heart

Heart, Blood Vessels, Blood

COMPONENTS OF CARDIOVASCULAR SYSTEM

Vein

toward the heart

Artery

away from the heart

size of a fist and weighs less than 1 lb.

Size and weight of heart

between lungs in thoracic cavity (mediastinum)

Location of heart

apex (bottom) towards left side

Orientation of heart

Pericardium

double-layered sac that anchors and protects heart

Parietal pericardium

membrane around heart's cavity

Visceral pericardium

membrane on heart's surface

Pericardial cavity

space around the heart. Inside is pericardial fluid (prevents friction in our heart)

Epicardium

surface of heart (outside)

Myocardium

thick, (middle) layer composed of cardiac muscle

Endocardium

smooth, (inner) surface of heart

CARDIOMYOCYTES

Cells of cardiac muscle/ heart

Ca2+ and ATP

used for contractions of heart

Left atrium (LA), Right atrium (RA), Left ventricle (LV), Right ventricle (RV)

4 chambers of heart

Coronary sulcus

separates atria from ventricles

ATRIA

Upper portion; Holding chambers (receiving chambers); Small, thin walled; Contract minimally to push blood into ventricles

Interatrial septum

separates right and left atria

VENTRICLES

Lower portion; Pumping chambers; Thick, strong walled; Contract forcefully to propel blood out of heart

Interventricular septum

separates right and left ventricles

VALVES

Structure that ensure 1 way blood flow

ATRIOVENTRICULAR VALVES (AV)

Between atria and ventricles

Tricuspid valve

AV valve between RA and RV; 3 cusps

Bicuspid valve (mitral)

AV valve between LA and LV; 2 cusps

CHORDAE TENDINEAE (HEART STRINGS)

Attached to AV valve flaps; Support valves

Pulmonary valve

base of pulmonary trunk

Aortic valve

base of aorta

TAKOTSUBO CARDIOMYOPATHY

Broken heart syndrome; heart strings are destroyed because of intense emotions.

CARDIOMEGALY

Increase in size of the heart. An enlarged heart is when your heart is abnormally thick or overly stretched, becoming larger than usual, with difficulty pumping blood.

Blood flows from LA into LV; Aortic semilunar valve is closed; Tension on chordae tendineae is low

What happens when the Bicuspid valve is Open?

Blood flows from LV into aorta; Aortic semilunar valve is one; Tension on chordae tendineae is high

What happens when the Bicuspid valve is closed?

Pulmonary circuit

Carries blood from heart to lungs; Blood is O2 poor, CO2 rich

RIGHT ATRIUM

Receives blood from 3 places (vena cavas and coronary sinus)

Superior vena cava

Drains blood above diaphragm (head, neck, thorax, upper limbs)

Inferior vena cava

Drains blood below diaphragm (abdominopelvic cavity and lower limbs)

Coronary sinus

Drains blood from myocardium

RIGHT VENTRICLE

Opens into pulmonary trunk

Pulmonary trunk

Splits into right and left pulmonary arteries

Pulmonary arteries

Carry blood away from heart to lungs

Systemic circuit

Carries blood from heart to body; Blood is O2 rich, CO2 poor

LEFT ATRIUM

4 openings (pulmonary veins) that receive blood from lungs

LEFT VENTRICLE

Opens into aorta; Thicker, contracts more forcefully, higher blood pressure than right ventricle has to get to body

AORTA

Carries blood from LV to body

Blood in the heart chambers

does not nourish the myocardium

The heart

has its own nourishing circulatory system

CORONARY ARTERIES

Supply blood to heart wall; Supply the capillaries of the myocardium with blood; Originate from base of aorta (above semilunar valve)

Right Coronary Artery

Originates at the right side of the aorta; Supply most blood to the right ventricle; Posterior interventricular artery, Right marginal artery

Left Coronary Artery

Has 3 branches; Anterior interventricular artery, Circumflex artery, Left marginal artery; Supplies the anterior wall of the heart and most of left ventricle

CARDIAC VEINS

Drain blood from cardiac muscle; Some small cardiac veins drain directly into the right atrium

CORONARY SINUS

a large vein located within the coronary sulcus into the right atrium; returns blood to the right atrium.

THE HEART

Conduction system

Sinoatrial Node

"pacemaker" initiates each heart beat; 60 to 100/min

Atrioventricular Node

junction of the atria and ventricles

Atrioventricular Bundle

in the interventricular septum

Bundle (Right and Left) Branches

in the interventricular septum

Purkinje Fibers

spread within the ventricle wall muscles

pacemaker potential

Changes in membrane channels' permeability are responsible for producing action potentials and is called

Depolarization Phase

Na+ channels open; Ca2+ channels open

Plateau Phase

Na+ channels close; Some K+ channels open; Ca2+ channels remain open

Repolarization Phase

K+ channels open; Ca2+ channels close

Plateau phase

prolongs action potential by keeping Ca2+ channels open.

2 msec

In skeletal muscle action potentials tak

200-500 msec.

in cardiac muscle they take

CONDUCTION SYSTEM OF HEART

Contraction of atria and ventricles by cardiac muscle cells

Sinoatrial Node (SA Node)

In right atrium; Where action potential originates; Functions as pacemaker; Large number of Ca2+ channels

Sinoatrial node, Atrioventricular node, Atrioventricular bundle, Right and Left Bundle branches, Purkinje fibers

PATH OF ACTION POTENTIAL THROUGH HEART

ELECTROCARDIOGRAM

Record of electrical events in heart; Diagnosis cardiac abnormalities; Uses electrodes; Contains P wave, QRS complex, T wave

P wave

depolarization of atria

QRS complex

depolarization of ventricles; contains Q, R, S waves

T wave

repolarization of ventricles

Heart

is 2 side by side pumps: right and left

Atria

primers for pump

Ventricles

power pumps

CARDIAC CYCLE

Repetitive pumping action which includes contraction and relaxation; Cardiac muscle contractions produce pressure changes within heart chambers

Pressure changes

are responsible for blood movement

of high to low pressure

Blood moves from areas

Atrial systole

contraction of atria

Ventricular systole

contraction of ventricles

Atrial diastole

relaxation of atria

Ventricular diastole

relaxation of ventricles

Stethoscope

is used to hear lung and heart sounds

lubb

First sound is

dupp

second is

Sounds

result from opening and closing valves

Murmurs

are due to faulty valves

Stroke Volume

Volume of blood pumped per ventricle per contraction; 70 ml/beat

Heart Rates

Number of heart beats in 1 min.; 72 beats/min.

Cardiac Output

Volume of blood pumped by a ventricle in 1 min.; 5 L/min.

INTRINSIC REGULATION OF HEART

Mechanisms contained within heart

Venous return

amount of blood that returns to heart

Preload

degree ventricular walls are stretched at end of diastole

Starlings Law of the Heart

Relationship between preload and stroke volume; Ex. exercise increases venous return, preload, stroke volume, and cardiac output

Afterload

pressure against which ventricles must pump blood

EXTRINSIC REGULATION OF HEART

Mechanisms external to heart; Nervous or chemical regulation

Baroreceptor Reflex

Mechanism of nervous system which regulates heart function; keeps heart rate and stroke volume in normal range

baroreceptors

monitor blood pressure aorta and carotid arteries (carry blood to brain)

changes in blood pressure

cause changes in frequency of action potentials; involves medulla oblongata

Chemoreceptor Reflex

chemicals can affect heart rate and stroke volume

epinephrine and norepinephrine from adrenal medulla

can increase heart rate and stroke volume