Ch.20 ❤️

Heart circulation

Double cardiovascular system

Congestive Heart failure

Layers of Heart

in → out

1. Endocardium (simple squamous & connective tissue)

2. Myocardium

3. Parietal Pericardium

• Pericardial cavity = pericardial fluid

Where is the Heart?

b/t Lungs at MEDIASTINUM = b

Why are the ventricles the same size?

to stop congestion = same volume → ventricles same size but the left has more myocardium

Functions of Heart Skeleton - Passive 80% filling of ventricles & delay?

Vacuum - atria contracting 20% into ventricles rest is like a medicine dropper
1. Electrical insulator b/t atria & ventricles

• delay → skeleton stops action potential from going straight to ventricles

2. anchors myocardium → spiral structure alows most output

3. Valve seat - memo

how do we prevent congestion on RIGHT atria?

fibrous connective tissue - chordae tendineae f that attached to papillary muscles on the ventricles
- attatch to flap of atriventricular valve
when heart contaracts blood preasurre pushing up - papillary will keep it from inverting(prolapsing)

Heart skeleton

InterATRIAL septum

Foramen ovalis → Fossa ovalis after birth

Heart sounds

LUB - AV valves CLOSIN
DUB - Semilunar Pulmonary & aortic valves CLOSING w/ more force

Left side Ventricular preassure - 10 torr which increases to 120?

Heart murmurs - Valve disease LESS CARDIAC OUTPUT → CONGESTIVE HR FAILURE

1. Valvular STENOSIS
   - hardening & Narrowing
   Result - pump faster/harder

2. Valvular incompetence/Regurgitation
   Closes weird - blood goes back → flaging sound
   
   CONGESTIVE HR FAILURE → Chronic disease on Cardiac Output that could lead to Respiratory problems etc all because of different pressure equlization

Coronary Circulation

Blood supply to myocardium
coronary arteries taking blood to capillary muscle

Cardiac Cycle

1. Mid diastole - ventricles = relaxing & expanding
   - Passive filling 80%, 20% atria contraction

5. End of systole/start of distole - ventricles relax and their preassure drops (L 120→80) when this occurs semiluar valves close
   - all 4 valves shut → isovolumetric relaxation and we have end systolic volume =70ml

Stroke volume

SV- volume of blood pumped out Left Ventricle (& right V) EACH BEAT
SV= EDV(150ml)-ESV(70ml) = 80ml/stroke

Cardiac Output

volume of blood pumped our of LV in 1min
CO= stroke volume x stroke rate
CO= 80ml/stroke x 70 stroke/mins = 5,600 ml/min AT REST

Average Human has how much blood?

~5500ml of blood
avg human 165 lbs 5’8

Can stroke volume and cardiac output change? look over this

Yes, increased or decrease

Action potentials

Membrane resting potential = average cell potential energy = -70mv , inside = 12 Na⁺ , 155 K⁺ 155 protein-, Outside = 145 Na , 4 K⁺ , 0 protein

Na/k Pump = To keep them at the proper distribution to stop equalization through diffusion and maintain charge

Cardiac Muscle (myocardium) consists of

1. Single cells w/ nucleus

2. connected by INTERCALATED DISCS

3. Autorhythmic (myogenic contractions) '
   Generates OWN action potentials

4. Fibers=branched

Intercalated discs → thanks to gap junctions myocardium → connects them as two big cells (atria/ventricles) because theres no membrane

• adhesion fibers stronger than membrane

• HIGHLY permeable

Skeletal muscle fiber - connected to neurons

2 types of Myocardium

1. Contractile cell→ pump

2. Conductive cell→ specialized myocardium = generate & conduct AP

Pacemaker Sinoatrial node (SA)

1. No resting potential

2. NO NEED FOR EXTERNAL STIMULUS = no neuron connection

3. Rate is 100-120bpm

Na continuously leaks gets to threshold +50
Ca⁺⁺ chennels open & leaks → spike UP Depolarization (two charges make it quicker)
+20 Na channelscloses
K open K goes out cell → -60 → K channels close → K UP

Contractile cells

Resting potential -90 → +20
If it wasn’t under ANS → 110 bpm
Long refractory period → avoids cramping, allows Contraction→ Relax

Electrical flow

1. SA node sets pace by generating PP (55-200bpm)

2. intermodal fibers 1m/sec - conduct AP → ATRIA & AV node

AV node 0.1 m/sec

• Delays AP

Cardio skeleton = electrical insulator so AP goes through AV bundle → bundle branches→ purkinje fibers
4-6 = 8-10 m/sec

4. AV bundle in septum

5. bundle branches each ventricle

6. Purkinje fibers

7. myocardium of ventricles
   
   moderate → slow→sonic speed

Contractile cells

conducts pacemaker potentials and leads it to contractile cells