Cardiovascular System Lecture -2 PDF

Tishk International University Faculty of Nursing Physiology of Cardiovascular System Lecture - 2 1st Grade – Spring Semester 2021-2022 Objectives: 1. Study general organization of cardiovascular system (CVS). 2. Explain the functions of the parts of CVS. 3. Describe some important measurement of CV...

Tishk International University Faculty of Nursing Physiology of Cardiovascular System Lecture - 2 1st Grade – Spring Semester 2021-2022 Objectives: 1. Study general organization of cardiovascular system (CVS). 2. Explain the functions of the parts of CVS. 3. Describe some important measurement of CVS. The Cardiovascular System  A closed system of the heart and blood vessels  The heart pumps blood  Blood vessels allow blood to circulate to all parts of the body  The function of the cardiovascular system is to deliver oxygen and nutrients and to remove carbon dioxide and other waste products The Heart: Coverings  Pericardium – a double serous membrane  Visceral pericardium  Next to heart  Parietal pericardium  Outside layer  Serous fluid fills the space between the layers of pericardium External Heart Anatomy The Heart: Chambers  Right and left side act as separate pumps Four chambers:  Atria = Receiving chambers  Right atrium  Left atrium  Ventricles = Discharging chambers  Right ventricle  Left ventricle Right Atrium (RA)right upper chamberreceives blood from body- deoxygenated blood Left atrium (LA)- left upper heart.- receives oxygenated blood from lungs and sends it to the left ventricle Right ventricle- (RV)right lower chamberreceives blood from right atrium and sends it to the lungs through pulmonary artery Left Ventricle (LV)lower left chamberreceives blood from left atrium and sends it through the aorta to the body. Aorta: The main trunk of the systemic arteries, carrying blood from the left side of the heart to the arteries of all limbs and organs. Aorta pulmonary artery Left Atrium Right Atrium Pulmonary Artery carries blood to lungs Left Ventricle Right Ventricle The Heart: Valves  Allow blood to flow in only one direction  Four valves  Atrioventricular valves – between atria and ventricles  Bicuspid valve (left)  Tricuspid valve (right)  Semilunar valves between ventricle and artery  Pulmonary valve  Aortic valve Tricuspid valve controls blood flow between the right atrium and ventricle Mitral valve controls blood movement between the left atrium and ventricle Left Atrium Right Atrium Right Ventricle Tricuspid Valve Mitral Valve Left Ventricle Pulmonary valve controls blood movement from right ventricle into pulmonary artery Pulmonary valve Mitral Valve Left Atrium Right Atrium Aortic valve controls blood flow from the left ventricle to the aorta Right Ventricle Tricuspid Valve Left Ventricle Aortic valve The Heart: Valves  Valves open as blood is pumped through  Held in place by chordae tendineae (“heart strings”)  Close to prevent backflow The Heart: Associated Great Vessels  Aorta Leaves left ventricle  Pulmonary arteries Leave right ventricle  Vena cava Enters right atrium  Pulmonary veins (four) Enter left atrium Coronary Circulation  Blood in the heart chambers does not nourish the myocardium  The heart has its own nourishing circulatory system  Coronary arteries  Cardiac veins  Blood empties into the right atrium via the coronary sinus The Heart: Conduction System  Intrinsic conduction system (nodal system)  Heart muscle cells contract, without nerve impulses, in a regular, continuous way The Heart: Conduction System Special tissue sets the pace  Sinoatrial node  Pacemaker  Atrioventricular node  Atrioventricular bundle  Bundle branches  Purkinje fibers parts Heart Contractions  Contraction is initiated by the sinoatrial node  Sequential stimulation occurs at other autorhythmic cells The Heart: Cardiac Output  Cardiac output (CO)  Amount of blood pumped by each side of the heart in one minute  CO = (heart rate [HR]) x (stroke volume [SV])  Stroke volume  Volume of blood pumped by each ventricle in one contraction The Heart: Regulation of Heart Rate  Stroke volume usually remains relatively constant  Changing heart rate is the most common way to change cardiac output The Heart: Regulation of Heart Rate  Increased heart rate  Sympathetic nervous system  Crisis  Low blood pressure  Hormones  Epinephrine  Thyroxine  Exercise  Decreased blood volume The Heart: Regulation of Heart Rate  Decreased heart rate  Parasympathetic nervous system  High blood pressure or blood volume Dereased venous return BloodVessels: The Vascular System  Taking blood to the tissues and back  Arteries  Arterioles  Capillaries  Venules  Veins Differences BetweenBlood Vessel Types  Walls of arteries are the thickest  Lumens of veins are larger  Skeletal muscle “milks” blood in veins toward the heart  Walls of capillaries are only one cell layer thick to allow for exchanges between blood and tissue The Vascular System BloodVessels: Anatomy  Three layers (tunics)  Tunic intima layer = tunic  Endothelium  Tunic media  Smooth muscle  Controlled by sympathetic nervous system  Tunic externa  Mostly fibrous connective tissue Movement of Blood Through Vessels  Most arterial blood is pumped by the heart  Veins use the milking action of muscles to help move blood Capillary Beds  Capillary beds consist of two types of vessels  Vascular shunt – directly connects an arteriole to a venule Capillary Beds  True capillaries – exchange vessels  Oxygen and nutrients cross to cells  Carbon dioxide and metabolic waste products cross into blood Diffusion at Capillary Beds Capillary Exchange  Substances exchanged due to concentration gradients  Oxygen and nutrients leave the blood  Carbon dioxide and other wastes leave the cells Major Arteries of Systemic Circulation Major Veins of Systemic Circulation Arterial Supply of the Brain Hepatic Portal Circulation Pulse  Pulse – pressure wave of blood  Monitored at “pressure points” where pulse is easily palpated Blood Pressure  Measurements by health professionals are made on the pressure in large arteries  Systolic – pressure at the peak of ventricular contraction  Diastolic – pressure when ventricles relax Measuring Arterial Blood Pressure BloodPressure: Effects of Factors  Neural factors  Autonomic nervous system adjustments (sympathetic division)  Renal factors  Regulation by altering blood volume  Renin – hormonal control BloodPressure: Effects of Factors  Temperature  Heat has a vasodilation effect  Cold has a vasoconstricting effect  Chemicals  Various substances can cause increases or decreases  Diet Variations in Blood Pressure  Human normal range is variable  Normal  140–90 mm Hg systolic  90–60 mm Hg diastolic  Hypotension  Low systolic (below 90 mm Hg)  Often associated with illness  Hypertension  High systolic (above 140 mmHg)  Can be dangerous if it is chronic Thank you