Structure and Functions of Heart

The human heart is life for humans because without a heart they cannot even live. Blood transportation over the body is done by the heart itself and also air transportation from the environment to the lungs is done by the heart. The average heartbeat in a day is 100,000 times. Male heart weight is about approximately 340 grams whereas female heart weight is approximately 280 grams. The human heart pumps blood around 60000 to 7,5000 liters in a day through the body.

What is a Human Heart?

The heart is an internal organ that is located in between the lungs in the thoracic cavity in humans. The main function of the heart is to control the flow of blood throughout the body for each part. In humans, the heart has four chambers. Those four chambers are given below.

• Two atria 
• Two ventricles

Diagram of Human Heart

The labelled diagram of Human heart is shown below:

👁 Human-Heart-Diagram

Structure of the Human Heart

The human heart is a muscular organ that plays a important role in blood circulation throughout the body, providing oxygen and nutrients to each cells while removing waste products. Human heart consists of several chambers and valves that work together to ensure proper blood flow in the body. Here's an overview of the structure of the human heart:

Atria

Atria are two types. They are the right atrium and left atrium. These are called the upper chambers of the heart.

• Right Atrium: The right atrium is used to receive blood from veins. Veins contain circulated blood. The right atrium receives that circulated blood from the veins and pumps that blood over the right ventricles.
• Left Atrium: Left atrium is used to receive the oxygen-rich blood from the lungs and pumps it into the left ventricle.

Ventricles

Ventricles are muscular chamber, larger in size. Ventricles are responsible for pumping blood out from the heart. Ventricle are of of two types, right ventricle and left ventricle. These are called the lower chambers of the heart.

👁 Heart

• Right Ventricle: The right ventricle has a pulmonary valve that is used for transferring the blood to the lungs to pick up oxygen. The pulmonary valve helps in the regulation of blood flow from the right ventricle to the pulmonary arteries.
• Left Ventricle: The left ventricle pumps the oxygen-contained blood to the body through arteries. The Mitral valve helps to move blood from the left atrium to the left ventricle.

Position of Human Heart in the body

The human heart is located between the lungs in the thoracic cavity and its little bit towards the left of the sternum which is derived from the embryonic mesodermal germ layer.

Evolution of Heart

The heart was coined by William Harvey. In the fourth century B.C, Aristotle identifies the heart as one of the most crucial organs in the human body. Aristotle was a Greek philosopher. The heart receives blood from the vein and then pumps it to all organs through arteries. The heart is a four-chambered organ. It is in-between the lungs. Each chamber has its own specialty. 

External Structure of the Heart

A fluid-filled cavity which enclosed the human heart and is located to the left side of the chest, this cavity is called as pericardial cavity. The pericardial cavity walls and lining are made up of a membrane which is called as pericardium. Pericardium is the external covering of the heart, it produce a serous fluid which act as the lubricant for the heart and protects the heart. It is the first structure which is observed first when the external structure is viewed. Pericardium has two layers:

1. Visceral layer: It directly attached to the heart.
2. Parietal layer: It is a sac like structure which is present around the outer region of the heart.

Structure of the Heart Wall

The wall of the heart is made of three layers: epicardium, myocardium and endocardium.

1. Epicardium: It is the outermost layer of the heart which is composed of a thin-layer membrane which act as lubricant and protect the outer section of the heart.
2. Myocardium: It is the middle layer of the heart which is of muscle tissue layer. It is a thick layer and and participates in the pumping action.
3. Endocardium: It is the inner layer which lines the inner heart chambers and covers the heart valves.

Internal structure of the Heart

Internal structure of the heart has several chambers and valves which controls the blood flow. The heart is a four-chambered organ in the humans.

Four chambers are two atria and two ventricles. Arteries are used for receiving blood from the body whereas two ventricles are used for pumping purpose of blood to all body parts. 

• Chamber-1: Right atria takes deoxygenated blood and gives it to the right ventricle.
• Chamber-2: Right ventricle takes deoxygenated blood from the right atria and converts deoxygenated blood to oxygenated blood when it goes through the lungs and then it pumps to all parts of the body with pure oxygenated blood.
• Chamber-3: Left atria takes oxygenated blood and gives it to the left ventricle
• Chamber 4:Left ventricle takes all the oxygenated blood through the left atria it pumps the blood through the aorta.

The function of the Four chambers

Chambers in the heart act like doorsteps to open the valve or close the valve based on the functions of chambers. Four chambers have a four-valve is used to distinguish the oxygen-rich blood from deoxygenated blood. Chambers of the heart are made of muscles allowing the heart their contract and then it forms a beat called a heartbeat. The flow of blood in our body is a cycle that follows

human body----->heart------> lungs------->heart--------> human body.

Right Atrium

The right atrium takes all the deoxygenated blood from our body. Deoxygenated blood means blood has low oxygen. That deoxygenated blood enters through two large veins which are called superior vena cava. This right atrium passed the blood next chamber called the right ventricle.

Left Atrium

The left atrium takes all the oxygenated blood for our body. We have two atriums the right atrium holds oxygen-poor blood whereas the left atrium holds oxygen-rich blood. This left atrium sends this oxygen-rich blood through the mitral valve to the left ventricle.

Right Ventricle

Deoxygenated blood in the right atrium is entered through the tricuspid valve into the right ventricle. The function of the right ventricle is pumping blood through the pulmonary valve into pulmonary arteries and it came out to our lungs. In the lungs, blood takes oxygen to nourish. After this blood travels from pulmonary veins and gives back to the left atrium.

Left Ventricle

The left ventricle is the last chamber of the heart. The function of the left ventricle is to pump the blood through our aortic valve this is why it travels throughout the body.

Valves

Valves that help in the flow of blood from one chamber to another chamber:

• The tricuspid valve: Tricuspid valve helps in control blood flow from the right atrium to the right ventricle. 
• The pulmonary valve: Pulmonary valve is used to regulate blood flow from the right ventricle to the pulmonary arteries. 
• The mitral valve: Mitral valve that opens to allow blood to move from the left atrium to the left ventricle. 
• The aortic valve: The aortic valve is divided into three cusps some people called the tricuspid aortic valve, whereas some people are born with two cusps called the bicuspid aortic valve. The aortic that allows oxygen-rich blood to move from the left ventricle to the aorta, the body’s largest artery. 
• Tricuspid aortic valve: Tricuspid valve is located between the right lower heart chamber which is called the right ventricle and the right upper heart chamber which is called the right atrium. The main function of the tricuspid valves is to transfer blood flowing into the heart from the body to the right ventricle where it needs to pump the oxygen to the lungs.
• Bicuspid aortic valve: Bicuspid aortic valve is an aortic valve that only has two leaflets or two cusps, instead of three. The bicuspid aortic valve regulates blood flow from the heart into the aorta.

The heartbeat of different aged people is tabled below

Age of a human being	Heartbeat
Newborn baby	120-160 beats per minute
5 months baby	90-150 beats per minute
6-12 months baby	80-140 beats per minute
1- 3 years	80-130 beats per minute
3- 5 years	80-120 beats per minute
6-10 years	70-110 beats per minute
11-14 years	60-105 beats per minute
15+ age	60-100 beats per minute

Function of Human Heart

Function of human heart are as follows:

• The main function of the heart is to pump blood to every part of the body.
• The human heart is to maintain suitable pressure in the body.
• The human heart is to transfer oxygen, Hormones, and glucose to other parts of the body while pumping blood.

Facts about Human Heart

Some interesting facts about Human heart are:

• The average heartbeat in a day is 100,000 times.
• Male heart weight is about approximately 340 grams whereas female heart weight is approximately 280 grams.
• The heart pumps blood around 60000 to 7,5000 liters in a day through the body.