A& P Review:
-Cardiac Output: Each time the heart beats, a volume of blood is ejected. This stroke volume (SV),times the number of beats per minute (HR), equals the cardiac output CO = SV X HR
-Stroke Volume
SV is the difference between:
End-diastolic volume (EDV), or volume of blood at the end of relaxation and End-systolic volume (ESV), or residual volume of blood remaining in the ventricle after ejection
Any factor that alters either EDV or ESV will change stroke volume, and thus cardiac output will be changed as well
Three major factors influence stroke volume:
1. Preload (volume of blood in the heart)
2. Afterload (force opposing ejection of the blood from the ventricle)
3. Contractility (contractile capabilities of the heart)
1: Preload
Definition = stretch of cardiac muscle cells before contraction
In other words, preload is related to the chamber volume just prior to contraction
A lower preload leads to a lower stroke volume and vice versa (See Frank-Starling Law, next slide)
Example: a client with hypovolemia will have less ventricular filling, reduced preload, and lower stroke volume
Frank-Starling Law
This law states that an increase in resting muscle fiber length results in greater muscle tension
This is also called the “length-tension” relationship
The heart has the ability to change its force of contraction (and stroke volume) in response to changes in venous return
2: Afterload
Definition = resistance that must be overcome in order to eject blood from the chamber
Left ventricular afterload is primarily determined by aortic blood pressure
An increase in afterload will lead to a decrease in stroke volume unless the heart compensates
Example: A person with high blood pressure will have high afterload and be at risk for a lower stroke volume
3: Contractility
Definition = contractile force of the heart muscle cells
Contractility is primarily determined by the amount of free calcium within the myocardial cell
Increased contractility increases stroke volume by causing a greater % of the volume to be ejected
** BE ABLE TO LABEL A HEART DIAGRAM
Blood Flow through the Heart Chambers You should be able to trace the blood flow through the heart chambers, starting with the veins and going through the entire cardiovascular system
1: Right atrium receives blood from the vena cavae and the coronary sinus. Blood passes to the right ventricle.
2: Right ventricle pumps blood into the pulmonary artery and lungs.
3: Oxygenated blood flows from the pulmonary veins to the left atrium.
4: Blood passes into the left ventricle
5: Blood is ejected into the aorta
CARDIOVASCULAR PART 1
-Once diagnosed with Coronary Heart/Artery Disease, a person will always have CAD.
Etiology
Atherosclerosis!_ (primary cause of CAD)
Low blood oxygen (like anemia and COPD)
Poor perfusion (someone hemorrhaging or bleeding out- not enough preload)
Vasospasm (coronary arteries spasm)
Non-Modifiable Risk Factors
Age
Family history
Gender
Modifiable Risk Factors
Hypertension
Tobacco
Diabetes
Obesity
Inactivity
Diet
Hyperlipidemia
Depression/Stress
VIDEO: Heart Disease
-When did heart disease become a problem in our country? Why?
Post WW2. Men died in their 50s-60s and ppl didn’t know the cause
-What was unique about the Framingham study?
They followed a group of healthy people for 20 years.
During the study, ppl became less active because of inventions like the dishwasher, washing machines, cars, TVs
There was a change in the American diet. Ate more fatty foods
Soldiers were given free cigarettes during the war and they brought them back to America.
-What were the first 3 risk factors for heart disease that they discovered?
Took the study 13 years to find the risk factors: High BP (HTN), High Cholesterol, and Smoking
Definition- Stable Angina
Predictable occurrence of angina r/t transient myocardial ischemia note difference btwn ischemia- (lack of O2 or dec. blood flow) and
