Human Heart

The human heart is an important muscular organ that pumps blood. It has four chambers—two atria and two ventricles—that work together to circulate oxygen-rich blood to the different organs. In this article, the human heart, the anatomy of the human heart, functions of the human heart, facts about the human heart, and heart health are discussed. Human heart is a topic of the chapter Body Fluids and Circulation in Biology.

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1. Human Heart
2. Anatomy of the Human Heart
3. Functions of the Human Heart
4. Facts About The Human Heart
5. Heart Health

Human Heart

The human heart is one of the human organs providing vital support to the flow of blood in the human body through the circulation of blood to deliver new oxygen, and nutrients to the tissues and organs; in return, it removes the waste products from these tissues and organs. It is basic to understand the function and significance of the heart considering that it pumps blood and keeps the blood circulation within acceptable limits. Structurally, the heart has four sections; two upper chambers or the atrium and two lower chambers known as the ventricles; these valves control the direction of blood circulation. These contractile movements are due to the creation of muscular walls, and commands of electrical impulses also help the heart to be a perfect pump that will supply the health and proper functioning of the entire body system.

Anatomy of the Human Heart

The anatomy of the human heart is discussed below-

Location And Size

• The human heart is situated in the mediastinum, more specifically in the thoracic cavity and in front of the lungs in coordination with the left side of the sternum axis.

• It is situated behind the sternum and above the diaphragm, although is located in the mediastinum.

• Specifically, an average human heart is as large as a fist and weighs between 250-350gm (9-12oz) in an adult.

Heart Structure

The human heart is made of the following components:

Pericardium

• The overall structure in which the heart is surrounded is called the pericardium and is made up of two elementary structures, namely the fibrous pericardium and the serous pericardium.

• Serous pericardium, in turn, gets subdivided into the parietal and visceral layers, whereas the latter is referred to as the epicardium.

• The pericardium acts as a shield to the heart, it holds the heart in position and acts as a constraint to the heart’s ventricular filling.

Heart wall

• Epicardium: The first one is the protection layer for giving protection to the inner part.

• Myocardium: The middle, the muscular layer is characterized by the power of contraction and performing the act of pumping.

• Endocardium: The endocardium is the inner layer that faces the blood flow in the heart chambers and over the valves.

Chambers

• Atria: The two right and left atria are the upper chambers of the heart that receive the blood coming to the heart.

• Ventricles: The last two chambers of the heart are the ones that pump blood out of the heart, these are the right and left ventricles.

Valves

The human heart is muscular and relatively small in size, including four valves that ensure one-way blood circulation.

• Atrioventricular Valves: These two are the tricuspid valve, belonging to the right side of the heart and the mitral valve on the left side of the heart.

• Semilunar Valves: This includes; the pulmonary valve at the right side and the aortic valve at the left side.

Blood Vessels

The blood vessels of the heart include:

Arteries

• Aorta: The largest artery; carries oxygenated blood from the left ventricle through the aortic arch and onto the body.

• Pulmonary Arteries: Transport deoxygenated blood from the right ventricle and take it to the lungs.

Veins

• Superior and Inferior Vena Cava: Pump deoxygenated blood from the body back to the right atrium.

• Pulmonary Veins: Pump oxygenated blood from the lungs and deliver it to the left atrium.

Human Heart Diagram

Conduction System

• SA Node (Sinoatrial Node): The heart also contains a small organ called the pacemaker which is sited in the right atrium to determine the rate of contraction.

• AV Node (Atrioventricular Node): It is located between the atria and the ventricles; it gets impulses for the stimulation of the contractions from the SA node and conveys them to the ventricles.

• Bundle of His: An avenue for electrical impulses originating from the AV node to the ventricles.

• Purkinje Fibers: Bundle of nerves that convey electrical stimulus to other chambers of the heart namely the ventricles to make them contract.

Also Read-

• MCQ Practice on Human Heart
• Body Fluids and Circulation
• Components of Blood
• Functions of Blood

Functions of the Human Heart

The functions of the human heart are discussed below-

Pumping Blood

The blood in the body is circulated by the heart through two main loops which are known as circuits.

• Systemic Circuit: Pumps the oxygenated blood from the left ventricle to the different body parts and brings back the deoxygenated blood in the right atrium.

• Pulmonary Circuit: Brings deoxygenated blood from the right ventricle to the lungs to get oxygenated and pumps oxygenated blood to the left atrium.

Cardiac cycle:

The mechanisms of the cardiac cycle may be divided into two major stages:

• Systole: The heartbeat cycle, the period that describes the contraction of the heart muscle, followed by pumping blood out of the atrial or ventricular chambers into the arteries.

• Diastole: The period in which the heart muscle is at rest, thus the chambers receive blood.

Maintaining Blood Pressure

• Many factors are involved in the regulation of blood pressure; the force and rate of the contractions of the heart.

• This helps avoid inadequate blood flow in the body to meet the necessary needs of the human body.

• The circulation system also involves blood vessels which can also narrow or expand to assist in the regulation of blood pressure.

• More specifically, arteries are in charge of providing rather constant pressure and blood flow in this regard.

Supplying Oxygen And Nutrients

• Oxygenated blood is developed for the process of respiration where the cells get their required oxygen for the production of energy.

• The circulatory system transports material such as glucose and amino acids in their developed forms to cells and embraces products such as carbon dioxide and urea.

Endocrine Function

• It also plays the role of an endocrine gland because it has the capability of secreting hormones that control other activities in the body.

• Similar to CNP, ANP is released from the atria of the heart when blood volume and pressure are high.

• ANP aids in the prevention of an increase in blood volume by promoting sodium and water elimination in the urine.

• ANP has significant effects on controlling the blood pressure and regulating the fluid volume in the body hence it is involved in the body’s homeostasis.

Circulation Types

• A part of circulation called pulmonary circulation is in charge of returning oxygenated blood to the heart after transporting deoxygenated blood to the lungs.

• Another aspect of circulation is systemic circulation, in which the heart pumps oxygenated blood to all of the body's organs and tissues while returning deoxygenated blood to the heart.

• Coronary Circulation includes coronary arteries that supply oxygenated blood to the myocardium; and coronary veins that carry deoxygenated blood away from the heart muscle.

Facts About The Human Heart

• The human heart rate is determined by the number of times it beats per minute; this ranges from 60-100 bpm when a person is at rest.

• Pulse can be felt by lightly palpating arteries underneath the skin specifically the radial pulse at the wrist or the carotid pulse on the neck.

• Finding out the total number of beats in one minute will indicate the rate at which the heart is beating.

• Cardiac output is defined as the volume of blood that is pumped by the heart within one minute.

• It plays a very important role in the provision of oxygen and nutrients to all body tissues.

• Cardiac output is affected by physical activity, the size of the body and the overall health of a person.

Heart Health

Caring for our hearts is among the core values for the quality of life free from diseases, mishaps, and untimely deaths.

Coronary Artery Disease

A condition that affects the blood vessels called the coronary arteries leading into the heart muscle and which get blocked thus limiting the amount of blood that is delivered to the muscle.

Heart Attack

This happens when a section of the heart does not get an adequate amount of blood and nutrients hence becoming damaged.

Heart Failure

A state in which the heart is not able to pump blood as it should, hence accumulating fluids within the body.

Preventive measures:

• Diet: A healthy diet characterised by increased consumption of fruits and vegetables, whole grain products, lean meats, and healthy fats helps to maintain healthy bones and muscles.

• Exercise: Physical activity in postmenopausal women has been established to be beneficial as it enhances the working capacity of the heart muscle, and circulation and keeps the body lean.

• Lifestyle Changes: Not smoking, taking a moderate amount of alcohol, learning how to handle stress and getting checkups are important in the promotion of heart health.

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