Download Human Physiology Unit 3D: Cardiophysiology Pt. II

Human Physiology Unit 3D:
Cardiophysiology Pt. II
Supplemental Instruction
Iowa State University
Leader:
Course:
Instructor:
Date:
Paige Stieneke
BIOL 256
Dr. Karri Haen
March 13, 2013
(Systole, Diastole) is contraction of the heart while blood is pumped out, while (systole, diastole) is the
relaxation of the heart when
blood fills its chambers.
Phases of the Cardiac
Cycle
a. Mid-to-Late Diastole
I.
Ventricular
Filling
i. Blood
pressure
is low as
blood
enters the
atria and flows into the ventricles
II.
Atrial Contraction
i. AV valves open, and atria empty into ventricles.
ii. Atrial systole occurs
III.
AV Valves are open, Semilunar Valves are closed
b. Systole
I.
Isovolumetric Contraction
i. Ventricular systole occurs, and atria relax.
ii. Rising ventricular pressure causes AV valves to close
iii. Is volume the same or different? Same
II.
Ventricular Ejection
i. Semilunar valves open
III.
AV Valves are closed, Semilunar Valves are open
c. Early Diastole
I.
Isovolumetric Relaxation
i. Ventricles relax
ii. Semilunar valves close
II.
Ventricular Filling
i. Dicrotic Notch: Brief rise in aortic pressure due to blood rebounding off closed
semilunar valves
III.
AV Valves are open, Semilunar Valves are closed
Supplemental Instruction
1060 Hixson-Lied Student Success Center v 294-6624 v www.si.iastate.edu
1. What is Stroke Volume? Amount of blood pumped per beat. It can be calculated by taking:
SV = EDV – ESV (Stroke Volume = End Diastolic Volume – End Systolic Volume) Expressed
in mL
a. The average heart pumps about 70 mL per beat
b. The average heart rate is 75 beats/minute
c. List the three factors that affect Stroke Volume:
i. Preload: Amount that ventricles are stretched due to contained blood
ii. Contractility: Heart cells contracted due to factors other than EDV
iii. Afterload: Pressure exerted by blood in large arteries (aorta) leaving the heart
d. Frank-Starling Law of the Heart: More blood in the left ventricle increases stroke volume,
characterized by a slow heartbeat. Decreased stroke volume would be due to a fast
heartbeat and less blood
2. What is Cardiac Output? Amount of blood pumped by the heart in one minute. CO = SV x HR
or Cardiac Output = Stroke Volume x Heart Rate (measured in mL/min)
a. If Jane’s EDV is 90 and her ESV is 5, what is her Stroke Volume? 85 mL
b. If her heart rate is found to be 60 bpm, calculate her CO: 5,100 mL/min
Regulation of Heart Rate
1. Autonomic Nervous System
• Cardiovascular center of the medulla: regulates rates of depolarization of the SA node
• Sympathetic Nervous System
i. Activated by: Stress, anxiety, excitement, exercise
ii. Positive Chronotropic Factors: Increase heart rate
§ Norepinephrine binds B1 receptors
§ Increased Ca2+ entry
• Parasympathetic Nervous System
i. Which Cranial Nerve is associated with the PNS? Vagus
ii. Negative Chronotropic Factors: Decrease heart rate
§ Acetylcholine causes hyperpolarization by opening K+ channels
2. Hormones
3. Ions in Blood Plasma
Normal Heart Rate
• Males: 64-72 bpm
• Females: 72-80 bpm
•
•
•
•
Tachycardia: >100 bpm
Bradycardia: <60 bpm
What is the condition where the heart cannot pump blood to the rest of the body? Congestive
Heart Failure
What is it caused by? Coronary atherosclerosis (fatty buildup in coronary vessels, not enough
Oxygen for heart), chronic high blood pressure, MIs (dead heart cells), dilated
cardiomyopathy (stretched ventricles, flabby)
Supplemental Instruction
1060 Hixson-Lied Student Success Center v 294-6624 v www.si.iastate.edu