BIOL 2060 Ch.19-Heart

Cardiovascular system

Organs and tissue that work together to transport respiratory gases, nutrients, wastes, hormones, and antibodies

Functions of cardiovascular system

Maintain internal environment

Removes toxic and pathogenic materials from body

Function in temp regulation

Repairs leaks and compensates for damage

Pulmonary circuit

Pathway of blood to and from the heart and the lungs

Deoxygenated blood is transported away from the heart and towards the lungs while oxygenated blood is returned to the heart from the lungs

Systemic circuit

The pathway of blood from the heart and the body

Oxygenated blood is transported away from the heart and toward the body and deoxygenated blood is returned from the body to the heart

Heart

Serves as the pump, which provides the force necessary to push blood to the lungs and body and draw blood back into the heart

Arteries

Carry blood away from the heart

Veins

Carry blood back into the heart

Apex

Inferior conical end that lies to the left of the midline; formed by left ventricle

Base

The broad posterior-superior surface

Pericardium

three layered sac that surround the heart

Fibrous pericardium

Made of dense CT

Forms the outer most layer of pericardium

Holds the heart in place and keeps it from over-filling

Serous pericardium

double-layered coelomic cavity filled with serous fluid

Pericardial cavity

Coelomic cavity between the outer parietal pericardium and inner visceral pericardium

Filled with serous fluid which reduces friction around the pumping heart

Myocardium

Covering of heart created by cardiac muscle tissue

Cardiac Skeleton

Dense irregular CT of the heart wall surrounds all 4 valves

Functions of cardiac skeleton

1. Reinforces the myocardium and anchors cardiac muscle fibers

2. Anchors valve cusps

3. Prevents over-dilation of valve openings

4. Main point of insertion for cardiac muscle

5. Blocks direct spread of electrical impulses

Right Atrium

receives deoxygenated blood from the body and the heart wall into the right atrium

Characteristics of right atrium

1. contains superior vena cava, inferior vena cava, and coronary sinus

2. Right auricle

3. Pectinate muscles

4. Crista terminalis

5. Fossa ovalis

6. Tricuspid valve

Right ventricle

Receives deoxygenated blood from right atrium and pumps it to the lungs

Characteristics right ventricle

1. internal walls marked by trabeculae carneae

2. Papillary muscles

3. Chordae tendineae- connected to cusps of tricuspid valve

4. Pulmonary semilunar valve

5. Pulmonary trunk

Left atrium

Receives oxygenated blood from lungs

Left atrium characteristics

Right and left pulmonary veins empty into it

Pectinate muscles line auricle only, inner wall of LA smooth

Blood leaves through Mitral valve/bicuspid valve

Left ventricle

Receives oxygenated blood from left atrium and pumps it to the rest of the body

Characteristics of left ventricle

1. More muscular and larger than right ventricle

2. Forms apex of heart

3. trabeculae tendineae

4. papillary muscles and chordae tendineae attach to cusps of mitral valve

5. Blood leaves through aortic semilunar valve and enters aorta

Heart valves

flaps of endothelial endocardium and dense connective tissue; ensures one-way flow of blood through the heart and arteries

Tricuspid valve/right atrioventricular valve

located between right atrium and right ventricle

Bicuspid/ left atrioventricular valve/ mitral valve

located between left atrium and left ventricle

Aortic semilunar valve

located between the left ventricle and aorta

Pulmonary semilunar valve

located between right ventricle and pulmonary trunk

Cardiac cycle

Changes within the heart from initiation of one heartbeat to the start of the next

pressure diff facilitate unidirectional blood movement

pressure increases during systole and decreases during diastole; blood moves from high to low pressure

Heartbeat

Single sequence of atrial and ventricular contraction

systole

contraction

diastole

relaxation

myogenic

generates own impulse to contract, no external regulation required

Conducting system

specialized cardiac muscle cells that carry impulses, which signal the heart chambers to contract

sinoatrial/SA node

located in right atrium; it signals the beginning of each heartbeat and sets the base rate

internodal pathway

connect the SA node to the AV node

Atrioventricular node/AV node

serves to delay the electrical signal between the atria and ventricles

Atrioventricular bundle/ Bundle of His

is located within the interventricular septum

bundle branches

composed of right and left sides, signal travels along bundle branches

Purkinje fibers

starts about halfway down the interventricular septum toward the apex and then turns superiorly along the ventricular walls

parasympathetic fibers

branches of vagus nerve

decrease heart rate

innervate SA node, AV node, coronary arteries

Sympathetic nerves

travel to heart from cervical and upper thoracic chain ganglia

innervate SA node, AV node, coronary arteries

Also innervate cardiac musculature throughout the heart

increase heart rate and strength of contraction

cardiac veins

carry deoxygenated blood from heart wall toward right atrium

coronary sinus

Three tributaries of coronary sinus

Great cardiac vein, middle cardiac vein, small cardiac vein

Left coronary artery

anterior interventricular artery, circumflex artery

Right coronary artery

Marginal artery, posterior interventricular artery