BMS100 ClinPhys Systems and Heart.docx

BMS100: CLINICAL PHYSIOLOGY REVIEW NOTES LEVELS OF ORGANIZATION, SYSTEMS – HEART BASICS AND VITAL SIGNS Tissue Level of Organization Four major tissue types: Muscular Epithelial Nervous Connective Epithelial tissue Functions: Protection – physical, chemical, thermal, microbes Transport – abs...

BMS100: CLINICAL PHYSIOLOGY REVIEW NOTES LEVELS OF ORGANIZATION, SYSTEMS – HEART BASICS AND VITAL SIGNS Tissue Level of Organization Four major tissue types: Muscular Epithelial Nervous Connective Epithelial tissue Functions: Protection – physical, chemical, thermal, microbes Transport – absorption, secretion or removal of wastes, optimize diffusion Secretion of useful substances Types of epithelial tissue: Simple squamous – thin, easy diffusion, not much protection Simple cuboidal – increased thickness, protection, secretory, absorptive and excretory functions Simple columnar – absorptive and motility, protection Stratified squamous – protection against abrasion and water loss; keratinized or non-keratinized Stratified cuboidal – protective, excretory Pseudostratified columnar – cilia, single but has multiple layers Most membrane in the body are epithelial membranes epithelium faces a cavity, tube or outside world Important in gastrointestinal, urinary, respiratory, cutaneous, cardiovascular, reproductive systems Connective tissue membranes = no epithelial lining Ex. protection of skin stratified squamous epithelium and secretions Ex. protection of respiratory tract pseudostratified columnar epithelium and macrophages Connective tissue Structural and protective functions Stronger structures – bone/cartilage, dense regular tissue (tendons, ligaments), dense irregular tissue (dermis of skin) Weaker structures – areolar and reticular, adipose tissue Fluid connective tissue Red blood cells, platelets carry O2/CO2, clotting Lymph remove fluid, transport for immune cells Immune cells response to pathogens and damage Bone endocrine organ, mineral storage depot Fat endocrine organ, metabolic energy storage, thermoregulator Connective tissue proper Cell types include: fibroblasts, osteoblasts/osteocytes, chondroblasts, adipocytes, mesenchymal cells Matrix consists of: Fibres – collagen, elastic fibers, reticular fibres Ground substance – polysaccharide and protein complexes Connective tissue proper: one of four main types of connective tissues in the body; loose and dense connective tissue categories Made up of – cells + matrix Fibres: proteins that are responsible for structural characteristics of connective tissue Collagen – type I = very strong and type IV = delicate linking epithelial tissue to connective tissue Elastic fibres – elasticity of organs and tissues Ground substance: similar to globular proteins; aggregates of proteoglycans; both surrounded by water Fibroblasts: produce the matrix Macrophages: immune cells Adipocytes: central large fat-storing vacuole Muscle tissue Skeletal Voluntary, movement; striated fibres with orderly arrangement Cardiac Involuntary, only in heart for pumping blood; similar arrangement as skeletal Smooth Involuntary, in variety of organs; less order to cytoskeleton, lower ATP expenditure Nervous tissue Peripheral nervous system (PNS) – detects stimulus and relays to CNS (sensory) CNS integrates information into a response which is carried to effectors via the PNS (motor) Cells of nervous system: Neurons: excitable cell that receives stimulus from neuron/receptor (dendrite) integrates it (cell body/axon hillock) passes to along another stimulus (axon) Axons: carried in bundles; most cell bodies reside in CNS except dorsal root ganglia, autonomic ganglia and enteric ganglia Glial cells: supporting cells of the nervous system Astrocytes: support neurons within CNS Oligodendrocytes: insulate axons with myelin in CNS Schwann cells: myelinate axons in the PNS Microglial cells: clean up debris, detect invaders/injury in PNS Physical Exam Findings – Lower-Level Function and Dysfunction Most diseases due to dysfunction at the molecular, cellular or tissue level Anemia example Anemia – due to decrease in red blood cell count In a physical exam, will detect: Increased heart rate (less RBC’s) lower oxygen-carrying capacity need for an increase in blood flow to body heart rate increases, deliver more RBC’s/minute Rapid respiratory rate Turbulent flow in heart due to increased cardiac output = murmur Pallor of conjunctiva Jaundice or scleral icterus if anemia due to destruction of RBCs; yellow pigment due to Hb breakdown products Findings of exam can be explained by: reduced tissue oxygenation and breakdown products of RBC’s Organ Systems and Primary Functions Integumentary – protection and sensation Additional functions: vitamin D production, removal of wastes, thermoregulation, acid-base balance, vitamin storage and production Skeletal – protection, support, movement Additional functions: mineral balance Muscular – movement Blood sugar regulation Nervous – detects and processes sensory information = responses Additional functions: acid-base balance, thermoregulation, endocrine control Endocrine – secretes hormones that impact metabolism, activity and growth Additional functions: destruction of cancer cells, electrolyte balance, mineral balance, thermoregulation, tissue repair, growth, blood sugar regulation Cardiovascular – delivery of nutrients and oxygen to tissues, removal of wastes Additional functions: acid-base balance, electrolyte balance, thermoregulation, and waste removal Lymphatic and immune – protection from microbes Additional functions: tissue repair, waste removal, removal of cancer cells Respiratory – oxygenates blood and removes carbon dioxide Additional functions: acid-base balance, waste removal Digestive – processes food and removes undigested wastes Additional functions: vitamin D production, blood sugar regulation, vitamin storage Urinary – water balance, waste removal Additional functions: vitamin D production, endocrine production, acid-base balance, electrolyte balance, mineral balance, waste removal Reproductive – produces gametes, supports embryo/fetus Additional functions: growth Basics of the Heart Systemic and pulmonary circulations Systemic Left heart applies high pressure to high O2 and low carbon dioxide blood systemic arteries and arterioles deliver blood to tissues Systemic capillaries allow tissues to extract O2 from and deliver CO2 blood Systemic veins return low O2, high CO2 blood to the right heart Pulmonary Right heart applies moderate pressure to low O2, high CO2 blood pulmonary arteries and arterioles deliver this blood to the lung Pulmonary capillaries allow lung tissue to deliver O2 to and extract CO2 from blood Pulmonary veins return high O2, low CO2 blood to the left heart Pulmonary System Systemic Circulation Pump Diaphragm Ventricles of the heart Substance being pumped Gas Blood Gas diffusing out of blood CO2 O2 Gas diffusing into blood O2 CO2 pH in capillary bed Higher – CO2 being taken out Lower – CO2 and lactate build up Heart – 2-phase pump Diastole = relaxation pressure within heart drops and draws blood from veins (refills) Systole = contraction applies pressure to blood and ejects proportion of it to arteries 4 chambers: Left side: Left atrium – receives blood from pulmonary vein; passes to left ventricle (atrial systole) Left ventricle – applies pressure to blood; ejecting proportion into arteries of the aorta (ventricular systole) Right side; Right atrium – receives blood from veins of vena cava; passes blood to right ventricle (atrial diastole) Right ventricle – applies pressure to blood; ejects a proportion into pulmonary artery Two main functions of the heart: Applies pressure to blood during ventricular systole – establishes pressure gradient to drive blood forward Sends proportion of full (diastolic) volume into arteries (pulmonary artery and aorta) every systole Stroke volume (SV) x heart rate (HR) = flow (cardiac output or CO) Arteries and arterioles Arteries: larger more elastic vessels conducting blood away from the heart (pressure “reservoirs”) Left ventricle – alternates between high pressure (120 mm Hg) during systole and low-pressure (0 mm Hg) during diastole Blood pressure never drops to 0 = because of elasticity of arterial walls Full of elastic fibres in smooth muscular wall and membranes – in ventricular diastole; potential energy stored in the stretch to maintain BP and drive blood forward Arterioles: smaller, muscular vessels that feed capillary tissue beds; constrict or dilate to modify flow Large blood vessels unable to divert blood from one organ to another = arterioles constrict or dilate in different organ/tissue beds depending on: Overall BP Metabolic needs of tissue Capillaries Capillaries: very small vessels allowing exchange of gases, nutrients, metabolites, wastes between blood and tissues Lined by single endothelial cell and large surface area = good for diffusion Veins and venules – return blood to heart; store 60% of blood volume Control of Cardiorespiratory Apparatus Pressure sensors – baroreceptors Major baroreceptors are = carotid arteries and arch of the aorta Drop in pressure message to brainstem activation of sympathetic nervous system release E and NE elevation of HR and constrict arterioles Gas sensors – chemoreceptors for CO2 and O2 (peripheral) Drop in O2 or increase in CO2 increase respiratory rate increase in volume ventilated in each breath Medulla and pons in brainstem regulate activity of the major muscles of ventilation pH sensors – detect H+ in form of CO2 in the brain (central) Basics of Fluid Movement Flow: volume of fluid that passes through a tube over a unit of time Units – mL/sec, L/min, mL/min Pressure: force that fluid exerts on the walls of its container; type of potential energy Pressure gradient: difference in pressure between two areas in space; one high and one low Ex. job of the ventricles – apply pressure (potential energy) which is converted to kinetic energy promote forward movement of blood and bulging of walls of large arteries Vital Signs Normal HR in adults – 60-100 beats/min at rest Healthy BP – 140 mm Hg systolic and 90 mm Hg diastolic at rest Below 90/60 considered low enough to be abnormal Respiratory rate – at rest, normal is between 12 and 20 breaths/min Heart Basic Anatomy Basic structures: Chambers – left and right atrium; left and right ventricle Interventricular septum – thick muscular wall that separates the left and right ventricle Great vessels: Pulmonary trunk – connected to: right ventricle Left and right pulmonary arteries Aorta – connected to: left ventricle Superior and inferior vena cava – connected to: right atrium Pulmonary veins – connected to: left atrium Papillary muscles – finger-like projections in heart ventricles Chordae tendinae – heart strings; tough fibrous cords or tendons that connect papillary muscles to cusps or flaps of heart valves (prevent inverting) Coronary sulcus (atrioventricular groove) – separates atria from ventricles; holds important blood vessels Apex of heart – pointed, lower tip of heart; usually formed by left ventricle Anterior surface – easier to auscultate and palpate Major structures include: Part of right atrium (auricle) Right ventricle Tip of left ventricle – easiest place to palpate cardiac impulse; point of maximal impulse (PMI) Lateral side of left ventricle (superior) Surface anatomy – anatomical landmarks for physical exams Sternal borders – lateral edges of sternum where bone meets ribs Mid-clavicular line – vertical line that runs through midpoint of clavicle and each side of chest Key locations for auscultation and palpation: 2nd intercostal space, left sternal border – pulmonic valve 2nd intercostal space, right sternal border – aortic valve 4th/5th intercostal space, left sternal border – sounds from right ventricle and right AV valve 5th intercostal space, mid-clavicular line – sounds from left AV valve and left ventricular sound; palpate the PMI LUB-DUB sounds S1 – lub Caused by closure of atrioventricular valves – tricuspid and mitral S2 – dub Caused by closing of semilunar valves Valves – two main types: Atrioventricular valves Between atria and ventricles = prevent backflow Left ventricle contracts – blood moves to aorta Right ventricle contracts – blood moves to pulmonary trunk Larger; floppy Anchored by chordae tendinae – keeps them from prolapsing (flopping back) into atria during ventricular contraction Semilunar valves Between ventricles and great arteries Ventricle relaxes during diastole – blood is not sucked back into ventricle Arterial blood still moves forward because pressure gradient and contraction of heart musculature Smaller; tighter – no chordae tendinae Systemic Pressures and the Cardiac Cycle Lub – atrioventricular close Dub – semilunar close Left Atrium Left atrium contracts to fill the left ventricle Left ventricle contracts pressure increases causing left AV valve to close (Lub) *right after there is slight temporary pressure in atrium from blood pushing against valve Left atrium fills while pressure in left ventricle is high Pressure in the left ventricle drops, resulting in opening of left AV valve Left atrium fills Left Ventricle Relaxed left ventricle experiences bump in pressure as left atrium fills it Left ventricle contracts increased pressure causes left AV valve to close (Lub) Left ventricle relaxes and pressure starts to drop Left ventricle pressure is less than the left atrium pressure, the AV valve opens Left ventricle fills The Aorta Diastolic pressure just prior to ventricular contraction Left ventricle contracts pressure increase overcomes aortic diastolic pressure aortic valve opens Left ventricle applies maximal (systolic) pressure to the aorta When left ventricle pressure is less than aortic pressure, aortic valve closes (dub) Types of Heart Sounds Always hear a valve CLOSING AV valve S1 Lub Lower frequency because the valve is bigger/floppy Semilunar valve S2 Dub Higher frequency because valve is smaller/tighter Valve opening = pathology; opening snaps Laminar flow – normal; smooth and orderly blood flow Turbulent flow – rapid, forming disorderly eddies and vibrations Often caused by valvular abnormalities – murmurs, extra heart sounds Can be normal in patients Types of Valvular Abnormalities Stenosis: valve doesn’t open widely enough Higher pressure causes noisy turbulent flow (murmur) Can be heard when blood is flowing across the valve when valve should be open Scarring due to physical stresses can cause narrowing Regurgitation: valve doesn’t close fully; backflow occurs when the chamber before relaxes Backflow causes noisy turbulent flow (murmur) Can be heard when blood is flowing across the valve when valve should be closed Ex. if mitral valve didn’t close after left ventricle relaxed – hear the murmur between S1 and S2 (mainly at S1) Damage to heart valves can make them unable to close fully