Module 3: The Heart

The heart

the organ responsible for pumping blood through the vessels of the cardiovascular system.

pericardial cavity

contains the heart

Base

The superior end of the heart, to which the "great veins and arteries," are attached

Apex

The inferior tip of the heart

Atrium

small chamber in the human heart that receives blood from the veins

Ventricule

A larger chamber of the heart that pumps blood out to the lungs and body

Pulmonary

pertaining to the lungs

pulmonary circuit

Blood vessels that carry blood from the heart, to the lungs, then back to the heart

Systematic circuit

Blood vessels that carry blood from the heart to all other parts of the body and then back to the heart.

Pericardium

A set of membranes that cover the heart

Fibrous pericardium

outermost layer of pericardium, anchors the heart in place

Parietal Pericardium

outer layer of the pericardium, lines the pericardial cavity

Visceral Pericardium

innermost layer, covers the heart

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Outermost layer of the heart

Pericardial Fluid

fills the space between the parietal and visceral layers, lubricates the heart, and reduces friction as it pumps.

3 layers of the heart

epicardium, myocardium, endocardium

Epicardium

outermost layer of the heart, additional layer of protection from trauma or friction for the heart under the pericardium.

Myocardium

thickest layer of tissue that makes up the heart,made of cardiac muscle, blood vessels, and nerves.

Endocardium

a thin layer of epithelial tissue that lines the chambers of the heart.

Septa

Walls of tissue separating the four chambers of the heart

interatrial septum

thin layer of myocardium that separates the two atrias

interventricular septum

a thick layer of myocardium that separates the two ventricles

atrioventricular septum

layer of tissue between the atria and ventricles

Orfice

an opening

Valves

prevent back flow of blood

tricuspid valve

prevents blood from flowing back into the right atrium from the right ventricle

bicuspid valve/ mitral valve

prevents blood from flowing back into the left atrium from the left ventricle

chordae tendineae

Connective tissue fibers that help to prevent the valves from being forced to open backwards

pulmonary semilunar valve

prevent blood from flowing back into the right ventricle

aortic semilunar valve

of prevents blood from flowing back into the left ventricle

Contractile cells

contracts and generates the force to pump blood

Conducting cells/ "autorhythmic cells"

control electrical activity of the heart, and set the heart beat

hypertrophic cardiomyopathy

A condition in which the heart muscle becomes abnormally thick.

Shape of heart

cone-shaped, similar to a pinecone

Size of heart

size of fist

Left ventricle

pumps blood into the systemic circuit via the opening to the aorta.

Right Ventricle

pumps blood into the pulmonary circuit via the opening to the pulmonary trunk.

Left Atrium

flows into the left ventricle through the bicuspid orifice

Right Atrium

flows into the right ventricle through the tricuspid orifice.

Intercalated discs

Link cardiac muscle cells together

Desmosomes

Help link the cells together with strength

functional syncytium

describes how branches and gap junctions link the entire myocardium into a single functional unit

Cardiac muscle cells structure

Short, small in diameter, and branched

4 Great vessels

* Superior + inferior vena cava
* aorta
* pulmonary trunk
* Pulmonary veins

4 Chambers

* Left atrium
* Right atrium
* Left ventricle
* Right ventricle

4 Valves

* Tricuspid
* Bicuspid (mitral)
* Pulmonary semilunar
* Aortic Semilunar

Flow of Blood

Superior and inferior vena cavae - right atrium - tricuspid valve - right ventricle - pulmonary semilunar valve - pulmonary artery - pulmonary veins - left atrium - bicuspid valve - left ventricle - aortic semilunar valve - aorta

Left side of heart (Systemic circuit)

pumps blood to the body

Right side of heart (Pulmonary circuit)

Pumps blood to and through lungs

serous membrane

Thin, shiny lining covering the heart. Also lines the inside of the heart

5 layers of the heart + membrane

* Fibrous pericardium
* Parietal pericardium
* visceral pericardium/ epicardium
* myocardium
* endocardium

Functional syncytium

multiple cells coming together and acting as one unit

Cardiac cycle

period from the beginning of one heartbeat to the beginning of the next

Systole

Contraction of the heart

diastole

Relaxation of the heart

Interatrial septum

Thin layer of myocardium

Interventricular septum

thick layer of myocardium

Intrinsic and extrinsic control mechanisms

Controls the rate at which the heart beats

contractile cells

Contract and generate the force to pump blood

Where are contractile cells located

myocardium

Conducting cells

control electrical activity of the heart and set the heart beat.

functional syncytium

branches and gap junctions link the entire myocardium into a single functional unit.

Which node depolarizes at the fastest rate?

The Sinoatrial (SA) Node

Atrioventricular node

picks up electrical impulses and spreads it across the atria and carries it to the ventricles at a slower speed

Purkinje Fibers

picks up electrical activity and rapidly spreads a wave of depolarization across the myocardium of the ventricles.

Cardiac cycle

the period from the beginning of one heartbeat to the beginning of the next one.

Atrial systole

contraction of the atria

End-diastolic volume (EDV)

the volume of blood in the ventricles is maximal after atrial systole

End- systolic volume( ESV)

The volume of blood in the heart at the end of ventricular systole

Stroke Volume

the quantity of blood ejected by the ventricles

Ejection Fraction

Percentage of blood pumped out

Isovolumetric contraction

Volume of fluid remains constant while all ventricles are contracting

Isovolumetric relaxation

All four valves are closed simultaneously

Cardiac Output

The volume of blood pumped by each ventricle in a minute

Contractility

The force exerted by the myocardium

Positive inotropic effect

Any factor that increases contracitility

Negative inotropic effect

Any factor that decreases contractiility

Afterload

the amount of force the ventricles must produce to eject blood through the semilunar valves

Filling time

The duration of ventricular diastole

Venous return

the rate of flow back to the heart from the body

Stroke Volume equation

SV= EDV- ESV

Cardiac Output equation

CO(ml/min)= HR (beat/min) x SV (ml/beat)

intercalated disk

Links cardiac muscle cells

Ejection fraction equation

SV/EDV x100

Cardioacceleratory center

stimulates sympaatheric neurons to send signals to the heart

Vagus nerves

release acetylcholine (ACh)

P wave

Depolarization of atria

QRS complex

Contraction of ventricles

T wave

Repolarization of the ventricles

Depolarization

Contracting

Repolarization

Relaxed