heart - prevet (module 6)

Cardiac system purpose

transport oxygen/nutrients throughout body to tissue and dispose of waste products to be excreted at different organs

Heart

pumps fluid through the cardiac system

Arteries are ___ and why

thicker due to the need to pump with high pressure

Veins are ___ and why

thinner due to real low pressure

The heart has ___ chambers

4

What do the four chambers of the heart consist of

two atrium, two ventricles (one atrium/ventricle on left, one atrium/ventricle on right)

The atria and ventricles are separated by

the atrioventricular valve (AV valves)

The two sides of the heart are separated by

the septum

The septum that is thicker and separates ventricles

interventricular septum

The heart is made of specialized muscle called

cardiac muscle

Muscles arrange themselves in the heart to form networks called

syncytium

The syncytium ensures that

fibers in the heart all contract at the same time - this is how the atria and ventricle are able to contract together to pump blood

The heart has an intrinsic contracting ability in the absence of a stimulus

True

The impulse for contract stems from the

Sino-atrial node (or SA node)

The SA node, to make a contraction will

transmit its impulse to the AV node from where it is propagated

After the impulse reaches the AV node from the SA node

it will propagate through the rest of the heart through specialized fibers called Purkinje fibers that form “Bundles of His”

Fibers from the right branch of the Bundle of His pass through a muscular band called the

Trabecula septomarginalis (or moderator band)

Heart rate can be increased or decreased through

autonomic nerves or other mediators

Most of the blood that the heart pumps, goes to the rest of the body and is called the

functional blood supply

Nutrient supply to the heart is through a small fraction of the blood that is distributed through the

coronary blood vessels

The inside walls of the heart have

specialized muscles called “papillary muscles”

The thick cords that attach the papillary muscles to the valves are called

chordae tendinae

The inside of the heart is covered by a thin membrane called

endocardium

The heart muscle itself is called the

myocardium

The outside of the heart is covered by another thin membrane called the

epicardium

The heart has a ___ that runs around the heart separating the atria from the ventricles

coronary groove (contains coronary blood vessels)

The left ventricle is very large compared to the right ventricle because

it has to be strong enough to pump blood through the aorta to the rest of the body

The left ventricle extends through the

right and left side of the heart

The 2 grooves on either side of the heart separating the right from the left ventricle

1. Paraconal groove

2. Subsinosal groove

The paraconal groove is found beside the

conus arteriosus

conus arteriosus

a cone-shaped prominence on the right ventricle from which the pulmonary trunk arises

The subsinosal groove is found below the ___

coronary sinus - this is a "pool" that collects venous blood from the heart muscle

The heart is covered by a fibrous sac called the

pericardial sac

The pericardial sac contains a few mls of a thin, watery fluid called

“pericardial fluid” - this sac is a protective covering for the heart

Arteries consist of three layers

1. Tunica intima

2. Tunica media

3. Tunica adventitia

Tunica intima

the thinnest layer and consists of endothelial cells surrounded by connective tissue

Tunica media

the thickest layer, consists of elastic fibres, connective tissue vascular smooth muscles

Tunica intima

made up of connective tissue and contains nerves that regulate the vessels

Arteries branch into

arterioles

Veins

carry blood to the heart

Veins branch off to form

venules

Veins also have the capacity to

dilate to accommodate the increase in blood volume

Artery qualities

elastic in nature, relax and contract in rhythm with the heart and maintain the blood pressure

Capillaries act as

a bridge between arteries and veins and have very thin walls to allow for oxygen to pass from blood to tissues