Chapter 40

Respiration: A Summary

AP BiologySpring 2011

The Basis of Gas Exchange Respiration: sum of physiological processes

that move oxygen gas from surrounds to all metabolically active tissues in animal body and carbon dioxide from tissues to outside

Relies on diffusion of gases down pressure gradients

Gases enter and leave internal environment by crossing moist respiratory surfaces

Factors Influencing Gas Exchange Surface to volume ratio

As animal grows, its surface area increases at a lesser rate than its volume

Makes diffusion of gases into interior a problem Animals either must have a small flattened body

that keeps internal cells close to surface or they must have specialized respiratory organs to move gases inward

Factors Influencing Gas Exchange Ventilation

Moving air or water past a respiratory surface keeps pressure gradient across the surface high and thus increases rate of gas exchange

Humans and frogs breathe in and out to move air in and out of the lungs

Fish and other animals that live in the water have mechanisms that move water across their respiratory surfaces

Factors Influencing Gas Exchange Respiratory Pigments

The main transport pigment is hemoglobin (are proteins)

Each molecule of hemoglobin binds 4 molecules of oxygen in the lungs (high concentration) and releases them in the tissues where oxygen is low

Myoglobin is another iron-containing respiratory, which is a good storage molecule

of oxygen because it has a higher affinity for oxygen

Invertebrate Respiration Integumentary exchange: gases diffuse

directly across a moist body surface Adequate for small animals such as sponges,

cnidarians, flatworms

Invertebrate Respiration Gills: highly folded, thin walled projections

from the body Enhance exchange rates between blood of aquatic

animals and their watery environment Snails and slugs live on land and water, have

lungs in addition to gills

Invertebrate Respiration

Tracheal System: consists of repeatedly branching, air-filled tubes reinforced with chitin Tubes start at tiny openings

(spiracles) across the integument

Tube branches, then branches again; fluid fills tips of finest branches which end next to body cells

Insects and spiders Spiders have book lungs in

addition to tracheal tubes to enhance respiration

Vertebrate Respiration The Gills of Fish

Gills contain filaments that hold many capillary beds where gases are exchanged with blood

In all fish, respiration occurs when water flows into the mouth, enters pharynx, then moves out of body through gill slits

Vertebrate Respiration The Gills of Fish

Water flows over the gills and blood circulates through them in opposing directions

Countercurrent flow: highly efficient in extracting oxygen from water, whose oxygen content is lower than air

Vertebrate Respiration Evolution of Paired Lungs

Lungs became increasingly important as aquatic tetrapods spent more time on land

Vertebrate Respiration Various animals use different mechanisms for

respiration Frogs in the larvae stage utilize gills and skin; as

adults they use paired lungs and skin for respiration

Amniotes have waterproof skin and no gills; they use well developed lungs for respiration

Human Respiratory System Lungs accomplish gas exchange via alveoli The respiratory system assists in sense of

smell and in speech It also helps return venous blood to the heart

and helps rid the body of excess heat and water

Controls over breathing adjust the body’s acid-base balance as well as the body’s temperature

Human Respiratory System: airways to lungs Air enters or

leaves the respiratory system through nasal cavities where hair and cilia filter dust and particles, blood vessels warm the air, and mucus moistens the air

Human Respiratory System: airways to lungs Air moves via this route:

Human Respiratory System: airways to lungs Vocal cord lies at entrance to larynx When air is exhaled through the glottis, the

folds of the cords vibrate to produce sound Under regulation by nerve commands to the

elastic ligaments that regulate the glottal opening

Human Respiratory System: airways to lungs

Human Respiratory System: paired lungs Human lungs are located in the thoracic cavity,

one on each side of the heart Rib cage encloses and protects lungs Each lung is covered with a plural membrane

Covers lung’s outer surface and line inside of the thoracic cavity

Inside lungs, respiratory bronchioles bear outpouchings of their walls called alveoli, which are usually clustered as alveolar sacs

Alveoli provide a tremendous surface area for gaseous exchange with the blood located in the dense capillary network surrounding each alveolar sac

Human Respiratory System

Human Respiratory System: muscles and respiration Diaphragm: sheet of smooth muscle beneath

the lungs Intercostal muscles: skeletal muscles

between ribs Diaphragm and intercostal muscles interact

and exchange the volume of the thoracic cavity breathing

Gas Exchange and Transport Exchanges at the respiratory membrane

The alveolar epithelium, the capillary epithelium, and their basement membranes form a respiratory membrane

Oxygen and carbon dioxide passively diffuse across the membrane in response to partial pressure gradients

Gas Exchange and Transport Oxygen transport

Blood cannot carry sufficient oxygen and carbon dioxide in dissolved form to satisfy the body’s demands Hemoglobin helps enhance its capacity

Gas Exchange and Transport Oxygen transport

Gas Exchange and Transport Oxygen transport

Hemoglobin gives up its oxygen in tissues where partial pressure of oxygen is low, blood is warmer, partial pressure of carbon dioxide is higher, and pH is lower All four conditions occur in tissues with high metabolism

Myoglobin is found in cardiac muscle and some skeletal muscles Helps to store oxygen

Gas Exchange and Transport

Carbon Dioxide transport Because carbon

dioxide is higher in body tissues, it diffuses into the blood

Ten percent is dissolved in plasma

Thirty percent binds with hemoglobin to form carbaminohemoglobin

Sixty percent is in bicarbonate form

Gas Exchange and Transport Carbon Dioxide exchange

Bicarbonate and carbonic acid formation is enhanced by the enzyme carbonic anhydrase, which is located in the red blood cells

Hemoglobin buffers these reactions, keeping the blood from becoming too acidic

Gas Exchange and Transport Carbon monoxide threat

Hemoglobin has a higher affinity for carbon monoxide than oxygen

Carbon monoxide prevents proper oxygen transport causing carbon monoxide poisoning

Cyclic Reversals in Air Pressure Gradients The Respiratory Cycle

In inhalation, diaphragm contracts and flattens Muscles lift rib cage upward and outward Chest cavity volume increases Internal pressure decresaes Air rushes in

Cyclic Reversals in Air Pressure Gradients The Respiratory Cycle

In exhalation The actions in inhalation are reversed Elastic lung tissue recoils passivly

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Cyclic Reversals in Air Pressure Gradients The Respiratory Cycle

Pressure gradients between air inside and outside respiratory tact change in each respiratory cycle of inhalation and exhalation

Exhalation is passive when you are quietly breathing; it is active and energy requiring when exercising with the need to expel more air

The Heimlich maneuver forces air out of lungs into the trachea and can dislodge the food, allowing victim to resume breathing

Cyclic Reversals in Air Pressure Gradients Respiratory Volumes

The maximum volume that the lungs can hold is the vital capacity Vital capacity is 5.7 liters in men and 4.2 liters in

females Tidal volume: the volume of air flowing in and

out of the lungs during one respiratory cycle Tidal volume is about 0.5 liters

Cyclic Reversals in Air Pressure Gradients Control of Breathing

Respiratory centers in the brain control the rate and depth of breathing

When activity levels increase, chemoreceptors sense changes in the blood pH and signal the respiratory center to alter breathing levels

Reflexes, such as swelling or coughing, and commands from the sympathetic nerves alter breathing patters

Control of Breathing

Respiratory Diseases and Disorders Interrupted breathing

Sleep apnea, SIDS Infections

TB, pneumonia Bronchitis, Emphysema Smoking (cigarettes, marijunana)

High Climbers and Deep Divers Explain what occurs to those who are at high

altitudes and those who deep-sea dive in terms of respiration

Review http://www.youtube.com/watch?v=HiT621PrrO

0 http://www.youtube.com/watch?v=TaAvhG2SI

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