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Chapter 11
The Cardiovascular System
Heart(Cardiac Muscle)
• General– continuous, rhythmic beating– delivers: to cells thru blood• oxygen• nutrients• hormones• electrolytes
– pump to lungs • exchange CO2 for O2
Heart• Anatomy of the Heart– lies in the mediastinum
• medial cavity of the chest• big as fist 2nd rib and 5th rib
– pericardium• sac around heart• film of serous fluid friction free • Pericarditis - inflammation
– heart wall• epicardium - visceral pericardium• myocardium - thick cardiac muscle and
connective tissue• endocardium
– endothelial lining of heart chambers
• Chambers of the Heart– right atrium
• recieves blood “deoxygenated”• superior & inferior vena cava• tricuspid valve
– right ventricle• pumps blood to lungs• pulmonary artery• semilunar valve “pulmonary”
– left atrium• recieves blood “oxygenated”• pulmonary veins bicupsid(mitral) valve
– left ventricle• pumps blood to body• aorta• semilunar valve “aortic”
• Septum– divides chambers (wall)
• Auricles– wrinkled flap like appendages on atria– musculi pectinati
• muscle bundles in atria
• Valves– prevent backflow– atrioventricular valves
• tricupsid valve• mitral valve “bicuspid”• chordae tendinae
– white cords anchor flaps of valves attached to papillary muscles
– semilunar valves• pulmonary• aortic
• Cardiac Circulation–coronary arteries - O2 and nutrients–arise from aorta–coronary veins take CO2 & wastes–coronary sinus ---> right atrium
Cardiac Function• General– 70 beats/min– its own conduction system– contracts independently
• Conduction– sinoatrial (SA) node “pacemaker”• in right atrium ---> depolarization• atrical contract
– internodal fiber bundles• depolarization node to node
– atrioventricular (AV) node• junction of atria & ventricle• ventricular contraction
• Atrioventricular Bundle– purkinje fibers– rapid impulses
• failed pacemakers– slow h.r. – bradycardia < 60 beats/min– rapid h.r. -tachycardia > 100
beats/min– fibrillation
• rapid uncoordinated heart beat
• Cardiac Cycle– initiated by the SA node– Cycle• Systole -contraction ventricles• Diastole -relaxed atria fill
• Heart Sounds– auscultation– ‘lubb dubb’• Lubb AV valves close• Dubb semilunar valves close
– murmurs• abnormal heart sound• incompetent valve swishing sound• Stenosed- narrow valves
• Cardiac Output– stroke volume• volume of blood pumped w/ each beat
– cardiac output• 4900 ml/min ---> 4.9 l/min• SV x VR 70 ml/ beat x 70 beats/ min
– exercise• increase SV increase venous return
– cardiac reserve• ability of heart to increase cardiac output
• Stroke Volume Regulation– healthy heart increase SV– Starling’s Law of the Heart• more cardiac muscle stretches greater
stroke volume
• Regulation of Heart Rate– autonomic nervous system• parasympathetic innervation–vagus nerve ---> ACH–slows h.r.
• sympathetic innervation–speeds h.r. stimulate SA node–norepinephrine–AV cardiac muscle
– hormones and ions• epinephrine speeds up h.r. • Ca++ levels down - h.r. down• thyroxine levels up -h.r. up• K + levels drop causes abnormal heart
rate
– temperature, gender, exercise, & age• fetus 140 - 160• heat h.r. goes up
–congestive heart failure• hypertension•worn out and weak• age & coronary atherosclerosis
• Electrocardiogram– three basic features of ECG• atria–P wave- depolarization of atria-
atria contract• ventricle–QRS complex depolarization of
ventricles–T wave repolarization of
ventricles– shapes of the waves and the time
intervals
• Disturbances in Heart Rate & Rhythm–myocardial infarction- heart
attack– Ischemia- lack of oxygen–Fibrillation- irregular heart beat–Atherosclerosis- narrowing of
arteries–Artherosclerosis- scar tissue Ca
build up
Systemic & PulmonaryCirculation
• Capillaries ----> cells ----> capillaries ---->venuoles ---> veins ---> superior or inferior vena cava ---> right atrium ---> tricuspid valve --> right ventricle ---> pulmonary valve ---> pulmonary artery ---> lungs ---> pulmonary veins ---> left atrium ---> bicuspid valve --> left ventricle ---> aortic valve ---> aorta --->arteries ---> arterioles ----
Blood Vessels• General– closed system
• blood in vessels
– principal types of blood vessels– arteries
• blood away from heart• arterioles
– capillaries• exchange materials w/ cells• capillary beds
– veins• venuoles• blood toward heart
• Blood Vessel Wall– tunica interna ~ simple squamos– tunica media ~ smooth muscle– tunica adventitia ( externa) ~
connective• Major Arteries– aorta ~ largest artery• head and neck
– carotid, brachiocephalic, subclavian
• upper limbs and thorax– brachial, radial, ulnar
• abdomen– hepatic
• pelvis and lower limbs– renal - kidneys
• Major Veins– superior vena cava
• head and neck• jugular & subclavian• upper limbs and thorax• brachial & radial
– inferior vena cava• abdomen• hepatic and mesentaric• pelvis and lower limbs• renal and femoral
• saphenous (LONGEST VEIN)
• Capillaries– wall only one layer thick– exchange between blood & tissues
• nutrients, oxygen, CO2, & wastes
• Special Circulation– brain• Circle of Willis• brain blood barrier
– hepatic• digestive organs• liver
– mesenteric• intestine
Physiology of Circulation• Pulse– expansion and recoiling of artery– carotid, brachial, and radial
• Blood Pressure– general• systolic / diastolic• pressure against walls of artery
– Gradient auscultatory method• 120 mm Hg / 80 mm Hg brachial artery
–Measuring Ventricular pressure• Systolic- contraction• Diastolic- relaxation
• Factors Effecting Blood Pressure– resistance• directly related to cardiac output• vasoconstriction ~ sympathetic• chemicals , temperature, diet• Kidneys- blood volume• autonomic nervous system• Blood viscosity- > resistance
– variations in pressure• hypotension
– systolic < 100 mm Hg– diet
• hypertension– > 140 / 90 sustained– myocardium enlarged
Cardiovascular Disease• Developmental– con genital– heart defects
• Aging– atherosclerosis ~ narrowing of veins– cholesterol “LDL’s” ~ form plaque– ischemic heart disease ~ lack of oxygen– angina pectoris ~ heart pains–myocardinal infarction ~ heart attack– varicose veins ~ venous valves weakenthrombophlebitis