PNB Heart

• Endocardium (covers heart wall)
• myocardium (middle layer, consists of cardiac muscle)
• epicardium (visceral layer of serous pericardium)
• pericardial cavity (paricardial fluid-prevents friction and heat)
• Parietal Pericardium
• Fibrous Pericardium (fibro-serous membrane, covers heart-made of collagen=high tensile strength/NO compliance)

• 1.Aortic Semilunar valve 
• 2.Coronary artery  
• 3.Systemic Capillary bed 
• 4.Coronary vein  
• 5.Coronary sinus 
• 6.Tricuspid valve
• 7.Pulmonary trunk 
• 8.Pulmonary vein

• -prevent eversion of bicuspid valve
• -contract during ventricular systole

• -SA node depolarizes
• -depolarization of atrial myocytes (AP spreads through gap junctions in intercalated disks)
• -AV node depolarizes
• -signal is slowed down/delayed
• -signal reaches bundle of His
• -two bundle branches (right/left)
• -signal reaches APEX of ventricles
• -Purkinje fibers (originate from the bundle branches--spread superiorly and laterally; also spreads into the ventricular muscle.

OXYGENATED BLOOD: LT atrium-->AV valve-->LT ventricle-->aortic SL valve-->aorta-->elastic arteries-->muscular arteries-->arterioles-->capillaries (bed)-->


O2 blood out the aorta,--> elastic arteries-->muscular arteries--> to arterioles, to capillaries for exchange, back to heart via Vena Cava

DEOXYGENATED: RT ATRIUM-->RT VENTRICLE --> pulmonary trunk-->pulmonary arteries-->lungs-->arterioles-->pulmonary capillaries-->OXYGENATED venules-->pulmonary veins-->left Atrium

• -valves
• -compliance, stretch

• VENTRICLES: blood AWAY from heart
• ATRIA: RECEIVES blood

• tricuspid (right AV)-- supported by papillary musc/choridae tendon 
• pulmonary SL 
• SA node

• Bicuspid (Left AV) --- supported by papillary musc/choridae tendon 
• Aortic SL

BLOOD FLOW: vena cava OR pulmonary veins-->atrium-->AV valve-->Ventricle

-->AV/SL valves CLOSE (leading to isovolumetric)-->ventricular filling-->ventricular pressure EXCEEDS aortic or pulmonary trunk-->SL valves open-->ventricular ejection

BEGINS: when ventricle relaxes after ejection, blood flowing back to ventricle causes SL to close. BOTH VALVES CLOSED

atrial pressure GREATER than ventricular pressure, AV VALVES OPEN-->ventricular filling

end of ventricular systole

visceral pericardium, squamous epithelium, areolar CT, fat

• cardiac muscle attached to fibrous skeleton of heart
• "wringing" contraction
• made of collagen and elastin

• areolar CT and squamous endothelium
• anchored by thing CT layer

• -Coronary artery delivers O2 blood to cardiac muscle  (branching off aorta)
• -capillary within cardiac muscle, blood drains into coronary veins
• -coronary vein--empty into coronary sinus
• -blood returned to RIGHT atrium

• inferior vena cava-systemic circ.
• superior vena cava-systemic circ. 
• coronary sinus

AV bundle

angina: ischemia (cut off blood flow), vasospasm, short-lived, no cell death

MI: blockage of O2 to cardiac muscle, cell death

sinus rhythem

EDV-ESV

(EDV-ESV)/EDV

>55%

Diastolic + 1/3 pulse pressure

CO(max) - CO (rest)

• length of ventricular DIASTOLE
• venous return (inc. EDV)

• Mean Arterial Pressure
• contractility (harder contraction, dec. ESV)

• DEGREE OF STRETCH
• increased EDV (main INTRINSIC factor)

• any factor that increases volume or speed of venous return, thus increasing EDV --> increase stretch and force of contraction to pump out "extra blood"INTRINSIC (ESV&EDV)
• due to length tension curve...
• the more the heart is filled with blood, the more blood will be pumped out.

• EXTRINSIC: ANS/hormones
• -sympathetic stimulation
• -EPI from adrenal medulla (increase Ca2+)
• -increase force of contraction and rate-->more blood ejection
• (Independent to EDV/muscle stretch)
• -lower ESV, higher stroke volume

radius(to the 4th power) THEN divide 1/R4

• INTRINSIC:
• ventricular pressure must exceed arterial pressure

92!

afterload increases, affecting ESV and lowering stroke volume

heart must increase force of contraction-->DAMAGE longterm

Flow=change of pressure/radius

• AV....
• SA pushes AV to threshold

Depolarization of atria (following by Atrial contraction)

depolarization of ventricles (followed by ventricular contraction

Repolarization of ventricles

atria contract and begin to relax

appx length of time it takes for ventricles to contract (depolarization) and relax (repolarization)

Pacemaker in the wrong place

• Medulla/cardioacceleratory
• inc rate and inc force

• Medulla/cardioinhibitory by G-protein inhibiting adenyl cyclase, decrease in cAMP, decrease activity of HCN acting on channels
• (vagus nerve)

heart rate ONLY

heart rate AND ventricular muscle strength of contraction (stroke volume)

blood pressure regulation

• increased MAP/BP-->
• increased strength of wall-->
• stimulate baroreceptors -->
• inhibit sympathetic
• increase parasympathetic .....

pH and O2 level