
Flattens
When the intercostal muscles contract, they…
Raise the ribcage
The contraction of the diaphragm and intercostal muscles results in a(n) ____ in the volume of the thoracic cavity.
Increase
During inhalation, the pressure in the lungs ____ to draw air in.
Decreases
During exhalation, the pressure in the lungs ____ to force air out.
Increases
When the diaphragm relaxes, it…
Becomes dome-shaped
When the intercostal muscles relax, they…
Lower the ribcage
The relaxation of the diaphragm and the intercostal muscles ____ the volume of the thoracic cavity.
Decreases
The diaphragm and intercostal muscles ____ during inhalation and ____ during exhalation.
Contract ; relax
Neurons in the medulla oblangata are sensitive to ____ and adjust breathing rate to maintain homeostasis.
The partial pressures of oxygen and carbon dioxide
An increase in CO2 levels in the blood triggers a(n) ____ in respiratory rate.
Increase
An increased level of CO2 in the blood ____ the pH of the blood.
Decreases
A decrease in blood pH is detected by ____ in the aorta and carotid artery, which send signals to the respiratory center in the medulla.
Chemosensitive neurons
Respiration rate is controlled using a…
Negative feeback loop
The respiratory condition ____ refers to any disorder that obstructs airflow long-term.
COPD
(chronic obstructive pulmonary disease)
____ is an intense constriction of the bronchi which makes breathing difficult.
Asthma
Asthma is primarily the result of ____ that trigger histamine release.
Allergens
____ is chronic shortness of breath caused by breakdown of alveolar walls and fusion of alveoli via fibrous tissue.
Emphysema
Emphysema results when less surface area is available for gas exchange, which is linked to…
Inhalation of toxins
____ is inflammation of the bronchial lining which may be acute or chronic.
Bronchitis
Acute bronchitis often results from….
Infection
Chronic bronchitis often results from…
Smoking
____ is an agressive disease that affects the epithelial lining of the respiratory system and is usually caused by smoking.
Lung cancer
Most oxygen transported by the blood is bound to ____ in red blood cells.
Hemoglobin
____ is the primary oxygen-carrying protein in all vertebrates and many invertebrates.
Hemoglobin
Hemoglobin is made up of four polypeptide chains with four…
Heme groups
A(n) ____ is located at the center of each heme group.
Iron atom
Each iron atom can bind one molecule of oxygen, resulting in ____ molecule(s) bound per hemoglobin.
Four
Hemoglobin that is fully loaded with oxygen is called…
Oxyhemoglobin
Hemoglobin that has released some or all of its oxygen molecules is called…
Deoxyhemoglobin
Some invertebrates use ____ to transport oxygen instead of hemoglobin.
Hemocyanin
In hemocyanin, the oxygen-binding atom is…
Copper
Hemocyanin is a ____, located in the circulating hemolymph.
Free protein
An ____ is a graph that plots the partial pressure of oxygen in the blood against the percent oxygen saturation.
Oxyhemoglobin dissociation curve
In arteries, ____% of hemoglobin exists as oxyhemoglobin.
97%
In arteries, the oxygen saturation is ____ and the oxygen partial pressure is ____.
97% ; 100 mm Hg
In veins at rest, the oxygen saturation is about ____ and the oxygen partial pressure is ____.
75% ; 40 mm Hg
When the body is at rest, only about ____% of oxyhemoglobin releases its oxygen to the tissues.
22%
In veins during exercise, the oxygen saturation is about ____ and the oxygen partial pressure is ____.
35% ; 20 mm Hg
During periods of activity, about ____% of oxygen is released from the hemoglobin.
62%
The body maintains a large oxygen reserve that can supply oxygen to tissues for ____ if breathing is interrupted or the heart stops.
4-5 minutes
A second oxygen reserve exists in ____, the oxygen-binding protein found in muscle cells.
Myoglobin
Myoglobin is a single peptide chain with one heme group. This means it can bind ____ molecule(s) of oxygen.
One
True or false:
Myoglobin has greater affinity for oxygen than hemoglobin.
True
If hemoglobin releases all its oxygen, ____ can supply additional oxygen to the tissues.
Myoglobin
A decrease in pH ____ hemoglobin’s affinity for oxygen.
Decreases
A decrease in pH causes ____ oxygen to be released into the tissues.
More
Blood pH often decreases during exercise because of…
Higher metabolism and higher CO2 release
The ____ describes the effect of pH levels on hemoglobin’s oxygen affinity.
Bohr shift
Higher temperatures ____ hemoglobin’s oxygen affinity.
Decrease
Both higher temperatures and lower pH may occur during ____, causing hemoglobin to unload more of its oxygen.
Exercise
List the three ways that carbon dioxide can be transported through the blood.
- Dissolved in plasma
- Bound to hemoglobin
- Diffused into red blood cells and converted into bicarbonate
True or false:
When carbon dioxide binds to hemoglobin, it binds to the iron atom.
False
It binds to the protein portion - thus it doesn’t compete with oxygen
The majority of carbon dioxide travels through the blood as…
Bicarbonate ions
Converting carbon dioxide to bicarbonate is important because it…
Removes large amounts of CO2 from the plasma, maintaining diffusion gradients
The major buffer (pH stabilizer) in the blood plasma is…
Bicarbonate
In the lungs, the lower CO2 partial pressure in the alveoli enables CO2 to…
Diffuse into the alveoli and leave the body
