The Heart



Unit 12 Notes: The Cardiovascular System

Transport Systems

I. Introduction to transport systems: Blood, Cardiovascular System, & Lymphatic System

a. Transport – ability to move materials both ______________________ of the body

b. Transport system – system of structures to ____________________ and convey the transport medium in one direction (___________________________) through the system from one exchange surface to another in the body

c. Transport medium – substance or structure in which materials can be conveyed throughout the body

i. Solvent – substance ______________________________________________

ii. Solute – substances ______________________________________________

d. A mechanism to control / adjust the mass flow of the transport medium in one direction through the system

i. Mass flow – movement of fluid in __________ direction usually through system of ___________________

e. Exchange surfaces – _________________________________ structures whose features permit the highly efficient transfer of materials across the structure

I. Types of properties

a. ________________________ properties – structures and processes not involving chemical reactions / changes

b. ________________________ properties – molecules being transported for involvement in chemical reactions / changes

c. ________________________ properties – cells and tissues involved in the transport process

II. Application examples: Cardiovascular System

a. Transport system: _____________________________________

b. Transport medium: Blood

i. Solvent: ____________________________

ii. Solutes: blood cells, proteins, etc.

c. Exchange surfaces: _____________________________

d. Mechanisms to control mass flow of blood: ______________________________________; pressure changes in heart; valve action

Heart Anatomy

I. Heart Anatomy: Your Objectives:

a. Determine the size & location of the heart.

b. Determine the function/importance/description of each of the following parts.

c. Determine the location of the parts on a heart diagram

II. Heart location and size

a. Weight in lbs and grams _______________________________________

b. Location in chest (give landmarks to describe)

III. Heart Structures:

a. Heart Wall & Pericardial Cavity

i. Pericardial cavity

ii. Parietal pericardium

iii. Visceral pericardium (aka. Epicardium)

iv. Myocardium

v. Endocardium: Why are the circulatory system organs lined with endothelium?

b. Chambers & associated structures

i. Atrium (atria = plural)

ii. Auricle

iii. Pectinate muscles

iv. Ventricles

v. Trabeculae carnae

vi. Chordae tendinae & Papillary muscles

vii. Septum

viii. Which chamber has thickest most muscular walls and why?

c. Valves and associated structures

i. Atrioventricular valves

1. Tricuspid

2. Bicuspid (aka. Mitral)

ii. Semilunar valves

1. Pulmonary SL

2. Aortic SL

iii. What is the purpose of the 4 valves?

iv. What is the first heart sound caused by?

v. What is the second heart sound caused by?

d. Know how valves open & close to prevent backflow of blood which is important in keeping oxygenated & deoxygenated blood from mixing and gets them to the right structures.

e. Blood vessels (major): Know the location & direction of blood flow

i. Superior vena cava

ii. Inferior vena cava

iii. Pulmonary trunk

iv. Pulmonary arteries (right and left)

v. Pulmonary veins (right and left)

vi. Aorta (ascending, descending, arch)

IV. Fetal structures – what is the purpose of these 2 structures in a fetal heart? What do they become in the adult heart?

i. Foramen ovale

ii. Ductus arteriosus

Heart Diagram: Label the following parts on this diagram.

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II. Pathway of circulation: Your Objectives – complete these on paper!!

← Differentiate between pulmonary circuit and systemic circuit: which side of the heart is involved in each and what is the purpose of each?

← Determine the complete pathway a drop of blood would take beginning in the superior and inferior vena cava

← Discuss the need for a separate cardiac circulation.

Intro to Heart Contraction

I. Two events happen in a heart beat

a. electrical event which causes:

b. muscular event/contraction

c. Either event can have problems so doctors need the ability to check each one.

The Conduction system

I. Conduction System of the Heart - Know parts on diagram

Cardiac muscle needs organization/rhythm and speed control for maximum efficiency- So two controlling/coordinating systems are needed:

A. autonomic nervous system divisions

1. sympathetic NS - ____________________ rate & force

2. parasympathetic NS - ________________ heart rate & force

B. Intrinsic conduction system:

1. gap junctions -

2. conduction system parts

a. sinoatrial (SA) node

b. atrioventricular (AV) node

c. AV bundle & bundle branches

d. Purkinje fibers

i. Auto rhythmicity: ability of the heart muscle to initiate contractions itself without external nervous system stimulation

Electrical Event

A. electrical events caused by conducting system are recorded as deflection waves transmitted to entire body by means of electrolytes.

B. The recording of heart electrical waves is called an ECG or EKG - electrocardiogram - A graphical representation of the electrical activity of the heart used in evaluating the function of the cardiac conduction system

B. ECG has 3 kinds of deflection waves

1. P wave

a. atrial depolarization (electricity)

b. then atria contract

c. ventricles are relaxed

2. QRS complex

a. ventricular depolarization (electricity)

b. then ventricles contract

c. atria are in process of relaxing - repolarization is hidden by QRS complex

3. T wave

a. ventricular repolarization (electricity)

C. healthy heart - consistent deflection waves

Be able to label the waves of an ECG and recognize normal and defective patterns.

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I. Application of Electrical Technology

a. Automated external defibrillator (AED)

b. Implantable cardioverter defibrillator

c. Internal cardiac pacemaker

d. Cardioversion

Muscular event – the Cardiac Cycle

I. alternate contraction and relaxation of heart

a. Contractility: innate ability of the cardiac muscle cells to forcefully shorten & cause movement – in response to stimulus from cardiac conduction system.

b. Gives muscle the ability to cause movement

1. described in terms of ventricular events

2. systole - contraction

3. diastole - relaxation

II. Phases of cardiac cycle

A. mid to late diastole (heart is in complete relaxation) - ventricular filling

1. pressure in heart is low - blood flows passively into atria then ventricles

2. AV valves open - semilunar valves closed

3. 70% of ventricular filling occurs

4. atria begin to contract forcing remaining 30% of blood into ventricles

5. pressure in ventricles begins to close AV valves

B. ventricular systole

1. BP in ventricles rises sharply - closes AV valves

atrial begin filling again

2. isovolumetric contraction phase

a. while both sets of valves are closed - the muscle contracts which builds pressure for a very short time period

3. BP exceeds BP in aorta & pulmonary trunk and forces SL valves open

4. ventricular ejection phase

a. blood expelled into aorta and pulmonary trunk

b. normal aorta pressure is 120 mm Hg

C. Early diastole / isovolumetric relaxation phase

1. ventricles relax and pressure drops

2. blood backflow closes semilunar valves

1. atrial pressure will then force open AV valves

D. Cardiac cycle = 0.8 secs

1. atria systole = 0.1 secs

2. vent systole = 0.3 secs

3. total heart relaxation (quiescent period) = 0.4 secs

only time heart gets to relax

E. Important points

1. flow of blood is controlled by pressure changes

2. blood flows along pressure gradient through any available opening

3. An echocardiogram is a sonogram of the heart and is used to

visualize the opening/closing of valves and working of muscles

II. Frank-Starling law of the heart

A. degree of stretch determines SV - more stretch = more force of contraction

B. Important function: ensure equal ventricular output to distribute blood evenly between systemic & pulmonary circuits. If one side of the heart starts pumping more blood, the increase in venous return causes the other side of the heart to stretch and increase its pumping power to an equal amount

C. Conditions affecting contractility

1. edema due to CHF or venous insufficiency

2. aneurysms: weakness in walls of major arteries

3. genetic factors such as Marfan’s syndrome – affects collagen strength in heart and blood vessels walls

End of Quiz #2 Material – Includes Diagrams

Discuss how age related changes affect the Cardiovascular system

▪ Age-related change

▪ Decrease in lumen diameter of arteries and arterioles

▪ Diminished arteriole elasticity

▪ Degenerative changes in cardiac muscle

▪ Thickening of valves and myocardium

▪ Effect on system

▪ Increased resistance to blood flow increasing the risk of myocardial infarction

▪ Increased systolic pressure

▪ Cardiac output declines during exercise

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Aorta

Label the diagram directly on the part without using leader lines: see example

Aorta

Aortic semilunar valve

Apex

Bicuspid valve

Descending Aorta

Inferior vena cava

Left Atrium

Left pulmonary artery

Left pulmonary veins

Left Ventricle

Pulmonary semilunar valve

Pulmonary trunk

Right Atrium

Right pulmonary artery

Right pulmonary veins

Right Ventricle

Septum

Superior vena cava

Tricuspid valve

Label the arrows only with the following structures:

← Trabeculae carnae

← Pectinate muscles

← Chordae tendinae

← Papillary muscles

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Diagram #2 – Trace the pathway of blood flow

← Use blue arrows for deoxy blood

← Use red arrows for oxy blood

End of Quiz #1 Material – Includes Diagrams

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