Functions of the Heart

Functions of the Heart

Generate blood Pressure Routing Blood Ensuring one way blood flow Regulating blood supply

The Heart

Located in the Thorax Part of the Mediastinum ( heart,

trachea and esophagus) Size of a Fist Blunt end is called apex, Flat portion

at the opposite end is the base

The Heart

Apex- most inferior anterior and to the left located at the fifth intercostal space

Base- superior and slightly posterior most superior part is in the

second intercostal space

The Pericardium

the heart is surrounded by a space called the pericardial cavity

the pericardium consists of a fibrous and a serous part

the serous pericardium consists of a parietal and a visceral pericardium

The Heart: Atria and Ventricles

Atria- located at the base

Ventricles- extends from apex to the base

Sulcus- Coronary Sulcus-extends around the heart and separates the atria from the ventricles

Vessels- veins and arteries and capillaries

Veins: Six large veins carry blood to the heart

- the superior vena cava- blood from body to right atrium - the inferior vena cava- blood from body to right atrium

- four pulmonary veins- blood from lungs to the left atrium

Arteries

The pulmonary trunks and the aorta exit the heart

The pulmonary trunk arises from the right ventricle splits into right and left pulmonary arteries which carry blood to the lungs

The Aorta carries blood to body

Blood Supply to the Heart Coronary Arteries- two coronary arteries originate from the

base of the aorta just above the aortic semi lunar valves

The left coronary artery originates on the left side of the aorta and it supplies most of the anterior wall of the heart and most of the wall of the right ventricle

The right coronary artery originates on the right side of the aorta and supplies most of the right wall of the right ventricle

The left coronary artery originates on the left side of the aorta and it supplies most of the anterior wall of the heart and most of the wall of the right ventricle

The right coronary originates on the right side of the heart and supplies most of the wall of the right ventricle

Heart Chambers

Consists of Four Chambers Two Atria

Two Ventricles

Internal Anatomy of the Heart

The Atria Atria- Right and Left atria receive blood

from veins

Right atria- reservoir for blood returning from

the body (superior vena cava, inferior vena cava and coronary sulcus)

Left atria – receive the blood from four

pulmonary veins

The Ventricles

The right and left ventricles of the heart are the major pumping chambers

The right ventricle pumps blood into the pulmonary arteries to the lung

The left ventricle pumps blood into the aorta which sends blood to the rest of the body

The Heart Valves

A- V ( Atrioventricular) Valves

Semilunar Valves ( Half Moon)

The A-V Heart Valves

A-V valves are located between the right atrium and right ventricle and between the left atrium and left ventricle

The A-V valves on the right are called the tricuspid valves (three cusps)

The A-V on the left side are called the bicuspid valves ( two cusps)

Heart Valves continued

Valves also exist between the right ventricle and the pulmonary arteries and the left ventricle and the aorta

These valves are called semilunar valves because they have a half moon shape.

Direction of Blood Flow through the Heart

Route of blood flow through the Right Heart

Blood returning from the body via the superior vena cava, the inferior vena cava and the coronary arteries empty into the right atrium

From the right atria blood flows through the tricuspid valve and enters the right ventricle

From the right ventricle blood flows through the pulmonary semilunar valves into the pulmonary trunk to pulmonary arteries ( to the lungs to pulmonary circulation)

Route of Blood flow through the Left Heart

Blood returning from the lungs enters the left atrium

From the left atrium blood passes through the Bicuspid valve into the left ventricle

From the left ventricle blood will then pas through the semilunar valves into the aorta and then to the systemic circulation

Animated Tutorial of the Circulation of Blood through the heart

ANSWER?

How is the movement of the blood through the heart accomplished ?

The Cardiac Cycle

To Main Pumps: The primer pump is the atria- because

they complete the filling of the ventricle

The power pump is the ventricle- because they produce the major force throught the systemic circulation

Contraction / Relaxation (Systole)/ ( Diastole)

Atrial Systole refers to contraction of the two atria

Ventricular systole refers to contraction of the two ventricle

Atrial diastole refers to relaxation of the two atria

Ventricular diastole refers to relaxation of the two ventricles

Major Events of the Cardiac Cycle Ventricular Systole- pushes blood back toward the atria, causing the A-V valves to

close - pressure in the ventricles exceeds the pressure in the pulmonary

trunk and aorta causing the semilunar valves to be forced open and blood is ejected into the pulmonary trunk and aorta

Ventricular diastole - The semilunar valves close, preventing blood from flowing back into the ventricles .

- The pressure continues to decline in the ventricle until finally the A-V valve open and the blood flows directly from the atria into the relaxed ventricle

.( During the previous ventricular systole, the atria were relaxed and the AV valves open, blood flows into the ventricles and fills them to approximately 70% of their volume

Atrial systole forces additional blood flow into the ventricles to complete their filling. The semilunar valves remain closed.)

Animated Tutorial of the Circulation of Blood through the heart

The Heart Sounds A stethoscope What you can hear S1 – The first heart sound (lubb) beginning of systole results from closure of the A-v

valves S2 – The second heart sound

(dupp) beginning of ventricular diastole results from closure of the semilunar valves ventricular systole – between S1 and S2 ventricular diastole- between S2 and S1

Abnormal Heart Sounds continued Murmur- result from faulty valves incompetent- the valves fail to

close tightly and blood leaks backward through the valve when it is closed

stenosed- the opening of the valve is narrowed

usually a swishing sound

Heart Sounds Demonstrations

Regulation of Heart Function Cardiac Output (CO)- the volume of

blood pumped by either ventricle per minute

Stroke volume (SV)- is the volume of blood pumped per ventricle each time the heart contracts

Heart Rate (HR)- number of heart contractions per minute

CO= SV x HR

The Vascular System

Arteries to Capillaries to Veins

Vessel Structure

Tunica Intima Tunica Media Tunica Adventitia

Blood Vessels

Arteries- are blood vessels that carry blood away from the heart

elastic muscular arterioles

Blood Vessels Continued

Capillaries- thin walled numerous site of gas and nutrient

exchange

Blood Vessels continued

Veins- carry blood to the heart veins are thinner, with less

elastic tissue venules small veins medium sized veins large veins

The Aorta

All Arteries branch from the aorta Three parts: ascending (coronaries) aortic arch ( head and upper

limbs) descending( thoracic, abdominal and common iliacs)

Blood Pressure

Blood pressure is a measure of the force blood exerts against the bllod vessel walls.

When the ventricles contract, blood is forced into the arteries , and the pressure reaches a maximum callled the systolic pressure

When the ventricles relax, blood pressure in the arteries falls to a minimum called the diatolic pressure