• Arteries - carry blood away from the heart
• Capillary Beds - where material exchange, between  the blood and the interstitial fluid occurs
• Veins - carry blood toward the heart

• a viscous fluid that circulates around the body carrying substances to and from tissues

• Upper chamber
• Receives blood returning to the heart from teh veins
• Pumps blood into the ventricles

• Lower chambers
• Receive blood from the atria
• Pump blood out into arteries

• Blood should only flow in one direction through the heart
• Valves prevent backflow
• Atrioventricular (AV) valves separate atria and ventricles
• Semilunar valves separate ventricles and arteries

• right heart chambers and the pulmonary arteries and veins

right atrium->right ventricle->pulmonary arteries->

capillary beds in lungs->pulmonary veins->systemic circuit

• Left heart chambers, and the systemic arteries and veins

left atrium->left ventricle->systemic arteries->

capillary beds in body (except lungs)->

systemic veins->right atrium

• in the systemic circuit

• left and right atria contract at the same time
• left and right ventricles contract at the same time

• cardiac muscle cells that fire spontaneous action potentials
• key regulator cells
  • do not generate force of a heartbeat
• present in large concentrations in two locations
  • sinaotrial (SA) node - control the initiation of a heartbeat cycle
  • atrioventricular (AV) node - stimulated by impulses traveling from the SA node

• Cardiac muscle cells that transmit action potentials, via gap junction, to neighboring cells

• cardiac muscle cells - most numerous
• generate almost all of the force of the heart as it pumps

• SA node - pacemaker cells generate spontaneous action potentials-conduction fibers transmit action potentials to contractile cells of the atrial walls
  • atria contract
• conduction fibers transmit action potentials to AV node
• AV bundle carries the signal to the right and left bundle branches-this is the only electrical connection between atria and ventricles
• left and right bundle branches carry the signal to branches known as Purkinje fibers
• Purkinje fibers carry the signal to contractile cells of the ventricles
  • ventricles contract

• records the electrial activities of pacemaker cells, contractile cells, conduction fibers and purkinje fibers

• flows from higher pressure to areas of lower pressure

• open and close due to pressure differences
  • when the pressure in the chamber upstream of a valve is higher than the pressure in the chamber downstream, the valve will be open
  • when the pressure in the chamber downstream of a valve is higher than the pressure in the chamber upstream the valve will be closed

• relaxation - ventricular diastole

• contraction - ventricular systole

• early and mid-diastole - atria and ventricles are filling due to the fact that they have low pressure because they are relaxed
  • lower than the pressure in the veins that feed into them
• late diastole - ventricles still relaxed but atria contract forcing more blood into the ventricles

• aorta pressure - relatively high just before systole begins
• early systole
  • ventricles contract
  • AV valves close-no blood flows in or out of ventricles (called isovolumetric contraction)
• mid-to-late systole
  • ventricles continue contraction
  • semilunar valves open-blood flows out into the arteries (called ventricular ejection)

• the pressure inside them increases
• but their pressure inceases most quickly when they are contracting

• do not exert force while they are expanding
• only exerts force when it is contracting
• blood flows into a chamber simply because it is being forced in due to the higher pressure in teh more upstream location

• are due to the rush of blood as the valves close

• the rate at which a ventricle pumps blood
  • expressed as liters per min

• The rate of contractions of the ventricles
  • usually expressed in beats per minute

• volume of blood pumped by a ventricle in one contraction
  • usually expressed in liters per beat

• the rate at which the ventricles pump blood depends on the heart rate and the volume of blood pumped in each heart beat

• must have the same CO, ove the long run
• have exactly the same heart rate, because they pump synchronously
• have the same stroke volume on average

Heart average values for

 CO, HR, and SV

at rest

• HR - 72 - 90 beats per minute
• SV - 0.07 liters per beat
• CO = HR x SV = 5 liters per minute

Heart average values for

 CO, HR, and SV

light exercise

• HR = 135 beats per minute
• SV = 0.08 liters per beat
• CO = 11 liters per minute

• Medulla oblongata integrates information about blood pressure, particle concentrations, and emotion stress
• it then sends commands to the sympathetic division and parasympathetic division

Control of cardiac output

Sympathetic control

• increases heart rate by affecting pacemaker cells of the SA and AV nodes
• increase stroke volume by affecting contractile cells

Control of cardiac output

parasympathetic control

• decreases heart rate by affecting pacemaker cells of the SA and AV nodes

Control of cardiac output

endocrine system control

• several hormones affect heart rate
  • epinephrine has the greatest effect - it increases heart rate

• pacemaker cells generate spontaneous action potentials-conduction fibers transmit action potentials to contractile cells of the atrial walls

• transmit action potentials to AV node

• carries the signal to the right and left bundle branches-this is the only electrical connection between atria and ventricles

• carry the signal to contractile cells of the ventricles
• ventricles contract