week 8 (cardiac system, heart function/structure, cardiac physiology, circulation) Flashcards
pericaridum
The membrane that surrounds and protects the heart
It confines the heart to its position in the mediastinum, while allowing sufficient freedom of movement for vigorous and rapid contraction.
two main parts:
(1) the fibrous pericardium
(2) the serous
pericardium
fibrous pericardium
composed of tough, inelastic, dense irregular connective tissue
prevents overstretching of the heart, provides protection, and anchors the heart in the
mediastinum
serous (partieal and visceral pericardium)
layers of the serous pericardium is a thin film of lubricating serous fluid known as pericardial fluid which reduces friction between the layers of the serous pericardium as the heart moves
The space that contains the few milliliters
of pericardial fluid is called the pericardial cavity
significant of pericardial space
mechanical protection for the heart and big vessels, and a lubrication to reduce friction between the heart and the surrounding structures
endocardium
thin layer of endothelium overlying a thin layer of connective tissue. It provides a smooth lining for the chambers of the heart and covers the valves of the heart. The smooth endothelial lining minimizes
the surface friction as blood passes through the heart
myocaridum
is responsible for the pumping action of the heart and is composed of cardiac
muscle tissue.
The cardiac muscle fibers are organized in bundles that swirl diagonally around the heart and generate the strong pumping actions of the heart
epicardium
epicardium is composed of two tissue
layers. The outermost is the visceral layer of
the serous pericardium and is composed of mesothelium. Beneath the mesothelium is a variable layer of delicate fibroelastic tissue and adipose tissue.
imparts a smooth, slippery texture to the outermost surface of the heart. The epicardium contains
blood vessels, lymphatics, and vessels that supply the myocardium.
why is the is the myocardium of ventricles thicker than the myocardium of the atrium
This is because blood is pumped out of the heart at greater pressure from these chambers compared to the atrium
how does endocardium serve protective function for the heart
A tissue covering the inside of the heart, the endocardium keeps the blood flowing through the heart separate from the myocardium,
difference between normal and the specialized tissue of the conduction system in the heart
specialized cardiac muscle fibers called autorhythmic fibers
They act as a pacemaker, setting the rhythm of electrical excitation
that causes contraction of the heart.
They form the cardiac conduction system
cardic cycle
Atrial and Ventricular diastole (chambers are relaxed and filling with blood) Atrial systole (atria contract and remaining blood is pushed into ventricles) Ventricular systole (ventricles contract and push blood out through aorta and pulmonary artery)
systole
During atrial systole, which lasts about 0.1 sec,
the atria are contracting. At the same time, the ventricles are relaxed
During ventricular systole, which lasts
about 0.3 sec, the ventricles are contracting
diastole
ventricles relax in ventrical disstole
artia relax during atrial distole
sinoartial node (SA)
generates an electrical signal that causes the upper heart chambers (atria) to contract
atriventricular node (AV)
controls the passage of the heart’s electrical signal from the atria to the ventricles
atrioventricular bundle
specialized for electrical conduction that transmits the electrical impulses from the AV node
right and left bundle branchesx
The bundle of His is an important part of the electrical conduction system of the heart, as it transmits impulses from the atrioventricular node, located at the anterior-inferior end of the interatrial septum, to the ventricles of the heart.
purkinje fibres
electrical conduction of impulse to the ventricular muscle
autorhythmicity
Contractions of the heart (heartbeats) are controlled by specialized cardiac muscle cells called pacemaker cells that directly control heart rate
conduction pathway
sinoatrial (SA) node
atrioventricular (AV) node
atrioventricular
(AV) bundle
right and left bundle branches
location of heart (cavity)
The heart is located in the mediastinum, with two-thirds of its mass to the left of the midline.
it is by the thoriac cavity
apex
You can visualize the heart as a cone lying on its side. The pointed apex is formed by the tip of the lef ventricle (a lower chamber of the heart) and rests on the diaphragm. It is directed anteriorly, inferiorly, and to the lef .
base
base of the heart is opposite the apex and is its posterior aspect. It is formed by the atria (upper chambers) of the heart, mostly the lef atrium
blood supply to and from the myocardium
The coronary arteries provide the main blood supply to the heart. The coronary arteries also supply the myocardium with oxygen to allow for the contraction of the heart and thus causing circulation of the blood throughout the body
coronary circulation
part of the systemic circulatory system that supplies blood to and provides drainage from the tissues of the heart. … Deoxygenated blood is returned to the chambers of the heart via coronary veins; most of these converge to form the coronary venous sinus, which drains into the right atrium.
electrocardiogram(ECG)
records the electrical signal from your heart to check for different heart conditions.
P wave
a P wave happens when the atrium systole
QRS complex
happens when atrium fills ventricles
T wave
happens when there is ventriclukar sytoles
atrial systole
- *conduction system role:** exicte the artuim walls to contract
- *myocardium role**: contract atrium
- *pressure change**: lower pressure in heart
- *action of valves**: the valves of the atrium are open
- *direction of blood flow**: from superior/inferior vena cava to atrium, blood also starts going to the ventricules
ventricular filling
- *conduction system role**: to not exicte the ventricules as they need to be relaxed to fill
- *myocardium role**: relax ventricules to allow for filling
- *pressure change**: aortic pressure decreases and the pressure in ventricles are low
- *action of valves:** valves are open to allow for filling
- *direction of blood flow**: into the ventricles
ventricular systole (early atrial diastole)
- *conduction system role**: to exicte the ventricles
- *myocardium role**: contract the ventricles and start to relax the atriums
- *pressure change**: high pressure in aoarta and ventricles low in atriums
- *action of valves:** bicups and tricusp valves close, aortic valve opens
- *direction of blood flow:** from the ventricles to the aorta
ventricular diastole
- *conduction system role:** to not exicte the ventricules
- *myocardium role**: to keep the ventrciles relaxed
- *pressure change**: pressure is very minimum everywheree
- *action of valves**: aortic valve closed, bicups valve open
- *direction of blood flow:** into atrium/ventricules
automatic regulation of heart
Heart rate is controlled by the two branches of the autonomic (involuntary) nervous system. The sympathetic nervous system (SNS) and the parasympathetic nervous system (PNS).
The sympathetic nervous system (SNS) releases the hormones (catecholamines - epinephrine and norepinephrine) to accelerate the heart rate.
The parasympathetic nervous system (PNS) releases the hormone acetylcholine to slow the heart rate.
cardiac accelrator nerves
cardioaccelerator center stimulates cardiac function by regulating heart rate and stroke volume via sympathetic stimulation from the cardiac accelerator nerve.
will realse epipierhein from the medula and of the adrenal gland
vagus nerve
Parasympathetic nerve impulses reach the heart via the right and lef vagus (X) nerves. Vagal axons terminate in the SA node, AV node, and atrial myocardium. They release acetylcholine, which decreases heart rate by slowing the rate of spontaneous depolarization in autorhythmic fibers.
temp on heart rate
High temperatures and high humidity can cause more blood flow to the skin. This causes the heart to beat faster while circulating twice as much blood per minute than on a normal day.
exersise on heart rate
When exersising, the muscles need more blood to do the hard work, causing the heart to beat faster
emotions on heart rate
if one is in fear or anxious hard rate will most likely go up but if one if relaxed it will go down
sex on heart rate
heart rate will increase to send blood to reproductive areas needed for sex
age on heart rate
As you grow older, your pulse rate is about the same as before. But when you exercise, it may take longer for your pulse to increase and longer for it to slow down afterward.
epinephrine on heart rate
will accerate heart rate
cation concentrations on heart rate
increase of sodium stiffens and narrows your blood vessels making your heart pump faster with more pressure to get oxygen to where your body needs it — resulting in higher blood pressure.
Potassium helps keep your heart beating at the right pace
Heart rate was increased by calcium
artial blood pressure
Arterial blood pressure is defined as the force that is exerted by the blood on the arterial wall.
arterial blood volume
the adequacy of the arterial blood volume to “fill” the capacity of the arterial vasculature.
relationship between arterial blood volume and pressure
higher the volume, higher the pressure
three critical factors that influence arterial blood pressure
cardiac output: the volume of blood moved from each ventricle per minute
total peripheral (vascular) resistance: the opposition to blood flow mainly due to friction between the blood and the walls of the arteries, capillaries and veins
blood volume: the amount of blood present in the circulatory system
heart rate
how fast your heart beats
stroke volume
Stroke volume is the amount of blood ejected from the ventricle with each cardiac cycle.
effect of heart rate and stroke volume on cardiac output
heart rate added to stroke volume equals cardiac output
effect of cardiac output on arterial blood volume and arterial blood pressure
if there is more output there will be higher blood volume and blood pressure
how does heart rate influence blood pressure
higher heart rate would increase blood pressure
skeletal muscle contraction in relation to blood flow
if there is more muscle contraction there will be higher blood flow and also higher heart rate
respiration on blood flow
Pulmonary circulation facilitates the process of external respiration: Deoxygenated blood flows into the lungs. It absorbs oxygen from tiny air sacs (the alveoli) and releases carbon dioxide to be exhaled
preload
the degree of stretch on the heart before it contracts
moyocardial contractiability
the forcefulness of contraction of individual ventricular muscle fibers
afterload
the pressure that must be exceeded before ejection of blood from the ventricles can occur.
vasular resistance
is the resistance in the circulatory system that is used to create blood pressure, the flow of blood and is also a component of cardiac function. When blood vessels constrict (vasoconstriction) this leads to an increase in SVR. When blood vessels dilate (vasodilation), this leads to a decrease in SVR.
why are artioles a major site for controlling total peripheral restistace
becuase they shink the size of the vessel the blood is in which causes more pressure and more restistance. If this was not done, the capillaries would have a more likely chance of bursting.
heart rate in relation to nerbous system
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blood vessel diameter in relation to heart rate
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areas of myocardium supplied by right cornoy artery
The right coronary artery supplies blood to the right ventricle, the right atrium, and the SA (sinoatrial) and AV (atrioventricular) nodes
areas of myocardium supplied by left conoary artery
he left main coronary artery supplies blood to the left side of the heart muscle (the left ventricle and left atrium).
function of coronary sinus
The coronary sinus is the major venous tributary of the greater cardiac venous system; it is responsible for draining most of the deoxygenated blood leaving the myocardium
