Respiration (Chapters 21, 22, and 23)

 

I.  Oxygen and carbon dioxide physiology

          A.  Diffusion of gases 534

                Gases diffuses more readily through gas than aqueous phase

                Gas transport in animals—alternate convection and diffusion 541

          B.  Partial pressure of gases

          C.  Physical properties of air and water 549-551

 

II. Physical properties of the lungs-              

          A.  Compliance- distensibility - changes in lung volume                       

          B.  Elasticity - tendency of a structure to return to its initial size after being stretched.                 

          C.  Surface tension - the force that act to resist distention- exerted by

                  fluid in alveoli.  Surfactant lowers surface tension - prevents the

                  alveoli from collapsing during expiration  568

 

III. External respiration:  Physiology of breathing

          A.  External breathing and gas exchange

          B.  Vertebrate breathing 552

                All-breathing vertebrates have lungs connected to the outside by hollow tubes

                   Fish 554

                   Amphibians 558

                   Reptiles 560

                   Mammals—control of ventilation, high altitude 561

                   Birds 569

          C.  Aquatic invertebrates 572

          D.  Insects 570

 

IV. Regulation:  mediated by chemoreceptors and effect of CO2

A.  Two major pathways: 

                   1.  Cerebral cortex- voluntary

                   2.  Medulla oblongata- involuntary-controls diaphragm

and intercostals

 

B.  Chemoreceptors and CO2: 

1.  Respiratory centers in the medulla (in the brain),

                        neurons in medulla- influenced by neuron in the pons

                        and by sensory feedback from receptors sensitive to

                        a. P CO2,         b.  pH,     c.  PO2 of arterial

 

2.  The brain is more sensitive in a rise in blood CO2, pH, than in

                        sensing a decrease in O2.  When partial pressure of CO2 I, pH L

 

3.  The peripheral chemoreceptors in the aortic and carotid bodies are

               sensitive to changes in blood PCO2 indirectly, because of consequent

               changes in blood pH

 

 C.  Hering-Breuer reflex- inflation reflex- involves stretch receptors

                 which inhibit inspiration

 

V.  Transport of oxygen and carbon dioxide in body fluid 579

          A.  Chemical properties and distribution of respiratory pigments 587

          B.  O2 binding characteristics of respiratory pigments 591

          C.  The functions of respiratory pigments in animals 597

          D.  CO2 transport 603

 

 VI. Diving physiology- Weddell seal- sensitive to CO2 643-652

 

Problems-1. Holding breath,

               2.  Hydrostatic pressure- bubble formation if surface after deep dive.        

            Solutions- Seals have: 

1.     2X volume of blood per body weight as compared to non-diving animals           

2.     2X more O2 per Kg of body weight - mostly in blood and muscle- e.g. human- 36% O2 in lungs, 51%- blood; seal- 5% in lungs, 70% in blood

3.     Seals have huge spleen- during diving, spleen contracts, increase rbcs, increasing O2 supply

4.     Increase myoglobin in muscle- 25% O2 stored in muscle; human- 13%    

5.     Diving reflex – heart rate decreases, cardiac output decreases

6.     ATP derived from anaerobic respiration

7.     Exhale before diving- lung volume decreases, air out of alveoli, lungs collapse except trachea and bronchi; no diffusion of gases into blood as pressure increases

 

VII.  High altitude physiology 602

 

Tissue changes in mammals at high altitude:

1.      Decrease in muscle fiber diameter shorter diffusion distance between blood, capillaries and muscle fiber mitochondria,

2.      Increase in concentration of myoglobin,

3.      Suppress metabolism in some tissues,

4.      Switch of cardiac muscle toward greater use of glucose yielding most ATP,

5.      Use aerobic respiration for skeletal muscle do not want lactic acid to form,

6.      Use metabolic pathway to maximize the yield of O2 delivery to tissues.

 

 

 

VIII. Acid base physiology 607

 

IX.  Work sheet-- Oxygen dissociation curve 591

 

 

Effects of various factors on oxyhemoglobin dissociation curve- showing the relationship between the percent oxyhemoglobin saturation and PO2

 

A curve shifted to the right indicates-- more oxygen is readily given up by the hemoglobin

 

A curve shifted to the left indicates-- oxygen more readily binds to the blood.

 

At rest:

Arterial PO2 = 100 mm Hg

Venous PO2 = 40 mm Hg                            % oxygen released = ______________

 

During exercise-I temperature, I H+:  If there is no shift--

 

Arterial PO2 = 100 mm Hg

Venous PO2 = 40 mm Hg                            % oxygen released = __________

 

During exercise:  If there is a shift to the right.

 

Arterial PO2 = 100 mm Hg

Venous PO2 = 40 mm Hg                            % oxygen released = __________

Increased O2 released to tissue after shift = _________________

 

 

At low temperature or high altitude (llama)-

Drop in PO2 in atmosphere:

Arterial PO2 = 50 mm Hg (curve B)    % oxygen saturation = __________

Arterial PO2 = 50 mm Hg (curve C)    % oxygen saturation = __________            

Increase O2 uptake in lungs = ___________________

 


Factors that shift the curve:

1.

2.

3.

4.