• Pulmonary circulation- must more despensible ( place to hide fluid) not as controllable.

• Systemic circulation-

These two systems rely on 2 things for control

Volume & Pressure distribution (work opposite) ex High pressure Low volume- (highest pressure in left ventricle- aorta- lrg arteries, sm arteries, arteriols, cap, vein) .

  These two systems are dependent on Flow & Volume

Hemodynamics of Blood flow

Pressure vs Resistance- Heart creates pressure, size of vessels create resistance(bigger vessel less resistance)

Flow types?

•   Laminar Flow- Serum fluid on outside of lumin that is next to the vessel all other elements are inside- this makes nice smooth flow of blood.

• Turbulant Flow- elements are bouncing around of the walls sometimes d/t obstruction or valve problem. Elements fall out of solution and into walls, we can hear this (brewy, murmur) We don’t want this because it causes damage to blood flow.

Layers of Heart?

Pericardium- Fibrous sac that covers the heart

Myocardium- Heart muscle.
Sarcomeres- contracts heart, interwoven in myocardium then called SYNCYTIUM- all of these fibers will work together so we have good even smooth contractions=GOOD start at top go to bottom.

Intercalted disc- connect the fibers- provide for easy conduction for action protential from one fiber to next keep their from being a delay.Small cells with large mitochondria d/t work hard and use up energy small endoplasmic retic d/t not making anything protein- Rely on extracelluar CA+  to start the process.(cardiac myocytes side)

Endocardium- membrane lines inside of heart

 Valves & Fibrous Skeleton- Inside heart

Cardiac Myocytes

• ·         Myocardial Myoctyes conduct AP cell to cell via conjunction gap, interac disk in their allows AP to move smoothly from one fiber to the next

• ·         Many contractile elements in each cell

Sarcoplasmic reticulium

• ·         inside cardiac myocte- this is a labryth hollow membrain that stores calcium

• ·         Extracellular Calcium- move into cell as AP begins it opens up sarcoplasmic reticulum and allows large amounts of CA+ into the cytoplasm to initiate a muscle contraction. We do not want calcium in our cells at all times we want to keep it in the sarcoplasmic reticulium because to much can cause damage.

Protiens that enable contraction of Cardiac Muscle( Ca+ starts this)

• ·         Globular actin proteins- forms helix around nebulin

• ·         Troponin & Tropomysin- come together to for stability to form

• ·         Thin filament- interacts with thick filament to become stable.

o   Ca+ comes out of SR-hooks up to troponin turns and becomes thick filament-

• actin & myocin want to hook up and when they do this causes muscle shortening which is muscle contraction itself- Need ATP when muscle moves this is known as power stroke – after power stroke mycin lets go- filament turns away- this is how muscle moves.

From action potential to mechanical contraction

• AP- extracellular ca comes in- calcium released from SR- intracellular free calcium attaches to troponin- actin & Myocin cross-bridge- myocardial cell shortening= movement.

Cardiac Cycle- Starts with Systole- Pumps blood out of heart

• ·         Isovolumetric contraction= vessel has been loaded full of fluid stretches- stretch creates contraction amount of stretch determines strength of contraction

• ·         Veticles are filled with blood- ventricles contract

• ·         Pushes thru tricuspid & mitral values closing= first heart sound

• ·         Pushes thru semilunar valves into aorta and pulm artery out of heart

• ·         Blood flows into lungs & aorts= whole process systole

Cardiac Cycle- Diastole- relaxed- prepares heart fills heart

• ·         Ventricles relax pressure on pulm and aortic valve stop they close= 2^nd heart sound

• ·         Blood enters artia flows thru AV vlaves into ventricles

• ·         Atria contracts forcing blood into ventricles.

• o   During diastole when heart is relaxed coronary arteries are perfuse= diastole is important

Effective CO depends on 3 factors= meaning of life

1. Preload
2. afterload
3. contractibility

Preload

• ·         Volume wrk of heart( pool) Volume/ pool of blood

• o   Starling Law- force of contraction determined by amount of stretch

• o   Higher amounts of volume= to much stretch= bad actin and myocin can’t hook up= saggy stretched out heart is what will happen and you will never have good preload.

Afterload

• ·         Pressure work of heart(pipes) Reistance of size of pipes= blood pressure

• o   The pressure the heart must overcome to pump blood out of the body

• o   The size and dispensability of vessels control this= is my artery clear or clogged?

·         Contractility-(pump)

• o   HR- determis time spent in diastole filling time of ventricle and perfusion of arteries

Don’t want tachy/brady  Filling time has to be just right

• o   Rythem- Orderly contract of myocardium= effective pumping action

  Orderly progression- A-V-A-V

How do we control our heart?

Autonomic control of cardiac function

• ·         Parasympathetic

• Medulla

• o   Vagus Nerve

• o   Slowing for heart

• o   Neurotransmitter is ACH

• ·         Sympathetic

• o   Thoracic spinal nerves

• o   SA, AV myocardium
•  Increase rate of contraction
• o
  
•   Neruotransmitter is Norepi

Vascular System- differenct b/t veins & Ateries (MECHANICAL)

• ·         Aterial- Ateries- thick muscle layer can control easier.

• o   Pump Left Vent for arterial side- goes through capillaries and then enters Venous side which has no pump

• ·         Venous-veins=no pump

• ·         Depend on valves to open and close once past valve cant move backwards

• ·         Skeletal muscles provide pump for venous muscles- squeeze veins to move blood.

Humoral Control of Blood Flow- change size of vessel

• Short term-Localized area

• o   Autoregulation- Need for 02 or waste removal vessels will dilate to creat more blood flow in area.

• o   Reactive Hyperemia- Increase in blood flow after lose of blood flow- ex lean on arm for awhile turns red you move to releize pressure blood flows back.

·         Endothelial Control- vessels monitor need

• o   Create Nitric Oxide- causes constant smooth muscle relaxation = make vessel bigger & same time there is vasoconstrictors (endothelins, All, PG) they will constrict make vessel smaller.

Nitric Oxide

• ·         secreted into leuman protects against clotting and vasoconstriction d/t it constantly tries to relax muscle to control vessels.

·         Long term- control

• o   Angiogenesis/ collateral circulation to control area- created in response to over the wall hall.

• o   Microcirculation- all living takes place

1. Capillary structure

1.  Interstitum- a lot of fluid protein collogen & fiber way to get stuff to cells that are not directly against a capillary.

·         Capillary- Interstitium fluid exchange

• o   Capillary hydrostatic pressure- fluid inside pushing out

• o   Capillary colloidal osmotic pressure- pulls particles in

• o   Intertial fluid hydrostatic pressure pressure pushing on vessel

• o   Intertial fluid osmotic pressure- pulls particle out.