ppt heart unfv

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Structure of the Heart



Arteries

• Arteries are elastic vessels that

transport blood away from the

heart. The largest artery of the

body is the aorta. The aorta

originates from the heart and

branches out into smaller arteries.The smallest arteries are called

arterioles which branch into

capillaries.



Veins

• Veins are elastic vessels that transport blood to the heart. Thesmallest veins in the body are called venules. They receive blood

from the arteries via the arterioles and capillaries. The venules

branch into larger veins which eventually carry the blood to the

largest veins in the body, the vena cava. The blood is then

transported from the vena cava to the right atrium of the heart.

Vein Size

1 millimeter to 1-1.5 centimeters in diameter.



• Most veins have one-way flaps called venous valves

that prevent blood from flowing back and pooling in

the lower extremities due to the effects of gravity.

These are in-foldings of the tunica intima. The precise

location of veins is much more variable from person to

person than that of arteries.



Venous return

• During physical exercise, muscles contract and expand laterally.

• The intramuscular pressure exerted on the veins by the surrounding muscle

pushes blood through the one-way valves of the veins, returning it to the heart.

This pumping action keeps blood from pooling in the lower limbs, and individuals

that stand still for extended periods of time can experience reduced venous returnto the heart and low blood pressure (hypotension) leading to dizziness or fainting

(syncope).



List of important named veins

Jugular veins

Pulmonary veinsPortal vein

Azygos vein

Superior vena cava

Inferior vena cava

Iliac vein

Femoral veinPopliteal vein

Great saphenous vein

Small saphenous vein



Capillaries

• Capillaries are extremely small vessels located within the tissuesof the body that transport blood from the arteries to the veins.

Capillary walls are thin and are composed of endothelium (a

single layer of overlapping flat cells). Oxygen, carbon dioxide,

nutrients and wastes are exchanged through the thin walls of

the capillaries.



Capillary Exchange

• The Starling equation is an

equation that illustrates the

role of hydrostatic and

oncotic forces (the so-called

Starling forces) in the

movement of fluid across

capillary membranes.

• Capillary fluid movement

may occur as a result of two

processes:

• diffusion

• filtration

http://en.wikipedia.org/wiki/Hydrostatic_pressure

http://en.wikipedia.org/wiki/Oncotic_pressure

http://en.wikipedia.org/wiki/Capillary

http://en.wikipedia.org/wiki/Capillary

http://en.wikipedia.org/wiki/Oncotic_pressure

http://en.wikipedia.org/wiki/Hydrostatic_pressure



Respiratory Diffusion



Sinusoids• The liver, spleen and bone marrow contain vessel structures called instead of

capillaries. Similar to capillaries sinusoids are composed of endothelium. The

individual endothelial cells however do not overlap as in capillaries and are

spread out. Oxygen, carbon dioxide, nutrients, proteins and wastes are

exchanged through the thin walls of the sinusoids.



Where Is Your Heart?The heart lies behind the body of the sternum, extending from the

2nd

rib to the fifth intercostal muscle. About two thirds of the heart liesto the left of the mid line with the remaining third to the right.



An average adult heart is about the shape and size of a closed fist.

Like a valentine heart, yours is slightly pointed at the lower end.The pointed end is called the apex



Although your heart is hollow, it isn't empty. In an average adult, about 5

quarts (4.7 litres) of blood flow through the heart each minute.

Your heart's walls are made mostly of strong muscle, called the

myocardium. The myocardium is the strongest, hardest-working muscle in

your body. It continuously pumps your blood through 60,000 miles (96,560

kilometres) of blood vessels for a lifetime, without rest!



Heart Chambers

The hollow centre of your heart is divided into four sections, called

chambers. Each chamber is like a separate room, with doors that let

blood in and out.



Where Blood Flows In— The Atria

The two upper chambers in your heart are called the atria . The atriaare the receiving chambers of your heart. When blood flows into

your heart from the body or lungs, it always flows into either the

right or left atrium—never anywhere else. (One upper chamber is

called an atrium. Both upper chambers together are called the atria.)



Where Blood Is Pumped Out — The Ventricles

The two lower chambers in your heart are called ventricles. The ventricles are

the pumping chambers of your heart. When blood leaves your heart, it is

always pumped out from the ventricles—never from anywhere else. The

ventricles are very strong because they have to pump hard enough to push

blood through your lungs and entire body.



Your Heart's Right and Left Sides

Sometimes the right and left sides of your heart are called your right heart andleft heart. The right atrium and right ventricle are, of course, on the right side of

your heart (the same side as your right arm), and the left atrium and left ventricle

are on the left side of your heart. However, when you look at a picture of the

heart, the right heart is on your left

A wall, called the septum, separates the left and right sides of your heart. Blood

that hasn't yet been to the lungs (blood with no oxygen) stays on the right side of

the septum. Blood returning from the lungs (blood with oxygen) stays on the left

side of the septum.

right left



right



• The superior vena cava is a large, yet short vein that carriesde-oxygenated blood from the upper half of the body to theheart's right atrium.

• It is formed by the left and right brachiocephalic veins, (alsoreferred to as the innominate veins) which receive blood fromthe upper limbs and the head and neck, behind the lower

border of the first right costal cartilage.

• The azygous vein (which receives blood from the rib cage) joins it just before it enters the right atrium, at the upper rightfront portion of the heart.



• The inferior vena cava (or IVC) is the large vein that carries de-

oxygenated blood from the lower half of the body into the heart.

• It is posterior to the abdominal cavity and runs along side of the

vertebral column on its right side (i.e. it is a retroperitoneal

structure). It enters the right atrium at the lower right, back side

of the heart.



• The right atrium (in older texts termed the "right auricle") is

one of four chambers (two atria and two ventricles) in the

human heart. It receives de-oxygenated blood from thesuperior and inferior vena cavae and the coronary sinus, and

pumps it into the right ventricle through the tricuspid valve.

• The coronary sinus is a collection of veins joined together to

form a large vessel that collects blood from the myocardium

of the heart

• The atria do not have valves at their inlets



Tricuspid Valve

• The tricuspid valve prevents the blood from returning to

the right atrium when the right ventricle contracts

• The tricuspid valve is composed of tough connective

tissue covered in endocardium (thin layers of cells lining

the entire heart.)

• The tricuspid valve has three cusps and is Y’ shaped.

• It is one of the ATROVENTRICUALR valves.



• The right ventricle is one of four chambers (two atria and

two ventricles) in the human heart. It receives de-

oxygenated blood from the right atrium via the tricuspid

valve, and pumps it into the pulmonary artery via thepulmonary valve.

• It is triangular in form, and extends from the right atrium to

near the apex of the heart.



• The pulmonary arteries carry blood from the heart to thelungs. They are the only arteries (other than umbilical arteriesin the fetus) that carry deoxygenated blood.

• In the human heart, the pulmonary trunk (pulmonary artery or main pulmonary artery) begins at the base of the rightventricle. It is short and wide - approximately 5 cm (2 inches)

in length and 3 cm (1.2 inches) in diameter. It then branchesinto two pulmonary arteries (left and right), which deliverdeoxygenated blood to the corresponding lung.



• The pulmonary valve, also known as pulmonic valve, is the

semilunar valve of the heart that lies between the right

ventricle and the pulmonary artery and has three cusps



left



• The pulmonary veins carry oxygen-rich blood from the lungsto the left atrium of the heart. They are the only veins in thepost-fetal human body that carry oxygenated (red) blood.

• The pulmonary veins return the oxygenated blood from thelungs to the left atrium of the heart.

• They are four in number, two from each lung, and arewithout valves. They are

• right inferior

• right superior

• left inferior

• left superior



The left atrium is one of the four chambers in the human heart.

It receives oxygenated blood from the pulmonary veins, and

pumps it into the left ventricle.

• Normal left atrium may be up to 5.5cm in maximum

diameter; any larger than this is a sign of cardiac failure



• The mitral valve (also known as the bicuspid valve or leftatrioventricular valve), is a dual flap (bi = 2) valve in the heartthat lies between the left atrium (LA) and the left ventricle(LV).

• In Latin, the term mitral means shaped like a miter, orbishop's cap. The mitral valve and the tricuspid valve are

known collectively as the atrioventricular valves because theylie between the atria and the ventricles of the heart andcontrol flow.



• The left ventricle is one of four chambers (two atria and

two ventricles) in the human heart. It receives oxygenated

blood from the left atrium via the mitral valve, and pumps it

into the aorta via the aortic valve.



• The aortic valve has three cusps. These cusps are half moon

shaped hence also called aortic semilunar valve.

• Dilatation of the wall of the aorta behind these cusps is

called aortic sinus. When the aortic valve is open, the normalsize of the orifice is 3-4 cm² in adults.



The aorta is the largest artery in the human body, originating

from the left ventricle of the heart and bringing oxygenated

blood to all parts of the body in the systemic circulation.

The aorta is an elastic artery, and as such is quite distensible.

When the left ventricle contracts to force blood into the aorta,

the aorta expands. This stretching gives the potential energy

that will help maintain blood pressure during diastole, as during

this time the aorta contracts passively.



• The course of the aorta

• The aorta is usually divided into five segments/sections

• Ascending aorta — the section between the heart and thearch of aorta

• Arch of aorta — the peak part that looks somewhat like an

inverted "U"

• Descending aorta — the section from the arch of aorta to thepoint where it divides into the common iliac arteries

– Thoracic aorta — the half of the descending aorta abovethe diaphragm

– Abdominal aorta — the half of the descending aorta belowthe diaphragm



What Do Your Valves Do?

Your heart valves keep blood flowing in one direction through your heart, just like

the one-way valves in your home's plumbing. They open to let blood flowthrough, and then close to prevent blood from flowing back the way it came.

When a valve closes, flaps of tissue on the valve close tightly together to create a

seal. These flaps of tissue are called leaflets.

Where Are Your Heart Valves?

Your heart has four valves. Blood flows through each valve one time on its

way through your heart. The four valves can be grouped by their job.



Heart Valves

What Makes the Sound of Your Heartbeat?

When you listen to your heartbeat through a stethoscope ("lubb-dubb lubb-dubb"), you hear the sound of your heart valves closing. Although your heart has

four valves, the valves open and close two at a time. That's why you hear only

two thumps (one "lubb-dubb") per heartbeat, rather than four.



• Systemic circulation is the portion of the cardiovascular



Systemic circulation is the portion of the cardiovascularsystem which carries oxygenated blood away from the heart,to the body, and returns deoxygenated blood back to theheart

• In the systemic circulation, arteries bring oxygenated blood tothe tissues. As blood circulates through the body, oxygendiffuses from the blood into cells surrounding the capillaries,and carbon dioxide diffuses into the blood from the capillarycells. Veins bring deoxygenated blood back to the heart.



• Pulmonary circulation is the portion of the cardiovascular

system which carries oxygen-depleted blood away from the

heart, to the lungs, and returns oxygenated blood back to the

heart. The term is contrasted with systemic circulation.

ppt heart unfv

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