CIRCULATORY SYSTEM

• Generate blood pressure

• Routing of blood

• Ensure one-way blood flow

• Regulate blood supply

Circulatory System (Cardiovascular System) Functions

Heart

A muscular pump consisting of two receiving chambers (atria) two pumping chamber (ventricles)

Pulmonary Circuit

Responsible for oxygenating the blood.

Pulmonary Circuit

Flow of deoxygenated blood from the right side of the heart to the lungs, where it picks up oxygen and releases carbon dioxide

Pulmonary Circuit

What type of circuit?

Right heart -> Lungs -> Left heart

Systemic Circuit

Responsible for delivering oxygenated blood to all the tissues and organs of the body.

Systemic Circuit

Flow of oxygenated blood from the left side of the heart to the body's tissues, where it releases oxygen and picks up carbon dioxide

Systemic Circuit

What type of circuit?

Left heart -> Body -> Right heart.

Pulmonary Circuit

Systemic Circuit

Types of Circuits

Arteries

Carry blood away from the heart

Arteries

Typically carry oxygenated blood except for the pulmonary arteries

Capillaries

Tiny, thin-walled vessels that allow for the exchange of gases, nutrients, and waste products between the blood and tissues

Capillaries

Form intricate networks that connect arterioles and venules.

Veins

Carry blood back to the heart

Veins

Typically carry deoxygenated blood except for the pulmonary veins

1. Arteries

2. Capillaries

3. Veins

Type of Blood Vessels

middle mediastinum

Heart is a four-chambered, hollow, muscular organ lying between the lungs in the ______.

Heart

It is about the size of a man’s fist, and in the normal male weights approximately 250-390gm; normal female 200-275gm.

250-390gm

Normal weight of a man’s heart

200-275gm

Normal weight of a woman’s heart

Heart

is shaped like an inverted cone, with its apex pointed downwards and to the left, the base upwards and to the right

5th Intercoastal Space, Midclavicular Line (ICS, MCL)

The Heart

Its apex anteriorly and inferiorly to the left at the _______.

Pericardium

Fluid-filled sac that surrounds and protects the heart.

Fibrous Pericardium

Covering of the heart that is tough and the outermost layer.

Fibrous Pericardium

Covering of the heart that is made of dense, irregular connective tissue.

Fibrous Pericardium

Covering of the heart that protects the heart from overexpansion and anchors the heart within the mediastinum, preventing excessive movement.

Serous Pericardium

Covering of the heart that is the thinner, inner layer

Serous Pericardium

Covering of the heart that is a double-layered membrane

Parietal Layer

Lines the inner surface of the fibrous pericardium

Visceral Layer (Epicardium)

Tightly adhered to the surface of the heart itself.

Pericardial Cavity

Between the parietal and visceral layers

Pericardial Cavity

Contains a thin layer of serous fluid, which lubricates the surfaces of the pericardium and reduced friction as the heart beats.

Epicardium

External layer, the visceral layer of the serous pericardium

Myocardium

Middle muscular layer of the walls of the heart

Myocardium

Contains the intercalated discs, complex structures that connect individual cardiomyocytes, allowing them to function as a coordinated unit.

Endocardium

Inner layer of the endothelium

Right Atrium

Right border of the heart

a. Superior Vena Cava

b. Inferior Vena Cava

c. Anterior Cardiac Veins

d. Vena Cordis Minimae

e. The Coronary Sinus

Right atrium receives blood from:

Superior Vena Cava

Crista Terminali

Interatrial Septum

Musculi Pectinati

Fossa Ovalis

Tricuspid Valve

Opening Coronary Sinus

Inferior Vena Cava

Anatomical Features of the Right Atrium

Superior Vena Cava

Large vein that returns deoxygenated blood from the upper body to the right atrium

Crista Terminalis

C-shaped muscular ridge on the internal surface of the right atrium

Crista Terminalis

Separates posterior wall from the rough anterior wall

Interatrial Septum

Wall that separates the right and left atria

Musculi Pectinati

Muscular ridges on the anterior wall of the right atrium and within the right auricle

Musculi Pectinati

Increase the surface area of the atrium

Fossa Ovalis

Shallow depression in the interatrial septum

Fossa Ovalis

The remnant of the foramen ovale, an opening present in the fetal heart that allows blood to bypass the lungs.

Tricuspid Valve

Valve between the right atrium and the right ventricle

Tricuspid Valve

Three leaflets and prevents backflow of blood into the right atrium

Opening Coronary Sinus

The opening through which the coronary sinus (a large vein that drains blood from the heart muscle) returns deoxygenated blood to the right atrium.

Inferior Vena Cava

Large vein that returns deoxygenated blood from the lower body to the right atrium.

coronary sinus

a large vein that drains blood from the heart muscle

Right Ventricle

Forming most of the anterior surface of the heart

Right Ventricle

Chamber of the heart receiving venous blood from right atrium and ejecting this to the pulmonary arteries

infundibulum

is the upper most part of the wall which has no muscular bundles, leads into pulmonary arteries.

Trabeculae Carna

Papillary Muscle

Chordae Tendineae

Moderator Band (Septomarginal Band)

Anatomical Features of the Right Ventricle

Trabeculae Carna

Irregular muscular ridges probably to hold more blood

Papillary Muscle

Conical in shape with the base attached to the ventricular wall and the apices receiving the end of chordae tendineae

Chordae Tendineae

Thread-like structures connected to the apices of the papillary muscle and to the cusps of ventricular valves

Chordae Tendineae

Prevent the eversion (prolapse) of the atrioventricular (AV) valves during ventricular contraction.

Moderator Band (Septomarginal Band)

A muscular band attached to septal wall and to the anterior margin of right ventricle

Moderator Band (Septomarginal Band)

Prevents overdistention of the right ventricle

Moderator Band (Septomarginal Band)

Only present in the right ventricle

Left Ventricle

Cavity is longer and narrower than the right and the walls are 3x thicker than right ventricle

Left Ventricle

The lower anterior part forms the apex of the heart which is at the level of the 5th intercoastal space, midclavicular line

Left Ventricle

Apex of the Heart

a. Triscuspid Valve

b. Mitral/Bicuspid Valve

Atrioventricular Valves

a. Aortic Valve

b. Pulmonic Valve

Semilunar Valves

Tricuspid Valve

Valve between the right atrium and right ventricle

Mitral/Bicuspid Valve

Valve located between the left atrium and left ventricle of the heart

Aortic Valve

Valve located between the left ventricle and the aorta

Pulmonic Valve

Valve located between the right ventricle and the pulmonary artery

Septa

Structures separating the chambers

Interatrial Septum

Separates the right and left atrium

Interventricular Septum

Separates the right and the left ventricles

Coronary Arteries

Blood supply of the heart

Coronary Sinus

Main venous drainage of the heart

Coronary Arteries

Nerve supply of the Heart

Parasympathetic (vagus) nerve

Nerve supply of the Heart which is inhibitory to the heart

Sympathetic

Nerve supply of the Heart which is excitatory to the heart

Sino-Atrial Node

Located at the posterior wall in the groove between the superior vena cava and the right atrium

Sino-Atrial Node

Pacemaker of the Heart

Atrio-Ventricular Node

Located at the lower part of the interatrial septum

Bundle of His

Pale bundle, approximately the size of a matchstick, located in the interventricular septum.

Bundle of His

Divides into right and left bundle branches.

Subendocardial Network of Purkinje Fibers

Lies beneath the endocardium and is distributed throughout the heart

1. Sino-Atrial Node (Pacemaker of the Heart)

2. Atrio-Ventricular Node

3. Bundle of His

4. Subendocardial Network of Purkinje Fibers

Impulse Conducting System of the Heart

S1 (First Heart Sound)

Closure of the AV valves.

S2 (Second Heart Sound)

Closure of the semilunar valves

S3 (Ventricular Gallop)

Indicates rapid ventricular filling.

S4 (Atrial Gallop)

Caused by atrial contraction against a stiff ventricle.

Arteries

Carries blood away from the heart

Arteries

Oxygenated (except pulmonary artery)

Arteries

Blood vessel that has thicker walls

Tunica media

Thickest wall of arteries

Arteries

Its lumen is usually rounded and smaller

Arteries

blood vessel that is deeply located

Arteries

In spurts when injured

Arteries

Blood vessel that doesn’t have the presence of valves

Veins

Carries blood toward the heart