BIO307: Test #3: Chapter 14: Cardiovascular

septum

Dividing walls between the chambers of the heart

Pulmonary Arteries

Carry blood from heart to lungs

Pulmonary Veins

carry blood from lungs to heart

resistance

(in relation to fluid), resistance increases as length of tube and viscosity of fluid increases, and as radius of tube decreases. Radius has the largest effect of resistance.

Electrocardiogram (ECG)

surface recording of the electrical activity of the heart

Autorhythmic Cells

Cells that depolarize spontaneously, having an unstable membrane potential which is referred to as the pacemaker potential

Vasodilation

widening of blood vessels as a result of relaxation of blood vessel muscular walls

Vasoconstriction

narrowing of blood vessels resulting from contraction of muscular wall of the vessels

Pericardium

a serous membrane with two layers that surrounds the heart, consists of outer fibrous layer and inner double serous membrane

Myocardium

Cardiac muscular tissue of the heart, striated muscle

Systole

Contraction phase of cardiac cycle

Diastole

relaxation phase of cardiac cycle

Stroke Volume

amount of blood pumped by one ventricle during one contraction

End-Systolic Volume

volume of blood in the ventricles at the end of contraction

Ejection Fraction

percent of EDV (end diastolic volume) ejected with one contraction (stroke volume / EDV)

Order of Blood

Heart -> Arteries -> Arterioles -> Capillaries -> Venules -> Veins -> SVC/IVC -> Heart

Blood Flow vs Pressure Gradient

Blood flows down the pressure gradient, rate of blood flow is proportional the blood pressure difference between the two sites.

Blood Vessel Radius to Resistance: a 4th power relationship:

Ex: Do the larger number over the smaller number, the factor ^ 4 is the difference

Label Heart Exterior

Label Heart Interior

Heart Valves

ensure unidirectional blood flow, are like gates, open and close to allow blood to flow from one area of the heart to another

Atrioventricular Valves: between atrium and ventricles
Semilunar: between ventricle and arteries

Issues:

Prolapse: when a chordae fails, valve is pushed back into atrium during ventricular contraction

If a valve fails, the blood would not have the control system to prevent blood from flowing backward (can be seen moving backwards through the chambers on ultrasound)

Muscle Cells and Gap Junctions

Ions are transported between adjacent cells to allow for the electrical signaling for the pacemaker potential throughout the cardiac muscle

Spontaneous Generation of Action Potential in Heart

Pacemaker potential is created by autorhythmic cells

Pathway:
Sinoatrial (SA) Node -> Internodal Pathways -> Atrioventricular (AV) Node -> Atria -> Septum -> Apex of the Heart -> Upward through the Ventricle

ECG/EKG Reading:

P wave: atrial depolarization
P-R segment: conduction through AV node and AV bundle
QRS complex: ventricular depolarization
T wave: ventricular repolarization

ECG Reading W/ Depolarization Events

Start: superior atria depolarization = P wave

medial atria + P-Q + P-R segment = conduction through AV node

Septum = Q wave

Apex of the Ventricle = R wave

Depolar. of Ventricles = S Wave

Contraction of Ventricles = S - T segment

Ventric. Repolarization = T wave

Wiggers Diagram

Shows QRS complex

Events of Cardiac Cycle

1) Late Diastole: both sets of chambers relaxed, ventricles fill passively
2) Atrial Systole: small amount of blood enters ventricles
3) Isovolumic Ventricular Contraction: AV valves close once cavity fills, doesn't open semilunar valves until volume of ventricle fills up
[EDV, end diastolic volume] = Max Blood Volume of Ventricle
4) Ventricular Ejection: Semilunar valves open due to ventricular pressure
5) Isovolumic ventricular relaxation: ventricles relax, ventricular pressure falls, semilunar valves now close
[ESV, end systolic volume] = Minimum Blood Volume in Ventricles

Cardiac Output

CO = SV * HR

^ Venous Return: CO increases
^ Blood Volume: CO increases
^ Sympathetic Activity: CO increases (epinephrine direct relationship on HR)
^ Parasympathetic Activity: CO decreases (Ach. direct relationship on HR)
^ Heart Rate: CO increases
^ SV: CO increases

Factors Normally Affect Venous Return

EDV directly affects Venous Return (amount of blood returning to heart from venous circulation)

Factors Affecting it:
1) Contraction/Compression of Veins Returning Blood
2) Pressure changes in abdomen and thorax during breathing (the respiratory pump)
3) Sympathetic innervation