BIOL 1410 L12: The Cardiovascular System

The circulatory system includes (4)

• Heart

• Blood vessels

• Blood

• Lymphatic system

Circulatory system functions to (2)

1. Transport gases, hormones, lymph nutrients, and waste

2. Protect against disease and fluid loss

Chambers of the heart (4)

1. Right atrium

2. Right ventricle

3. Left atrium

4. Left ventricle

What side of the heart carries oxygenated blood?

Left

What side of the heart carries deoxygenated blood?

Right

Veins carry blood ___

To the heart

Arteries carry blood ___

Away from the heart

Right atrium receives what type of blood from where?

Deoxygenated blood from the superior and inferior vena cava and the coronary sinus

Right ventricle connects to

Pulmonary trunk - 2 pulmonary arteries

Right ventricle sends what type of blood to where?

Deoxygenated blood to the lungs

Left atrium connects to

4 pulmonary veins

Left atrium receives what type of blood from where?

Oxygenated blood from the lungs

Left ventricle connects to

Aorta

Left ventricle sends what type of blood to where?

Oxygenated blood out to the rest of the body

What divides the chambers of the heart?

Septa:

• Interatrial septum

• Interventricular septum

Interatrial septum

Separates the atria

Interventricular septum

Separates the ventricles

What does the interventricular septum look like?

Apparent from the outside of the heart as a shallow and often fat-covered groove called the interventricular sculus

Vessels that enter and exit the heart (4)

• Superior and inferior vena cava

• Pulmonary veins

• Pulmonary arteries

• Aorta

Superior and inferior vena cava function

Deliver blood into the right atrium of the heart

Pulmonary veins function

Return blood that has been oxygenated in the lungs back to the heart (left atrium)

Pulmonary arteries function

Deliver deoxygenated blood from the right ventricle into the lulngs to be oxygenated

Aorta function

Deliver oxygenated blood from left ventricle into the systemic circulation

Heart wall is composed of (3)

1. Epicardium

2. Myocardium

3. Endocardium

Epicardium

Makes up the visceral layer of the pericardium (surface of heart)

Epicardium types of tissues

Simple squamous epithelium and connective tissue

Myocardium

Cardiac muscle of the heart; portion that contracts

Myocardium characteristics (2)

• Arranged in spiral or circular bundles

• Reinforced by connective tissue - fibrous skeleton of the heart

Endocardium

Endothelium that lines the inner surface of the heart and all blood vessels

Endocardium type of tissues

Simple squamous epithelium and connective tissue

Fibrous skeleton of the heart

Connective tissue fibers that surround the muscles of the heart; connective tissue rings present between the atria and ventricles

Fibrous skeleton of the heart function (2)

• Provide electrical insulation

• Prevents stretching of the vessels and valves due to the continuous flow of pressurized blood through the heart

What are the rings of connective tissue of the fibrous skeleton?

Valves

Valves

Provide the ability to close off certain portions of the heart inhibiting blood flow in certain directions

Where are valves located in the heart?

Specifically found at the atrioventricular groove between the atria and the ventricles

Cardiac muscle cells striation

Striated

Cardiac muscle cells composed of

Myofibrils - thin and thick filaments arranged in sarcomeres

How do cardiac muscle cells differ from skeletal muscle cells? (2)

• Cardiac muscle cells are branched and uninucleate

• Adjacent cardiac muscle cells are bound to one another by the plasma membrane forming intercalated disks

How are cardiac muscle cells bound to one another by the plasma membrane?

Disks are attached to one another via desmosome and gap junctions

Function of desmosomes in bounded cardiac muscle cells

Prevent the adjacent cells from separating from one another during contraction

Function of gap junctions in bounded cardiac muscle cells

Allow the exchange of ions between adjacent cells which allows the heart to conduct electrical impulses and to have all of the cells contract in unison

Which cardiac muscle cells do not contract?

Modified cardiac muscle cells that form the conduction system

Components of the conduction system and location

1. Sinoatrial node

2. Atrioventricular node (AV node)

3. Bundle of HIS (AV bundle)

4. Bundle branches (from bundle of HIS)

5. Purkinje fibers (from bundle branches)

Location of sinoatrial node

In the right atrium at the base of the superior vena cava

Function of sinoatrial node

Pacemaker

Location of atrioventricular node

The base of the right atrium

Function of bundle of HIS (AV bundle)

Electrically connects the atria to the ventricles

Function of the bundle branches

Connect the bundle of HIS to each of the ventricles

Function of the Purkinje fibers

Supply the signal through each of the ventricles

Two main groups of heart valves

1. Atrioventricular valves

2. Semilunar valves

Atrioventricular valves of the heart (2)

1. Bicuspid (mitral) valve

2. Tricuspid valve

Bicuspid (mitral) valve divide which sections?

Left atrium and the left ventricle; contains two cusps (bi)

Tricuspid valve divide which sections?

Right atrium and the right ventricle; contains three cusps (tri)

Chordae tendinae

Attach the cusps of the valves to the cardiac muscle → papillary muscles

What is the chordae tendinae composed of?

Collagen connective tissue

What is chordae tendinae also referred to as?

Heart strings

Semilunar valves of the heart (2)

1. Aortic semilunar valves

2. Pulmonary semilunar valves

Aortic semilunar valves divide which sections?

Left ventricle and the aorta

Pulmonary semilunar valves divide which sections?

Right ventricle and the pulmonary trunk

Where is the heart located in the body?

Within the mediastinum

Pericardium

Double walled sac that surround the heart; has 3 layers

3 layers of pericardium

1. Fibrous pericardium

2. Parietal - serous pericardium

3. Visceral - serous pericardium

Fibrous pericardium type of tissue

Dense irregular connective tissue

Fibrous pericardium function

Anchors the heart to surrounding tissue such as the diaphragm and large vessels such as the aorta

Parietal layer function

Fused to the fibrous pericardium - together make up the pericardial sac

Visceral layer function

Epicardium; fused to the surface of the heart as a key portion of the heart wall

Pericardial cavity

Fluid filled area between the visceral layer and the parietal layer to provide lubrication

Adult circulations (2)

1. Pulmonary circulation

2. Systemic circulation

Pulmonary circulation function

Deliver and return blood to and form the lungs for oxygenation

Process of pulmonary circulation (3)

1. Deoxygenated blood in the right atrium → right ventricle

2. Right ventricle passes deoxygenated → pulmonary arteries → lungs

3. Blood is oxygenated in the lungs → pulmonary veins → left atrium

Systemic circulation function

Deliver and return blood to and from the entire body

Process of systemic circulation

1. Left atrium passes oxygenated blood → left ventricle

2. Left ventricle passes oxygenated blood → aorta → blood out to the body (organs)

3. Oxygenated blood in the organs → oxygen (& nutrients) removed from blood cells + load with carbon dioxide and metabolic waste

4. Dirty blood → vena cava → right atrium

In developing fetus, what organs are non-functional?

Lungs and liver

What happens to the blood due to non-function organs?

Blood is shunted/diverted away from these organs as oxygen and nutrient requirements are capped

Placenta function during fetal development

Site of gas and nutrient / waste exchange between the mother and the fetus

Blood pressures on each side of the heart of the developing fetus

Opposite of the situation in adult circulation:

Right - high blood pressure

Left - low blood pressure

Shunts in fetal circulation

1. Foramen ovale

2. Ductus venosus

3. Ductus arteriosus

Foramen ovale

Opening between the right atrium to the left atrium to shunt blood away from the lungs by diverting blood from right to left aftrium

Ductus venosus

Shunt blood away form the liver by diverting blood from the umbilical vein to the inferior vena cava

Ductus arteriosus

“Bridge” that shunt blood away from the lungs by diverting blood from the pulmonary trunk (blood that passed into the right ventricle) to the aorta

When are shunts of fetal circulation closed?

Shortly after birth once lungs and liver become functional

How does the fetus get adequate blood to supply and support growth of its lung?

Partially oxygenated (mixed) blood from the aorta is returned to the placenta through umbilical arteries where it enters into the maternal circulation