Principles of Animal Physiology

Principles of Animal Physiology 

▪ Functions: 

▸ Provides O2 Respiratory System 

Introduction 

▸ Eliminates CO 2 

▸ Regulates blood [H + ] (pH) 

▸ Phonation 

▸ Defends against microbes 

▸ Remo Removes es some chemicals as well as producing 

others 

▸ Trap and dissolve blood clots 

▸ Temperature control


▪ Atmospheric pressure 

Respiratory System 

Introduction


▪ Composition of air 


Introduction



Introduction 

▪ Diversity of gas exchange structures



External & Internal Respiraton 

▪ External respiration can 

involve four major steps: 

▸ External bulk transport 

▸ Respiratory surface 

diffusion 

▸ Circulation 

▸ Tissue diffusion



Water Breathers 

▪ It is more difficult to exchange gases in water 

▸ O 2 relatively insoluble in water, 10k slower 

▸ CO CO2 is 20 times more soluble in water than O O2 ▸ Their solubility decreases with increasing salinity 

▸ Th Their i soulbility lbilit decreases d with ith iincreasing i 

temperature 

▸ O O2 content in water varies more than in air 

▸ Unlike air, water has other life-sustaining 

components other than gases, gases like dissolved ions, ions 

organic matter and water



Introduction 

▪ Respiration in gill-breathing fish



▪ Nonrespiratory functions of aquatic respirers 

▸ Fluid and solute balance 

♦ Regulate osmotic and ionic gradients 

▸ Acid-base balance 

♦ Removal of H + and HCO 3- 

▸ Excretion 

♦ Removal of ammonia 

▸ NNutrient i and d mineral i l uptake k 

♦ Intake of NaCl and Ca2+ ▸ FFeeding di 

♦ Ciliated gills trap plankton 

▸ T t l ti



Air Respirers 

▪ Transition from water to land had its 

challenges 

▪ Air has much more oxygen yg than water 

▪ Air is less viscous than water 

▪ It takes less energy to pump air 

▪ However, respiratory surfaces must be kept 

moist i t for f proper diffusion 

diff i



Air Respirers 

▪ Since respiratory surfaces must be kept moist 

for proper diffusion 

▸ Land animals must remain in moist conditions 

▸ Land animals must have covered or fully internal 

structures for gas exchange 

♦ Internal air tubes - tracheae (insects) 

♦ Gill-like book lungs (scorpions) 

♦ MMantle tl cavities iti (snails) ( il ) 

♦ Vascularized sacs - lungs (snails & land vertebrates)


▪ Book lung of a 

Spider 

▸ Modified gill? 


Air Respirers


▪ Bimodal breathers 


Air Respirers 

▸ Have gills & another respiratory surface 

♦ Integumentary exchange 

♦ Modified gills 

♦ Digestive system 

♦ Air sacs (lungs)



Air Respirers 

▪ Bimodal breather - Frogs g 

▸ From eggs, laval stages have gills 

♦ Uses lungs g & skin to breathe 

♦ Uses buccal pump to force air into lungs (like fish) 

♦ Several inspiratory oscillation needed to fill lungs 

♦ One long exhalation empties lungs 

♦ O2 intake mainly through lungs 

♦ CO CO2 elimination i i i through cutaneous



Air Respirers 

▪ Bimodal breather - Frogs g - Fig g 11-11 

▸ Open nostrils 

▸ Lower floor of buccal cavity 

▸ Air rushes into buccal cavity 

▸ Close nostrils 

▸ Elevate floor of buccal cavity 

▸ Open glottis 

▸ Pump air into lungs 

▸ Close glottis 

▸ Repeat to inflate lungs 

K l tti d th t h l



Air Respirers 

▪ Comparative lung structure of amphibians, 

reptiles, and mammals 

▪ Fig g 

11-10


▪ Avian respiration 

▸ Lungs are inelastic 

▸ Several air sacs 


Air Respirers 

▸ Unidirectional or flow-through 

▸ Membranous diaphragm



Air Respirers 

▪ Avian respiration - Gas exchange surface 

▸ Capillaries smaller than mammals: 3-10µm vs 35µm 

in mammals 

▸ Air capillaries are not blind-ending, but 

communicate with each other 

▸ Diameter of air capillaries do not change during the 

respiratory p ycycle y 

▸ Surfactant’s role is limited to restricting fluid 

movement from blood to air capillaries 

▸ Mean thickness of the blood-gas barrier is less in 

birds


▪ Respiration in birds 

▪ Fig 11-16 


Air Respirers



Air Breathers 

▪ Movement of pure O 2 (shaded) through the 

avian lung 

▪ Fig g 

11-16, Part II



Air Respirers 

▪ Nonrespiratory functions of the avian 

respiratory system 

▸ Regulation of water loss and heat exchange 

▸ Circulation - enhances venous return 

▸ Acid Acid-base base balance 

▸ Vocalization, mating calls and other sounds 

▸ Defense 

▸ Removal, modification, activation, or inactivation 

of various materials 

▸ Olfaction



Air Respirers 

▪ Anatomy of the respiratory system in a 

mammal 

▪ Fig 11 11-12 

12



Air Respirers 

▪ Mammalian respiratory pathway



Air Respirers 

▪ Ciliated respiratory epithelium cells



Air Respirers 

▪ Diagram representing the human airways



Air Respirers 

▪ Respiratory zone structures



Air Respirers 

▪ Alveolus and associated pulmonary capillaries 

▪ Alveolar epithelial cells 

▸ Type I: flattened processes which cover most of the 

inner surface 

▸ Type II: produce and store surfactant 

▸ Macropharges: phagocytic cells 

▸ pores of Kohn permit airflow between adjacent 

▸ pores of Kohn - permit airflow between adjacent 

alveoli, a process known as collateral ventilation



Air Respirers 

▪ Alveolus and associated pulmonary capillaries 

▪ Fig 11-13


▪ Pleural sac 

▪ Fig 11-14 


Air Respirers



Respiratory Mechanics 

▪ Pressures associated with breathing 

▸ Atmospheric (barometric) pressure 

♦ At sealevel = 760mm Hg (1atm or 101.3 kPa) 

▸ Intrapulmonary (intra-alveolar) pressure 

♦ May be less ess tthan, a , equal equa to oor ggreater eate tthan a at atmospheric osp e c 

pressure 

▸ Intrapleural (intrathoracic) pressure 

♦ Always less than atmospheric pressure, except during 

maximal, forced expiration 

▸ TTransmural l pressure 

♦ Pressure difference between alveolus and pleural cavity 

♦ Pressure difference betwen atmostphere and pleural




▪ Pressures important to ventilation of a 

mammalian lung




▪ Transmural pressure gradient in a mammalian 

lung


▪ Boyle’s Boyle s law 


Respiratory Mechanics




▪ Anatomy of the respiratory muscles in 

mammal




▪ Respiratory p y muscle activity y during g inspiration p 

in humans




▪ Respiratory p y muscle activity y during g expiration p in 

humans




▪ Pressures changes during breathing




▪ Pressures associated with breathing




▪ Sufactant and Law of LaPlace




▪ Lung volumes & Spirometry




▪ Variations in lung volume




▪ Dead Space - regions where there is not gas 

exchange 

▸ - Anatomical Dead Space (ADS) 

♦ Man - 0.15 L 

♦ Giraffe - 1.7 L 

♦ Horse - 1.8 L 

▸ - Alveolar Dead Space p


▪ Pulmonary Ventilation 



▸ Total pulmonary ventilation = minute ventilation = 

minute respiratory p yvolume 

▸ Minute ventilation = Tidal volume x respiratory 

frequency q y 

▸ If VE = 500 ml, f = 12 breaths/min, then VE (V dot E, 

minute ventilation) ) = 6000 ml/min 

▸ Alveoli ventilation = amount fresh air reaching 

alveoli per minute 

▸ VA (V dot A) = (VE -VD) x f , if VD = 150 ml then, 

▸ V dot A = (500 - 150) x f = 350 x 12 = 4200 ml/min



Gas Transport 

▪ O 2 and CO 2 levels in the respiratory system of 

mammals



Gas Transport 

▪ Most O 2 in animals is carried bound to 

respiratory pigments 

▸ O 2 carried in blood in two forms 

♦ Physically dissolved 

♦ Chemically y bound 

– Hemoglobin (Hb), most common 

– Hemocyanin - crustaceans & mullusks 

Hemerythrin some worms 

– Hemerythrin - some worms 

♦ Most insects do not need respiratory pigments



Gas Transport 

▪ Hemoglobin molecule from a mammal



Gas Transport 

▪ Oxygen-hemoglobin Oxygen hemoglobin dissociation curves



Gas Transport 

▪ Factors that affect the O 2-Hb 2 Hb curve



Gas Transport 

▪ Effects on the O O2-Hb 2 Hb dissociation curve 

▸ Amount of O2 combined with Hb varies with major 

factors accompanying p y g tissue metabolism, , eg: g 

♦ Acidity: Bohr effect:- ↑PCO2 & [H + ] → shift to the right 

♦ Temperature: ↑temp → shift to the right 

♦ Organic Phosphates 

– 2-3-diphosphoglycerate: Affinity of Hb to O2 decreased in its 

presence presence. Acute or chronic exposure to low PO 2 → ↑2-3-D ↑2 3 D.P.G. PG → 

shift to the right (in mammals) 

– Inositol pentaphosphate (IPP) in birds 

– Nuleoside triphosphates (NTPs) in fishes 

– Adenosine triphosphate (ATP) in salmonoids, sharks and rays 

– Guanosine triphosphate (GTP) in eels, carp, goldfish


▪ Bohr and root effects 


Gas Transport



Gas Transport 

▪ Carbon dioxide transport in blood



Gas Transport 

▪ Abnormal blood-gas blood gas levels 

▸ Arterial O 2 abnomalities 

♦ Hypoxic hypoxia 

– Low arterial blood O 2 - inadequate Hb & blood saturation 

♦ Anemic hypoxia 

– Reduced O 2-carrying capacity 

♦ Circulating hypoxia 

– Too little oxygenated blood delivered to tissues 

♦ Histoxic hypoxia 

–O 2 delivery normal, but cells cannot use the O 2 delivered to them



Gas Transport 

▪ Abnormal blood-gas blood gas levels 

▸ Arterial CO 2 abnomalities 

♦ Hypercapnia 

– Excessive CO2 in arterial blood, caused by hypoventilation - 

underbreathing 

♦ HHypocapnia i 

– Below normal arterial CO 2 levels, caused by hyperventilation - 

overbreating


▪ Effects of 

hyperventilation and 

hypoventilation yp 

on blood 

gasses 


Gas Transport



Control of Respiration 

▪ Peripheral chemoreceptors 

▸ pH 

▸ PCO 2 

▸ PO 2




▪ Central Chemoreceptors 

▸ Mediate response by changes in PCO 2 and H + 

▸ Arterial PCO 2 crosses BBB → CSF PCO 2 

▸ In CSF: CO2 + H2O → H + + HCO - 

3 

▸ H + ▸ H causes ↑ ventilation 

* H + ▸ * H d tdiff BBB 

+ do not diffuse across BBB




▪ Respiratory control centers in the brainstem




▪ Neural and chemical influences


▪ Stop here 

▪ RReview i 

Respiratory System

Principles of Animal Physiology

Create successful ePaper yourself

Delete template?

Save as template?