Lab #4. Heart

Question 1

what does blood pressure represent? what do the numbers mean?

Answer 1

Blood pressure is the pressure exerted by circulating blood on the walls of blood vessels (arteries).

Systolic/ diastolic

Systolic BP represents the pressure as your heart beats and pushes blood through the blood vessels (contraction)

Diastolic BP is the pressure when the vessels are relaxed when the heart rests between beats.

Question 2

Lack of blood supply to the brain results in a ______.

Answer 2

stroke

Question 3

what happens to the heart muscle upon “myocardial infraction”?

Answer 3

During a myocardial infraction the blood supply and O2 supply to a part of the heart is interrupted. Usually caused by an occlusion (blockage) of a coronary artery which can by caused by an atherosclerotic plaque detachment which will result in Ischemia (restriction of blood supply) and eventually the shortage of O2 will cause death of myocites.

Question 4

What is normal blood pressure? What is hypotension and hypertension?

Answer 4

Normal BP= 120/80

Hypotension= low blood pressure = < 90/60

Hypertension= high blood pressure= > 140/90

Question 5

How can one lower BP ??

Answer 5

• stop smoking
• exercise
• reduce weight
• lower salt
• sufficient rest
• low protein
• no cafeine

Question 6

what is arteriosclerosis? what can it cause?

Answer 6

Arteriosclerosis is the hardening of arteries which can be caused by hypertension (high blood pressure) and can lead to collection of lipids + macrophades in the walls of arteries causing plaque.

Question 7

What happens in Ischemia?

Answer 7

Ischemia restricts the blood supply to a part of the heart. The myocardial cells that die first are the ones part of the myocardium that is most distal to the arterial blood supply, The ENDOCARDIUM cells (the farthest away first). the area of myocardial cell death spreads with time extending from the endocardium to the myocardium and then the epicardium

Question 8

How can you tell by looking at the tissue that the myocardial cells are dead or dying?

Answer 8

• loss of striations
• loss of branchng patterns
• loss of nuclei
• infiltration of neutrophils
• Na/K membrane gated channels are degraded –> edema
• Na : depolarized
• K: repolarized

Question 9

What are the names of the heart coverings?

Answer 9

1. Pericardium: fluid filled sac providing protection against friction
2. Epicardium: outer layer of heart wall (visceral layer)
3. Myocardium (muscle itself): muscle tissue of heart
4. Endocardium: inner layer of heart wall

Question 10

What are the chambers of the heart? what do they do?

Answer 10

• Left and Right Atria: 2 superior chambers of the heart, receive the blood
• Left and Right Ventricles: 2 lower chambers of the heart, pump blood up into the aorta or pulmonary arteries

Question 11

What are the valves of the heart? where are they located? what is their function?

Answer 11

The valves are mechanical devices that permit the flow of blood in one direction only (prevent backflow)

1. Atrioventricular: between the atria and the ventricle - (Right AV = tricuspid valve, Left AV= bicuspid or mitral valve)
2. Semilunar valve: half-moon shaped flaps growing out from the lining of the pulmonary artery and the aorta. - ( Pulmoary semilunar valve = in the pulmonary trunk, Aortic semilunar valve = in the aorta)

Question 12

What can be found only in the right ventricle and not in the left ventricle? what is its function?

Answer 12

the Trabeculae septomarginalis, it carries part of the right branch of atrioventricular bundle (bundle of His) from the septum to anterior papillary muscles.

Question 13

How does the heart supply itself with blood?

Answer 13

The heart is supplied with blood by ways of the right and left coronary arteries which fill from the aorta when the ventricle relaxes. Both arteries originate from the aortic sinus:

1. Right coronary artery - (supplies blood to the RA & RV)
2. Left coronary artery- splits into:
   a) circumflex artery (coronary groove)
   b) anterior interventicular branch (paraconal in pig) (paracoronal interventicular groove)

The blood is then returned to the right atrium via the coronary sinus and the great cardiac vein.

Question 14

what are the parts of the conduction system of the heart? where are they located?

Answer 14

1. sinoatrial node or Pacemaker: autorythmic cells located in right atrial wall near the superior vena cava
2. atriventicular node: located in right atrium along the lower part of the interatrial septum
3. atrioventricular bundle (bundle of his) & Purkinje fibers: originating in AV node extend down septum, become purkinje fibers at lateral walls of ventricles and papillary muscles

Question 15

which are the only vessels in the body that fill when the heart is in diastole?

Answer 15

the coronary arteries

Question 16

Where are the sympathetic and parasympatic control fibers of the heart located? what do they do?

Answer 16

Sympathetic: increases heart rate

• segments T2, T3, T4 of the spinal cord
• distributed through the middle cervical and cervico-thoracic (stellate) ganglia
• 1st four ganglia of the thoracic sympathetic chain

Parasympathetic: decreases heart rate

• vagus (cranial nerve 10)

Question 17

what is an ECG? what does it record?

Answer 17

ECG or electrocardiogram records the heart’s electrical activity (conduction impulse)

Question 18

What are the stages of the ECG graph? what do they represent?

Answer 18

1. P wave: depolarization of the atrial walls
2. PR interval: delay of AV node to allow filling of ventricles- atrial walls are completely depolarized
3. QRS complex: atria repolarize and venticular walls depolarize
4. ST segment: atrial walls are repolarized, venticular walls are depolarized
5. T wave: venticular repolarization

Question 19

When are the semilunar valves and atrioventricular valves open and closed?

Answer 19

semilunar valves are closed during P wave up to just after S and opens between S and end of T wave and then is closed again.

AV valves are open up until R (peak) and then close until after T wave at which point they open.

Question 20

What are the sounds the heart makes? what do they represent?

Answer 20

LUB= closing of the AV valves and opening of the Semilunar valves

DUP= closing of the Semilunar valves and opening of the AV valves

Question 21

Which parts of a ECG represent diastole and systole?

Answer 21

DIASTOLE: between one T wave and S = DUP–> LUB

SYSTOLE: between S and T = LUB–> DUP

Question 22

what kind of muscles are found in the auricles ?

Answer 22

Pectinate muscle

Question 23

What is the structure shown in this picture (in right ventricle)? what is its function?

Answer 23

Trabeculae Septomarginalis

Function: allows electrical signals to pass from the septum to the lateral wall faster.

Question 24

Describe Systemic Blood Circulation.

Answer 24

Starts at S/I vena cava >RA>RAV (tricuspid)>RV>PSV>PT>left and right pulmonary arteries> to the lungs > CO2–> O2 exchange> PV>LA>LAV (mitral/bicuspid)>ASV>aorta> to the body + into left and right coronary arteries

Question 25

What two blood vessels experience reverse blood flow?

Answer 25

Pulmonary artery/Trunk : carries deoxygenated blood to the lungs

Pulmonary Vein: carries oxygenated blood from the lungs

Normally ateries carry oxygenated blood and veins carry deoxygenated blood.

Question 26

How do trabeculae carnae relate to pectinate muscles? where are these structures located?

Answer 26

trabeculae carneae are larger and thicker than pectinate muscles

trabeculae carneae - in ventricles

pectinate muscles - in atria

Question 27

what is the order of conduction starting from the SA node?

Answer 27

SA node–> AV node–>AV bundle (bundle of His)–>perkinje fibers–> ventricle wall