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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
Yc2AOJ3
Yc2AOJ3
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
nM&feature=related
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