PSL 214 Pharmacy Level 3 CVS Physiology PDF

PSL 214 Pharmacy Level 3 - CVS Physiology Cardiovascular System – part B Prof Bahjat Al-Ani Department of Physiology College of Medicine King Khalid University  The Cardiac cycle It is the group of events from the beginning of one beat to the begi...

PSL 214 Pharmacy Level 3 - CVS Physiology Cardiovascular System – part B Prof Bahjat Al-Ani Department of Physiology College of Medicine King Khalid University  The Cardiac cycle It is the group of events from the beginning of one beat to the beginning of the next beat. Normally with heart rate: 70/ min, the duration of one cardiac cycle is 0.8 sec.  The Cardiac cycle During the cardiac cycle the heart chamber muscles are either contracting or relaxing The period of contraction is called systole The period of relaxation is called diastole During systole the blood is pushed out of the chamber = Emptying During diastole the chamber is filling with blood = Filling  Events of the cardiac cycle Laper wks i opan Atrial Ventricular 1 Complete diastole two systole systole 0.1 sec. 0.3 sec. 0.4 sec. won WWI in ventricular Diastole 0.5. sec. Atrial Diastole 0.7 sec.  Comments The cardiac cycle starts with atrial systole. tape ventrial are contracted The ventricular systole is associated with: 1. Closure of the A-V valves (mitral and tricuspid valves) (Lub sound = 1st heart sound) WW 2. Opening of the semilunar valves (aortic & pulmonary valves) 3. Pumping of blood into the arteries.  Comments aorta The ventricular diastole is associated with: 1. Closure of the semilunar valves (aortic & pulmonary valves) (Dup sound= 2nd heart Sound) 2. Opening of the A-V valves (mitral and tricuspid valves) 3. Filling of the ventricles The Cardiac Cycle lub’ 0 ‘ First heart sound (Lub): sound Is a loud heart sound is due to closure of AV valves during ventricle systole Second heart sound (Dup ): Is a softer heart sound is due to closure of aortic and pulmonary valves (ventricle ‘dup’ diastole). sound complete cardiac diastole (0.4s) = atria and ventricles are relaxed, the ventricles are filling in preparation for the next cardiac cycle 70times in a min  Electrical changes in the heart (ECG) SA node  Atrial depolarization  P wave AV node  Ventricular depolarization  QRS wave  Ventricular repolarization  T wave Atrial repolarization Bardiccycle occurs during ventricle depolarization 1 1 (contraction) and so is not seen as a wave in the ECG because it is covered by the larger QRS complex.  Volume changes during a Cardiac Cycle End Diastolic volume: 5255 344 is the volume of blood in the ventricle at the end of diastole = 110 -140 mlIblood End systolic volume: wT II 4 is the volume of blood in the ventricle at the end of systole= 40 -70 ml.  Stroke volume It is the volume of blood ejected by each ventricle per beat. It equals 70 ml. It equals the difference between End Diastolic Volume and End Systolic Volume. Stroke volume = EDV- ESV = 140 - 70 = 70 ml 2.318K tw IyI  Cardiac output (COP) The volume of blood ejected by gs 8isp wissh each ventricle per minute. JII It equals 5 L/min. IIJYONFOAI.IT 70ml WJY.I.IN Jm Cardiac output= stroke volume X heart rate. misi 70mL 70 490 5000m  Factors affecting C.O.P. Cardiac output= Stroke volume X heart rate. on 901 70m 1) Venous return i WE.IM 2) Force of contraction statios 3) Arterial blood pressure IN Ypj 4) Heart rate IT  Factors affecting C.O.P. 1) Venous return : return The most important factor. Jenous In a normal heart the V.R. = C.O.P. (because of Starling law) faith cardic output Increasing the V.R.  increases the C.O.P 2) Force of contraction: Increased cardiac force of contraction  increases C.O.P. whos muserne the volume Y Cardicoutput the muscle it is sulf  Cardic output Factors affecting C.O.P. HR 3) Heart rate: Increasing the H.R. Increase the C.O.P up to a limit ( when it start to reduce ventricular filling) Both decreased H.R. and too much increased HR can decrease C.O.P. cardicoutput Is cardiccycle is ftp.JFIblm 4) Arterial blood pressure: Increase ABP decrease the COP  Factors affecting C.O.P. Venous Force of Heart rate. Arterial return contraction Physiological blood Increased change in H.R. pressure : The most  increase cardiac COP. Increased important force of Pathological ABP V.R. = Extreme contractio decrease C.O.P. change in H.R. n  decrease C.O.P ↑↑V.R. increased C.O.P. ↑↑C.O.P. C.O.P.  High venous return = High COP Venous return End diastolic volume Length of the ventricular muscle fibers The force of contraction is directly proportional to the initial (Starling law) length of the muscle fibers Force of contraction Stroke volume COP  Low venous return = low COP The muscle pump: Contraction of the skeletal muscles pumps blood towards the heart e The venous valves IIIs w prevent blood from going back wards 4 Standing still for long time cause pooling of blood in the lower limbs Decrease venous return Decrease cardiac output III fainting  Control of Heart rate The resting adult heart rate is about 70 beats/min 1. It is higher in children 2. Decreases during sleep 3. Increases during exercise 4. Increases with excitation 5. Increases with fever Increase body temperature by 1 degree C, increase the heart rate by about 10 beats more per minute. This will increase COP, more blood going to the skin in order to reduce the heat caused by the fever.  Control of Heart rate The resting adult heart rate is about 70 beats/min Fast resting heart rate: Tachycardia 9100 abi hart rate Slow resting heart rate: Bradycardia 60 IT hart rate Tachycardia: Heart rate more than 100 beats per minute Bradycardia: Heart rate less than 60 beats per minute  Control of Heart rate Heart rate is mainly controlled by the autonomic nervous system The heart beat is normally initiated by the sino-atrial node (SAN) The SA node is controlled by the sympathetic and parasympathetic - Sympathetic stimulates SAN = increase HR - Parasympathetic inhibits SAN = Decrease HR  Summary slide 5 L/min 60-80 beats/min 70-80 ml/beat Starling Law  Physiological variation Exercise  increases C.O.P. Pregnancy  increases C.O.P. Emotions  increases C.O.P. food intake  increases C.O.P.  Is Pathological variation Increased C.O.P. heart rate 1) Anaemia : To compensate for the lowered oxygen content Anaemic blood is less viscous , so less resistance to blood flow. 2) Fever- increases heart rate. (1:10) 3) Hyperthyroidism- increases heart rate 4) Pathological increase secretion of adrenaline- increases cardiac contraction.  Pathological variation Decreased C.O.P. 1. Haemorrhage. 2. Pathological decreased heart rate. 4 feb y 3. Aortic stenosis. hartswsia.is 4. Ischemic heart disease. 5. Heart failure