Heart Model 1

Heart Model 2

Heart Model 3

Heart Model 4

Heart Model 5

I. DESCRIPTION OF THE HEART

  1. HOLLOW, MUSCULAR ORGAN THAT LIES BETWEEN THE LUNGS IN THE MEDIASTINUM
  2. APEX - DIRECTED DOWNWARD, THE BASE DIRECTED UPWARD
  3. ENCLOSED IN THE PERICARDIUM
    1. VISCERAL - INNER LAYER
    2. PARIETAL - OUTER THICK CONNECTIVE LAYER INNER SEROUS LAYER
    3. SEPERATED BY THE PERICARDIAL CAVITY
  4. MYOCARDIUM -
  1. ENDOCARDIUM -
  2. EPICARDIUM -
  3. HEART CHAMBERS :

RIGHT AND LEFT ATRIA - RECIEVE BLOOD
RIGHT AND LEFT VENTRICLES - PUMP OUT

  1. EACH OPENING BETWEEN ATRIUM AND VENTRICLE IS GAURDED BY AN ATRIOVENTRICULAR ( AV ) VALVE

AV LEFT – BICUSPID ( MITRAL )

AV RIGHT - TRICUSPID

  1. SEMILUNAR VALVES ARE BETWEEN EACH VENTRICLE AND THE ARTERY IT SUPPLIES.

 

AORTIC - LEFT VENTRICLE AND DESCENDING AORTA
PULMONIC - RIGHT VENT. AND PULMONARY ARTERY

*** BLOOD FLOW :

RIGHT ATRIUM - RIGHT VENTRICLE - PULMONARY CIRCULATION - LEFT ATRIUM - LEFT VENTRICLE - SYSTEMIC CIRCULATION

J.       * BETWEEN THE TWO ATRIA IS THE INTERATRIAL SEPTUM
* BETWEEN THE TWO VENTRICLES IS THE INTERVENTRICULAR SEPTUM
* A DEPRESSION IN RIGHT ATRIUM IS THE FOSSA OVALIS :

( MARKS THE OPENING THAT ONCE WAS THE FORAMEN OVALE )

K.    * AURICLES IN EACH ATRIUM INCREASE THE STORAGE CAPACITY
* ATRIUM HAS SMALL MUSCULAR BUNDLES - MUSCULI PECTINATI
* WALLS OF ATRIUM ARE THINNER THAN VENTRICLES
* INFERIOR AND SUPERIOR VENA CAVA EMPTY INTO R. ATRIUM
* THE CORONARY SINUS RETURNS BLOOD FROM THE HEART - R.A.

  1. CORONARY ARTERIES :

* TWO - BRANCHED RIGHT AND LEFT
* RIGHT ORIGINATES FROM THE AORTA
* BRANCHES OF RIGHT INCLUDE :

MARGINAL BRANCH
POSTERIOR INTERVENTRICULAR
AV NODE BRANCH

* LEFT ORIGINATES FROM THE ASCENDING AORTA
* MAJOR BRANCHES INCLUDE :

ANTERIOR INTERVENTRIC
CIRCUMFLEX

II. CARDIAC CYCLE

    1. HEART CAN BEAT INDEPENDENT OF THE NERVOUS SYSTEM

* EACH BEAT INIATED IN THE SINOATRIAL (SA ) NODE
* ACTION POTENTIAL SPREADS OVER THE ATRIA
* CAUSES ATRIAL CONTRACTION
* FIBERS CONDUCT THE ACTION POTENTIAL TO THE AV NODE
* SPREADS THROUGH PURKINJE FIBERS TO FIBERS OF VENT.
* SHORT PAUSE .1 SEC. AT AV NODE ( ALLOWS ATRIUM TO CONTRACT FULLY )

    1. SEQUENCE OF EVENTS IN ONE CARDIAC CYCLE
      • ACTION POTENTIAL GENERATED IN SA NODE
      • THIS RESULTS IN ATRIAL SYSTOLE
      • BLOOD FORCED INTO VENT. AS ATRIUM CONTRACTS
      • VENTRICULAR SYSTOLE IS NEXT
      • FORCES BLOOD INTO EITHER PULMONARY OR AORTA
      • AT SAME TIME, ATRIA HAVE RETURNED TO DIASTOLE
      • ATRIA BEGIN FILLING WITH BLOOD
      • VENTRICLES ENTER DIASTOLE
      • AORTIC AND PULMONARY VALVES CLOSE
      • TRICUSP AND BICUSP OPEN
      • ATRIUM FILLS WITH BLOOD - SEQUENCE REPEATS

80 TIMES PER MINUTE AVERAGE VOLUME
4800 PER HOUR 5000 ml
115,200 PER DAY MAX - 14 liters
42,048,000 PER YEAR ( X AGE )

B.     * HEART SOUNDS ARE THE RESULT OF VALVES CLOSING
* FIRST SOUND - CLOSING OF TRICUSP AND MITRAL AVLVE
* SECOND SOUND - VENT. SYSTOLE - CLOSE PUL. AND AOTRIC VALVES
* SOMETIMES A THIRD SOUND CAN BE HEARD - BLOOD MOVING TO VENT.

C.     * PQRS COMPLEX
* P - Q INTERVAL : PERIOD TIME BETWEEN P WAVE AND QRS COMPLEX
* P IS THE DEPOLARIZATION OF THE ATRIA
* QRS IS POINT WHERE VENTRICLE DEPOLARIZES
* T IS REPOLARIZATION OF VENTRICLE
* ATRIAL REPOLARIZATION IS NOT SEEN BECAUSE IT OCCURS AT THE SAME TIME AS THE DEPOLARIZATION OF THE VENTRICLES

III. BLOOD VESSELS

    1. STRUCTURE OF THE ARTERIES :
      • THREE TUNICS :

* TUNICA INTIMA - INNERMOST - EPITHELIUM
* TUNICA MEDIA - MIDDLE - SMOOTH MUSCLE
* TUNICA ADVENTITIA - CONNECTIVE TISSUE : ELASTIC,COLLAGEN
* SEROUS OUTER LAYER

      • ARTERIOLES ARE MICROSCOPIC BRANCHES OF ARTERIES
      • META ARTERIOLES JOIN THE CAPALLARIES
      • SMOOTH MUSCLE ALLOWS VASO DILATION AND CONSTRICTION
      • SMOOTH MUSCLE IS INNERVATED BY SYMPATHETIC BRANCHES
      • ARTERIOVENUS SHUNTS - SOME METARTERIOLES CONNECTED DIRECTLY TO VEINULE .
    1. CAPILLARIES
      • OPENINGS IN CAPILLARY WALLS ARE THIN SLITS
      • SIZES VARY
      • ENDOTHELIAL CELLS OF BRAIN ARE TIGHT - BLOOD BRAIN BARRIER
      • LARGEST OPENINGS ARE FOUND IN THE LIVER, SPLEEN, RED MARROW
      • SMALL IN SMOOTH, CARDIAC, SKELETAL MUSCLE
      • CAPILLARY DENSITY VARIES WITH METABOLIC RATE OF TISSUE
      • HIGH RATES FOUND IN MUSCLE AND NERVE
      • LOW RATE FOUND IN CARTILAGE, CONNECTIVE TISSUE, ETC
      • SUBSTANCE LEAVES CAPILLARY BY HYDROSTATIC PRESSURE
      • ENTER CAPILLARIES BY OSMOTIC PRESSURE
      • DIFFUSION IS IMPORTANT IN GAS TRANSPORT

* PRESSURE FROM HIGH TO LOW :
ARTERY - ARTERIOLE - CAPILLARY - VEINULE - VEIN
* LIPID SOLUABLE ( O, CO2, FATTY ACID ) DIFFUSE THROUGH MEMBRANE
* LIPID INSOLUABLE ( H2O, CL, NA, ) DIFFUSE THROUGH PORES
(( REFER TO PAGE 673 IN TEXT ))

    1. VEINS :
      • VEINULES CONTINUE FROM CAPILLARIES
      • CARRY BLOOD TOWARD THE HEART
      • WALLS ARE SIMILAR TO ARTERIES BUT THINNER
      • LESS MUSCLE AND ELASTIC TISSUE
    2. BLOOD PRESSURE :
      • ARTERIAL BP CAUSED BY ACTION OF HEART MUSCLE
      • SYSTOLE - VENTRICULAR CONTRACTION
      • DIASTOLE - VENTRICLE RELAXES
      • CONTROL OF BLOOD PRESSURE :

* CONTROLLED BY MECHANISMS THAT REGULETE CARDIAC OUTPUT AND PERIPHERAL RESISTANCE
* CARDIAC OUTPUT IS THE VOLUME OF BLOOD FORCED OUT OF VENTRICLE IN EACH CYCLE
* REGULATED BY THE CARDIAC CENTER OF THE MEDULLA OBLONGATA
* PERIPHERAL RESISTANCE CONTROLLED BY THE VASOMOTOR CENTER OF THE MEDULLA OBLONGATA

VEINOUS BLOOD FLOW :

* NOT DIRECTLY CAUSED BY HEART PRESSURE
* DEPENDS MOSTLY ON SKELETAL MUSCLE CONTRACTION
* RESPIRATORY ACTION ALSO MOVES VEINOUS BLOOD
* VEINS CONTAIN VALVES TO PREVENT BACK FLOW
* CENTRAL VEINOUS PRESSURE IS THE PRESSURE IN THE R. ATRIUM
* VARICOSE VEINS

H.