A&P - Chapter 18 - The Heart

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For Christian Life School Anatomy & Physiology Students

Physical characteristics of the heart

Size of a fist
Hollow
Cone-shaped
Weighs less than a pound
Enclosed in the mediastinum
2/3 is to the left of the sternum; 1/3 is to the right of the sternum

Apex

Point of the heart that rests on the diaphragm and is considered the point of the 'cone'; found at approximately the level of the 5th rib.

Base

The posterosuperior part of the heart that points toward the right shoulder and lies beneath the second rib.

Meaning of PMI

Stands for 'Point of Maximal Intensity'

Definition of PMI

The area just under the left nipple and between the 5&6th ribs where the apex can be felt because it touches the chest wall.

Be able to label the following layers of the heart

pericardium
fibrous pericardium
serous pericardium
parietal layer
visceral layer
pericardial cavity

Functions of the Pericardium

Protects and anchors the heart
Prevents overfilling of the heart with blood
Allows for the heart to work in a relatively friction-free environment

Pericarditis

Inflammation of the pericardium.
Causes pain deep to the sternum.
Heart rubs against the pericardial sac creating a creaking sound.
The pericardial layers can begin to stick together causing inflammatory fluid to build up.

Cardiac tamponade

Means 'Heart plug'
Occurs when the layers of the pericardium start to stick together and inflammatory fluid builds up so much that it limits the pumping action of the heart.
Have to drain using a needle.

Name the three layers of the heart wall

Epicardium
Myocardium
Endocardium

Epicardium

Outer, fatty layer of the heart wall.

Myocardium

Middle layer of the heart wall that consists of thick bundles of cardiac muscle; layer that contracts

Endocardium

A thin, glistening sheet of endothelium that lines the heart chambers and helps make up the valves.

Number of chambers of the heart

4

Name the four chambers of the heart

Right atrium
Right ventricle
Left atrium
Left ventricle

Auricles

Holding tanks for blood that make sure that there is always blood available for the atria to send to the ventricles.

Interventricular septum

Divides the ventricles

Interatrial septum

Divides the atria

What is the function of the atria?

Receive blood returning to the heart

What is the function of the ventricles?

Pump blood to the lungs and to the rest of the body.

Know the pathway blood, returning to the heart from the body systems, takes as it goes through the heart.

-->Deoxygenated blood enters the heart via the Superior & Inferior Vena Cava
--> into the Right Atrium and through the Tricuspid (AV) Valve into the Right Ventricle
--> blood is pumped through the Pulmonary (SL) Valve and into the Pulmonary Trunk to the Right and Left Pulmonary Arteries
--> blood then travels to the lungs to become oxygenated and then returns to the heart via the Right and Left Pulmonary Veins
--> into the Left Atrium and through the Mitral or Bicuspid (AV) Valve to the Left Ventricle
--> blood is then pumped through the Aortic (SL) Valve and into the Aorta which will distribute the oxygenated blood to the rest of the body and then the whole process starts again.

Function of the valves

To ensure that blood flows in only one direction and the prevent the backflow of blood.

Names of the AV (atrioventricular) Valves

Tricuspid valve
Mitral or Bicuspid valve

Chordae tendineae

"Heart strings"; white collagen cords attached to each AV flap which help to anchor muscles

Names of the SL (semilunar) Valves

Pulmonary valve
Aortic valve

Where does the superior vena cava return blood from?

Areas of the body superior to the diaphragm.

Where does the inferior vena cava return blood from?

Areas of the body inferior to the diaphragm.

Incompetent valve

Forces the heart to pump and repump the same blood because the valve does not close properly and blood backflows.

Valvular stenosis

Valve flaps become stiff, often because of repeated bacterial infection of the endocardium. This forces the heart to contract more vigorously than normal.

Angina pectoris

Crushing chest pain caused by low levels of oxygen reaching the myocardium.

Myocardial infarction

Heart attack or coronary; blockage of the coronary arteries caused by a thrombus or embolus leading to oxygen deprivation.

Congestive heart failure

A progressive decrease in the efficiency of the heart. Usually occurs because of a clogging of the coronary vessels with fatty buildup (artherosclerosis), persistent high blood pressure, or multiple myocardial infarcts - leads to repair with scar tissue and not good tissue.

Tachycardia

Rapid heart rate (over 100 beats per minute)

Bradycardia

Heart rate that is substantially slower than normal (less than 60 beats per minute)

Be able to label all the parts of the heart

Superior vena cava
Inferior vena cava
Right atrium
Tricuspid valve
Right ventricle
Pulmonary valve
Pulmonary trunk
Right Pulmonary artery
Left Pulmonary artery
Right Pulmonary vein
Left Pulmonary vein
Left atrium
Mitral (or Bicuspid) valve
Left ventricle
Aortic valve
Aorta

Name and describe the two phases of a heartbeat

Phase 1 - Systole - Occurs when the ventricles contract, closing the AV valves and opening the SL valves to pump blood into the two major vessels leaving the heart
Phase 2 - Diastole - Occurs when the ventricles relax, allowing the back pressure of the blood to close SL valves and open AV valves

How do you properly take someone's blood pressure?

Cuff is inflated to stop blood flow to the artery in the arm.
Air pressure in the cuff is slowly released.
The 1st sound heard means that the ventricles have pumped with enough pressure to overcome the pressure of the cuff; should be around 120.
Air is released from the cuff until no more sound is heard which means there is a steady blood flow; should be about 80.

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