Biol 216 Circulatory System Summary

CIRCULATORY SYSTEM
 Blood and its components:
o Plasma - aqueous solution of proteins, ions, nutrient molecules, and gases (91% water)
o Erythrocytes (RBC) - oxygen carriers of blood
o Leukocytes (WBC) - front line of defense against disease
o Platelets - induce blood clots that seal breaks in the circulatory system
 Mammalian Blood
o Fluid connective tisse (4-5 liters in humans)
o Blood cells (erythrocytes, leukocytes, platelets)
o Suspended in fluid matrix (plasma)
o Human blood cells--> develop in red bone marrow of vertebrae, sternum, ribs, pelvis
 Arise from multi-potent stem cells that give rise to:
 Myeloid stem cells
 Lymphoid stem cells
 Plasma contains---> mostly water, Ions, Dissolved gases (O2 and CO2), Glucose, Amino acids, Lipids, Vitamins,
Hormones and plasma proteins
o Plasma proteins:
 Albumins - osmotic balance, pH, transport hormones, waste, drugs
 Globulins - transport lipids (cholesterol), fat soluble vitamins, immunoglobulin
 Fibrinogen - blood clotting
o Plasma ions: (electrolytes) - Na+, K+, Ca2+, Cl-, HCO3-
 Blood cells
o Erythrocytes (BRC) - contain hemoglobin (transports O2 from lungs to body)
 Mature erythrocytes don't have a nucleus, do have organelles
 Flexible - can squeeze through capillaries
 Life span = 4months
o Leukocytes (WBC) - mostly involved in immune system
 Defend body against infecting pathogens
 Eliminate dead and dying cells, debris
o Platelets
 Cell fragments enclosed in a plasma membrane
 Trigger clotting - stick to collagen that is exposed when blood vessels are damaged--> release
factors to bring more platelets to the region--> seal off the damaged site
 Hematocrit (Packed cell volume - PCV)/(erythrocyte volume fraction - EVF)--> volume percentage of red blood
cells in blood
o How much RBC is in blood
o Normally 45% for men, 40% for women
o Anemia - abnormally low hematocrit --> less RBC, less hemoglobin, less oxygen
 Lub-up sound you hear through stethoscope placed over the heart is the---> valves being forced shut
 The mammalian Heart
o A four-chambered pump
 Two atria at top of heart
 Two ventricles on bottom
 Atrioventricular (AV) valves -
between atria and ventricles
 Semilunar (SL) valves
o Blood is pumped into two separate circuits
- pulmonary and systemic

o Know above diagram ^
o Left and Right atria fill simultaneously =
period of diastole

,CIRCULATORY SYSTEM
 Right atria fills with deoxygenated
blood - systemic circuit
 Left atria fills with oxygenated
blood - pulmonary circuit
o When they fill up the pressure builds -
then blood flows through the AV valves to the
ventricles--> diastole--> getting ready to send
AP through cardiac muscle for contraction to
occur through the ventricles to pump blood
out
o Right side=tricuspid AV valve
o Left side=Bicuspid AV valve
 Know the above diagram -
o Pulmonary vein = oxygenated blood
o Pulmonary ARTERY = deoxygenated
blood
o Arteries carry blood Away from the heart
 What is an advantage of separate systems:
pulmonary/systemic?
o TWO COMPLETELY DIFFERENT PRESSURES
o Systemic circulation
 HIGH blood pressure in the
arteries - pulsatile
 Does NOT fall to zero between heartbeats
 One the rise up = heart contracting
 Slope down = heart relaxing
 (even when heart relaxing, pressure still
above 0
o Pulmonary circuit - pressure is lower
o We do not want too much pressure in our lungs-->
exchange pathway is shorter with lower resistance:
fluid could leak out of vessels into the lungs
 Design of transport systems
o Large tubes for bulk transport over distance
 F(flow) =  P (pressure)
R (resistance)
 More resistance=less flow
 Greater change in pressure=increase in flow
 Note: when the heart beats, it creates higher pressure at the end of the tube (by the ventricle) than
the other end = delta P
 R = 8L
 r 
  = fluid viscosity
 L = length of the tube
 R=inside radius of the tube
 Longer the tube=more resistance
 As radius gets bigger==> resistance gets smaller
 Keeping these relationships in mind: what will be the effect on fluid flow of increasing the radius by a
factor of 2?
 Flow will increase by a factor of 16
 Resistance will be 1/16 of what it was before--> flow will INCREASE by a factor of 16

, CIRCULATORY SYSTEM
 Basic Heart beart
o Systole - ventricle contracting
o Diastole - ventricle relaxing--> chambers filling,
atria contracting
o Blood moves as a result of PRESSURE
DIFFERENCES
o Systole-diastole sequence is --> cardiac cycle
 At rest - typical systolic BP = 110-140
mmHg;
 diastolic BP = 60-90 mmHg
 Thumping sound=systolic pressure
 No turbulence, no sound = diastolic
pressure
 The cardiac cycle
o Triggered by action potentials that spread across
the cardiac muscle cell membranes
o Systolic pressure - contraction of ventricles
pushes blood into arteries at peak pressure
 Isovolumetric ventricular contraction -
both AV and semilunar valves closed
 Ventricular ejection - AV valve closed;
semilunar valves=open

o Diastolic pressure - between ventricular contractions, blood pressure in arteries falls to a minimum
pressure
 Isovolumetric ventricular relaxation -
both AV and semilunar valves closed
 Ventricular filling - blood flows into
ventricle
 AV valve=open to fill the
ventricle
 Small period of time where
atrium contracts a little bit to squeeze
out the last bit of blood to get into the
ventricle
 No valve going into right atrium--> have
constant flow of deoxygenated blood into it