Exam 3 chapter 25 Flashcards
Describe the function of the pericardial membrane
o Protection: shields the heart from external trauma and physical shock
o Lubrication: reduces friction as the heart beats by secreting fluid that lubricates the surface of the heart
o Maintenance of cardiac function: helps maintain the proper position of the heart within the chest cavity and helps to maintain its function
o Prevention of infection: acts as a barrier against invading microorganisms
describe the electrical activity/route of the heart conduction system
- SA node (located in the upper right atrium and acts at the heart’s pacemaker): generates the electrical impulses and sends it to the atria, causing them to contract and push blood into the ventricles
- Electrical impulse reaches AV node (located at the base of the right atrium, and acts as the gatekeeper) delays it for a brief moment to allow the ventricles to fill with blood before contracting.
- The impulse then travels down the bundle of His, which divides into two branches that transmit the impulse to the ventricles
- The impulse spreads throughout the ventricles through a network of fibers called Purkinje, causing the ventricles to contract and pump blood out of the heart and into the arteries.
Mnemonics
“Some Angry Elephants Have Powerful Hearts”
SA node, AV node, bundle of His, Purkinje fibers, heart muscle
Or
SABP
define cardiac output
volume of blood flwoing through either the systemic or pulmonary circuit in liters per minute
describe how myocardial hypertrophy compensates for the heart
- Walls of the heart chambers thicken in response to increased workload or pressure. The thickening of the heart muscle allows it to contract with greater force to help maintain cardiac function but it can lead to heart failure
o Ex: hypertension, heart valve problems
describe the frank-starling mechanism
- Describes the heart’s ability to increase stroke volume in response to increased blood volume
- The heart chambers can stretch to accommodate increased blood volume. When the chambers stretch, the myocardial fibers are pulled apart, which allows them to contract with more force and push more blood out of the heart with each beat
describe how the sympathetic nervous system affects for the heart
release of norepinephrine can increase heart rate, contractility, and conduction which can help maintain cardiac output in response to stress or exercise. it also allows the heart to pump more blood due to increase O2 demands
describe how the renin-angiotensin-aldosterone system (RAAS) compensates for the heart
- Activated in response to low blood pressure or reduced blood flow to the kidneys. It causes the release of renin, which leads to the formation of angiotensin II. Angiotensin II can increase blood pressure and stimulate the release of aldosterone, which can help the body retain salt and water, thereby increasing blood volume
in simple terms, describe the different compensation processes
make heart muscle thicker, pump harder, increase the amount of blood the heart pumps out, speed up heart rate
describe the normal cardiac flow
o Normal cardiac flow
1. Deoxygenated blood enters the heart through the superior vena cava to the right atrium
2. From the right atrium, the blood flows into the right ventricle. The right ventricle pumps the blood out of the heart and into the pulmonary artery which carries the blood to the lungs
3. The lung picks up oxygen and releases carbon dioxide
4. Oxygen-rich blood flows back to the heart through the pulmonary veins which enter the left atrium
5. From the left atrium, the blood flows back into the left ventricle
6. The left ventricle pumps the blood out of the heart and into the aorta
7. The aorta carries the oxygen-rich blood to the rest of the body’s tissue where the oxygen is used, and carbon dioxide is produced
8. The blood then flows back to the heart through the superior and inferior vena cava and the process starts again
Some – Superior Vena cava
People – pulmonary artery
Enjoy – pulmonary veins
Going – left atrium
Places – left ventricle
what are the three layers of the heart in order from the outermost layer to the innermost layer?
- pericardium
- myocardium
- endocardium
which side of the heart has a thicker myocardium?
left side
which of the following layers of the heart is the thickest layer and its main function is to generate the force necessary to pump blood throughout the body?
a. pericardium
b. myocardium
c. endocardium
d. exocardium
b. myocardium
the main function of the pericardium is to: SELECT ALL THAT APPLY
a. protect and anchor the heart in the chest cavity
b. help blood flow smoothly
c. generate force to pump blood throughout the body
d. physical protection and barrier to infection
a. protect and anchor the heart in the chest cavity
and
d. physical protection and barrier to infection
the endocardium lines the ______ and is the ________ layer
heart; innermost
the endocardium is exposed to
blood and bacteria
how do positive chronotrope and inotropes control the action of the heart
increases contraction and heart rate
the sympathetic nervous system also causes the blood vessels to constrict, which increases blood pressure and ensures that blood flow is directed to the vital organs. these responses are part of the body’s “fight or flight” response, which prepares the body for physical activity or stress
*+chronotrope and inotrope
define chronotropic and inotropy
chronotropic: refers to the heart rate. A negative chronotrope slows down the heart rate while a positive chronotrope increases it
inotropy refers to the strength of the heart’s contraction. A negative inotrope weakens the force of the contraction, while a positive inotrope strengthens it
How do automaticity, rhythmicity, conductivity, and contractility affect cardiac function?
automaticity: generating spontaneous depolarization (enables SA and AV node to generate cardiac output)
rhythmicity: generation of action potential by the heart’s conduction system
conductivity: ability to conduct from SA node through Purkinje fibers
contractility: ability to contra in sequence by means of action potential
what are the beta-adrenergic receptors and what do they do?
B1- heart
B2- lungs
they signal the sympathetic nervous system by binding catecholamines (epi, norepi)
how does adrenergic receptor function control the heart?
the sympathetic system controls heart actions by releasing neurotransmitters called norepinephrine. norepinephrine binds to specific receptors on the heart muscle cells (beta1) which stimulates the heart to beat faster and stronger
how does the parasympathetic nervous system affect cardiac function?
Parasympathetic: releases acetylcholine which slows down heart rate, and reduces the force of contraction, and reduces conduction resulting in a decrease in cardiac output
a. Also causes vasodilation in the digestive system and other non-essential organs which increases blood flow to these areas and vasoconstriction in the skeletal muscles, which reduces blood flow to these tissues
- -chronotrope and inotrope
how is cardiac output determined?
o Cardiac output: HR (beats/min) x stroke volume = cardiac output
Stroke volume: volume of blood ejected during systole in liters/beat
Reflects the heart’s ability to deliver oxygen and nutrients to the body’s tissue
* Exercise –> increased cardiac output
what factors determine cardiac output?
preload
afterload
myocardial contractility
heart rate
define preload
volume/pressure inside ventricles at the end of diastole
depends on the amount of blood in the ventricles (the amount of stretch during diastole)
