Week 5 Cardiac Anatomy & Physiology Study Guide

Question 1

What are intercalated discs?

Answer 1

The cells of cardiac muscle (cardiomyocytes) attach to one another with specialized cell junctions called intercalated discs.

These discs:

Transfer force of contraction between muscle fibers. (Make sure that all the muscle cells & fibers contract when they are supposed to at the same time to give us the maximum heartbeat.)

Question 2

Characteristics of the heart

Answer 2

-Located in mediastinum with slight prevalence to the left.
-About 300g in the adult
-Wide superior border with an inferior border that comes to an apex.

Question 3

Heart Coverings

Answer 3

-Fibrous pericardium (pericardial sac)-outermost covering of the heart

-Pericardium (made up of two layers:
1)Visceral pericardium (epicardium)-innermost covering surrounding the heart muscle (closest to the heart)

2)Parietal pericardium-inner lining of fibrous pericardium.

-Paricardial cavity filled with serous fluid

-Pericarditis

-Cardiac Tamponade-when bleeding from the heart seeps into the pericardial sac into serous fluid in pericardial cavity.

Question 4

Heart wall structure

Answer 4

Epicardium
-Visceral percardium (aka epicardium)
-Its a serous membrane
-Epi-means on top of

Myocardium
-Muscle of the heart(muscle layer)
-cardiac muscle tissue
-Forms atria and ventricles
-largest portion of the heart
-Myo-means muscle

Endocardium
-Inner lining of the heart
-Endocarditis- inflammation of the inner lining of the heart

-Endo-means inside

Question 5

Be able to Identify these anatomical parts of the heart.

Answer 5

-Atria
-Ventricles
-Interatrial Septum
-Interventricular Septum
-Tricuspid Valve
-Bicuspid Valve
-Papillary Muscle
-Chordae Tendinae
-Trabeculae Carnea
-Pulmonary Semilunar
Valve

Question 6

Know the vessels that enter and which chambers they enter.

Answer 6

Superior vena cava, inferior vena cava, and coronary sinus all enter the heart through the right atrium.

Question 7

Know the vessels that leave the heart and which chambers they exit.

Answer 7

Blood leaves the right ventricle through the pulmonary semilunar valve (PSL).

Blood leaves the left ventricle through the aortic semilunar valve (ASL).

Question 8

Trace a drop of blood starting with the right atrium and ending with the Aorta through a pulmonary circuit.

Answer 8

1. Right Atrium-A drop of blood enters the heart from the superior vena cava, inferior vena cava, and coronary sinus through the right atrium.

2.Triscuspid valve-That drop of blood will the go through the tricuspid valve.

3. Right Ventricle-From the tricuspid valve into the right ventricle.
4. Pulmonary Semilunar Valve-The right ventricle will send that drop of blood to the pulmonary semilunar valve.
5. Pulmonary Trunk-then the pulmonary semilunar valve will send the drop of blood to the pulmonary trunk.
6. Pulmonary Artery-then blood will be sent to the pulmonary artery.
7. Alveolar Capillaries in the lung tissue-this is where the and carbon dioxide exchange will happen. (pulmonary circulation)
8. Pulmonary Veins-the capillaries will merge together to form veins that we call pulmonary veins.
9. Left Atrium-pulmonary veins will then enter the heart through the left atria.(Blood from veins will enter the heart.)
10. Bicuspid (Mitral) Valve-then blood will leave left atria and enter bicuspid/mitral valve.
11. Left Ventricle-(Then to left ventricle.
12. Aortic Semilunar Valve-then to aortic semi-lunar valve.
13. Aorta-then to the aorta and then out to the body tissues(systematic circulation)

Question 9

Atrium receives veins, ventricles give rise to arteries. Arteries leave ventricles, veins enter the atria.

Question 10

Right & Left Coronary Arteries

Answer 10

Right Coronary Artery-Supplies blood to the right atrium, portions of both ventricles and some of the cardiac conduction system. (SA node and AV node).

Left Coronary Artery-Supplies blood to the left ventricle, left atrium, and interventricular septum.

Question 11

We get in the heart muscle of capillaries through the coronary arteries. We have blood in the heart, but that blood is useless unless it gets to the capillaries. Everything happens at the cellular level in our body. If the coronary artery gets blocked and blood can’t get to the muscular portion of the heart, it has to get to the capillary level of the heart so oxygen, carbon dioxide, nutrients to be exchanged.

Question 12

Arteries will branch, branch and get smaller until they form arterial vessels (very small vessels) and capillaries. Capillaries merge together to form veins.

Arteries supply blood to areas. (oxygenated blood).

Veins drain blood from the areas. (Deoxygenated blood)

Question 13

Cardiac Conduction System(depolarization, plateau, repolarization)

Answer 13

-Specialized autorhythmic tissue in the heart.

-Responsible for initiating and distributing electrical impulses throughout the myocardium.

Components-
-sinoatrial node
-atrioventricular node
-atrioventricular bundle
-Bundle branches
-Purkinje fibers

Question 14

Cardiac Conduction System(depolarization, plateau, repolarization)

Answer 14

1)Depolarization

-When the threshold potential is reached, sodium channel open.

-Sodium ions rush into the contractile fibers and produce rapid depolarization
-Nerve impulses carried throughout cardiac muscle through the use of intercalated discs. (All cardiac muscles will contract at the same time.)

Question 15

Cardiac Conduction System(depolarization, plateau, repolarization)

Answer 15

2) Plateau

-Calcium channels open and calcium enters the contractile fibers from the extra cellular fluid.

-Calcium also moves from the sarcoplasmic reticulum into the cytosol of the contractile fibers. Depolarization is maintained for 250ms. Calcium binds troponin and contraction of cardiac muscle begins. (Like a delay to allow the heart to do what it needs to do.)

Question 16

Cardiac Conduction System(depolarization, plateau, repolarization)

Answer 16

Repolarization
-Potassium channels open and begin to defuse out of the contractile fibers

-Sodium and calcium channels close

-Original resting membrane potential is restored.

Question 17

Characteristics of Cardiac Contraction

Answer 17

-The presence of a plateau is the major difference between cardiac muscle contraction and skeletal muscle contraction.

-Calcium continues to enter the contractile fibers during the plateau period to increase the contractility of the cardiac muscle.

-Epinephrine increases contraction force by increasing calcium influx into the contractile fibers. (causes an increase in cardiac contractility.)

-Calcium channel blockers reduce calcium influx thereby diminishing contraction force.

Question 18

Know the basic segments of an EKG and what those segments denote.

Answer 18

EKG-A recording of electrical changes occurring in the myocardium during a cardiac cycle.

Determines if:

-Conduction pathway is normal.

-If heart is enlarged
-If certain heart regions is damaged.

-Uses electrocardiograph to record.

ECG tracing:

P Wave:
-Reperesents atrial depolarization
-O.I seconds after P-wave, atria contract.

QRS Complex:
-Represents ventricular depolarization

-Also contains atrial repolarization
-Just after QRS begins, atria contract.

T Wave-
-Represents Ventricular repolarization
-Occurs just before ventricles begin to relax.
-Slow process

Question 19

Describe the correct order of events in one cardiac cycle.

Answer 19

1. Atrial Systole phase begins:
   -Atrial contractions forces a small amount of additional blood into relaxed ventricles.
2. Atrial Systole ends and atrial diastole begins.

3) Ventricular Systole(first phase)-Ventricular contraction pushes Av valves closed but does not create enough pressure to open semi-lunar valves.

4) Ventricular Systole (2nd Phase)
-As ventricular pressure rises and exceeds pressure in the arteries, the semi-lunar valves is opened and blood is ejected.

5) Ventricular Diastole (early)
-As ventricles relax, pressure in ventricles drops; blood flows back against cusps of semi-lunar valves and forces them closed. Blood flows into the relaxed atria.

6) Ventricular Diastole(late)-All chambers are relaxed. Ventricles fill passively.

Question 20

What occurs to make two heart sounds?

Answer 20

first heart sound represents the closing of Av valves (Loud and long sound)

second heart sound represent the closing of Semi-lunar valves. short and sharp sound.

Question 21

Cardiac Output

Answer 21

Volume of blood pumped by each ventricle in one minute.

Question 22

Stroke Volume

Answer 22

Volume of blood pumped out by a ventricle with each heartbeat.

Question 23

How to calculate cardiac output?

Answer 23

Heart Rate(HR) X Stroke Volume (SV)

Question 24

Normal Cardiac Output?

Answer 24

5 Liters

Question 25

Ischemia?

Answer 25

Low blood flow to a tissue which can cause hypoxia.

Question 26

Hypoxia?

Answer 26

low oxygen content in a tissue.

Question 27

Agina Pectoris?

Answer 27

Pain in the chest; does not mean it is a heart attack.

Question 28

Myocardial Infarction?

Answer 28

Heart attack. Means “muscle heart stops”

Question 29

Arrhythmias?

Answer 29

1) Tachycardia-Heartbeat above 100 bpm

2) Bradycardia-Heartbeat below 60 bpm

Question 30

Premature Ventricular Contractions?

Answer 30

A skipped heartbeat-Ventricles are contracting before the atria prematurely.

Question 31

Ventricular Tachycardia?

Answer 31

Ventricles are contracting very fast at 100 -250 bpm and not allowing the atria to contract. Needs medical treatment immediately.

Question 32

Ventricular Fibrillation

Answer 32

The ventricles are no longer beating. No blood is being pumped to the body. No oxygen is getting to the body. The ventricles are defibrillated. A person will die in a matter of minutes in this condition.

Question 33

Asystole?

Answer 33

Flat line. No heart contractions.