Chapter 46: The Respiratory System

What is external (physiological) respiration?

Process of inhaling oxygen from the air or water and exhaling carbon dioxide

What is internal (cellular) respiration?

Exchange of gases between blood and tissue; occurs in mitochondria; leads to the production of ATP.

List 3 functions of the respiratory system.

Providing oxygen to the blood; eliminating carbon dioxide from the blood; forming speech sounds; defending against inhaled microbes; traps and dissolves blood clots; influences arterial concentrations of chemical messengers.

True or False: Thick epithelium facilitates simple diffusion

False.

What two main properties facilitate simple diffusion?

THIN epithelium at the respiratory surface and Large surface area.

Choose the statement that is false about the rate of diffusion: a) Increases as surface area increases b) Increases as temperature increases c) Increases with larger concentration gradients d) Increases as the thickness of the membrane increases

d) Increases as the thickness of the membrane increases. False - a thicker membrane has a slower rate of diffusion. The thinner the membrane, the faster the rate.

Match the animal with its respiratory system: human

Lungs.

Match the animal with its respiratory system: nudibranch

External gills.

Match the animal with its respiratory system: insect

Tracheal system; Extended body surface.

Match the animal with its respiratory system: cuttlefish

Internal gills.

Match the animal with its respiratory system: flatworm

Extended body surface.

Match the animal with its respiratory system: bony fish

Internal gills.

Match the animal with its respiratory system: amphibian

Positive pressure breathing; Lungs.

Match the animal with its respiratory system: bird

Parabronchi; Lungs.

Ventilation

Flow of the respiratory medium (air or water) over the external side of the respiratory surface.

Perfusion

Flow of blood to the internal side of the respiratory surface.

What are some adaptations in animals with lungs to increase the respiratory surface area?

Branched tubes, folds, or pockets Ex: bronchioles, alveoli.

Match the medium to 'Holds less oxygen'

water.

Match the medium to 'Gas molecules diffuse faster in this medium'

air.

Match the medium to 'Require more energy to move this medium over a respiratory surface'

water.

Match the medium to 'High oxygen content'

air.

Bony fish have ___ gills covered by ____

internal gills covered by opercula.

____ gills must be immersed in water to keep from collapsing or drying

External gills.

Water must be continuously brought into ____ gills

internal gills.

Animals with ____ gills use countercurrent exchange.

internal gills.

In countercurrent exchange, water flows ____ to the flow of blood under the respiratory surface.

opposite.

True or false: In countercurrent exchange, the water is more highly oxygenated than the blood.

True, this forces oxygen to diffuse into the blood.

Insects breathe through air conducting tubes called _.

Tracheae.

The finest branches of the trachea are called _. They form the __.

Tracheoles; Respiratory surface.

What do internal air sacs act as in insects?

Air reservoirs.

What are some characteristics of positive pressure breathing?

Gulping motion that forces air into the lungs; Occurs in amphibians.

What are some characteristics of negative pressure breathing?

Muscular contractions that expands the lungs; Lowering the pressure and causing air to be pulled inward. Occurs in reptiles and mammals.

___ is attached to the surface of the lungs.

Visceral pleura.

___ lines the cavity itself.

Parietal pleura.

Tidal Volume

The volume of air entering and leaving the lung during inhalation and exhalation.

Vital Capacity

The maximum tidal volume of an individual.

Residual Volume

The amount of air that remains in the lungs after forceful exhalation.

Control Centers for respiration are located in the _ and .

Pons and Medulla Oblongata (contains DRG and VRG).

Reduced O2 concentration causes (local control):

Arteriole walls to contract giving blood more time to pick up O2.

Rising blood O2 concentration causes (local control):

Arteriole walls to relax, increasing the rate of blood flow through capillaries.

Partial pressure

The proportion of a gas present in a mixture or the pressure of an individual gas present in a mixture.

What are the two factors that reduce the carrying capacity of Hemoglobin?

Reduced P(O2) in tissues; Reduced pH in body tissues (Bohr’s effect).

Define physiological respiration.

The process whereby animals exchange air with the surroundings.

Define cellular respiration.

Cellular and mitochondrial oxidative reactions for the generation of ATP (OXPHOS).

What is the role of the respiratory medium?

Facilitates the exchange of gases; the source of oxygen and sink for carbon dioxide.

What type of animals use air as the respiratory medium?

Terrestrial animals.

What type of organisms use water as the respiratory medium?

Aquatic organisms.

How does the exchange of oxygen and carbon dioxide occur across the respiratory surface?

By simple diffusion.

What are the two key properties of a respiratory surface?

It has to be thin (contains simple epithelium) and possess a large surface area.

Rate of diffusion is inversely proportional to:

The square of the distance over which diffusion occurs. Requires a thin surface for diffusion to happen.

Rate of diffusion is directly proportional to:

The surface area across which diffusion occurs. The larger the surface area, the higher the degree of diffusion.

Rate of diffusion gets higher with:

Larger concentration gradients – gas molecules move from a region of higher concentration to a region of lower concentration.

Define gills.

Evagination of the body surface.

List three advantages of gills.

Helps animals to thrive in diverse habitats; efficient means of gas exchange than the skin; large surface area with tiny projections (gill lamellae); rich blood supply; countercurrent flow.

What are external gills?

Gills that are not protected by external coverings; extend out of the body surface directly in contact with water.

What are two risks associated with external gills?

High risk of mechanical damage and collapsing; must be kept wet all the time.

What are internal gills?

Gills located within body coverings protected from mechanical damage and drying.

How do clams and oysters bring water to their internal gills?

By beating ciliary movement.

How do cuttlefish bring water across their internal gills?

Use muscle contractions to pump water.

What is the operculum in bony fishes?

A gill chamber covering.

What are two functions of the operculum?

Help ventilate the gills; water enters the mouth→flows over the gills→ exits through the gill covers.

What is the primary benefit of countercurrent exchange?

Maximize gas exchange.

Countercurrent exchange uses what type of water flow over gills?

One-way flow.

In countercurrent exchange, water moves in what direction to the flow of blood?

In an opposite direction, thus establishing a favorable concentration gradient.

What are tracheae in insects?

Outer epidermal invaginations reinforced by chitinous exoskeleton.

How does air enter and exit the tracheal system?

Through openings called spiracles aided by alternating compression and expansion of the body.

What are tracheoles?

Finely branched ends of tracheae in contact with body cells.

What is the function of internal air sacs in insects?

Act as air reservoirs.

When do amphibians typically use their skin for respiration?

When in aquatic environments.

When do amphibians typically use their lungs for respiration?

In terrestrial habitats.

Describe positive pressure breathing in frogs.

A gulping motion that forces air into the lungs.

Lungs evolved as an adaptation for what environment?

Terrestrial environments.

In lung fishes, lungs evolved as an adaptation to live in what type of environments?

Oxygen-deprived environments.

How many pairs of air sacs do birds have in addition to their lungs?

Nine pairs.

What are parabronchi in bird lungs?

Fine tubes where a capillary network flows in a countercurrent pattern.

How many cycles of inhalation and exhalation are required to move a specific column of air through bird lungs?

Two cycles.

What is the primary function of lungs in mammals?

To provide oxygen to the blood.

Where are mammalian lungs located?

In the pleural cavity lined by pleural membrane.

What is the parietal pleura?

The layer that lines the pleural cavity.

What is the visceral pleura?

The layer that lines the lung itself.

What is the interpleural space and what does it contain?

The space between the pleural layers; contains pleural fluid which protects against friction and helps in cohesion.

What is the diaphragm?

A dome-shaped muscle situated below the lungs that separates the thoracic cavity from the abdominal cavity.

Describe the texture of mammalian lungs.

Spongy and elastic.

What is the lung parenchyma responsible for?

Gas exchange; includes the alveoli, alveolar ducts, and bronchioles.

What type of epithelium lines the alveoli?

Simple squamous epithelium.

What are Type I pneumocytes responsible for?

Gas exchange.

What are Type II pneumocytes responsible for?

The production of surfactant that maintains lung compliance and prevents lung collapse.

How many lobes does the right lung have?

Three, separated by an oblique and a horizontal fissure.

How many lobes does the left lung have?

Two, separated by a single oblique fissure.

What is the pathway of air during breathing?

Nostrils → Pharynx → Larynx → Trachea → Bronchi → Bronchioles → Alveoli.

What structural feature characterizes the larynx, trachea, and large bronchi?

Cartilaginous rings.

What structural feature characterizes smaller bronchi and bronchioles?

Smooth muscle.

What are the major muscles involved in inspiration?

Diaphragm and external intercostal muscles.

Air moves from a region of higher _ to a region of lower _.

Partial pressure to a region of lower partial pressure.

What is the barometric air pressure (atmospheric pressure) at sea level?

760 mmHg.

What happens to the diaphragm and external intercostal muscles during normal inspiration?

They contract, causing the rib cage to pull up and out, increasing intrathoracic volume.

According to Boyle's law, as volume increases, pressure ___.

Decreases, so air rushes in.

What muscles are involved in forced inspiration?

Accessory respiratory muscles contract and help the primary inspiratory muscles.

What happens to the diaphragm and external intercostal muscles during normal expiration?

They relax.

What expels air out of the respiratory tract during normal expiration?

Elastic recoiling of lungs.