Chapter 20 - The Heart - PART 2 Flashcards
What is the function of the atria?
to collect blood that is returning to the heart and convey it to the ventricles
The demands of the left and right atrium are ___
similar
What is the relationship in APPEARANCE between the left and right ventricle
they look almost identical
The demands of left and right ventricle are ____
very different (and they also have significant structural differences)
The right ventricle pushes blood through which circuit?
the pulmonary circuit
Why does the right ventricle not have to work very hard to push blood through the pulmonary circuit?
Because the lungs are close to the heart and the pulmonary blood vessels are short and wide
The muscular wall of the right ventricle is relatively _____
thin
____ to ____ times as much pressure must be exerted to push blood around the systemic circuit as around the pulmonary circuit
4-6 times as much pressure must be exerted
The muscular wall of the left ventricle is extremely _____
thick
The pressure generated by the left ventricle contraction is more than enough to do what?
to open the aortic valve and eject blood into the ascending aorta
The right ventricle has a ____ like shape
pouch
As the powerful left ventricle contracts, it bulges into….
the right ventricular cavity
“As the left ventricle contracts, it bulges into the right ventricular cavity.”
this makes the right ventricle more _____
efficient
Why is it that individuals with severe damage to the right ventricle may still survive?
because the contraction of the left ventricle helps push blood into the pulmonary circuit
the heart has ___ pairs of ___way valves
the heart has…
TWO pairs of ONE-WAY valves
What is the purpose of the 2 pairs of one way valves?
to prevent the backflow of blood as the chambers contract
The atrioventricular (AV) valves prevent the backflow of blood from the ____ to the ____ when the _____ are contraction
AV valves prevent the backflow of blood from the VENTRICLES to the ATRIA when the VENTRICLES are contracting
What 2 structures play an important role in the normal function of the AV valves?
the papillary muscles and the chordae tendineae
When the ventricles are relaxed, the chordae tendineae are _____, and the AV valves offer no _____ as blood flows from the atria into the ventricles
LOOSE, NO RESISTANCE
When the ventricles contract, blood moving back towards the _____ swing the _____ together, closing the ______
When the ventricles contract, blood moving back towards the ATRIA swing the CUSPS together, closing the VALVES
When the ventricles contract, the contraction of the ____ ____ tenses the ____ ____ , stopping the ____ before they swing into the atria
When the ventricles contract, the contraction of the PAPILLARY MUSCLES tenses the CHORDAE TENDINEAE, stopping the CUSPS before they swing into the atria
What would happen if the papillary muscles were damaged or if the chordae tendineae were cut?
REGURGITATION would occur
this is backflow of blood into the atria each time that the ventricles contract
What are the 2 semilunar valves?
The pulmonary and aortic valves
The semilunar valves prevent the backflow of blood from the ____ ____ and _____ into the right and left ______, respectively
the semilunar (aortic and pulmonary) valves prevent the backflow of blood from the PULMONARY TRUNK and AORTA into the right and left VENTRICLES
the pulmonary trunk is also known as the…..
pulmonary artery
do the AV valves need muscular braces?
yes
do the semilunar valves need muscular braces?
no
Why do the semilunar valves not need muscular braces?
because the arterial walls do not contract and the position of the cusps are stable
What is adjacent to each cusp of the aortic valve?
aortic sinuses – saclike dilations of the base of the ascending aorta
what is the FUNCTION of the aortic sinuses?
to prevent the individual cusps from sticking to the wall of the aorta when the valve opens
The right and left _____ ____ deliver blood to the myocardium
the right and left CORONARY ARTERIES deliver blood to the myocardium
where do the right and left coronary arteries originate?
at the right and left aortic sinuses
Inflammation of the heart
carditis
what does VHD stand for?
valvular heart disease
when may symptoms of VHD appear?
if valve function deteriorates to the point where the heart cannot maintain adequate circulatory flow
what does congenital mean?
present from birth
give 2 causes of valvular heart disease
may be caused by congenital malformations or develop as a result of carditis
what is an important cause of carditis?
rheumatic fever
what is rheumatic fever?
an inflammatory autoimmune response to an infection caused by streptococcal bacteria. most often occurs in children
What connective tissues are in the heart?
collagen and elastic fibers
What is each cardiac muscle cell wrapped in?
a strong but elastic sheath
How are adjacent cardiac muscle cells kept together?
they are tied together by fibrous cross links, or “struts”
Name 4 functions of connective tissue fibers in the heart
- Provide physical support for cardiac muscle fibers, blood vessels, and nerves of the myocardium
- Help distribute the forces of contraction
- Add strength and prevent overexpansion of the heart
- Provide elasticity that helps return the heart to its original size and shape after a contraction
The cardiac skeleton could also be called….
the fibrous skeleton
What does the cardiac skeleton consist of?
4 dense bands of tough elastic tissue that encircle that heart valves and bases of the pulmonary trunk and aorta
What are 2 functions of the tough bands of elastic tissue in the cardiac skeleton?
- Stabilize the positions of the heart valves and ventricular muscle cells
- Electrically insulate the ventricular cells from the atrial cells
Why do cardiac muscle cells need a very reliable supply of oxygen and nutrients?
because the heart works continuously
the _____ has its own, separate blood supply
the myocardium
coronary circulation supplies blood to where?
the muscle tissue of the heart (myocardium)
The left and right coronary arteries originate where?
at the base of the ascending aorta, at the aortic sinuses
Each time the left ventricle contracts, it forces blood where?
to the aorta
When the left ventricle relaxes, blood no longer flows into the _____, ___ declines, and the walls of the aorta_____.
blood no longer flows into the aorta, pressure declines, and the walls of the aorta recoil
“When the left ventricle relaxes, the walls of the aorta recoil”
What is this recoil called and what does it do?
this recoil is called elastic rebound. it pushes blood forward, into the systemic circuit, and backward through the left and right aortic sinuses and then into the respective coronary arteries
The combination of elevated blood pressure and elastic rebound ensures what?
ensures a continuous flow of blood to meet the demands of active cardiac muscle tissue
What is myocardial blood flow?
the amount of blood that flows through the coronary arteries and into the myocardium
Is myocardial blood flow steady?
no
explain why myocardial blood flow is not steady
it peaks while the heart muscle is relaxed and almost ceases when it contracts
What do coronary arteries do?
they deliver oxygenated blood and nutrients to the myocardiu
what structures are essential for establishing a normal heart rate?
the sinoatrial node (SA) and the atrioventricular (AV) node
what do coronary veins do?
remove carbon dioxide and wastes from the myocardium
Branches of the coronary veins converge where?
at the coronary sinus (empties there)
What is coronary artery disease characterized by?
interrupted blood flow to the myocardium
Damage to the semilunar valve of the right ventricle would affect blood flow into which vessel?
the pulmonary trunk (artery)
What prevents the AV valves from swinging into the atria?
Contraction of the papillary muscles (just before the rest of the ventricular myocardium contracts) pulls on the chordae tendineae, which prevent the AV valves from opening back into the atria
Why is the left ventricle more muscular than the right ventricle?
the left ventricle must generate enough force to propel blood throughout the body, except the lungs;
the right ventricle only has to generate enough force to propel blood a few centimeters to the lungs
