Physiology II Recent and SMS 235 PDF

CHAPTER I : RESPIRATION Definition & types: It is the extraction of energy from food Types : see fig 1 1. External respiration It is the exchange of gases between air in alveoli and pulmonary blood 2. Internal respiration It is the exchange of gases between blood and tissues 3. Cellu...

CHAPTER I : RESPIRATION Definition & types: It is the extraction of energy from food Types : see fig 1 1. External respiration It is the exchange of gases between air in alveoli and pulmonary blood 2. Internal respiration It is the exchange of gases between blood and tissues 3. Cellular respillularration It is the extraction of energy from food.It present in mitochondria, and this is the aim of respiration Fig 1 : types of respiration  Normal respiration ( = eupnoea ) Characterestics 1. It is silent 2. it is involuntary 3. shoulders should not be moving 4. has a rate of 16 /min in adults and 24 /min in newly born 5. it is formed of 3 phases in normal condition a. inspiration b. expiration, slightly longer c and expiratory pause , see fig 2 2. only 2 phases in rapid or hyperventilation, only inspiratory , expiratory then inspiratory of the next cycle without expiratory pause See fig. 2  Respiratory passages ( see fig :3) Starting from nose, naso pharynx, larynx, bronchus ,2 main branches, then smaller branches till 23 generations called bronchial tree. This pathway is divided physiologically into 2 main parts A) conducting part=non respiratory part of respiratory system= dead space,=upper respiratory passage ) from nose till first 16 generations of bronchial tree.This part does not undergo gas exchange ,as wall is thick Functions 1.conduction of air 2.filtering of air from dust 3.air conditioning of air 4.protective, through sneezing and coughing 5. vocalization 6. HO2(through evaporation of H2O from expired air & heat regulation ( some animals has no sweat glands )  B) none conducting part= respiratory part=lower rewspiratory passage. Wall is thin for exchange of gases Includes, 1. last 7 generations of respiratory passage called terminal bronchioles 2. alveoli Functions: 1.exchange of gases 2.regulation of pH of the blood 3.shares in mechanism of buffer 4.stimulation & regulation of respiration  Important definitions 1.Eupnoea = normal respiration 2.Hyperpnoea= hyperventilation 3.Apnoea= stoppage of respiration a, temporary as during deglutition, vomiting, coughing , during during labor, during straining, and during sneezing b, permanent, in death 4.Dyspnoea : difficulty of breathing types a.Orthopnea: difficulty in breathing on decumbency b.Paroxysmal nocturnal dyspnea= paroxysm of difficulty in breathing on decumbency only at night, NO 5 & 6 are present only in heart failure c. dyspnoea on exertion d. Dyspnoea at rest ,a to d occurs in heart failure Degree of dyspnoea 1.dyspnoea on exerction, severe ,then moderate , then mild 2. Paroxismal noctornal dyspnoea 3. Orthopnoea 4. dyspnoea at rest  Respiratory passage Fig. 3 Conducting part( upper respiratory passage &non conducting part( lower respiratory passage  Respiratory muscles ( see fig.3 ) Inspiration Expiration Normal respiration 1.Diaphragm, increases Passive , i.e no muscle is volume of thoracic cage working vertically,2/3 of the increased volume , main muscle 2. External intercostal muscle, increases thoracic cage transversely, 1/3 of the increased volume Deep respiration 1. The muscles of normal Active , includes inspiration ,i.e 1. Internal intercostal diaphragm & external muscle intercostal 2.Abdominal muscless 2. Accessory muscles i.e a sternomastoid muscle b serratus anterior muscle c scalene muscle Fig :3 Muscles of respiration  Respiratory pressures: include 3 pressures ( see fig 5 ) 1.intrapleural pressure= intrathoracic pressure, the most important one 2. intra alveolar pressure= intra pulmonary pressure 3. intra abdominal pressure 4. trans mural pressure= difference between intrapleural and intraalveolar pressures 1. intra pleural pressure= intrathoracic pressure Definition: it is the pressure inside pleural cavity Values normal inspiration deep inspiration beginning of insp - 4 mmHg -4mmHg end of inspiration -6 mmHg may reach -80 Beginning of expir -6 mmHg may reach -80 End of expiration -4 mmHg -4 mmHg i.e it is always negative  It becomes positive in Valsalva maneuver ( = during straining ) Causes of its negativity,see fig.4 The expansion tendency of anterior chest wall is working against recoil tendency of alveoli Importance of its negativity 1.It is the only cause of distension of alveoli and air entry to the chest 2.It helps venous return from lower limbs to heart 3. It helps lymphatic drainage from lower limb to heart 2.Intraalveolar pressure = intrapulmonary pressure Definition: it is the pressure inside alveoli Values at beginning of inspiration=0 mmHg pressure , means=atmospheric pressure Fig 4 : cause of negativity of IPP  At mid inspiratory phase = -1 mmHg At the end of normal insp.and beginning of normal exp. = 0mmHg AT the mid expiratory phase = + 1 mmHg At the end of normal expiration = 0mmHg 3.Intra abdominal pressure Definition: it is the pressure inside abdomen Values: At beginning of inspiration 0mmHg At end of normal insp.and bebinning of exp. + 1 mmHg At the end of normal expiration 0mmHg i.e it is always positive  Important definitions related to intra pleural space 1.pneumothorax : presence of air in pleural cavity , it might external or internal 2.hydrothorax: presence of fluid in pleural cavity 3. hydropneumothorax : presence of air & fluid in pleural cavity 4. hemothorax : presence of blood in pleural cavity. The main cause is presence of malignant tumour 5. Chylothorax : presence of bile in pleural cavity Fig 5: Respiratory pressures, intra abdominal Intraleural & antraalveolar pressures Differences between inspiration & expiration ( See fig.: 3) Inspiration Expiration Thoracic cage volume increases decreases Air movement To chest Out of chest Size of alveoli inflated deflated Muscles working Muscle mentioned above Muscles mentioned above Position of diaphragm down up Effort done More less Types of alveolar cells= pneumocytes ,see fig.6 1. type I : simple squamous epithelium , for gas exchange as they are thin cells 2. type 2: for secretion of surfactant, see later 3. pulmonary alveolar macrophage = PAM, has defensive function , originally these cells are phagocytic monocytes Fig 6; alveolar cells  Pulmonary function tests A) Static : not related to time B) Dynamic : related to time, more valuable A) Static pulmonary function tests( see Fig.8) - include 4 volume and 4 capacities , measured by an apparatus called respirometer or spirometer, ( see fig : 6 ) Volumes: 4 1. Tidal volume= 500 ml=TV= amount of air inspired or expired in the normal respiration 2.Inspiratory reserve e volume=3000ml=IRV=amount of air inspires in the deepest inspiration after normal inspiration 3.Expiratory reserve volume=110ml=IRV=volume of air expired in the deepest expiration after the normal expiration  4.Residual volume=1200ml=RV=volume of air remaining in lung after deepest expiration This volume has a very medico legal importance in diagnosis of intra and extra uterine fetal death B) Capacities : 4 1. Inspiratory capacity=3500ml=IC=volume of air inspired in the deepest inspiration=TV+IRV 2.Functional residual capacity=2300=FRC=volume of air remaining in lung after normal expiration=ERV+RV 3.Vital capacity=4600ml=VC= volume of air expired in the deepest expiration after the deepest inspiration=IRV+TV+ERV 4.Total lung capacity=5800ml=TLC=volume of air remaining in lung after deepest inspiration=IRV+TV+ERV+RV  Comments on lung volumes and capacities 1. these figures are measured in adult healthy male at rest 2. all these figures are (10-15%) less in female than in male for 2 reasons 1. muscles of respiration in male are stronger than female due to presence of testosterone hormone in male 2. breast in female is doing some effort and load on chest during respiration 3. All volumes and capacities can be measured by spirometer except A. residual volume B. functional residual capacity C. total lung capacity Fig : 7 SPIROMETER Fig 7: Modern spirometer Fig 8:Lung volumes & capacities Fig 8 :Lung volumes & capacities  B) Dynamic pulmonary function tests; 3 tests 1.Minute respiratory volume=MRV=6000-8000ml/min=6-8L/min= volume of air inspired in normal respiration=TVX respiratory rate(RR) 2. Maximal breathing capacity=MBC=80 L/min in female & 120 L/min in male=average=100L/min=amount of air inspired in the most deep and most rapid respiration/minute * Breathing reserve=BR= MBC-MRV=100L/min – 6-8Lmin=92-94L/min *Dyspnoeic index=DI=BR/MBCX100=92 OR 94% If DI = less than 70% this means that patient is suffering from dyspnoea 3. timed vital capacity=TVC=forced expiratory volume FEV= Fig 9= %amount of air expired in the first , second ,third and fourth second of deepest expiration after deepest inspiration. Normal person should expire  82% of vital capacity after the first second 92% of vital capacity after the second second 97% of vital vapacity after the third second 100% of vital capacity after the fourth second This test is more & very important in diagnosis of constrictive lug diseases as bronchial asthma as sometimes vital capacity becomes normal in bronchial asthma ,but diagnosed by timed vital capacity Important note : lung diseases are classified into 2 big categories 1.constrictive lung diseases e.g bronchial asthma 2, restrictive lung diseases e.g pneumonia, We can differentiate between the 2 as follows  Constrictive lung diseases Restrictive lung diseases Normal tidal volume normal decreased Timed vital capacity decreased normal Fig 9,timed vital capacity  Surfactant: Definition: it is chemical substance decreasing the surface tension of the fluid lining alveoli Chemical nature: phospholipid ( dipalmitoyl phosphatidyl choline ) Site of secretion: type II alveolar cell ( =type II pneumocytes ) Function : it decreases the surface tension of the fluid lining alveoli. That is why it helps distention of alveoli and prevents collapse of alveoli,see fig 10 Mechanism: of action; it prevents attractive force of the molecules of the fluid lining alveoli Hormones increasing it:1. T3&T4 2. cortisone Hormones decreasing it: insulin Conditions in which it is decreased 1. newly born infants born - a from diabetic mother -b premature Fig 10. function of the surfactant  This disease is called respratory distress syndrome(=RDS) or hyaline membrane disease (=HMD ) 2.smocking ,as components of cigarette destroys type II cell ( called adult RDS ) 3.breathing of pure O2 4.during open cardiosurgery 5 hyperinsulinism 6. hypocorticism , as in Addison disease 7. hypothyroidism  Dead space Definition: it is the part of respiratory system that does not undergoe gas exchange Value : 150ml Types : 1, anatomical dead space : starting from nose up to beginning of terminal bronchiole, 2. physiological dead space = any part of respiratory system that does not undergoe gas exchange=anatomical dead space (A)+non function alveoli(B) As normally all alveoli are functioning ,so B =0 So normally anatomical dead space = physiological If physiological dead space is more than anatomical ,so ,this means that some alveoli are not functioning, and there is restrictive lung disease Therefore , there is no conditions in which anatomical is more than physiological  Ventilation(V): 2 types ,see fig 11 A) Pulmonary ventilation: = normally 500 ml =tidal volume =dead space,150 ml ( no exchange of gases) + 350 ml ( alveolar ventilation( there is exchange of gases ) B) Alveolar ventilation= 350ml ,so Pulmonary ventilation(500ml) – alveolar ventilation(350) = dead space i.e in each 500 ml of the tidal volume, only 350 ml are doing gas exchange So alveolar ventilation /minute= 350X12(R.R)=4200ml/minute=approximately 4Liters Also ventilation of alveoli is not equal in all alveoli, will be discussed later on Fig. 11 pulmonary &alveolar ventilation  Perfusion(P): = amount of blood reaching alveoli /minute=CO= 5Liters So V/P ratio = 4/5 =0.8,howerver blood is not distributed equally in each part of the lung Regeonal distribution of V & P in alveoli of upper & and lower part of lungs ,see fig 12 Alveoli of upper upper part Alveoli of lower part of of lung lung distenstion More less distensibility less more distribution of pulmonary blood less more V/P ratio More than 0.8 Less than 0.8 TB affection More, due to less vitality Less due to more vitality Fig 12: Ventilation & perfusion in different parts of lun  O2 transport and carriage O2 is carried in 100 ml of arterial blood in the following forms 1) Physically dissolved O2 = 0.3 ml/dl 2) Chemically carried O2 on haem of Hb = 19.5 ml/dl This 02 is present in a tension= 100 mmHg And % saturation = 95% However O2 is carried in 100 ml of venous blood is as follows a ) Physically dissolved = 0.13 ml b) Chemically carried on hem of Hb = 14.5 ml  This amount is present in a tension = 40mmHg and the % saturation of Hb is 70% -So for every 100 ml of arterial blood the can take 5 ml of O2. -This amount is called tidal 02 To summarize look to the following diagram Difference between arterial and venous blood Fig 13 Fig 13: arterial & venous O2 carriage CO2 carriage as follows ,see fig. 14 Fig 14 arterial & venous CO2 carriage O2 dissociation curve: illustrate the relation of O2 carriage and different tensions of O2 and causes of shifting to right & left , see fig 15 Fig 15:O2 dissociation curve IIIustrated O2 dissociation curve : see fig 15 Fig 15; O2 dissociation curve Remember: O2 content : actual amount of O2 carried by Hb Hb full saturation; 20ml How does it come? Every I gram of Hb can carry 1.33 ml of O2 So 15 gram of Hb can carry …………? So 15 gram of Hb can carry 20 ml of O2 Question : if Hb carries 15 ml of O2 calculate % saturation? Sol:%saturation= Hb content/saturationX100, 15/20X100= 75% Hypoxia, decrease in O2 in blood and tissue Types : 4 types, hypoxic, anemic, stagnant and histotoxic,see fig 16 Fig 16: types of hypoxia  Cyanosis Definition: bluish discoloration of skin & mucous membrane due to increased reduced Hb (= Hb + CO2) more than 5gm/dl in blood Types: A) Central cyanosis in all parts of the body, defect in heart or lung B) Peripheral in which cyanosis is present only in a localized area Threshold of cyanosis : 5 gm%. reduced Hb ( CO2 carrying Hb ) Factors modifying cyanosis: A: color of skin B: color of plasma * Hypoxia associated with cyanosis: hypoxic and stagnant hypoxia  Chapter 2 : General physiology Methods of transport of substance through cell membrane A) Passive methods ,i.e does not need energy==downhill transport We have 3 types : see fig.18 1. simple diffusion: it is the transport of substance from higher concentration into a lower concentration without need of energy ,e.g a diffusion of CO2 & O2 through alveoli. Diffusion increases by increase in concentration gradient, decrease in molecular size, & by increase in temperature ,see fig 15 2. facilitated diffusion: the same as simple diffusion but with help of carrier ,to widen pores for diffusion 3.Osmosis:it is the transport of fluid from higher concentration of fluid to a lower concentration of fluid without need of energy Fig 18, passive methods of transport  The power by which the fluid is moving ,is called osmotic pressure Osmotic pressure of blood =5000mmHg=osmotic pressure of saline(0.9NaCl%)=osmotic pressure of glucose 5%.So saline( with blue paper label ) & glucose 5%( red paper label) are iso osmotic solution with blood. These 2 types of solutions are very commonly used solutions in hospitals see fig.19 A. Active methods; i.e need source of energy=uphill transport,3 types see fig.20 1. primary active transport: Here the source of energy is from ATP directly e.g Na-K pump present in cell membrane of every cell,see fig 16 2. secondary active transport: Here the source of energy is rather than from ATP. Source of energy is from passive transport of another substance , see fig 16.We have 2 types of sec. active transport Fig 20. active methods of transport  a co-transport : in which the actively transported substance & the passively transported substance are in the same direction b counter-transport : in which the actively transported substance & the passively transported substance are in opposite direction , see fig 17 3.Vesicular transport(see.fig. 20 : If the transported substance is big & has high molecular weight ,it is transported by a vesicle formed by cell membrane. We have 2 typed of vesicular transport a endocytosis; where the tranported substance is from outside to inside the cell b exocytosis, where the transported substance is from inside to outside the cell Chapter 3 ; nerve & muscle Action potential : see fig 21 Fig 21 :Action potential  Synapse : junction between two nerves , see fig. 22 Types 1- Axo-dendritic. 2- Axo-somatic. 3- Axo-axonic. Fig 22: synapses Characteristics of synapse 1. unidirectional i.e. from presynaptic to postsynaptic 2. synaptic delay = 0.5 msec 3. can be fatigued, importance of fatigue in human Neuromuscular-junction(= NMJ= MEP ) Types of muscles: See fig.23 Types of muscles Fig 23; types of muscles ISOTONIC AND ISOMETRIC CONTRACTION,see fig 24: ISOTONIC ISOMETRIC Factors affecting skeletal muscle contraction: