Heart

Question 1

Describe the location of the heart

Answer 1

-In the Mediastinum in the thoracic caviety

Question 2

Name the membrane that surrounds the heart, what is its function?

Answer 2

-Pericardial sac protects the heart and prevents over distention of heart.

Question 3

Name the three layers of the heart wall

Answer 3

• Epicardium-outer layer- thing why layer
• Myocardium- Muscle (L side is thicker)
• Endocardium- innermost layer

Question 4

Where might pericardial fluid be found

Answer 4

• Pericardial caviety

Question 5

Name the 4 hear champers and the spatae and valve that seperate them

Answer 5

• Atria (L&R)
  
  • Interatrial Septum
• Ventricles (L&R)
  
  • Interventricular septum
• Valves between atria and ventricles are called Atrioventricular valves (R tricuspid, L bicuspid)
• The pulmonary semilunar valve lies between the right ventricle and the pulmonary trunk
• the aortic semilunar valve lies between the left ventricle and the aorta.

Question 6

Define Coronary Sulcus

Answer 6

-An external groove separating the atrium from ventricle and contain coronary blood vessels

Question 7

Define Cordae tendineae

Answer 7

• the tendons that anchor the heart AV valves to the papillary muscles, making sure they do not fold in

Question 8

Define Papillary Muscle

Answer 8

-anchor muscle for the chordae tendineae

Question 9

Define Trabeculae carneae

Answer 9

-irregular ridges of the myocardium adding strength without weight

Question 10

Trace the coronary circuit of blood flow

Answer 10

-aorta to coronary arteries to myocardium and then through cardiac veins to a big collecting vein called the coronary sinus which dumps into the Right atrium

Question 11

Describe the cells comprising the myocardium. Name the structure between these cells and its primary purpose

Answer 11

-Striated cardiac muscle cells linked by intercalated disc that carries excitement for contraction from one heart muscle cell to the next, linking them all together.

Question 12

Explain why a refractory period is necessary following cardiac muscle cell excitation

Answer 12

-sustained reaction without relaxation does not allow the heart chambers to fill with blood.

Question 13

Name the source of energy for cardiac muscle-

Answer 13

-ATP from aerobic metabolism

Question 14

Describe the excitation of cardiac muscle cells and where this occurs

Answer 14

• Spontaneous depolarization can occur in all cardiac muscle cells but happens the quickest at the Sinoatrial node
  
  • thus setting the pace for the entire heart since all cells are linked by the intercalated discs

Question 15

Describe the pathways for conduction of electrical impulses through the heart.

Answer 15

Starts with the SA node, L&R Atria go at the same time, followed by the AV node with a breif delay for atria to finish
-AV Bundle is on the interventricular septum into the Purkinje= conduction fibers that branch up the outer walls of the ventricles

Question 16

Describe systole and diastole. Which heart chamber has the highest systolic pressure and why?

Answer 16

• Systole is the contraction phase (squeezes blood out)
• Diastole is the relaxation phase. (fills with blood)
• Highest systolic pressure is the LV since it has to pump blood from head to toes.

Question 17

Describe and illustrate the pressure changes in the left atrium, left ventricle, and aorta though one complete cardiac cycle

Answer 17

• When LA has higher pressure than LV, the Left AV valve is open.
• As the LV contracts, its pressure exceed that of the LA and the Bicuspid valve closes causing the first heart sound.
• As the left ventricle is pushing blood into the aorta with high pressure, the aortic semilunar valve is open, but when the ventricle enters into diastole, quickly, its pressure drops below that of the elastic aorta resulting in semilunar valve closure causing the second heart sound.

Question 18

Define cardiac output and cardiac reserve

Answer 18

• Cardiac output is the volume pumped out of the ventricle in a minute CO = HR x SV. (heart rate X stroke volume)
• Normal CO is 5-6 liters/minute (our total amount of blood)
• Cardiac reserve is the difference between the maximum cardiac output and resting cardiac output.

Question 19

Describe the controls of heart rate and describe how heart rate relates to cardiac output

Answer 19

• Sympathetic NS increases heart rate, increasing Cardiac output
• Parasympathetic NS decreases heart rate, decreasing CO.
• Normal resting heart rate is 70 bpm

Question 20

Define stroke volume and describe how it relates to cardiac output.

Answer 20

• Volume pumped from ventricle per beat

- Normal resting is 80 beats per minute, SV increases so does CO

Question 21

Define end-diastolic volume and factors that influence it.

Answer 21

• Volume at the end of ventricles filling
  
  • Venous return, blood that returns to heart, movement increases this
  • Length of diastole- longer more blood

-Stroke volume= End diastolic volume-end systolic volume

Question 22

Describe the (frank) Starling law

Answer 22

-.As the wall of the ventricle stretches due to an abundance of blood, the force of the ventricular contraction is greater, thus decreasing End Stroke Volume, and preventing pooling of blood in the ventricle.

Question 23

List some factors that influence cardiac function.

Answer 23

• The cardiac center in the brainstem regulates heart function
• as does exercise, temperature, sex, age, and certain ions, such as potassium and calcium.

Question 24

Describe the origin of the lub dub sound as your heart beats

Answer 24

• Lub is closure of the AV valves

- Dup is closure of the semilunar valves

Question 25

Describe the basis of electrocardiography, what are leads

Answer 25

-detecting and recording the electrical depolarization of the heart muscle. Lead describe where the electrodes are placed on the skin.

Question 26

Describe the waves of a normal ECG and each wave represents

Answer 26

- P wave represents atrial depolarization. - QRS complex represents ventricular depolarization - T wave represents ventricular repolarization.