topic 5: circulatory system Flashcards
- List the three layers of the heart wall and describe the pericardial cavity.
Endocardium: Inner layer, smooth, lines the chambers
* Myocardium: Middle, muscular layer, responsible for contraction
* Epicardium: Outer layer, part of the heart’s protective sac
Pericardium consists of two layers.
* Inner visceral pericardium= epicardium, forms the outer surface of the
heart.
between is perciarial cavity containing pericaridal fluid
* Outer parietal pericardium is a thin and semitransparent membrane enclosing the
heart.
- What are the locations and functions of each tricuspid valves?
tricuspid valve: Situated between the right
atrium and right ventricle. Composed of three leaflets or
cusps.
function: Prevents backflow of
blood from the right ventricle to
the right atrium during
ventricular contraction.
What are the locations and functions of mitral valves?
Located
between the left atrium and left
ventricle.Bicuspid valve, having two
cusps.
function: Prevents backflow of blood
from the left ventricle to the left atrium
during ventricular contraction
What are the locations and functions of pumonary valves?
Located
at the entrance to the pulmonary
artery.Comprises
three semilunar cusps
function: Opens during right
ventricular contraction to allow
blood flow into the pulmonary
artery and prevents backflow into
the right ventricle
What are the locations and functions of aortic valves?
Positioned at the junction of the left
ventricle and the aorta. Comprises
three semilunar cusps.
function: Opens to allow
oxygenated blood to flow from the
left ventricle into the aorta; closes to
prevent backflow.
What are the differences among arteries, veins and capillaries in terms of the structures and functions?
arteries: thick wall, carry oxygenated blood away from heart
veins: thinner walls, have valves, return deoxygenated blood to heart
capillaries: single cell thick, exchange of gases, nutrients, waste between blood and tissue
what are the two parts that make up the cardiac cycle
-systole and diastole
what happens during systole
- Ventricles contract
- pushing blood into the aorta and pulmonary artery.
- Semilunar valves open.
- AV valves close to prevent backflow.
what happens during diastole
Ventricles relax
* blood filling the ventricles.
* The AV valves (tricuspid and mitral) are open,
* while the semilunar valves (aortic and pulmonary) are closed.
* atria contract
mechanism of the pumonary circulation
- Right Ventricle to Lungs: Deoxygenated blood from the body enters the
right atrium of the heart and is pumped into the right ventricle. From the
right ventricle, it is pumped through the pulmonary artery to the lungs. - Gas Exchange in the Lungs: In the lungs, carbon dioxide is released
from the blood and oxygen is absorbed. This exchange occurs in the tiny
air sacs in the lungs, known as alveoli. - Lungs to Left Atrium: The now oxygen-rich blood returns to the heart via
the pulmonary veins, entering the left atrium.
mechanism of the systemic circulation
Left Ventricle to Body: Oxygen-rich blood is pumped from the left
ventricle into the aorta, the body’s main artery. From the aorta, blood
flows through a series of arteries, arterioles, and capillaries, reaching
every part of the body.
* Nutrient and Gas Exchange: In the capillaries, oxygen and
nutrients are delivered to tissues, and waste products like carbon
dioxide are collected.
* Return to the Heart: Deoxygenated blood then returns to the heart
through venules and veins, culminating in the cranial and caudal
vena cava, which empty into the right atrium of the heart.
function of the coronary circulation
supply oxygenated blood to heart muscle
what are the two different coronary arteries
-right coronary artery
-left coronary artery
mechanism of the coronary circulation
Oxygenated Blood to Heart Muscle: The coronary arteries branch
off the aorta near the point where the aorta and the left ventricle
meet. These arteries supply oxygen-rich blood to the heart muscle
itself.
* Veins Collect Deoxygenated Blood: After passing through the
capillaries in the heart muscle, the deoxygenated blood is collected
by the coronary veins.
* Return to Right Atrium: This blood is then returned to the right
atrium of the heart.
explain how blood flows through the heart
Deoxygenated blood from the body returns to the right atrium.
* Blood from the upper body returns to the cranial vena cava.
* Blood from the lower body returns to the caudal vena cava.
* As the RA is filled with blood, RV is relaxed, Tricuspid valve opens and
blood is filled into RV; RA contract, the rest blood is pumped into the RV.
* Once the right ventricle is filled with blood, Tricuspid valve closes to
prevent blood from flowing back into the atrium.
* RA then relaxes.
* RV contracts, pulmonary valve opens and blood is pumped into the
lungs where oxygenation takes place.
* Pulmonary valve then closes to prevent blood from flowing back to the
RV. Oxygen rich blood returns from the lungs to the LA. LV is relaxed, the
mitral valve opens and blood is filled into LV;
* LA contract, the rest blood is pumped into the LV.
* Once the LV is full, mitral valve closes, and LA relaxes.
* LV contracts, the aortic valve opens.
* Oxygen rich blood is pumped into the aorta to reach all parts of the
body.
* Aortic valve then closes to prevent blood from flowing back to the heart,
and LV relaxes
- Describe the electrical conduction system of the heart
-The heart’s electrical impulse begins in the
sinoatrial (SA) node (the heart’s natural
pacemaker), located in the right atrium.
-The impulse spreads through the atria,
causing both of them to contract and push
blood into the ventricles.
-The impulse then reaches the
atrioventricular (AV) node, where it
slows slightly, allowing the ventricles to fill
with blood
-From the AV node, the impulse travels
through the bundle of His, down the left
and right bundle branches, and through
the Purkinje fibers, causing the ventricles
to contract and pump blood to the lungs
and the rest of the body
