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Mammalian Respiratory Systems - TeacherWeb-ag


									       UNIT 12
Introduction, Digestive, Circulatory,
     and Respiratory Systems
     (Chapters 40, 41, and 42)
                                Stratified              Tightly
                                = multiple layers       packed

                                       = single layer

                                                        Connective Tissue
                                                          Sparse in
                                                          extracellular matrix
Ca, Mg, P

                                                         Collagen Fibers=
                                                         Nonelastic/tensil strength
                                                         Elastic Fibers =
                             Tendons = Muscle  Bone     Reticular Fiber =
              Holds organs
                             Ligaments = Bone  Bone     Joins to Tissues
              In place
                                    Nervous Tissue

                                                             Muscle Tissue
                                                                Long “Contracting” Cells/ Fibers

                                Heart Contraction
Voluntary Movements

                      Involuntary Activities
                      Walls of Digestive Tract, Bladder, Arteries, etc.
 Biofeedback Circuits
Negative Feedback =
The change in the variable being monitored triggers the
control mechanism to counteract further change in the same direction

                 1. Receptor (detects change)

                 2. Control Center
                 (processes information)

                                      3. Effector
Positive Feedback =
A change in a variable that triggers
mechanisms that amplify the change

                   Child Birth

   Pressure of baby’s head on Uterus Contractions 
   + Pressure  More Contractions
Bioenergetics of an Animal
                             Metabolic Rate = the sum of all the energy-requiring
                             biochemical reactions occurring over a given time interval

                                 “The amount of energy an animal uses per unit time”

                               Energy measured in:
                               calories (c)
                               kilocalories (kcal or C)

                                   Inverse relationship with size:
                                   Smaller = Higher Metabolic Rate
                                                Higher breathing rate and heart rate
                                                Eat more food per unit body mass

                                   Surface Area to Volume = Maintaining Temp
            Maximum Metabolic Rates
                                                                        Total Annual Energy Expenditures

                                                                        Energy Expenditures per Unit Mass

Basal Metabolic Rate (BMR) = Endotherm at Rest, Fasting, No Stress
Standard Metabolic Rate (SMR) = Ectotherm at Rest, Fasting, No Stress

   Male Human BMR = 1,600-1,800 kcal/day
   Female Human BMR = 1,300-1,500 kcal/day
                                           CHAPTER 41: ANIMAL NUTRITION

        Homeostatic Regulation
                                                                                                         “Essential Nutrients”

                                                                                                              Essential Amino Acids
                     Pancreas secretes Insulin

          Blood Glucose is High                           Insulin enhances the transport of glucose
                                                          into body cells and stimulates the liver and
                                                          muscle cells to store glucose as glycogen
                                                          = blood glucose level drops

       Glucagon promotes the
       breakdown of glycogen
       and the release of glucose
                                   Blood Glucose is Low
       into the blood
       = blood glucose level rises
                       Pancreas secretes Glucagon

                                                                                                            Essential Fatty Acids
                                                                                                         (Synthesize Most that are Needed)

Glucose energy surplus stored as Glycogen in Liver and Muscle Cells
Liver glycogen expended first, then fat glycogen, then muscle glycogen
Vitamins =
organic molecules
needed in small quantities
Minerals =
simple inorganic
molecules needed
in small quantities


Heterotrophic   Ingestion Adaptations   4 Stages of Food Processing
                -Suspension Feeders     -Ingestion
                -Substrate Feeders      -Digestion
                -Fluid Feeders              Enzymatic Hydrolysis
                -Bulk Feeders           -Absorption
                        Specialized Compartments
                              for Digestion
“Intracellular”             (Don’t Digest Yourself)
Sponges and
Heterotrophic Protist
= Food Vacuole


                                                                          Hydra (Cnidarian)
                                                                          Gastrovascular Cavity

                                             Complete Digestive Tract
                                             “Alimentary Canal”
                                             Specialized Compartments

                                                       Directional Flow
                           The Mammalian Digestive System
                                         Physical and Chemical Digestion

Salivary Amylase =                                                         Swallow Reflex
Hydrolyzes Starch
and Glycogen


                                                                             Bolus   Windpipe moves upward    Peristalsis
                                                                                     Glottis and Epiglottis
                                                                                     “Went down wrong pipe”

Saliva =
+ 1 Liter/day of Saliva
Mucin – Glycoprotein protects cells and lubricates
Buffers – Neutralize food for tooth decay
Antibacterial Agents
Salivary Amylase
Upper Abdominal Cavity
Elastic/Accordianlike Folds
Store 2 Liters of food

                              Chemical Digestion:
                              Gastric Juice
                              -Secreted from the Epithelium Lining
                              -HCl (pH 2)
                                 Secreted by the Parietal cells
                                 Disrupt Extracellular Matrix that binds cells together
                                 Kills most bacteria from food
                                 Denatures (unfolds) proteins
                              -Pepsin – begins hydrolysis of proteins (peptide bonds)
                                 Pepsinogen- Inactive form secreted from Chief cells
                                 Activated by the HCl in the lumen of the stomach (+ feedback)

                               Mechanical Digestion:
                               -“Churning” from smooth muscle tissue
                               -Hunger Pangs when stomach is empty
                               -Acid Chyme – contents of the food in the stomach
                               -Secreted by the Epithelium cells
                               -Protect stomach lining
                               -Mitosis replaces stomach lining every 3 days

                               Cardiac Sphincter – “Heartburn”
                               Pyloric Sphincter – 2-6 hours for stomach to empty
Small Intestine
~6 meters in human
Most of the enzymatic hydrolysis
Most of the nutrient absorption

       -First 25 cm
       -Chyme mixes with digestive juices
           from the pancreas, liver, gallbladder
           and gland cells from the intestinal wall                     Lactase

                     Bile Salts
                     -Digestion of Fats                                           Emulsification – keep fats from coalescing
                     -Pigments “Brown”

                                                                                          Pancreatic Enzymes
                                                                                          -Inactive Form
                                                                                          -Enteropeptidase Activates Trypsin
                                                                                          -Trypsin Activates the others

                                      Hydrolytic Enzymes
                                      Alkaline Solution (Bicarbonate)
                                        Buffer acidity of Chyme
                                                  Animals expend 3-30% of the chemical energy contained in
  Rest of the Small Intestine                     food during digestion and absorption
                                                           Large Surface Area
Most of the Nutrient Absorption                            ~300m2 (size of a tennis court)
-A few nutrients in stomach and large intestine            -Villi = fingerlike projections in lining
                                                           -Microvilli = microscopic extensions of the villi

                                                       Absorption across epithelial cells  blood vessels
                                                       Blood Vessels (Capillaries)
                                                       Lacteal – small vessel of the lymphatic system
                                                       Passive Diffusion – some simple sugars like fructose
                                                       Active Transport – amino acids, small peptides, vitamins, glucose
        The Large Intestine: “Colon”
        -1.5 meters long
        -Water Absoption (90% efficient)

- Appendix (Lymphoid Tissue)

 -12-24 hours for feces to travel its length
 -Diarrhea = Irritation of the lining and less water absobed
                                                               -E.coli as an example
 -Constipation = Feces moved too slowly (+ water absorption)
                                                               -Gases: Methane and Hydrogen Sulfide
 -Fiber = helps move along
                                                               -Produce Vitamins: Biotin, Folic Acid, K, B
                                                               -Indicators of contaminated water supply
 -Stores Feces
 -Sphincters: Involuntary and Voluntary
 - “Bowel Movement”
Hormones Regulate Digestion

                               -Stimulated by food
                               -Secretion of Gastric Juice

                           From Duodenum lining
                           Secretion of Bicarbonate (Pancreas)
                         -Cholecystokinin (CCK)
                           Gall Bladder to release bile into Duodenum
                         Length of Intestines

Structural Adaptations



                         Microorganisms (Ruminant)
                                                      Water Removal
                              Bacteria and Protists

                                   Chapter 42: Circulation and Gas Exchange
 Gastrovascular Cavities for Transport
                             Thin Tissue


                                                                                             Common Features:
                                                                                             1. Circulatory Fluid
                                                   Circulatory System                        2. A Set of Tubes
                                                                                             3. A Muscular Pump
                                 Open Circulatory System        Closed Circulatory System    4. Fluid Pressure

Hemolymph – blood and
interstitial fluid mix                                                                      Blood – not mixed with interstitial fluid

Sinuses – spaces
surrounding the organs                                                                      Vessels branch into smaller vessels

Insects, other Arthropods,
and most Mollusk                                                                             Earthworms, Squid,
                                                                                             Octopus, Vertebrates
                            Cardiovascular System (Vertebrates)
                                 High Metabolic Rate = More Complex Circulatory System
                                 and More Powerful Hearts

Heart Chambers:                                 Vessels:                                       Pathway of Blood:
-Atria = Receiving Chambers                     -Arteries = Carry Oxygenated Blood             Heart  Arteries  Arterioles  Capillaries  Tissue
-Ventricles = Pumping Chambers                  -Veins = Carry Deoxygenated Blood              Tissue  Capillaries  Venules  Veins  Heart

                                                -Capillaries = Infiltrate Tissue/Diffusion

                                                                                                  Four Chambered Heart:
    Two Chambered Heart:                               Three Chambered Heart:                     -No Mixing of Blood
    -Gill Circulation = Blood/Respiratory              -Pulmocutaneous Circuit= lungs/skin        -Pulmonary Circuit = lugs
    -Systemic Circulation = Blood/Body                 -Systemic Circuit= body                    -Systemic Circuit = body
    -Two capillary beds lowers pressure                -Double Circulation= pumped twice/         -Double Circulation
                                                          Maintains pressure                      -Allowed Endothermic (use
                                                       -Ventricle= some mixing of blood but           10% more energy)
                                                           a ridge diverts most of the blood
                                                           into the correct circuit
Mammalian Double Circulation

                                Systemic Circuit

                                   Arteries = Oxygen Rich
                                   Veins = Oxygen Poor

                               Pulmonary Circuit
                                                                            Mammalian Heart
                                                                            -Below sternum
                                                                            -Size of a fist
                                                                            -Mostly cardiac tissue

                               Systemic Circuit


                                      -Thin walls
                                      -Collection chambers for
                                         returning blood
                                      -Pump only to the ventricles
                                      -Thick walls
                                      -Pumping chambers
                                      -Right Ventricle  Lungs
                                      -Left Ventricle  Body
     The Cardiac Cycle
     -One complete sequence of pumping and filling (rhythmic)
     -Contracts = Pumps
     -Relaxes = Chambers fill
                                                                                       Systole = Contraction phase
                                                                                       Diastole = Relaxation phase

                                                                                     Cardiac Output = volume of blood per minute from the left ventricle
                                                                                        Dependent upon:
                                                                                           Heart Rate (number of beats per minute)
                                                                                           Stroke Volume (amount of blood pumped by left ventricle)
                                                                                                     Avg ~75mL
                                                                                            If stroke volume is 75mL and heart rate 70bpm then
                                                                                                 Cardiac Output = 5.25 L/min
                                                                                                 Equivalent to the total volume of blood in the body
                                                                                             Increases during exercise

                                                                                     Valves (4):
                                                                                     -Connective tissue
                                                                                     -Prevent backflow
                                                                                     -Atrioventricular (AV) valves – between atria and ventricle
                                                                                             Close during ventricular contraction
                                                                                     -Semilunar valves – anterior ends of the ventricles
                                                                                             Open during ventricular contraction
                                                                                             Close following contraction

Pulse = rhythmic stretching of arteries caused by the pressure of blood driven by ventricle contraction
Measure heart rate by measuring your pulse

Heart Sounds:                                                                 Heart Murmur:
-Closing of the valves                                                        -Defect of one of the valves
-“Lub-dup”                                                                    -Hissing sound when a stream of blood squirts backwards through a valve
-Lub –created by the recoil of blood against the closed AV valves             -Born with or damaged by infection (rheumatic fever)
-Dup –recoil of blood against the semilunar valves                            -Usually do not reduce the efficiency of blood enough to warrant surgery
   Maintaining the Rhythmic Beat of the Heart
   -Brain cells within a few minutes without oxygen
   -Maintaining the beat is critical for survival

                                                                                                    Sinoatrial (SA) Node:
                                                                                                    -Self excitable (contract w/o nervous system)
                                                                                                    -Sets the rate and timing in which all cardiac muscles contract
                                                                                                    -Anterior wall of right atrium
                                                                                                    -Produces electrical impulses
                                                                                                    -Contract atria in unison (both at the same time)

                                                                                                    Atrioventricular (AV) Node:
                                                                                                    -Between wall of right atrium and right ventricle
                                                                                                    -Impulses delayed ~0.1 second (ensures atria are completely empty)
                                                                                                    -Impulse relayed to ventricles in unison via the bundle branches

                                                                                                    Bundle Branches and Purkinje Fibers (muscle fibers):
                                                                                                    -Conduct the signal from the AV node to the apex of the heart
              Atria Systole                                                   Ventricle Systole     -Ventricles contract from the apex toward the atria

                                                                                      re-priming of ventricles

Electrocardiogram (ECC or EKG):
-Use electrodes to record the heart cycle                                     Physiological Cues Influence SA node:
-Measures heart impulses that are conducted through body fluids to the skin   -2 sets of nerves (1 speeds up the pacemaker and 1 slows it down)
                                                                              -Hormones: Epinephrine “fight or flight” from adrenal gland speeds it up
                                                                              -Body Temperature: increase in 1oC raises heart rate by ~10 beats/min (fever=+rate)
                                           Vessel Structure
                                                                                    Differences between Arteries and Veins:
Similarities between Arteries and Veins:
-Connective tissue with elastic fibers (exterior)
                                                                                      Thicker middle and outer layers = higher velocity and pressure
-Smooth muscle tissue with elastic fibers
                                                                                       Highly elastic
-Endothelium – single layer of flattened cells; minimizes flow resistance
                                                                                       Blood moves due to pressure
                                                                                       Thinner walls = lower velocity and pressure
                                                                                       Blood moves due to skeletal muscles pinching the veins and
                                                                                           smooth muscle tissue contractions (peristalsis)
                                                                                       Valves that allow unidirectional flow to heart



                                                                -Lack the outer two layers
                                                                -Very thin walls with basement membrane
                                                                -Facilitates the exchange of substances between the blood and interstitial fluid
         Blood Flow Velocity
         Vessel Area increases due to the increase in the
         total number of vessels = Total Area
         Velocity decreases as the vessel area increases

         Blood travels over a thousand times faster in the
         aorta (~30 cm/sec) than in capillaries (~0.026 cm/sec)

         Blood Pressure
         = the hydrostatic force that blood exerts against the wall
         of a vessel and that propels blood
             Fluids exert a force called hydrostatic pressure against surfaces they contact
             Fluids flow from areas of high pressure to low pressure

        Peaks in blood pressure corresponding to ventricular systole
        alternate with lower blood pressures corresponding to diastole

        Resistance to flow through the arterioles and capillaries, due
        to contact of the blood with a greater surface area of endothelium,
        reduces blood pressure and eliminates pressure peaks

                                                                                        Cuff is further loosened until the blood flows
                  Healthy 20 year old = 120 mm Hg/ 70 mm Hg                             freely (no sound) = Diastolic Pressure

                                                                -Stethoscope s used to listen for sounds of blood flow
Sphygmomanometer cuff inflated to                               -Cuff is gradually deflated until blood pressure exceeds cuff pressure
+120 mm Hg (pressure of cuff exceeds pressure of artery)            (hear blood pulsing) = Systolic Pressure
                Capillary Exchange                                                                   Lymphatic System

-So much blood passes through the capillaries that the cumulative
    loss of fluid adds up to about 4 L per day
-There is also some leakage of blood proteins

                                               Lymphatic System:
                                               -Returns blood fluids and blood proteins back to the blood
                                               -Fluid enters by diffusing into tiny lymph capillaries intermingled among capillaries of the cardiovascular system
                                               -Lymph – the fluid in the lymph capillaries
                                               -Drains into the circulatory system near the junction of the venae cavae with the right atrium
                                               -Lymph vessels have veins to prevent backflow
                                               -Depend on skeletal/smooth muscle contractions for movement
                                               -Lymph nodes = connective tissue filled with white blood cells specialized for defense (filter pathogens)
                               Blood                                                                                        Erythrocyte (Red Blood Cells):
                               -Connective Tissue                                                                           -Most numerous – 25 trillion in body’s 5L of blood
                               -Specialized cells suspended in a liquid matrix (plasma)                                     -Structure = Function
                                                                                                                                Small 7-8.5 micrometers in diameter
                                                                                                                                Biconcave disks –thinner in the center
                                                                                                                                Greater surface area for carrying/diffusing oxygen
                                                                                                                                 Mammalian cells lack nuclei = more space for hemoglobin
                                                                                                                                 Lack mitochondria = use anaerobic metabolism (+ efficiency)
                                                                                                                                 Hemoglobin – the iron containing protein for oxygen transport
                                                                                                                                    ~250 million molecules per cell
                                                                                                                                    Each hemoglobin can bind 4 oxygen molecules
                                                                                                                                    One erythrocyte can transport ~1 billion oxygen molecules

-Inorganic salts in the form of ions
-“blood electrolytes”
-Maintain osmotic balance
-Help buffer = pH 7.4
-Muscle and nerves depend upon
-Kidney helps maintain electrolytes

Plasma Proteins:
-Buffers against pH changes
-Maintain osmotic balance
-Contribute to viscosity (thickness)
-Some are escorts for lipids
-Immunoglobulins = fight pathogens
-Fibrinogens = clotting factors

                                                                                          Leukocytes (White Blood Cells):
                                                                                          -5 types (see diagram)
                                                                                          -Collective function = fight infections
                                                                                          -Monocytes and Neutrophils are phagocytes (engulf and digest bacteria and debris)
                                                                                          -Spend most of their time outside of circulatory system patrolling in the interstitial fluid
                                                                                          -Numbers increase temporarily when body is fighting an infection

                                                                                          -Fragments of cells about 2-3 microns in diameter
                                                                                          -No nuclei
                                                                                          -Originate as pinched-off cytoplasmic fragments of large cell in the bone marrow
                                                                                          -Function in blood clotting
Replacement of Cellular Elements in Blood
-Cellular elements of blood wear out and are replaced constantly
-Erythrocytes usually circulate for only ~3-4 months and then are destroyed by phagocytic cells in the liver and spleen
    Components are recycled into new erythrocyte cells through biosynthetic processes
-These cellular elements develop from pluripotent stem cells in the red marrow of bones, particularly the ribs, vertebrae, breastbone, and pelvis
-Pluripotent = have the ability to differentiate into any type of blood cell or into cells that produce platelets

                                                                               -A cancerous line of the stem cells that produce leukocytes
                                                                               -The cancerous stem cells crowd out cells that make red blood cells and produce an unusually
                                                                                     high number of leukocytes, many of which are abnormal
                                                                               -Treatment is to remove pluripotent stem cells from a patient, destroy the bone marrow, and
                                                                                     restock it with noncancerous pluripotent cells
                                                                               -As few as 30 of these cells can repopulate the bone marrow

     Blood Clotting
     -Fibrinogen = sealant (inactive form)
     -Fibrin (active form) aggregates into threads  Clot
     -Clotting factors, derived from platelets, begin the process
     -Clotting factors activate fibrin from fibrinogen

     -Spontaneous clot that develops when platelets clump and fibrin
                coagulates within a vessel
     -Normally, anticlotting factors in blood prevent spontaneous clotting
     -Potentially dangerous (cardiovascular disease)
     -”Throw a clot”  Stroke if brain oriented or Heart Attack if heart oriented

     -Inherited defect in any step of the clotting process
     -Treated by injections correcting the defected step
                                Cardiovascular Disease
                                -Diseases of the heart and blood vessels
                                -Cause more than half the deaths in the US

                                            Heart Attack:
                                            = the death of cardiac muscle tissue resulting from prolonged
                                            blockage of one or More coronary arteries (the vessels supplying
                                            the heart muscle with oxygen/nutrients)

                                            = the death of nervous tissue in the brain, usually resulting from
                                            rupture or blockage of arteries in the head

                                               Both frequently result from a thrombus that dislodges and clogs
                                               an artery

                                                 Normal Artery                  Artery partially closed by plaque

= build up of plaque on the inner walls of the arteries, narrowing their bore               -These conditions can be inherited
-Can be caused by cholesterol                                                               -Nongenetic factors such as smoking, lack of exercise,
-Encourage the development of thrombus formation                                                diet rich in animal fat, high cholesterol
= the plaque becomes hardened by calcium deposits (“hardening of the arteries”)
                                                                                            -Low-density lipoproteins (LDL’s) = “bad” cholesterol
Hypertension (high blood pressure):                                                         -High-density lipoproteins (HDL’s) = “good” cholesterol by
-Encouraged by atherosclerosis (narrowing vessels and reducing elasticity)                            reducing deposition
-Can be controlled by diet, exercise, medication, or a combination of these                 -Exercise increases HDL’s
-Diastolic pressure greater than 90 = concern                                               -Smoking increases LDL’s
-200/120 = courting disaster
               Gas Exchange in Animals: The Respiratory System

Role of Gas Exchange in Bioenergetics                                                          Diversity of Gill Structures
                                                                                 Gills = outfoldngs of the body surface that are suspended in the water
                                                                                 Total surface area often exceeds that of the rest of the body

                                                                                    Distributed over most of the body               Flip-like covering one segment

-O2 in and CO2 out
-Respiratory medium: atmosphere (terrestrial) and water (aquatic)
   Dissolved oxygen in water is always less than atmospheric oxygen
-Respiratory surface = where gases are exchanged with environment                                     Restricted to a local body region
  Tend to be thin and have large surface areas
  Moist for diffusion
  Endotherms have a larger respiratory surface area than similar sized ectotherms
  Simple animals (sponges, cnidarians, flatworms) every cell is close enough to
      the external environment for diffusion = usually small, thin, flat, large surface area
  In more complex animals, the bulk of the body doesn’t have direct external access
       = respiratory organs
Structure and Function of the Gill
-   Oxygen concentration is very low in water
-   Gills must be very effective

                                                  -Increases the flow of medium over the gill
                                                  -Crayfish/Lobsters have paddlelike appendages that drive the current
                                                  -Fish Mouth Pharynx  Gill  Exits = pulled by operculum

                                                Countercurrent Exchange:
                                                -Blood flows in opposite direction to the movement of water past the gill
                                                -Allows efficient transfer of oxygen to blood
                                                -As blood moves through a gill capillary, it becomes more and more loaded with oxygen,
                                                    but it simultaneously encounters water with ever higher oxygen concentrations
                                                -Diffusion gradient favors the transfer of oxygen from the water to blood
                                                -Efficiency = 80% of dissolved oxygen is removed
                                                Terrestrial Adaptations
  Gills are unsuitable for terrestrial life:                                       Atmospheric Air
  -Too much evaporation from moistened surface                                     Advantages:
  -Gills would collapse and cling together                                         -Higher concentration = ~210 mL/L compared to ~6 mL/L in water
  -Terrestrial animals have respiratory surfaces within the body                   -Oxygen and carbon dioxide diffuse much faster = less ventilation required
    with tubes opening to the atmosphere                                           -Less energy needed to ventilate due to air being lighter and easier to pump
                                                                                   -Desiccation of the large and moist respiratory structures – moved internally

                    Tracheal System (Insects)                                                                           Lungs
-Made up of air tubes (tracheae), opened to the outside, that branch throughout the body         -Lungs are restricted to one location
-Gas exchange is through diffusion                                                               -Circulatory system is needed to transport gases
-Virtually every cell is within a short distance of the respiratory medium                       -Size and complexity is correlated with the animal’s metabolic rate
-The open circulatory system is not involved in transporting gases

                                                                                                   -Amphibians have relatively small lungs
                                                                                                   -Rely on diffusion through skin to supplement

Insect Flight:
-Demands of gas exchange are heightened (10-200 times)
-Alternating contractions/relaxation of flight muscles pump air through tracheae (ventilation)
-Flight muscles are packed with mitochondria (bioenergetics)                                          -Reptiles, Birds, and Mammals rely entirely on lungs
                Mammalian Respiratory Systems
                                                             Air Passage:
-Located in the Thoracic (chest) cavity
                                                             Nostrils  Nasal Cavity  Pharynx  Larynx  Trachea  Bronchi 
-Spongy texture
                                                                  Bronchioles  Alveoli  Exchange
-Honeycombed with a moist epithelium (respiratory surface)
                                                             Reversed for carbon dioxide

                                                               Nostrils/ Nasal Cavity– filtered by hairs, warmed, humidified, and sampled for odors

                                                                                                        -Voicebox with vocal cords
                                                                                                        -High pitch = cords are stretched tight and vibrate rapidly
                                                                                                        -Low pitch = less tightly and vibrate slowly


                                                                                                        Epithelium Lining:
                                                                                                        -Covered by cilia and a thin film of mucus
                                                                                                        -Mucus traps contaminants (dust, pollen, etc)
                                                                                                        -Cilia beat and move the mucus upward to the pharynx
                                                                                                               where it is swallowed

                                                                                                  Alveoli (Alveolus = singular):
                                                                                                  -Site of gas exchange
                                Alveoli (SEM)                                                     -Millions in humans
                                                                                                  -Total surface area of 100 m2
                                                                                                  -Oxygen dissolves and rapidly diffuses into capillaries
                                                                                                  -Carbon dioxide is reversed
                                     Negative Pressure Breathing
            Breathing = the alternate inhalation and exhalation of air that ventilates the lungs

            Negative Pressure Breathing :
            -Works like a suction pump, pulling air instead of pushing it into the lungs

                                                                                                                      Tidal Volume:
                                                                                                                      -The volume of air an animal inhales
                                                                                                                         and exhales with each breath
                                                                                                                      -Average ~500 mL at rest in humans

                                                                                                                      Vital Capacity:
                                                                                                                      -The maximum tidal volume during
                                                                                                                         forced breathing
                                                                                                                      -Approx 3.4 L and 4.8 L for college age male
                                                                                                                         and females respectively

                                                                                                                      Residual Volume:
                                                                                                                      -The air remaining in the lungs after we
                                                                                                                         forcefully exhale as much as we can
                                                                                                                      -Due to the lungs ability to hold more air
                                                                                                                          than the vital capacity
                                                                                                                      -Mixing of oxygen-rich and oxygen depleted
                                                                                                                          air = decrease efficiency

Inhalation:                                                                     Exhalation:
-Lung volume increases as a result of contraction of the rib cage muscles       -Rib muscles and diaphragm relax
    and the diaphragm                                                           -Lung volume is reduced
-Contraction of the rib muscles expands the rib cage by pulling the ribs        -The increase of air pressure within the alveoli forces air up the tract
    upward and the breastbone outward
-At the same time, the chest cavity expands as the diaphragm contracts
    and descends like a piston                                                  Vigorous Exercise:
-All these changes increase the lung volume, and as a result, air pressure      -Other muscles of the neck, back, and chest further increase ventilation volume
    within the alveoli becomes lower than atmospheric pressure                  -Raise the rib cage even more
-Because air flows from a region of higher pressure to lower pressure,
    air rushes through the respiratory tract to the alveoli
            Ventilation in Birds
            -Much more complex than in mammals
            -Birds have eight or nine air sacs that penetrate the abdomen, neck, and even the wings
            -These air sacs act as bellows that keep air flowing through the lungs

-Air flows through the interconnected system in a circuit that passes through the lungs in one direction only, regardless of inhalation or exhalation
-Parabronchi = tiny channels through which air flows in one direction (not dead ends like alveoli)
-This system completely exchanges the air in the lungs with every breath (maximizing lung oxygen concentrations)
-Allows them to perform better at high altitudes (+9,000 meters during migration)
                                                            Breathing Control
                                               -We can hold our breath for a short period of time
                                               -We can consciously breath faster and deeper
                                               -Most of the time automatic mechanism regulate our breathing
                                               -This ensures coordination with the cardiovascular system

Breathing Control Centers
Medulla Oblongata:
-Sets the rhythm
-Inhibited during conscious breathing
-Monitors CO2 levels
   Monitors cerebrospinal fluid
   pH drops due to carbonic acid
   Increases depth and rate of breathing

Aorta and Carotid Arteries:
-Monitor CO2 levels and relay to Medulla
-Monitor O2 levels and relay to Medulla
  (high altitudes)

Coordination with circulatory system
-During exercise, increase cardiac output is
matched to the increased breathing rate,
which enhances O2 uptake and CO2 removal
as blood flows through the lungs
Oxygen Transport:
-Hemoglobin (quaternary protein)
-4 subunits each with a “heme” group
-Each heme group has an iron molecule at its center
-The iron binds oxygen
-Each hemoglobin can carry 4 oxygen molecules
-Hemoglobin binds oxygen reversibly (load and unload)
-The binding of oxygen to one subunit induces shape
   change in other subunits
-This change increases oxygen affinity
-This process is reversed at the tissue due to the low
   concentration of oxygen in the tissue (gradient) and the pH of
   carbonic acid causing a confirmation change in the subunits

Carbon Dioxide Transport:
-7% of CO2 released by respiring cells travels in plasma
-23% binds to the amino groups of hemoglobin
-70% is transported in the blood in the form of bicarbonate ions

-CO2 diffuses into plasma and then into rbc’s
-Inside the rbc’s it is converted into bicarbonate
-Carbon dioxide first reacts with water (assisted by carbonic anhydrase) to form carbonic acid
-The carbonic acid then dissociates into a hydrogen ion and a bicarbonate ion
-Most of the hydrogen ions attach to hemoglobin and therefore do not change the pH
-The bicarbonate ions diffuse into the plasma
-The process is reversed at the other end
                                                  Adaptations to Deep-Diving

-Humans can hold breath 2-3 minutes and swim to depths of 20 m or so
-Weddell seal can swim to 200-300 m and hold breath for ~20 minutes
   (sometimes for more than an hour)
-Penguins can do about the same
-Elephant seals can reach depths of 1,500 m (almost a mile) and stay
   submerged for as much as 2 hours
-Some whales can make even more impressive dives

Store large amounts of oxygen (twice as much as humans)
-Store it in blood and muscles
-About 36% of our total oxygen is in our lungs and 51% is in our blood
-Weddell seal holds only about 5% in lungs while stockpiling 70% in blood
-It has twice the volume of blood per kg of body mass as a human

Weddell seal has a huge spleen
-The spleen can store about 24 L of blood.

High concentration of myoglobin (an oxygen-storing protein) in their muscles
-Store about 25% of its oxygen in muscle, compared to only 13% in humans

Conserve oxygen
-Swim with little muscular effort
-Use buoyancy changes to glide passively upward or downward
-Heart rate and oxygen consumption rate decrease during a dive
-Blood is routed to the brain, spinal cord, eyes, and adrenal glands
-Blood supply is altogether shut off to muscles during the longest dives
-Derive their ATP from fermentation after deplete oxygen stored in myoglobin

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