Learn: Human Heart Anatomy and Function: Key Concepts for Biology

Function of the heart

To pump blood to the body that contains Oxygen (O2) and nutrients; to assist in the removal of Carbon Dioxide (CO2) and other waste material from the body

Location of the heart

The Mediastinum in the mid-thoracic cavity, between the lungs - lower portion (Apex) tilted toward the left; upper portion (Base) toward the right

Size of the heart

The size of your closed fist (Weighs about 9 oz.)

Shape of the heart

Triangular, yet cylindrical (cone-shaped)

Blood vessels

Arteries - take blood away from heart; Veins - take blood toward heart; Capillaries - Allow gas exchange within tissues and connect arteries and veins

Function of lungs in relation to the heart

Provide for intake and release of air & gas exchange

Chambers of the heart

4 Chambers - (spaces) separated by the septum

Atria

2 Receiving chambers called Atria (Upper)

Right Atrium

Receives blood from the body (deoxygenated) via the superior and inferior vena cava- largest veins

Left Atrium

Receives blood from the lungs (oxygenated) via the pulmonary veins

Ventricles

2 Discharging chambers called Ventricles (Lower)

Right Ventricle

Sends blood to the lungs (deoxygenated) via the pulmonary arteries

Left Ventricle

Sends blood to the body (oxygenated) via the aorta

Valves of the heart

4 Valves - "gates" that allow movement of blood through the heart, and prevent backflow

Atrioventricular valves

2 Atrioventricular valves (between an atrium & ventricle)

Tricuspid valve

Between Rt Atrium & Rt Ventricle with 3 flaps/cusps

Bicuspid valve

Between Lt Atrium & Lt ventricle with 2 flaps/cusps (Mitral valve)

Semilunar valves

2 Semilunar valves (between a ventricle and an artery)

Pulmonary valve

Between Rt Ventricle & Pulmonary artery (Blood is going to lungs)

Aortic Valve

Between Lt. Ventricle & Aorta (largest artery) (Blood is going to body)

Heart sounds

The sounds of the heart valves closing

First heart sound (lub)

Vibration and closure of AV valves during contraction of the atria (Tricuspid & Bicuspid)

Second heart sound (dub)

Closure of the semilunar valves during relaxation of the ventricles (Pulmonary & Aortic)

Layers of the heart

3 Layers

Endocardium

Innermost layer of the chambers, made of connective tissue. Also forms the chambers and valves.

Myocardium

Muscular walls of the heart and septum

Epicardium/Pericardium

Outer, protective layers of the heart

Visceral pericardium

Protective layer directly next to the heart muscle

Parietal pericardium

Outer protective layer referred to as the pericardial sac

Pericardial fluid

Fluid between the layers of the pericardium

Cardiac Tamponade

Increased fluid in the pericardial space between the layers causes pressure against the heart muscle, resulting in a Cardiac Tamponade (usually due to pericarditis)

Normal heart rate (HR)

60-100 BPM (Beats per minute)

Tachycardia

HR greater than 100 BPM

Bradycardia

HR less than 60 BPM

Finding your pulse

Using two fingers palpate (feel) for one of the common pulses; Never use a thumb - it has its own pulse; Count the pulsations for 60 seconds