electrocardiogram = EKG/ECG

intercalated discs
allow for synchronized contraction between heart muscle cells.  

they connect the sarcomeres of one cell to the sarcomeres of the next cell.

they also have channel proteins that allow ions to pass directly from one cell to another so the  action potential moves quickly from cell to cell.

  how is heart muscle different from skeletal and smooth muscle?

  Eosinophils
few in number/approx 3% of WBCs
bilobed nucleus
engulf antibody identified pathogens
release cytotoxic chemicals via exocytosis (can kill large
     parasites)
increase in # with allergen presence
reduce inflammation

an EKG measures the electrical activity of the heart. 

     Monocyte
2-8% of WBCs
large kidney bean shaped nucleus
become tissue macrophage after             24 hours in circ
release chemicals to attract other           WBCs

    platelets
1.5-5 x 10*5/ml blood
shelf life approx 10 days
1/3 found in spleen where they are also
     degraded
thrombocytopoiesis occurs via
     megakaryocytes; 1 = 4000 platelets 

 pacemaker cells initiate and regulate the heartbeat.

​ pacemaker calls are primarily found in the sinoatrial (SA) node which is a cluster of cells located in the upper wall of the right atrium. The electrical impulses generated by the SA node travel through the heart's conduction system which triggers the contraction of the heart muscle.

 lymphatic system 

pacemaker heart cells (cardiomyocytes) can generate electrical impulses (depolarize) without a stimulus.

  intercalated discs

  pacemaker cells are modified cardiac muscle cells.

    Leucopoiesis

  how is a capillary different from an
artery (or arteriole)
or a vein (or venule)
and why is it different?

relationship
​ between systems

 the AV node can slow down electrical signals from the atria before they pass to the ventricles so that there's enough time for the ventricles to fill with blood properly before contracting. 

measuring blood pressure with a cuff

coronary artery disease = CAD
formation of atherosclerotic plaque reduces diameter of coronary artery/reducing blood flow=  coronary ischemia
reducing cardiac efficiency

    Blood clotting

 toooo fast...
​too slow...

plasma proteins

  Blood Pressure

110/70   
The larger number is the pressure in the arteries as the heart pumps out blood during each beat. This is called the
systolic blood pressure.
The lower number is the pressure as the heart relaxes before the next beat. This is called the
​diastolic blood pressure.

Both are measured in units called millimetres of mercury (mmHg).​

WBCs

    vascular phase > platelet phase > coagulation phase

 myocardial infarction = ​MI
heart attacks occur when a coronary vessel is blocked
 commonly by plaque formation called coronary thrombus.
Diagnosis by:
pain (not always/silent killers)
ECG/blood tests for cardiac enzymes released by damaged cells

Artificial Pacemaker
uses electrical signals to prompt the heart to beat at a normal rate.

Needed to treat arrhythmias. 

  low cardiac output
    indicates poor peripheral circulation

 cardiovascular system 

           heart rate =
​ heartbeats per minute

RBCs

the main function of the AV node is to control the timing between atrial and ventricular contraction.

a blood pressure cuff works by temporarily compressing the brachial artery in your arm to measure blood pressure. The cuff is inflated to a pressure higher than your systolic pressure, temporarily stopping blood flow. 
​As the cuff deflates, the device detects the return of blood flow, measuring systolic and diastolic pressures. 

 our circulatory system

the lub of the heartbeat reflects the two atria contracting in sync w/ AV valves closing

the dub of the heartbeat reflects the two ventricles contracting in sync w/ semilunar valves closing

 what's the pericardium?

White blood cells WBCs are also
called leucocytes.
1ml of blood exhibits 5ish x 10*6 RBCs and just 7500 WBCs.
​Most WBCs are found in the lymphatic tissue or connective tissue proper.  
WBCs that are in circulation are:

1. moved to the site of an infection/injury by + chemotaxis
2. sometimes capable of phagocytosis
3. capable of ameoboid movement
through endothelium into peripheral tissues via diapedesis.    

Basophils
small and rare/ <1% of WBCs
release histamine (dilation) and heparin (< blood clotting)

review of ABO/Rh compatibility

kupffer cells line the sinusoids of the liver. they are phagocytes
that serve to breakdown "used" blood cells...

...more valves

                                                   Coagulation Phase
  extrinsic pathway: damaged endothelial cells begin the cascade   
  intrinsic pathway: activation of proenzymes in the blood begin the cascade

    Lymphocyte
20-40% of WBCs
large round nucleus
exhibit three classes:
    t cells: cell mediated immunity
    b cells: antibody production
    natural killer cells: on patrol

the EKG

  Blood pressure is the force of blood pushing against the walls of your arteries as your heart pumps. 
It's measured in millimeters of mercury (mm Hg) and expressed as two numbers:
systolic = top number
 diastolic = bottom number

          stroke volume =
volume of blood pumped out of the left ventricle during one contraction

   Resistance:
       blood viscosity 
       vessel length
       vessel diameter
       turbulance 

 pacemaker cells
will depolarize/initiate an action potential all by themselves. their membrane potential "at rest" is approx. -60mV
​ which is unstable. 
other cells have a resting potential at -70mv. 

 -60mv is called a pacemaker potential.

pacemaker cells have membrane channel proteins called "funny channels" that have a weird permeability. These unique ion channels allow for spontaneous depolarization. 

 ventricular systole = dub

 when reading an EKG... 
 depolarization -> contraction -> systole
  repolarization -> relaxation -> diastole

in a

capillary bed

 Heart Arrhythmias:
abnormal patterns of a heart's electrical activity which
​may reduce efficiency of heart

your heart is autorhythmic!

  Neutrophils
most abundant (60%)
segmented nucleus w/2-5 lobes phagocytic first strikers         that destroy bacteria by fusing  engulfed cell with                 lysozome containing defensins
release hormones that increase permeability
      of vessels and attract other WBCs 
short shelf life (30 min to 10 hours)

how does the impulse travel from the pacemaker cells in the SA node
to the rest of the heart?
 the cardiac conduction system

Types of WBCs

so what is a heartbeat?

blood pressure is a result of the heart pumping blood and the resistance it encounters along the way 

how are arteries and veins different?

  atrial systole = lub

   cardiac output 

Blood