Heart Sounds, Cardiac Conduction, and Blood Vessels

Unit 5: Lessons 3-5

Systole

when a chamber section contracts

Diastole

when a chamber section is relaxed

What happens in atrial systole?

Atria contract and ventricles relax (diastole)

What happens in ventricular systole?

Ventricles contract and atrium relax (diastole)

Cardiac Cycle

The series of events that make up a heart beat

Atrial Systole / Ventricular Diastole:

Both atrium contract and push blood to the ventricles through the A-V valves (tricuspid/bicuspid).

During atrial systole, which valves are open and which are closed?

A-V valves are open and semilunar valves are closed

Ventricular Systole / Atrial Diastole:

Both ventricles contract and push the blood through the semilunar valves to the Aorta and Pulmonary Artery. 

During ventricular systole, which valves are open and which are closed?

Semilunar valves are open and the A-V valves are closed

How is sound made in the heart?

Sound is made as blood travels through heart and valves

When is the “lubb” sound produced

During ventricular systole (when A-V valves are closing)

When is the “dupp” sound produced

During ventricular diastole (when semilunar valves are closing)

Cardiac Conduction System:

Areas of the heart which initiate and distribute impulses throughout the heart which lead to a cardiac cycle

What is the heart run by

Electricity

What do the special muscle fibers in the heart coordinate

Impulses sent through the heart that tell it when and how to beat

S-A (sinoatrial node)

small specialized cardiac muscle located in the superior region of the right atrium (aka the pacemaker)

Where does the electrical impulse begin in the heart?

S-A node

A-V node

small specialized cardiac muscle located in the inferior region of the right atrium

What does the A-V node do?

It provides a conduction pathway for impulse to get from atrium to ventricles

Purkinje fibers

Specialized fibers in the ventricles that allow electricity to flow through them

Fibrillation

Small areas of the myocardium that contract in an uncoordinated, chaotic fashion

Which type of fibrillation is fatal

Ventricular

EKG/ECG

recording of the electrical changes that occur in the myocardium during a cardiac cycle

what is an EKG used for

to measure the rate and regularity of heartbeats (has nothing to do with valves)

How is an EKG recorded

electrodes are placed on the skin and connected by wires to an instrument that records the electrical impulses in the heart.

EKG waves

Up-and-down movements that are recorded

What is true about the heart when it is at rest?

Electricity on an EKG is polarized (straight line)

P Wave - EKG

When the atrial chambers depolarize and systole

QRS Complex- EKG

When the ventricular chambers depolarize and systole (atrial chambers repolarize and diastole)

Why is the electrical charge higher in the QRS complex?

Walls of the ventricle are thicker than those of the atrium

T Wave

Ventricular chambers repolarize and diastole

Prolapse

to fall out of place

Mitral valve

biscuspid valve

Mitral Valve Prolapse

When the leaflets bulge up into atrium during ventricular contraction

What can Mitral Valve Prolapse cause

pain, palpitations, fatigue, and anxiety

Arrythimias

Disorder of the heart rate

Tachycardia

heart rate too fast

Bradycardia

heart rate too slow

Atrial contraction steps

1. S-A (sinoatrial node) initiates an impulse for the heart to beat.

2. Impulses are sent down right and left atrium initiating them to contract almost simultaneously.

3. Impulse arrives at A-V Node

Ventricular Contraction steps

1. Impulse sent down interventricular septum. 

2. Impulse then sent to right and left ventricles walls initiating them to contract.

3. Ventricles contract as a unit.

Blood Vessels:

Organs of the cardiovascular system that carry blood to and from heart

What are the different blood vessels

Arteries, veins, capillaries, venules, arterioles

Arteries

They are the strongest and most elastic blood vessels that carry blood away from the heart under high pressure

Why do arteries carry blood under high pressure?

They get the blood that is pushed out from the heart

Arterioles

Arteries that are subdivided into smaller, thinner, finer branched tubes.

How many walls do arteries have?

3

Inner artery layer wall

Smooth surface which allows blood cells and platelets to flow without damage

Middle artery layer wall

Arterial wall of smooth muscle which contracts and shrinks blood vessel when necessary. 

Outer artery layer wall

connective tissue

What can the sympathetic nervous system do in terms of blood vessels?

they can change the diameter of the blood vessels by initiating the middle layer of smooth muscle to contract

Vasoconstruction

reduce diameter

Vasodilation

Increase diameter

Capillaries

Smallest diameter blood vessels in the body that connect arterioles to venules

Why are capillary walls thin?

So substances can pass through

Where does blood move the slowest?

In the capillaries

Blood moving slow in capillaries allows for what?

Exchange to occur as capillaries wrap around organs and exchange with them

What do capillaries exchange?

Gases, nutrients, wastes

Precapillary Sphincters

On arterioles; constrict to allow less blood to flow to an area of the body

Sphincter

round smooth muscle that constricts involuntary

Venules

Small, fine blood vessels that branch off from capillaries and lead to veins.

Veins

Follow pathways that are roughly parallel to the arteries of the body and have thinner walls than arteries

Where do veins carry blood?:

to the heart

Valves

on many veins and are usually composed of two leaflets; pushed close if blood backs up in a vein

What do valves help with?

They aid in returning blood to the heart and allow for the lowest pressure blood to return to heart

Aorta

artery that goes down center of body and becomes ABDOMINAL AORTA

Carotid artery

artery that goes to neck and head

Brachial artery

artery that goes down arm

Femoral Artery

Artery that goes down leg

Superior/Inferior Vena Cava

Brings blood in from the upper and lower halves of body

Are the vena canvas veins or arteries?

veins