3. CS: Heart

Heart

• Principal organ of the circulatory system, it is the central hollow muscular organ which functions as suction and force pump; composed mainly of the heart muscle called myocardium

• It is cone-shaped and obliquely placed in the thorax so that its base faces dorsocranially and its apex is directed ventrocaudally and to the left side; 60% of it is lying to the left of the median plane; in carnivores, it is located in between 3rd and 6th rib

• It is found in the middle mediastinum enclosed in a fibroserous sac called the Pericardium.

The heart weight to body weight ratio in male dog is 1.3% and 1.2% in female dog (average is 1%)

The heart weight to body weight ratio in male dog is ___ and ___ in female dog (average is 1%)

Blood enters either atrium by veins, which is pumped into a respective ventricles, onto the lungs, or body through the arteries

CIRCULATION THROUGH THE HEART:

• Blood enters either ___ by ___, which is pumped into a respective ___, onto the ___, or body through the ___

The right atrium receives deoxygenated venous blood through a number of veins, but primarily the cranial and caudal vena cava

CIRCULATION THROUGH THE HEART:

• The right atrium receives ___ ___ blood through a number of veins, but primarily the ___l and ___vena cava

Then, the blood enters the right ventricle, which will be pump into the pulmonary trunk, then into the lungs (pulmonic circulation)

CIRCULATION THROUGH THE HEART:

• Then, the blood enters the ___ ___, which will be pump into the ___ ___, then into the ___ (pulmonic circulation)

Pulmonary veins carries oxygenated blood from the lungs into the left atrium.

CIRCULATION THROUGH THE HEART:

• ___ ___ carries oxygenated blood from the lungs into the ___ ___.

the blood in the left atrium will descend into the left ventricle; the left ventricle pumps it through the aorta to the rest of the body (systemic circulation).

CIRCULATION THROUGH THE HEART:

• The blood in the left atrium will descend into the ___ ___; the ___ ___ pumps it through the ___ to the rest of the body (systemic circulation).

Problems in the right side of the heart (pulmonic circulation) causes blood to back up in the caudal vena cava, filling the abdomen with fluid in dogs (ascites)

Clinical:

• Problems in the ___ ___of the heart (pulmonic circulation) causes blood to back up in the __ __ __, filling the abdomen with fluid in dogs (ascites)

On the left side of the heart (systemic circulation, causes blood to back up into the lungs (congestion of the lungs)

Clinical:

• On the __ __ of the heart (systemic circulation), causes blood to back up into the lungs (congestion of the lungs)

Auricular Surface

Atrial Surface

Apex

Base

features of the heart (4)

AURICULAR SURFACE (left side)

Side of the heart where the auricles are seen alongside with the pulmonary trunk in between them

ATRIAL SURFACE (right side)

Side of the heart were the cranial and caudal vena cava are seen entering the right atrium.

Apex

the most caudoventral part of the heart; always formed by the left ventricle

Base

it is the hilus of the heart facing dorsocranially.

ENDOCARDIUM

EPICARDIUM

MYOCARDIUM

structure of the cardiac wall (3)

ENDOCARDIUM

thin, smooth layer that lines the cardiac chambers, covers the atrial auricles and it is continuous with the lining of the blood vessels (endothelium)

EPICARDIUM

outermost layer; part of the visceral layer of the pericardium

MYOCARDIUM

heart muscles; it makes up the majority of the cardiac wall