The Heart

Blood

Specialized connective tissue that transports gases nutrients and waste across the body. Consists of plasma, erythrocytes, leukocytes, and platelets

Develops in bone marrow from multipotent stem cells which makes myeloid and lymphoid stem cells

Plasma

Aqueous solution of proteins, ions, nutrients, and gases.

Plasma proteins include:

Albumins for osmotic balance pH, hormones, waste, and drugs.

Globulins for lipid transport

Fibrinogen for blood clots

Ions include Na+, K+, Ca2+, Cl-, and HCO3-

Erythrocytes

RBCs. Oxygen carriers.

Has hemoglobin

No nucleus or organelles

Flexible and lasts 4 months

Leukocytes

WBCs. Front line defense

Platelets

Induces clots to seal breaks

Hematocrit

Packed cell volume (PCV) or Erythrocyte volume fraction (EVF) is the percentage of rbcs in blood. Anemia is low hematocrit

Heart

Organ made of cardiac muscles

Stretch affects contractile strength

Normal heartbeats not optimal length

Rate and strength altered by ANS and endocrine system

Structure of the Heart

4 chambered pump:

• 2 atria on top

• 2 ventricles on bottom

• Atrioventricular (AV) valves between atria and ventricles (tricuspid and bicuspid)

• Semilunar (SL) valves. Between ventricles and aorta/pulmonary arteries

• Blood pumped in two circuits:

  • Pulmonary and systemic circuits

Pulmonary Vein

Brings oxygenated blood to the heart

Pulmonary Artery

Takes deoxygenated blood away from the heart and to the lungs

Systemic Circulation

High blood pressure in arteries. Pulsatile.

Pressure doesn’t go to 0 between beats.

Large tube for transport

• F(flow) = Delta P(pressure)/R(resistance)

  • R = 8Ln/pi r^4 (n = fluid) (r = internal tube radius) (L = tube length)

Changing blood vessel diameter has major effects

Systole

Ventricle contracting. Max pressure

Diastole

Ventricle relaxing. Chambers filling and atria contracting. Minimum pressure

Systole-diastole

Cardiac cycle

Systolic Blood Pressure

Pressure pushing against arterial walls while blood is pumped out of the heart. 110-140mmHg

Diastolic Blood Pressure

Pressure pushing against arterial walls while heart is filling with blood. 60-90mmHg

Systemic Vascular Resistance (SVR)

Amount of resistance the heart must overcome to open aortic semilunar valve to push blood into systemic circulation

Left Ventricular End-Diastolic Pressure (LVEDP)

Amount of ventricular stretch at end of diastole

Stroke Volume

Amount of blood ejected per beat from the left ventricle. mL/beat

SV = EDV - ESV

SV Increases proportionally with exercise intensity

Untrained ~ 50-70mL/beat at rest and 110-130mL/beat during activity

End Diastolic Volume (EDV)

Blood volume after filling phase

End Systolic Volume (ESV)

Blood left after contraction

Cardiac Output

Amount of blood pumped in 1 min. L/min

Rest ~ 5L/min & 20-40L/min when intense

CO = SV x HR

Total flow