A+P Chapter 18 Cardiovascular System

Function of the cardiovascular system

Continuously circulate blood, oxygenate tissues, remove waste products (co2), circulate hormones, and deliver nutrients to tissues.

Pulmonary Circulation

Blood flow through the right side of the heart that sends deoxygenated blood to the lungs then returns that blood to the left side of the heart for distribution.

Systemic Circulation

Blood flow through the left side of the heart that sends oxygenated blood to the body, delivering nutrients and oxygen to tissues, picking up co2, and returning deoxygenated blood to the heart.

Heart

4 chambered (2 atria, 2 ventricles) muscular organ made from cardiac muscle that contract to generate pressure to push blood through the body.

Where is the heart located in the body?

In the pericardial cavity behind the sternum, between the lungs. The base (top) is between the 2nd and 3rd ribs. The apex (bottom/point) is between the 5th and 6th ribs towards the left side of the chest.

Where do major vessels attach at the heart?

The base

Pericardium

Protective sac that covers the heart. Includes three layers. Fibrous pericardium, parietal pericardium, visceral pericardium. Contains a fluid between the parietal and visceral layers called the pericardial fluid. This helps lubricate the heart as it beats.

Fibrous Pericardium

Outermost, and toughest layer of the pericardium.

Parietal Pericardium

Middle layer of the pericardium.

Visceral Pericardium

Innermost layer of the pericardium, against the heart wall. Also known as the epicardium.

What are the layers of the heart wall?

Epicardium (Outer layer, also known as visceral pericardium), myocardium (middle layer, cardiac muscle), and the endocardium (inner layer).

Identify the epicardium (visceral pericardium)

Identify the myocardium

Identify the endocardium

Interventricular Septum

Muscular wall in the heart that separates the right and left ventricles.

Congestive heart failure

Progressive disease where the heart becomes inefficient at pumping blood. Commonly associated with an enlarged heart. This leads to poor return of blood to the heart causing blood to backup in the venous system, specifically in the lungs. This causes pulmonary venous hypertension (increase in lung vein blood pressure) and can lead to increased fluid leakage in the lungs (pulmonary edema).

What is heart enlargement caused by when someone has congestive heart failure?

Heart enlargement is caused by either:

The heart working harder causes the muscles to grow or the heart wall expands and thins out as muscle breaks down.

Auricles

Small protrusions/appendages (ears) that allow for greater expansion of the heart chambers.

The left ventricle pumps ____ blood out of the ___ to the ____

Oxygenated; Aorta; body (other than lungs)

The right ventricle pumps _____ blood out of the _____ which splits into the ____ and flows to the ____

Deoxygenated; Pulmonary trunk; left and right pulmonary arteries; lungs

The superior and inferior vena cava carry ____ blood to the ______ from the _____

deoxygenated; right atrium; body

What parts of the body does the superior vena cava carry blood from?

Body above the diaphragm (Head, arms, chest)

What parts of the body does the inferior vena cava carry blood from?

Body below the diaphragm (Abdomen, legs)

Pulmonary veins carry ____ blood to the ____ from the ____

oxygenated; left atrium; lungs

Tricuspid Valve

Prevents backflow of blood as the right atrium pumps to the right ventricle. Connected to the papillary muscles by the chordae tendineae.

Bicuspid Valve (Mitral)

Prevents backflow of blood as the left atrium pumps to the left ventricle. Connected to the papillary muscles by the chordae tendineae.

Pulmonary (Semilunar) Valve

Controls blood flow between the right ventricle and pulmonary trunk.

Aortic (Semilunar) Valve

Controls blood flow between the left ventricle and aorta.

Heart Valves

Prevent backflow in the heart as it pumps. During the cardiac cycle, contraction of the chambers along with blood flow push blood against the valve forcing them open or closed depending on which chamber is contracting/relaxing. Valves close when blood pushes against the underside of their cusps.

What do the papillary muscles and chordae tendineae help the valves with?

They help prevent prolapse (opening in the wrong direction) during contraction.

When the ventricles contract which valves are open and which are closed?

The aortic and pulmonary valves open while the bicuspid and tricuspid valves close.

When the atria contract which valves are open and which are closed?

The tricuspid and bicuspid valves open while the aortic and pulmonary valves close.

List the blood flow through the entire heart starting with the return of deoxygenated blood

1. Superior and inferior vena cava and the coronary sinus

2. Right atrium

3. Tricuspid valve

4. Right ventricle

5. Pulmonary semilunar valve

6. Pulmonary trunk

7. R/L pulmonary arteries

8. Lungs + Pulmonary capillaries

9. Pulmonary veins

10. Left atrium

11. Bicuspid valve

12. Left ventricle

13. Aortic semilunar valve

14. Aorta

15. Systemic arteries

16. Systemic capillaries

17. Systemic veins

18. Return to the superior and inferior vena cava

Coronary Circulation

Circulation to the heart. As blood leaves the left ventricle, two arteries branch directly off the aorta. These are the left and right coronary arteries.

The coronary sinus is made up of the

Great cardiac vein, middle cardiac vein, and posterior vein of the left ventricle.

The coronary sinus returns ____ blood to the ____

deoxygenated; right atrium

Post-capillaries coronary blood flows to the ____

Coronary veins

Depressions along the heart wall are called ____ often found ____

Sulci; between chambers of the heart

What major coronary blood vessels can be found in the sulci?

The anterior interventricular artery (in the anterior interventricular sulcus) and the right coronary artery (in the coronary (or atrioventricular) sulcus)

Diastole

Relaxation/filling phase of the cardiac cycle. When the atria is in diastole the ventricles are in systole.

Systole

Contraction/ejection phase of the cardiac cycle. When the atria are in systole, the ventricles are in diastole.

What causes the lubb sound in a heart beat?

The closing of the tricuspid and bicuspid valves during the QRS complex

What causes the dupp sound in a heart beat?

The closing of the aortic and pulmonary valves at the end of the T wave

Heart Mummur

When extra sounds are present during auscultation (listening to) of the heart.

What 4 things heart murmurs can be caused by?

1. Failure of the foramen ovale to close

2. Failure of one of the heart valves to close properly

3. Heart valve stenosis (narrowing of the opening)

4. Septal defects (openings between ventricles)

What structures set the frequency of heart contractions?

The sinoatrial (SA) and atrioventricular (AV) nodes.

Does the heart need neural input for contraction?

No, but the brain can regulate the rate of contraction as needed.

Sinoatrial (SA) node

Known as the pacemaker of the heart. It sets the rhythm. Its cells are specialized to continuously depolarize (be super leaky) which allow sodium to move into the cell until the threshold is reached.

If the SA node fails, what can take over?

The AV node can take over, but normally at a lower rate

Map the electrical conduction of the heart from start to finish

1. The SA node initiates contraction by depolarizing

2. That signal spreads across atria causing them to contract before reaching the AV node

3. The AV node pauses for 0.1 sec to allow for the atria to fully empty

4. Branching from the AV node, the AV bundle (Bundle of His) and bundle branches transmit signals down to the apex to initiate contraction there

5. Bundle branches split into Purkinje fibers to stimulate across heart wall

Identify the SA Node

Identify the AV node

Identify the AV bundle

Identify the left bundle branch

Identify the right bundle branch

Identify the Purkinje fibers

P wave

Atrial depolarization initiated by the SA node

QRS Complex

Atrial repolarization and ventricular depolarization (at apex)

T wave

Ventricular repolarization (at apex)

P-R interval

Time between the start of atrial excitation and ventricular ecxcitation

S-T Segment

Period entire ventricular myocardium is depolarized

Pericarditis in an EKG

Characterized by an infection of the pericardium that may present as PR segment depression

What can ST elevation indicate?

A myocardial infarction (heart attack, STEMI)

Normal sinus rhythm

60-100 BPM

Tachycardia

Abnormally fast heart rate at rest, above 100 BPM

Ventricular Fibrillation

Life threatening condition where heart contractions aren’t coordinated.

Bradycardia

Abnormally low heart rate, below 60 BPM

Junctional Rhythm

SA node not functioning, P wave absent. AV node has taken over.

Fetal circulation

Mother supplies oxygen and nutrients to the fetus via the placenta. A baby’s lungs are not in use in utero and are filled with fluid. Specialized structures in use to bypass pulmonary circulation include the foramen ovale and the ductus arteriosis

Foramen ovale

In utero passes some blood from the right atrium to the left atrium. Assists in bypassing pulmonary circulation.

Ductus Arteriosis

In utero carries oxygenated blood from the umbilical cord (connected to the placenta) through the liver and connects to the inferior vena cava. Also passes blood from the pulmonary trunk into the aorta. Assists in bypassing pulmonary circulation.

Identify the ductus arteriosis

What does the ductus arteriosus degenerate into after birth?

Ligamentum arteriosum

What does the foramen ovale close into?

Fossa ovalis

What happens when the foramen ovale and ductus arteriosus don’t properly close?

A hole is left in the heart, oxygenated and deoxygenated blood may mix. This leads to inefficient pumping and may lead to congestive heart failure if left uncorrected. Called patent foramen ovale or patent ductus arteriosus.