APreviewPT5082022.pdf

PT 508 A&P REVIEW ‘- This material may not be replicated or used for any other purpose than classwork, without express written permission from the instructors. 1 Class learning objectives...

PT 508 A&P REVIEW ‘- This material may not be replicated or used for any other purpose than classwork, without express written permission from the instructors. 1 Class learning objectives Oxygen transport variables and how they are affected by different influences Brief thoracic anatomy review Normal Cardiac function review ‘- Ventilation and perfusion 2 O2 Transport ‘- 3 Variables in O2 transport ‘- 4 Continuous O2 needed for biologic work: Skeletal , cardiac, and smooth mm contraction Nerve impulse transmission Cellular metabolic process (ATP production) Cellular pumping mechanisms ‘- 5 Principles of O2 Transport Convection of O2- Movement of O2 from Lung alveoli to the tissue capillaries This is determined by hemoglobin concentration and saturation, and cardiac output (CO= SV x HR) Diffusion of O2- O2 moves from capillaries to cells-mitochondria, or across alveolar- capillary membrane ‘- This is determined by metabolic rate, vascular resistance, tissue oxygen consumption and extraction, thickness of tissue 6 Oxygen Transport DO2 – oxygen delivery- when at rest this is 3 to 4 x more than needed so does not affect VO2 (demand/consumption) In healthy people exercise causes the most change in VO2, which can increase 20 x higher than rest ‘- metabolism In various illness DO2 can be affected reducing O2 available for 7 O2 partial pressure from air to tissue ‘- 8 Oxygen Transport ˜Quality and quantity of blood Ø Quality - Composed of red blood cells, white blood cells, platelets, and plasma (more RBC than other cells) - Hematocrit in women: 38% ‘- - Hematocrit in men: 42% Ø Quantity - 70% in venous system - 15% in pulmonary circulation - 10% in systemic arteries - 5% in capillaries 9 Copyright © 2012 by Mosby, Inc., an affiliate of Elsevier Inc. Slide 9 Oxygen Transport Cardiac output Cardiac output = Stroke volume × Heart rate - CO = SV × HR Preload Amount of stretch placed on the ventricles before systole ‘- Afterload Resistance of ejected blood volume to flow 10 Copyright © 2012 by Mosby, Inc., an affiliate of Elsevier Inc. Slide 10 Factors that impact O2 transport Airways Quantity and Quality of blood- average volume 5000 mL O2 saturation of blood at alveolar level Lung perfusion and heart function ‘- Peripheral circulation Oxyhemoglobin dissociation 11 Outside factors affecting O2 transport Gravity Exercise Stress ‘- 12 Oxygen Debt Difference between O2 consumption and O2 delivery Healthy people can produce with exercise and use anaerobic metabolism for short time periods , correct debt with rest Oxygen extraction ratio= VO2/DO2 and is usually around 23% at rest ‘- Critically ill patients may have limited DO2 preventing minimum O2 needs from being met 13 Review slides for CV anatomy ‘- 14 ‘- 15 Muscles of Respiration ØDiaphragm Inspiration ØIntercostals Typically involves the ØSternocleidomastoid contraction of the ØScalenes diaphragm and ØSerratus anterior intercostal muscles ‘- ØPectoralis major Additional muscles used ØPectoralis minor during excretion and disease ØTrapezius ØErector spinae 16 Copyright © 2012 by Mosby, Inc., an affiliate of Elsevier Inc. Slide 16 ‘- 17 Muscles of Respiration Expiration Rectus abdominis Typically, a passive Obliquus externus process abdominis Additional muscles Obliquus internus recruited for voluntary abdominis ‘- exhalation or in disease Action of the abdominal state muscles Internal intercostals 18 Copyright © 2012 by Mosby, Inc., an affiliate of Elsevier Inc. Slide 18 ‘- 19 ‘- 20 ‘- 21 Cardiac Anatomy ‘- 22 ‘- 23 ‘- 24 ‘- 25 Heart sounds S1- low pitched (Lub)- closing of the mitral and tricuspid valves- listen at apex of heart S2- higher pitch (dub)- aortic and pulmonary valves close- base of heart If you hear additional sounds this is usually abnormal S3- lub-dub-dee- usually ventricular failure ‘- S4- dee-lub-dub- atrial contraction forces blood into stiff ventricle https://depts.washington.edu/physdx/heart/index.html Sounds under Examination tab 26 Fluid movement in microcirculation Capillary hydrostatic pressure Capillary oncotic pressure Interstitial hydrostatic pressure Interstitial oncotic pressure ‘- Should be close to equilibrium, see little more fluid filtering into the interstitial space 27 ‘- 28 O2 transport and dissociation Hemoglobin in arterial blood 99% saturated normally At high PO2 in arterial blood get little dissociation of O2 off hemoglobin, normally need PO2< 80% to see dissociation At PO2 =40 to 50 mmHg, still have 75% hemoglobin saturation ‘- Allows transport of O2 to tissue since the O2 doesn’t dissociate off hemoglobin until need O2 delivery 29 ‘- 30 CO2 transport Produced by cell metabolism, buffered and returned to lungs CO2+ H2O H2CO3 HCO3 + H+ ‘- Lungs can exhale much more CO2 than the kidneys can excrete acid Poor ventilation results in more CO2, and a drop in pH – acute respiratory acidosis 31 Ventilation Air moves into lungs Regional differences- gravity dependent Highest ventilation in lower lung fields no matter what position the body is in If seated, have most ventilation in the lower lobes ‘- 32 Diffusion Air crossing the alveolar-capillary membrane Oxygen must pass through the surfactant, and the alveolar and capillary membranes, then through the plasma to attach to hemoglobin molecule In disease states may have thicker membranes to pass through, fluid from edema ‘- 33 33 Perfusion How much blood flow to the lungs for O2 and CO2 exchange Very low pressure compared to systemic circulation Increased perfusion in lower lung fields Hypoxic vasoconstriction- pulmonary vessels constrict in areas‘- of low O2 concentration 34 ‘- 35 Ventilation to Perfusion V/Q Because of gravity get best air exchange in dependent areas of lungs- the base in standing/sitting, in side lying the dependent lung has best exchange Need a good matching ratio of blood to ventilation to supply O2 and remove CO2 V/Q=0.8 to maintain normal ‘- Ideally want 4 parts ventilation to 5 parts perfusion for O2 and CO2 exchange Not necessarily uniform throughout lungs 36 ‘- 37 ‘- 38 Shunt vs dead space ‘- 39 Other factors of ventilation Medulla and pontine centers- central control Central and peripheral chemoreceptors Lung compliance Airway resistance ‘- 40