Chapter 11
The Cardiovascular
System
Heart
(Cardiac Muscle)
• General
– continuous, rhythmic beating
– delivers: to cells thru blood
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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
• General
Cardiac Function
– 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
– 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 atriaatria 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 & Pulmonary
Circulation
• 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 ----
• General
Blood Vessels
– 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
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head and neck
jugular & subclavian
upper limbs and thorax
brachial & radial
– inferior vena cava
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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
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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 weaken
thrombophlebitis