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A&P II

Cardiovascular

QuestionAnswer
Examples of blood vessels Arteries, Veins, Capillaries
Two circuits Pulmonary circuit has O2 depleted blood to lungs Systemic circuit has O2 rich blood to all body systems
Cardiovascular System consists of Heart + Blood vessels
Structure of the Heart The Base is attachment to large vessels. The Apex is at 5th intercostal space, Distal (inferior) portion and Rests on Diaphragm. The heart has Four chambers: Two Atria and Two Ventricles.
Covering of the Heart: Pericardium (Pericardial Sac) Fibrous pericardium, the outermost structure.
Covering of the Heart: Parietal pericardium Lines inner wall of Fibrous pericardium
Covering of the Heart: Visceral pericardium Covers the heart
Covering of the Heart: Pericardial cavity Between Parietal and Visceral layers of pericardium Contains Pericardial (serous) fluid.
Walls of the Heart Epicardium Outer layer , Serous membrane, Visceral pericardium
Wall of the Heart Myocardium Middle layer, Cardiac muscle tissue
Wall of the Heart Endocardium Inner layer, Lines chambers, Covers heart valves, Continuous with inner lining of great vessels
Wall of the Heart Purkinje Fibers Cardiac conduction
Heart Chambers Right Atrium The right atrium receives blood from the vena cavae, two large veins: the superior and inferior vena cava. These veins return blood, which is low in o2, from tissue. A samller vein the coronary sinus, also drains venous blood into the right atrium
Heart Chambers Right Ventricle The right ventricle has thinner wall than the left. The right chamber pumps the blood a fairly short distance to the lungs against a relatively low resistance to blood flow. It receives blood from right atrium and delivers blood to pulmonary trun
Heart Chambers Left Atrium Receives blood from Pulmonary veins
Heart Chambers Left Ventricle Receives blood from Left atrium and Delivers blood to Aorta
Heart Valve What are the Atrioventricular valves Tricuspid and Mitral (Bicuspid valve)
Tricuspid Valve Located on the right atrioventricular orifice. Prevents blood from moving from the right ventricle into the right atrium during ventricular contraction.
Mitral (Bicuspid valve) Located on the left atrioventricular orifice. Prevents blood from moving from the left ventricle into the left atrium during ventricular contraction.
Heart Valve What are the Semilunar valves Aortic Valve and Pulmonary valve
Aortic Valve Location is the entrance to the aorta. Prevents blood from moving from the aorta into the left ventricle during ventricular relaxation.
Pulmonary valve Location is the entrance to the pulmonary trunk. Prevents blood from moving from the left ventricle into the left atrium during ventricular contractions.
Interatrial Septum and Interventricular Septum Wall of tissue separating right and left atria and ventricles
Chordae tendineae Fibrous connective tissue attached to Tricuspid and Mitral valves. It Originate from Papillary
Muscles in ventricular walls Assist with Ventricular contraction, Papillary muscle contraction, Tension on Chordae tendineae and Pull on valvular cusps. It prevent eversion of cusps into atria
Skeleton of the Heart Rings of Dense Fibrous connective tissue. Surround Pulmonary trunk and Aorta. Encircle AV openings, Provide support during contraction, Attachments for valves and muscle fibers.
Path of Blood Through the Heart Blood from system - Venae cavae and coronary sinus - R atrium - Tricuspid valve - R ventricle - Pulm valve - Pulm Trunk - Pulm arteries - Alveolar capillaries - Pulm veins - L atrium - Mitral valve - L ventricle - Aortic valve - Aorta - Blood t system.
Blood Supply to the Heart (Coronary Circulation) Left and Right Coronary Arteries The first two branches of the aorta, called the right and left coronary artery, supply blood to the tissues of the heart.
Blood Supply to the Heart (Coronary Circulation) Cardiac Veins Parallel paths to coronary arteries. Lead into Coronary Sinus Posterior surface Right atrium, Delivers de-oxygenated blood to Right atrium.
Systole Contraction of the heart chambers
Diastole Relaxation of the heart chambers
Atrial contraction Atrial systole
Ventricular contraction Ventricular systole
Ventricular relaxation Ventricular diastole
Atrial relaxation Atrial diastole
A Cardiac Cycle One complete heartbeat. During a cardiac cycle, the pressure in the heart chambers rises and falls.
What happens during Atrial systole and Ventricular diastole Pressure in Atria full of blood, A-V valves open, Ventricles relax, Semilunar valves close, passive blood flow in ventricles, Increased fluid volume causes increase in Ventricular pressure Atria contract to deliver rest of blood in ventricle.
What happens during Ventricular systole and Atrial diastole Pressure in Ventricles full of blood, The A-V valves close Semilunar valves open, Blood flows into pulmonary trunk and aorta as Ventricles contract,Atria relax, passively accept blood from Vena cavae, Coronary sinus.
“Lub” First” heart sound, Ventricular systole, Closing of A-V valves
“Dub” Second” heart sound, Ventricular diastole, Closing of Semilunar valves
What are individual mycardial cells connected by? Intercalated discs
Functional Syncytium A mass of cells performing as a unit; those of the heart are joined electrically. Atrial syncytium is the Atrial walls and Ventricular syncytium is in the Ventricular walls.
Intercalated discs The intercalated discs, which include gab junctions, join cardiac muscle cells, allowing action potentials to spread throughout a network of cells. As a result, cardiac muscle cells contract as a unit.
What does Fibrous Skeleton of Heart do? Separates Atrial and Ventricular Synctia and Prevents cardiac impulse conduction to ventricular syncytium while atria are in systole
Auto rhythmicity Ability to initiate contraction in absence of external nervous system stimulation
Cardiac Conduction System Clumps or strands of specialized cardiac muscle tissue which initiate and distribute impulses throughout the myocardium and Coordination of events of cardiac cycle.
Sinoatrial Node (SA node) Pacemaker of the heart, Right atrium near junction of opening of Superior vena cava,Fibers continuous with Atrial syncytium, Reaches threshold spontaneously,Generates action potential Impulse propagated across R and L Atria -Atrial contraction.
Junctional Fibers Receive propagated impulse from Atrial synctium and Impulse passes to Atrioventricular Node
AV Node In the inferior part of the interatrial septum and just beneath the endocardium. It provides the only normal conduction pathway btw the atrial and ventricular syncytia, because the fibrous skeleton does not conduct the impulse. Small fibers=slow impulse.
AV Bundle Enters superior interventricular septum,Divides into L and R bundle branches,Impulse propagated along interventricular septum by bundle branches,Large fibers move impulse quickly
Purkinge Fibers - Large fibers Halfway down interventricular septum,Receive propagated impulse from AV bundle, Fibers spread to papillary muscles and continue to Apex, Contraction at Apex (Ventricles) moves blood to Aortic and Pulmonary valves the Impulse re-initiated at SA node.
Electrocardiogram ECG , EKG, Recording of electrical changes in myocardium during cardiac cycle, Assess heart’s ability to conduct impulses
What Control of Heart Rate Parasympathetic and Sympathetic impluses
The parasympathetic fibers Innervate the heart rate from neurons in the medulla oblongata and make up parts of the vagus nerves. Most nerves branch to SA and AV nodes. the action potential reach nerve fiber endings, they secrete acetycholine, decrease heart rate.
Sympathetic impulses Accelerator nerves branch to SA, AV nodes, Norepinephrine, Increased HR.
Baroreceptor reflexes Originate in Cardiac Control Center of Medulla oblongata, Cardioinhibitor and Cardioaccelerator reflex centers, Balances parasympathetic inhibitory effects and sympathetic excitatory effects.
Baroreceptors Stretch receptors detect changes in blood pressure located by the Superior and Inferior Vena cavae at entry of Right atrium.
Rising Blood Pressure Stimulates stretches receptors, results in Medullary Cardioinhibitor signaling, Parasympathetic efferent impulses to Vagus nerve, decreased heart rate
Regulation of the Cardiac Cycle Baroreceptors, Cerebral and Hypothalamic impulses, Body Temperature, Concentration of Ions such as Potassium and Calcium; Physical exercise
Blood Vessels Organs of Cardiovascular system form a closed circuit to and from heart. Types of blood vessels are: Arteries, arterioles, capillaries, venules and veins.
Arteries Carry blood away from ventricles of heart Thick layer of smooth muscle (tunica media) Carry blood under relatively high pressure
Arterioles Receive blood from arteries Deliver blood to capillaries Microscopic, finer, more highly branched continuations of arteries
Capillaries Sites of exchange of substances between blood and tissue cells ex. Arterial capillaries & Venous capillaries.
Venules Receive blood from capillaries Microscopic vessels that continue from capillaries  merge to form veins
Veins Receive blood from venules Deliver blood to atria of the heart Tunica externa and media thinner than arteries Flap-like valves: Open as blood flows toward heart,Close to prevent back-flow,Carry blood under relatively low pressure Blood reservoirs
Common Structural Characteristics of Arteries and Veins Vascular walls comprised of three layers of tissue
Tunica externa (adventitia) Outermost layer Connective tissue: Elastic and collagenous fibers, Attaches vessels to surrounding tissues
Tunica media Middle layer, Smooth muscle fibers: Constrict or dilate vessels Elastic connective tissue: Elasticity to accommodate fluctuations in blood pressure and volume
Tunica intima Inner layer Smooth lining endothelial tissue
Common Functional Characteristics of Arteries and Veins Blood flow Sympathetic innervation of smooth muscle tissue in tunica media It Stimulation Vasomotor fibers: Smooth muscle contraction and Reduction in vessel diameter: Vasoconstriction. Inhibition Vasomotor impulses. Smooth muscle relaxation Increase in vessel diameter: Vasodilation
Metarterioles Microscopic, finer, more highly branched continuations of arterioles. They become Capillaries, Precapillary sphincters are Smooth muscle fibers, Encircle capillaries at metarteriole junction, Control blood flow into a capillaries. Then become Venules.
Capillaries cont. Smallest diameter blood vessels Endothelial walls: Extensions of inner linings of arterioles and Single layer of endothelial cells Connect smallest arterioles and smallest venules Semi-permeable
Capillaries cont: Biochemical Exchange Mechanisms (Passive transport): Diffusion Movement of substances along concentration gradient Higher concentration of O2, nutrients in systemic capillaries: Diffusion out of capillary to interstitial spaces Higher concentration of CO2, metabolic waste products in interstitial spaces: Diffusion
Capillaries cont: Biochemical Exchange Mechanisms : Filtration Hydrostatic pressure forces molecules through a membrane Blood pressure generated with ventricular contraction Pressure decreases as distance from heart increases due to peripheral resistance Occurs primarily at arteriole capillaries
Capillaries cont: Biochemical Exchange Mechanisms : Osmosis Movement of water through selectively permeable membrane toward a solution containing impermeable solute Osmotic pressure generated by presence of impermeant solute on one side of membrane
Capillaries cont: Biochemical Exchange Mechanisms : Colloid Osmotic Pressure Plasma proteins Movement of water from interstitial spaces to capillary spaces
Capillaries cont: Biochemical Exchange Mechanisms: Arteriole capillaries Predominantly Filtration (Hydrostatic pressure). Capillary blood pressure exceeds Colloid Osmotic pressure
Capillaries cont: Biochemical Exchange Mechanisms: Venular capillaries Predominantly Reabsorption. Capillary blood pressure is diminished and Colloid Osmotic pressure exceeds capillary blood pressure.
Net effect Net inward pressure at venular capillaries is less than Net outward pressure at arteriolar capillaries: Net fluid movement out of capillaries to interstitial spaces Excess fluid to Lymph capillaries to lymph vessels to venous circulation
Blood Pressure Force blood exerts against the inner walls of blood vessels Most commonly refers to pressure in Systemic Arteries
Arterial Blood Pressure Follows pattern related to cardiac cycle Rises with Ventricular contraction (Systole): Surge of blood entering arterial system expands elastic arterial walls. Falls with Ventricular relaxation (Diastole): Pressure begins to decline almost immediately as contraction ends.Arterial walls recoil
Systolic pressure Maximum arterial pressure during ventricular contraction
Diastolic pressure Lowest arterial pressure during ventricular relaxation
Pulse Palpable alternating expansion and recoil of arterial wall
Factors that Influence Arterial Blood Pressure Cardiac Output, Blood Volume, Peripheral Resistance and Viscosity
Cardiac Output (CO) Stroke Volume (SV) x Heart rate (HR): Volume of blood ventricle discharges with each heartbeat. Number of times heart beats / minute. Volume of blood discharged from ventricles / minute
Blood Volume (SV) Sum of formed elements and plasma volume
Peripheral Resistance (PR) Friction between blood and walls of blood vessels
Viscosity Resistance of molecular motion Concentration of formed elements / plasma volume
Control of Blood Pressure Blood pressure (BP) is determined by Cardiac Output (CO) and Peripheral Resistance (PR) BP = CO x PR and CO dependent upon SV and HR
Factors affecting SV, HR, and CO, PR Mechanical: Vascular Pressure: Baroreceptors Myocardial cell length and force of contraction: Starling’s Law: incre. Venous return, incre. Ventricular distention, incre. Myocardial contractility,incre. SV, increa CO Neural: Sympathetic and Parasympath
Factors affecting SV, HR, and CO, PR cont. Chemicals: Hormones: Epinephrine (HR), Angiotensin (PR) CO2, O2, H+: Decreasing pH = Vasodilation (PR)
Control of Blood Pressure Control of Peripheral Resistance (Arterial diameter) Vasomotor center of Medulla: Maintenance via Sympathetic impulses, Tonic contraction smooth muscle of vascular walls. Increased Sympathetic signaling, Vasoconstriction, Increased Peripheral Resistance , Increased B/P
Control of Blood Pressure Control of Peripheral Resistance (Arterial diameter) cont. Decreased sympathetic signaling, Vasodilation, Decreased Peripheral Resistance, Decreased B/P
Venous Blood Flow Mechanisms of increased venous return Skeletal muscle contraction: Muscles compress veins
Venous Blood Flow cont. Respiratory movements: Inspiration Decreased pressure: thoracic cavity Increased pressure in abdominal cavity Blood squeezed out of abdominal veins to thoracic veins
Venous Blood Flow cont. Venoconstriction: Stimulation sympathetic reflexes with decreased venous pressure
Central Venous Pressure (CVP) Indicative of volume of venous return and efficiency of stroke volume Measured at upper Right Atrium (typically)
Factor that increase CVP Increased blood volume Increased, widespread venoconstriction Decreased cardiac output
Signs of CVP Peripheral edema Jugular venous distention
Paths of Circulation Pulmonary circulation and Systemic circulation
Pulmonary circulation Vessels carrying blood from heart to lungs back to heart
Pulmonary circulation cont. Right Atrium, Tricuspid Valve Right Ventricle, Pulmonary Valve, Pulmonary Trunk: Extends upward and posteriorly from heart R and L Pulmonary Arteries, Lobar Branches:3 R side and 2 L side
Pulmonary circulation cont. Arterioles, Capillary networks in walls of Alveoli Epithelial cells of alveolar walls so tightly joined: Ions, glucose, urea remain in interstitial spaces High interstitial osmotic pressure, water drawn out of alveolar spaces Prevention fluid build-up
Pulmonary circulation cont. Diffusion of gases from capillaries to alveoli, alveoli to capillaries Capillaries merge into venules, veins, 4 large pulmonary veins, Left Atrium
Systemic circulation Vessels carrying blood from heart to all other tissues back to heart
Systemic circulation cont. Left Atrium, Bicuspid Valve Left Ventricle, Aortic Valve Ascending Aorta, Aortic Arch Descending Aorta, Arterioles, Capillaries
Systemic circulation cont. Aortic Bodies Epithelial lining of Aortic Arch Chemoreceptors for O2 and CO2: Respond mostly to reduction in O2 levels Signaling to respiratory centers in medulla Increase respiratory rate
Arteries to Brain, Head, Neck Brachiocepahlic, Arteries of the Head and Neck : Brachiocephalic Right common carotid: supplies head, neck Right subclavian: supplies right upper arm Left common carotid: supplies head, neck Left subclavian arteries: supplies left upper arm
Arteries to Brain, Head, Neck cont. Vertebral arteries Unite to form single Basilar artery supply the head
Arteries to Brain, Head, Neck cont Common carotid External carotids: Supply face and mouth Internal carotids: Cerebral arteries ,Supply the brain
Arteries to Shoulders and Upper Limbs: Arteries of Upper Limbs: Subclavian arteries (branch to form) Axillary arteries (branch to form) Supply axilla, chest wall Brachial arteries Humerus to elbow Radial arteries Radial side of forearm Ulnar arteries Ulnar side of forearm to wrist
Arteries to Thoracic Thoracic Aorta and Its Branches: Visceral branches Thoracic organs Parietal branches Thoracic wall
Arteries to Abdominal Walls Abdominal Aorta and Its Branches Visceral branches Abdominal organs Parietal branches Abdominal wall
Arteries to Pelvis and Lower Limbs Descending Abdominal Aorta
Arteries to Pelvis and Lower Limbs cont Common Illiac Arteries Internal Iliac Pelvic muscles and tissues External Iliac Main blood supply to legs
Arteries to Pelvis and Lower Limbs cont Femoral artery Femoral muscles and tissues
Arteries to Pelvis and Lower Limbs cont Popliteal Knee joint, calf, thigh
Arteries to Pelvis and Lower Limbs cont Anterior and Posterior tibial Lower extremities
Characteristics of Venous Pathways Vessels of the venous system originate with the merging of capillaries, venules, small veins, increasingly larger ones. Unlike arterial pathways, those of the venous system are difficult to follow due to irregular networks and unnamed tributaries
Created by: bonitasoul