circulatory system

purkinje fibers function

distribute the stimulus to the ventricular myocardium, conduct action potentials more quickly than other conducting cells

pulmonary circuit

Blood vessels between the pulmonary semilunar valve of the right ventricle and the entrance to the left atrium; the blood flow through the lungs

systemic circulation

the vessels between the aortic valve and the entrance to the right atrium; the system other than the vessels of the pulmonary circuit

Arteries

efferent vessels; carry blood away from the heart

Veins

afferent vessels; return blood to the heart

Capillaries

exchange vessels; small blood vessels located between am arteriole and a venue, whose thin walls permit the diffusion of gases, nutrients and wastes between plasma and interstitial fluids

complete the pulmonary circuit

what must blood do before re-entering systemic circuit

right atrium

receives deoxygenated blood from the systemic circuit and passes it to the right ventricle

right ventricle

pumps blood into the pulmonary circuit

left atrium

collects blood from pulmonary circuit and empties it in the left ventricle

left ventricle

pumps blood into the systemic circuit

when the heart beats

1. atria contract

2. ventricles contract, both at the same time ejecting equal amounts of blood into circuits

sternum

the heart is directly posterior to _______

3rd

which costal cartilage is the base of the heart directly posterior to

apex

pointed tip of the heart

mediastunum

region between the 2 plural cavities

mediastinum

where are great vessels contained

great vessels

largest veins and arteries, thymus, esophagus and trachea

pericardial sac (fibrous pericardium)

surrounds the heart; consists of a dense network of collagen fibers and stabilizes the position of the heart and associated vessels with the mediastinum.

peridcardium

fibrous sac that surrounds heart; its inner, serous lining is continuous with the epicardium

visceral pericardium (epicardium)

covers and adheres closely to outer surface of the heart

parietal pericardium

lines the inner surface of the tough pericardial sac surrounding the heart

pericardial fluid

lubricant that reduces friction between the opposing surfaces as the heart beats

cardiac tamponade

Compression of the heart as the result of buildup of blood or other fluid in the pericardial sac, leading to decreased cardiac output.

coronary sulcus

groove that marks border between atria and ventricles

interventricular sulcus

overlies the interventricular septum that divides the right ventricle from the left

auricle

externally visible flap formed by the collapse of the outer wall of a relaxed atrium

epicardium

Serous membrane covering the heart; Adipose in thick layer in some places; Coronary blood vessels travel through this layer

Myocardium

cardiac muscle tissue of the heart; muscular wall of the heart- forms atria and ventricles; contains cardiac muscle tissue, blood vessels and nerves; concentric

endocardium

the simple squamous epithelium that lines the heart and is continuous with the endothelium of the great vessels

intercalated discs

regions where adjacent cardiocytes interlock and where gap junctions permit electrical coupling between the cells

intercalated discs function

transfer the force of contraction from cell to cell and propagate action potentials

cardiac cell characteristics

small size, a single centrally located nucleus, branching interconnections between cells, presence of intercalated discs

interatrial septum

separates atria

interventricular septum

separates ventricles

atrioventricular (AV) valves

folds of fibrous tissue that extend into openings between atria and ventricles

Connect right atrium to right ventricle and left atrium to left ventricle

Permit blood flow in one direction - from atria to ventricles

right atrium function

receives blood from the systemic circuit through the two great veins (SVC, IVC)

superior vena cava

vein that carries blood to the right atrium from parts of the body that are superior to the heart

inferior vena cava

vein that carries blood from the parts of the body inferior to the heart to the right atrium

coronary sinus

a large thin walled vein that opens into the right atrium inferior to the connection with the superior vena cava

foramen ovale

oval opening that penetrates the intertribal septum and connects the two atria of the fetal heart

valve malfunction

what does a heart murmur indicate

chordae tendineae

fibrous cords that stabilize the position of the AV valves in the heart, preventing backflow during ventricular systole

ventricle systole

ventricle is filled with blood and contracts, pumping blood to the aorta and pulmonary arteries

trabeculae carneae

series of muscular ridges on internal surface of ventricles

moderator band

A muscular ridge that extends horizontally from the inferior portion of the interventricular septum and connects to the anterior papillary muscle

right AV node closes

right ventricle contracts

back flow of blood into right atrium is prevented

conus arteriosus

a cone shaped pouch that ends at the pulmonary valve

pulmonary valve

consists of 3 semilunar cusps of thick connective tissue

pulmonary trunk

blood flow: pulmonary valve ----> __________------> "beginning of pulmonary circuit"------> left and right pulmonary arteries

left atrium function

receives blood from two pulmonary veins (left and right)

atrium

what has an auricle?

left atroventricular (AV) valve

guards the entrance to the left ventricle, permits blood to flow from the left atrium to the left ventricle, but prevents back flow when the left ventricle contracts

bicuspid valve

aka left AV valve aka mitral valve

left ventricle

much larger than atrium because it has thicker walls

blood needs to be pushed through large systemic circuit

no moderator band

blood flow through LV

leaves through aortic valve ---> ascending aorta----> aortic arch----> descending aorta

ligamentum arteriosum

a fibrous band left over from an important fetal blood vessel that once linked the pulmonary and systemic circuits

the vena cava

where does the coronary sinus dump into

atria function

collect blood that is returning to the heart and conveys it to the ventricles

differences between left and right ventricles

1. muscular wall of right ventricle is thin, left is thick

2. right ventricle pumps blood to the lungs, left ventricle pumps to the body.

severe right ventricle damage

victims of _______ may still survive because the contraction of the left ventricle helps push blood into the pulmonary circuit

chordae tendineae function

anchor the AV flaps and prevent back flow of blood into the atria

atrioventricular valves

prevent backflow into atria when ventricles contract

loose

relaxed ventricles = ________ chordae tendineae

tense, contracting

contracting ventricles = ______ chordae tendineae and _____ papillary muscles

semilunar valves

the pulmonary and aortic valves prevent the backflow of blood from the pulmonary trunk and aorta into the left and right ventricles

the positions of the cusps are stable

why don't semilunar valves need muscular braces like AV valves do

aortic sinuses

prevent the individual cusps from sticking to the wall of the aorta when the valve opens

coronary arteries

deliver blood to the myocardium, originate at the left and right aortic sinuses

Valvular Heart Disease (VHD)

occurs when valve function deteriorates to the point at which the heart can't maintain adequate circulatory flow

a strong elastic sheath

what is each cardiac muscle cell wrapped in

struts function

separate the superficial and deep muscle layers

struts

what are adjacent cells tied together by

cardiac skeleton (fibrous skeleton)

four dense bands of tough elastic tissue that encircle heart valves and bases of the pulmonary trunk and aorta

cardiac skeleton function

bands stabilize position of the heart valves and ventricular muscle cells and electronically insulate ventricular cells

myocardium

which layer has its own separate blood supply

coronary circulation

supplies blood to the muscle tissue of the heart; includes an extensive network of coronary blood vessels

at the aortic sinuses

where is blood pressure the highest

connective tissue fibers function 1

provide physical support for cardiac muscle fibers, blood vessels and nerves of the myocardium

connective tissue fibers function 2

help distribute the forces of contraction

connective tissue fibers function 3

add strength and prevent the overexpansion of heart

connective tissue fibers function 4

provide elasticity to help return heart shape to normal after contraction

arterial anastomoses

Interconnect anterior and posterior interventricular arteries

Stabilize blood supply to cardiac muscle

aorta

blood is forced _____ when the left ventricle contracts, stretching the elastic walls

elastic rebound

walls of the aorta recoil when left ventricle relaxes and pressure declines

aorta

walls of _____ recoil, pushing blood forward into the systemic circuit and backward through the aortic sinuses and into respective coronary arteries

unsteady

myocardial blood flow is ______

right coronary artery

what supplies the right atrium, portions of both ventricles and portions of conducting system of heart (SA node and AV node) with blood

marginal arteries

extend across the surface of the right ventricle

right coronary artery

gives rise to marginal arteries

posterior interventricular artery

runs toward the apex within the posterior interventricular sulcus; supplies blood to the inter ventricular septum and adjacent portions of the ventricles

right coronary artery

gives rise to the posterior inter ventricular artery