Sectional Sonography Exam 3: Heart and Hemodynamics

What does the circulatory system include ?

heart blood vessels and lymphatics

left vetricle > aorta

small arteries

arterioles

capillaries

venules

small veins IVC and SVC > right atrium

What is the purpose of the circulatory system ?

transports O2, gases, nutrients, and other essential substances to tisssues and working muscles. Carries away waste products of cells to be excreted.

Thorax

upper part of the body, greater part is occupied by the lungs, which are enclosed by the pleural sac

separates the addominal cavity from the thorax

diaphragm

list the medial and lateral portions of the thorax

medial: mediastinum

lateral: pleurae and lungs

what does the sternum consist of anteriorly ?

manubrium, sterni body, xyphoid process

what does the thymus gland get replaced with with age ?

fat

Heart

hollow muscular organ

250-300 gm

What is the heart considered ?

anteposterior structure with its right sided chambers located more anterior than its left-sided chambers

What is the heart protected by ?

the sternum and rib cage anteriorly and the vertebral column and rib cage posteriorly

Heart Surfaces (3)

1. Sternocostal is anterior

2. Diaphragmatic (inferior and apex) Apex is inferior and forms left ventricle.

3. Base is posterior

APEX

formed by the left ventricle. The apex points downward, anteriorly and to the left

BASE

formed by the left atrium into which the pulmonary veins enter from the lungs. Broad superior portion of the heart that is opposite the apex. Projects superiorly and posteriorly to the right. Sometimes called the posterior surface

Pericardium

A fibroserous sac that surrounds the heart and proximal portions of the great vessels.

Serous pericardium

a thin, transparent serous membrane which has two layers.

Parietal pericardium

(outer layer) forms smooth moist lining for the fibrous pericardium.

Visceral pericardium

(inner layer) or epicardium covers and forms the outer layer of the heart wall

Pericardial Cavity

area in between visceral and parietal layers is a potential space

contains small amounts of serous fluid to prevent friction and allow for easy gliding during heart contractions

pericardial effusion

Excess fluid (fluid accumulation)

3 layers of heart wall

Epicardium: visceral layer- outer most layer.

Myocardium: heart or cardiac muscle - middle layer

Endocardium: a thin layer of endothelium, inner most layer. *Also covers the heart valves and is continuous with the endothelial lining of the blood vessels.

Atrioventricular valves

allows inflow of blood. Blood from atria’s to ventricles. Low pressure.

Right AV valve =

tricuspid valve

left AV valve =

bicuspid/mitral valve

Semilunar valve

allows outflow or exits of the ventricles. High pressure

Pulmonary semi lunar valve

outflow of blood from RV into pulmonary trunk

Aortic semi lunar valve

outflow of blood from LV into aorta

Rt atrium

Receives blood from the coronary and systemic circulation. Receives blood from the IVC & SVC. Coronary sinus receives blood that supplies the heart itself

Rt. Ventricle

anterior surface of the heart. Receives blood from RA through the Tricuspid Valve and ejects blood into the pulmonary artery/trunk for 02 exchange from lungs.

Left atrium

most posterior, forms most of the base. Four pulmonary veins return oxygenated blood to the heart form the lungs to the LA.

Left ventricle

receives blood through the mitral valve or bicuspid valve

has much thicker wall because it has to pump blood throughout the body

Blood exits into aorta through the aortic semi lunar valve

INTRAVENTRICULAR SEPTUM

Thick and muscular partition between the right and left ventricles. Has a muscular interventricular septum and a membranous interventricular septum.

5 Sections of Aorta

1. Root of Ao (which comes from LV) 2. ascending 3. descending 4. abdominal 5. bifurcation into iliacs

Aortic Arch

a continuation of the ascending aorta, Lies behind the manubrium sterni and runs upward, backward and to the left anterior to the trachea then passes down to the left where is continues as the descending aorta.

• Brachiocephalic artery arises on the right and divides into the right CCA and Subclavian arteries.

• The left CCA and subclavian arteries comes directly off the aortic arch.

3 layers of arterial wall

Tunica Intima: most inner layer consists of endothelial cells, which allows for smooth blood flow

Tunica Media: middle layer consists of smooth muscle fibers with elastic and collagenous tissues.

Tunica Adventitia: outer layer of loose CT with bundles of smooth muscle fibers and elastic tissue. Thicker in arteries than veins.

ARTERIES ARE…..

• Vessels that carry away from the heart

• Hollow Elastic Tubes– the elasticity of larger arteries helps maintain steady flow.

• Pulsatile (from heart contractions)

• Faster flowing than veins

• Enclosed within a sheath that include an accompanying vein and nerve.

where is plaque found?

arteries

Where are thrombus/clots found?

veins

Veins appear and can collapse because

they have less elastic tissue than arteries

3 layers of vein wall

Inner single endothelial layer ***Extensions of this layer called semi lunar valves.

semi lunar valves

prevent blood reflux

3 layers of vein wall

Tunica Intima: most inner layer consists of endothelial cells, which allows for smooth blood flow

Tunica Media: Middle layer consists of smooth muscle & elastic fibers. Much thinner than arteries.

Tunica Adventitia: Outer layer consists of strong CT. Smaller than arteries.

VEINS ARE……...

• Vessels that carry blood back to the heart

• Hollow compressible tubes

• Have valves that allow blood flow only towards the heart (EXCEPT: IVC, SVC & COMMON ILIACS)

VALSALVA MANEUVER

Flow pattern with respiration

Inspiration

Vein lumen narrows

Expiration:

Vein lumen widens

CAPILLARIES

branches of arterioles

• Site of exchange of gases, nutrients, wastes etc. between organs, working muscles and other tissues.

• Single layer of endothelial cells..allows for permeability and/or diffusion.

VENULES

the smallest veins

Vasa Vasorum

Comprise the tiny arteries and veins that supply the walls of the blood vessels.

1

superior vena cava

2

Right pulmonary arteries

3

pulmonary veins

20

atrial septum

7

tricuspid valve

9

inferior vena cava

6

right atrium

8

right ventricle

5

pulmonary valve

4

pulmonary artery

11

brachiocephalic

10

left CCA

12

left subclavian

14

left pulomonary arteries

15

left pulmonary veins

17

mitral valve

18

aortic valve

21

ventricular septum

1

Right common carotid artery

2

right subclavian artery

3

brachiocephalic trunk

4

right pulonary artery

5

right pulmonary veins

6

superior vena cava

7

left common carotid artery

8

left subclavian artery

9

aortic arch

10

left pulmonary artery

11

left pulmonary veins

12

ascending aorta

1

internal carotid

2

vertebral

3

thyrocervical trunk

4

subclavian

5

internal thoracic (internal mammary)

6

brachiocephalic (innominate)

7

ascending pharyngeal

8

superior thyroid

9

external carotid

10

common carotid

11

subclavian

12

aortic arch

step 1 of blood flow in arteries

Heart: The heart is potential/pressure energy and is the source of energy. Pressure is greatest at the heart. Blood flowing away from the heart has a decreased pressure and is considered a pressure or energy wave.

step 2 of blood flow in arteries

Energy gradient must exist in order to move blood around.

step 3 of blood flow in arteries

Velocity: Velocity is greatest during systole or the acceleration phase. Pressure is evenly distributed in all directions. PEAK SYSTOLE is the greatest amount of energy. There is a decrease during diastole, the deceleration of the the pulse phase and when there is change in the direction of flow.

step 4 of blood flow in arteries

Compliance: Blood vessels will stretch with increased pressure unless there is plaque build up.

step 5 of blood flow in arteries

Resistance: High resistance vascular beds get a quick burst of blood during systole. Low resistance vascular beds get a constant blood supply.

Increase in vessel length = increase resistance

Increase in vessel diameter = decrease in resistance

step 6 of blood flow in arteries

Viscosity: Blood thickness/viscosity is the main resistance to flow. Increase in hematocrit = an increase in RBS and the thicker the blood. The interaction of the RBC to each other slows the blood down.

Fourth step of blood flow in veins:

4) Gravity: When erect, venous blood flow must overcome the effects of gravity, also known as hydrostatic pressure, in order to return the blood to the heart. Hydrostatic pressure results in venous distention and pooling of blood in the lower leg.

Second step of blood flow in veins:

Calf/muscle pump: Calf muscles surround the intramuscular and deep veins of the leg, propelling blood toward the heart. The effectiveness depends on the strength of the contraction and the existence of properly functioning valves, which prevent retrograde flow.

First step of blood flow in veins:

1) 1) Pressure/energy gradient: Left ventricle contracts at a pressure of 100 mmHg which drops to 20mmHg by the time the blood flow has reached the venules. Therefore a pressure gradient of 20mmHg must exist in order to get blood to flow from the venules to the RT ATRIUM

Third step of blood flow in veins:

Respiration: During inspiration the intrabdominal pressure increases and intrathoracic pressure decreases, resulting in the collapse of the IVC which will decrease or stop flow coming from lower extremities. During expiration the intrabdominal pressure decreases and intrathoracic pressure increases and flow to the heart is increased from lower extremities. VALSALVA