HEART

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CHAPTER 15
2
CHAPTER 15

• HEART
• SIZE OF FIST
• WEIGHS LESS THAN A POUND
• LIES IN MEDIASTINUM
• APEX(POINTED END) IN POINTED LEFT
• RESTS ON DIAPHRAGM
• BASE (POSTERIOSUPERIOR ASPECT) WHERE LARGE
  BLOOD VESSELS EMERGE POINTS TO RIGHT SHOULDER

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CHAPTER 15

• COVERINGS
• DOUBLE PERICARDIUM
• VISCERAL PERICARDIUM (EPICARDIUM) ADHERES TO
  HEARTS SURFACE
• PARIETAL PERICARDIUM ANCHORED TO STERNUM AND
  DIAPHRAGM FILLED WITH FLUID WHICH REDUCES
  FRICTION

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CHAPTER 15

• HEART WALL
• EPICARDIUM MEMBRANE
• MYOCARDIUM CARDIAC MUSCLE CONTRACTING LAYER
  REINFORCED BY FIBROUS CONNECTIVE TISSUE
• ENDOCARDIUM EPITHELIAL TISSUE LINES HEART
  CHAMBERS CONTINUOUS WITH LINING OF BLOOD VESSELS

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CHAPTER 15

• CHAMBERS
• 2 ATRIA
• 2 VENTRICLES
• ATRIA (ATRIUM SINGULAR)
• RECEIVING CHAMBERS
• LOW BLOOD PRESSURE
• VENTRICLES
• PUMPING CHAMBERS
• THICK-WALLED
• WHEN THEY CONTRACT CAUSES BLOOD TO FLOW
  THROUGHOUT THE BODY

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CHAPTER 15

• RIGHT VENTRICLE
• MOST OF HEARTS ANTERIOR SURFACE
• PUMP BLOOD TO LUNGS
• LEFT VENTRICLE
• FORMS THE APEX OF HEART
• THICKER WALLS, MORE POWER
• PUMPS BLOOD TO BODY
• SEPTUM DIVIDES HEART
• INTERVENTRICULAR SEPTUM BETWEEN VENTRICLES
• INTERATRIAL SEPTUM BETWEEN ATRIA

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CHAPTER 15

• HEART
• FUNCTIONS AS A DOUBLE PUMP
• RIGHT SIDE PULMONARY CIRCUIT
• RECEIVES OXYGEN POOR BLOOD AND SENDS IT TO LUNGS
• RECEIVES BLOOD FROM SUPERIOR INFERIOR VENAE
  CAVAE
• SENDS BLOOD THROUGH PULMONARY TRUNK
• SPLITS INTO RIGHT/LEFT PULMONARY ARTERIES
• CARRIERS BLOOD TO LUNGS PICKS UP OXYGEN AND
  UNLOADS CARBON DIOXIDE
• 4 PULMONARY VEINS DRAIN OXYGEN RICH BLOOD FROM
  LUNGSPULMONARY CIRCULATION

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CHAPTER 15

• PULMONARY VEINS ? LEFT SIDE OF HEART?OUT OF HEART
  THROUGH AORTA? FROM WHICH SYSTEMIC ARTERIES
  BRANCH TO SUPPLY BODY WITH OXYGEN AT
  TISSUES?VEINS? SUPERIOR INFERIOR VENA CAVAE
  SYSTEMIC CIRCULATION

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CHAPTER 15

• VALVES
• PREVENT BACKWARD FLOW
• ATRIOVENTRICULAR VALVES (AV VALVES)
• LIE BETWEEN ATRIA VENTRICLES
• LEFT BICUSPID OR MITRAL VALVE
• TWO FLAPS OR CUSPS
• RIGHT TRICUSPID
• THREE FLAPS OR CUSPS

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CHAPTER 15

• CHORDAE TENDINEAE TINY WHITE CORDS ANCHORED TO
  FLAPS AND TO WALLS OF VENTRICLES
• HEART IS RELAXED
• AV VALVES HANG LIMPLY INTO VENTRICLE
• HEART IS CONTRACTING
• INTERVENTRICULAR BLOOD PRESSURE INCREASES
• CAUSES AV FLAPS TO BE FORCED UPWARD

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CHAPTER 15

• SEMILUNAR VALVES
• PULMONARY 3 LEAFLETS(FLAPS)
• LIES BETWEEN RIGHT VENTRICLE AND PULMONARY ARTERY
• AORTIC 3 FLAPS
• LIES BETWEEN LEFT VENTRICLE AND AORTA
• VALVES OPERATE AT DIFFERENT TIMES
• AV VALVES OPEN DURING RELAXATION CLOSED WHEN
  VENTRICLE CONTRACTING
• SEMILUNAR CLOSED DURING HEART RELAXATION OPEN
  WHEN VENTRICLES CONTRACT

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CHAPTER 15

• CARDIAC CIRCULATION
• BLOOD INSIDE CHAMBERS BEING PUMPED DOES NOT
  NOURISH HEART
• CORONARY ARTERIES SUPPLY BLOOD OXYGEN TO
  HEART WHEN HEART IS RELAXED
• RIGHT LEFT CORONARY ARTERIES BRANCH FROM AORTA
  ENCIRCLE HEART IN CORONARY SULCUS
  (ATRIOVENTRICULAR GROOVE)

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CHAPTER 15

• MAJOR BRANCHES OF CORONARY ARTERIES
• LEFT
• ANTERIOR INTERVENTRICULAR
• CIRCUMFLEX
• RIGHT
• POSTERIOR INTERVENTRICULAR
• MARGINAL
• DRAINED BY CARDIAC VEINS EMPTY INTO CORONARY
  SINUS (BIG VEIN) ON POSTERIOR SIDE OF HEART
  ?RIGHT ATRIA

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CHAPTER 15

• DISORDERS
• TACHYCARDIA BEATS TOO FAST
• MYOCARDIUM HAS INADEQUATE BLOOD SUPPLY BEATS
  FASTER TO ACCOMMODATE
• ANGINA PECTORIS MYOCARDIUM IS DEPRIVED OF
  OXYGEN
• CREATES CRUSHING CHEST PAIN
• INFARCT DEATH OF HEART TISSUE CAN LEAD TO
  MYOCARDIAL INFARCTION (HEART ATTACK)

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CHAPTER 15

• HEART PHYSIOLOGY
• ONE DAY 6 LITERS AROUND BODY 1000 TIMES
• CARDIAC MUSCLES CAN CONTRACT SPONTANEOUSLY
  INDEPENDENTLY
• UNFORTUNATELY NOT AT THE SAME RATE
• ATRIAL CELLS 60 BEATS /MIN
• VENTRICULAR CELLS 20-40 BEATS /MIN
• SO A CONTROL SYSTEM IS NEEDED

27
CHAPTER 15

• TWO SYSTEMS
• AUTONOMIC NERVOUS SYSTEM
• ACTS TO SLOW HEART OR ACCELERATE HEART DEPENDING
  ON WHICH PART OF ANS IS STIMULATED
• INTRINSIC CONDUCTION SYSTEM
• BUILT INTO HEART TISSUE IT SETS THE BASIC
  RHYTHM
• UNIQUE TISSUE IN BODY FOUND ONLY IN HEART

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CHAPTER 15

• MOST IMPORTANT
• CRESENT-SHAPED NODE OF TISSUE SINOATRIAL NODE
  (SA NODE) LOCATED IN RIGHT ATRIUM
• PACEMAKER BECAUSE IT HAS FASTEST RATE
• ATRIOVENTRICULAR NODE (AV NODE)
• LOCATED AT JUNCTION OF ATRIA VENTRICLE

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CHAPTER 15

• RIGHT LEFT BUNDLE OF FIBERS
• LOCATED IN INTERVENTRICULAR SEPTUM
• PURKINJE FIBERS SPREAD WITHIN MYOCARDIUM OF
  VENTRICLES
• SA NODE? AV NODE? BUNDLE FIBERS ?PURKINJE FIBERS
• CAUSES A WRINGING CONTRACTION BEGIN AT APEX
  MOVES UPWARD

31
ATRIA
VENTRICLES
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CHAPTER 15

• HEART BLOCK WHEN ANY PART OF CONDUCTION SYSTEM
  IS DAMAGED VENTRICLES BEAT AT LOWER RATE
  (SLOWER)
• FIBRILLATION RAPID UNCOORDINATED SHUTTERING
• BRADYCARDIA SLOW HEART RATE

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CHAPTER 15

• HEART CYCLE
• SYSTOLE CONTRACTION
• DIASTOLE RELAXATION
• AVERAGE HEART RATE 75/MIN
• HEART CYCLE LASTS ABOUT .8 SECONDS

34
CHAPTER 15

• HEART SOUNDS
• LUB DUP
• LUB CLOSING OF AV VALVES
• DUP CLOSING OF SEMILUNAR VALVES
• MURMURS ABNORMAL HEART SOUNDS
• USUALLY INDICATE HEART PROBLEMS
• VALVE NOT CLOSE TIGHTLY BLOOD FLOWS BACKWARD

35
CHAPTER 15

• CARDIAC OUTPUT (CO)
• AMOUNT OF BLOOD PUMPED OUT PER MINUTE
• HEART RATE (HR) x STROKE VOLUME (SV)
• EX 75 BEATS/MIN x 70 ML/BEAT
• 5250 ML/MIN

36
CHAPTER 15

• CARDIAC OUTPUT VARIES WITH DEMANDS OF BODY
• INCREASE BY INCREASE IN STROKE VOLUME OR HEART
  RATE INCREASE
• DECREASE BY DROP IN STROKE VOLUME OR HEART RATE

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CHAPTER 15

• STARLINGS LAW OF THE HEART
• FACTOR CONTROLLING STROKE VOLUME HOW MUCH
  CARDIAC CELLS ARE STRETCHED JUST BEFORE THEY
  CONTRACT
• MORE STRETCHED MORE CONTRACTION POWER
• ONE FACTOR CAUSING STRETCHING IS AMOUNT OF BLOOD
  ENTERING HEART

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CHAPTER 15

• FACTORS MODIFYING BASIC HEART RATE
• USUALLY STROKE VOLUME IS FAIRLY CONSTANT
• BLOOD LOSS WEAKENED HEART DECREASE STROKE
  VOLUME AND CARDIAC OUTPUT IS THEN MAINTAINED BY
  INCREASE IN HEART RATE

40
CHAPTER 15

• ANS CONTROL
• UNDER PHYSICAL EMOTIONAL STRESS
• SYMPATHETIC DIVISION OF ANS STRONGLY STIMULATES
  SA AV NODES AND CARDIAC TISSUE INCREASED
  HEART RATE
• PARASYMPATHETIC (MOSTLY VAGUS NERVE) SERVES TO
  SLOW STEADY THE HEART

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CHAPTER 15

• CONGESTIVE HEART FAILURE
• HEART IS NEARLY WORN OUT DUE TO
• AGE
• HYPERTENSIVE HEART DISEASE
• PATHOLOGICAL DISORDER
• HEART PUMPS WEAKLY
• DIGITALIS IS USUALLY PRESCRIBED TO INCREASE
  CARDIAC OUTPUT

43
CHAPTER 15

• EPINEPHRINE (HORMONE)
• MIMICS EFFECTS OF SYMPATHETIC NS BY INCREASING
  HEART RATE
• ALSO CALLED ADRENALINE
• LACK OF SODIUM POTASSIUM IONS ALSO CAUSES HEART
  TO BEAT FEEBLY OR ABNORMALLY

44
CHAPTER 15

• PHYSICAL FACTORS AFFECT HEART RATE
• AGE, GENDER, EXERCISE, BODY TEMPERATURE
• FETUS 140-160 BEATS/MINUTE GRADUALLY
  DECREASING THROUGH LIFE
• FEMALES 72-80 BEATS/MINUTE
• MALES 64-72 BEATS/MINUTE

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CHAPTER 15

• FEVER INCREASES HEART RATE
• EXERCISE INCREASES HEART RATE
• COLDNESS DECREASES HEART RATE
• BLOOD VESSELS
• VASCULAR SYSTEM
• WILLIAM HARVEY PROVED 300 YRS AGO THAT BLOOD DID
  CIRCULATE

46
CHAPTER 15

• ARTERIES ? CARRY BLOOD AWAY FROM HEART SEND
  BLOOD TO SMALLER AND SMALLER ARTERIES ?
  ARTERIOLES ? CAPILLARY BEDS LOCATED IN TISSUES
• CAPILLARY BEDS ARE DRAINED BY VENULES ? VEINS ?
  CARRY BLOOD TO THE HEART

47
CAPILLARY
VEIN
VALVE
ARTERY
OXYGENATED BLOOD
DEOXYGENATED BLOOD
48
CHAPTER 15

• DIAGRAMS
• RED BLOOD VESSELS SYMBOLIZE ARTERIES
  OXYGEN-RICH BLOOD
• BLUE BLOOD VESSELS SYMBOLIZE VEINS OXYGEN-POOR
  BLOOD

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CHAPTER 15

• ANATOMY OF BLOOD VESSEL
• TUNICA INTIMA
• ENDOTHELIUM MADE UP OF SQUAMOUS EPITHELIUM
• INNER LAYER
• TUNICA MEDIA
• SMOOTH MUSCLE ELASTIC TISSUE LAYER
• MIDDLE LAYER
• TUNICA EXTERNA
• FIBROUS CONNECTIVE TISSUE LAYER
• OUTER LAYER

50
CHAPTER 15

• ARTERIES
• WALLS THICKER
• ESPECIALLY TUNICA MEDIA
• CLOSER TO PUMPING ACTION OF HEART

• VEINS
• THIN WALLS
• FAR FROM HEART SO HAVE LOW BLOOD PRESSURE
• LARGER DIAMETER
• HAVE VALVES TO PREVENT BACKFLOW
• CARRY BLOOD AGAINST GRAVITY
• ENHANCED BLOOD FLOW BY SKELETAL MUSCLE ACTIVITY

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CHAPTER 15

• CAPILLARY
• WALLS ARE ONE CELL THICK ENDOTHELIUM
• SO CARBON DIOXIDE OXYGEN EXCHANGE EASIER
• FORM INTERWOVEN NETWORKS CAPILLARY BEDS
• VASCULAR SHUNT VESSEL THAT RUNS THROUGH CENTER
  OF CAPILLARY BED VESSELS ON EITHER SIDE OF THE
  SHUNT ARE THE TRUE CAPILLARIES

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CHAPTER 15

• AORTA
• LARGEST ARTERY OF THE BODY
• SIZE OF GARDEN HOSE
• AS IT COMES OUT OF HEART ASCENDING AORTA
• ARCHES TO LEFT AORTIC ARCH
• DOWN THROUGH CHEST THORACIC AORTA
• PAST DIAPHRAGM ABDOMINAL AORTA

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57
CHAPTER 15

• FETAL CIRCULATION
• PLACENTA NUTRIENT/WASTE EXCHANGE OXYGEN/CARBON
  DIOXIDE EXCHANGE BETWEEN FETUS MOTHER
• UMBILICAL CORD
• ONE LARGE VEIN
• TWO LARGE ARTERIES

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59
CHAPTER 15

• DUCTUS VENOSUS
• VESSEL THAT BYPASSES LIVER ENTERS INFERIOR VENA
  CAVA
• FETAL CIRCULATION BYPASSES LUNGS
• FORAMEN OVALE
• HOLE BETWEEN RIGHT LEFT ATRIA
• DUCTUS ARTERIOSUS
• CONNECTS AROTA PULMONARY TRUNK
• ALL VESSELS COLLAPSE AND FORAMEN OVALE CLOSES
  SHORTLY AFTER BIRTH

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63
CHAPTER 15

• VITAL SIGNS
• RESPIRATION RATE
• BODY TEMPERATURE
• PULSE
• BLOOD PRESSURE

64
CHAPTER 15

• PULSE
• ALTERNATING EXPANSION RECOIL OF ARTERY
  PRESSURE WAVE
• FEEL ARTERY LYING CLOSE TO BODY SURFACE
• PRESSURE POINTS SAME PLACES CAN FEEL PULSE
  WHEN COMPRESSED CAN STOP HEMORRHAGE

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CHAPTER 15

• BLOOD PRESSURE
• PRESSURE BLOOD EXERTS AGAINST INNER WALLS OF
  BLOOD VESSELS
• FORCE KEEPS BLOOD CIRCULATING BETWEEN BEATS
• HIGHEST IN LARGE ARTERIES NEAR HEART DROPS
  THROUGHOUT PATHWAY REACHING NEARLY ZERO AT VENA
  CAVAE

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CHAPTER 15

• ARTERIOSCLEROSIS HARDENING OF ARTERIES
• LOSE ELASTICITY

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CHAPTER 15

• MEASURING BLOOD PRESSURE
• SYSTOLIC PRESSURE PEAK OF VENTRICULAR
  CONTRACTION FIRST NUMBER
• DIASTOLIC PRESSURE VENTRICULAR RELAXATION
  SECOND NUMBER
• MEASURED IN MM OF Hg
• NORMAL _at_ 120/80

69
SPHYGMOMANOMETER
70
CHAPTER 15

• ARTERIAL BLOOD PRESSURE
• DIRECTLY REALTED TO CARDIAC OUTPUT PERIPHERAL
  RESISTANCE (PR)
• PRAMOUNT OF FRICTION ENCOUNTERED BY BLOOD AS IT
  FLOWS
• BLOOD PRESSURE CARDIAC OUTPUT x PERIPHERAL
  RESISTANCE

71
CHAPTER 15

• FACTORS AFFECT BLOOD PRESSURE
• 1. NEURAL FACTORS (ANS)
• SYMPATHETIC NS CAUSES VASOCONTRICTION
  (NARROWING OF BLOOD VESSELS) INCREASE IN BLOOD
  PRESSURE

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CHAPTER 15

• WHEN YOU STAND UP, GRAVITY CAUSES BLOOD TO POOL
  IN YOUR LEGS
• BARORECEPTORS IN LARGE ARTERIES OF NECK/CHEST
  SEND OFF WARNING SIGNAL
• RESULTS IN VASOCONTRICTION OF BLOOD VESSELS WHICH
  INCREASED BLOOD PRESSURE

74
CHAPTER 15

• HEMORRHAGE (BLOOD LOSS)
• CAUSES DECREASE IN BLOOD PRESSURE
• INCREASE IN HEART RATE
• VENOUS RETURN IS REDUCED BY BLOOD LOSS
• HEART BEATS WEAKLY INEFFICIENTLY
• SYMPATHETIC NS CAUSES VASOCONTRICTION AND
  INCREASE IN BLOOD PRESSURE

75
CHAPTER 15

• EXERCISE/FRIGHT
• CAUSES GENERAL VASOCONSTRICTION EXCEPT IN
  SKELETAL MUSCLES WHICH ARE FLOODED WITH BLOOD

76
CHAPTER 15

• 2. RENAL FACTORS
• KIDNEYS PLAY LARGE ROLE IN REGULATING BLOOD
  PRESSURE BY ALTERING BLOOD VOLUME
• INCREASE IN BLOOD PRESSURE KIDNEYS ALLOW WATER
  TO LEAVE BODY AS URINE TO DECREASE BLOOD VOLUME
  AND LOWER BLOOD PRESSURE

77
CHAPTER 15

• BLOOD PRESSURE DECREASES
• KIDNEYS RETAIN BODY WATER AND INCREASE BLOOD
  VOLUME WHICH INCREASES BLOOD PRESSURE
• KIDNEYS ALSO RELEASE ENZYME RENIN ? TRIGGERS
  SERIES OF CHEMICAL REACTIONS THAT RESULT IN
• FORMATION OF ANGIOTENSIN II
• VASOCONSTRICTOR ALSO STIMULATES ADRENAL GLANDS
  TO RELEASE ALDOSTERONE

78
CHAPTER 15

• ALDOSTERONE (HORMONE) ENHANCES SODIUM ION
  REABSORPTION
• WHEN SODIUM MOVES INTO BLOOD ? WATER FOLLOWS ?
  INCREASE IN BLOOD VOLUME ? INCREASE IN BLOOD
  PRESSURE
• 3. TEMPERATURE
• COLD ? VASOCONSTRICTS INCREASES BLOOD PRESSURE
• HEAT ?VASODILATES DECREASES BLOOD PRESSURE

79
CHAPTER 15

• 4. CHEMICALS
• EPINEPHRINE
• INCREASES HEART RATE AND BLOOD PRESSURE
• NICOTINE
• INCREASES BLOOD PRESSURE DUE TO VASOCONSTRICTION
• ALCOHOL
• CAUSES VASODILATION WHICH DECREASES BLOOD
  PRESSURE
• HISTAMINE
• CAUSES VASODILATION WHICH DECREASES BLOOD PRESSURE

80
CHAPTER 15

• 5. DIET
• LOW IN SALT, FATS, AND CHOLESTEROL ? PREVENT
  HYPERTENSION (HIGH BLOOD PRESSURE)

81
CHAPTER 15

• BLOOD PRESSURE
• ADULTS
• 110-140 SYSTOLE
• 75-80 DIASTOLE
• VARIES WITH AGE, RACE, MOOD, PHYSICAL ACTIVITY,
  AND POSTURE
• HYPOTENSION LOW BLOOD PRESSURE
• BELOW 100 SYSTOLIC (USUALLY CAUSED BY POOR
  NUTRITION AND INADEQUATE PROTEIN)
• HYPERTENSION 140/90 OR HIGHER

82
CHAPTER 15

• CAPILLARY EXCHANGE OF GASES
• SUBSTANCES DIFFUSE ACROSS (LIPID SOLUBLE)
• SUBSTANCES ENTER/LEAVE WITHIN VESICLES
  (EXOCYTOSIS ENDOCYTOSIS)
• PASS THROUGH INTERCELLULAR CLEFTS (GAPS BETWEEN
  CELLS) PRESENT IN ALL CAPILLARIES EXCEPT IN THE
  BRAIN (BLOOD BRAIN BARRIER)

83
CHAPTER 15

• FREE PASSAGE BY FENESTRATED CAPILLARIES WHERE
  ABSORPTION IS PRIORITY
• INTESTINES KIDNEY
• PORES (FENESTRA) ARE COVERED BY MEMBRANES THAT
  SUBSTANCES PASS THROUGH
• BULK FLOW
• BLOOD PRESSURE FORCES FLUIDS OUTWARD
• OSMOTIC PRESSURE PUSHES FLUID BACK INTO
  BLOODSTREAM

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85
CHAPTER 15

• BLOOD PRESSURE IS HIGHER AT ARTERIOLE END OF
  CAPILLARY BED
• OSMOTIC PRESSURE IS HIGHER AT VENULE END OF
  CAPILLARY BED
• FLUID MOVES OUT AT BEGINNING OF CAPILLARY BED AND
  INTO TISSUE
• FLUID MOVES BACK INTO BLOOD AT END OF CAPILLARY
  BED

86
CHAPTER 15

• ELECTROCARDIOGRAM (ECG)
• RECORDING OF ELECTRICAL CHANGES OCCUR IN THE
  MYOCARDIUM DURING CARDIAC CYCLE
• ELECTRODES ON SKIN INSTRUMENT RESPONDS TO
  CHANGES IN WEAK ELECTRICAL SIGNAL AND RECORDS

87
CHAPTER 15

• RESULTS IN SPECIFIC PATTERN

88
CHAPTER 15

• A Typical EKG Record Contains P, QRS and T Waves
• The P wave is caused by depolarization
  (excitation) of the atria

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CHAPTER 15

• The QRS is produced by depolarization
  (excitation) of the ventricles
• The T wave represents repolarization (recovery)
  of the ventricles

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CHAPTER 15

• Different electrodes give different views of
  these waves- the wave below is typical for lead
  II (positive electrode on left ankle and negative
  electrode on right wrist)

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