Function& Structure Of The Heart

Question 1

Blood

Answer 1

• fluid tissue
• transports oxygen and nutrients to the body tissue
• returns waste products from these tissues to the kidneys and Carrie’s carbon dioxide back to the lungs
• play an important role in immune system

Question 2

The heart

Answer 2

• pumps blood throughout
• located in thoracic cavity
• between lungs
• this area is called mediastinum
• ## the tip ‘ apex ‘ of the heart lies above the diaphragm to left of the midline

Question 3

Anterior cross section view of the heart

Answer 3

Anterior external view of heart

Question 4

Pericardium

• known as ‘ pericardial sac ‘
• double walled membrane enclosing the heart

Answer 4

1. Parietal pericardium
   - fibrous sac that surrounds and protects heart
2. Pericardial fluid
   - found between two layers
   - lubricates heart to avoid friction
3. Visceral pericardium
   - inner layer of the pericardium that also forms outer layer of heart
   - also known as ‘ pericardium’

Question 5

Heart wall - -3 layers

- endocardium

Answer 5

Epicardium
- external layer of heart / inner layer of pericardium

Myocardium

• thickest of the hearts wall
• also called ‘ myocardial muscle ‘
• capable of constant contraction and relaxation that creates the pumping movement

Endocardium

• epithelial tissue
• inner lining of heart
• comes in direct contact with blood as it is being pumped through the heart

Question 6

Coronary arteries

Answer 6

• myocardium needs continues supple of oxygen and nutrients + prompt removal of waste to survive
• coronary artery does the job
• the red in the image is the coronary artery - supplies oxygen rich blood
• blue are veins - remove waste products from myocardium

Question 7

Chamber of heart

- atria, ventricles,

Answer 7

• ‘ Atria’ are two upper chambers of the heart
• divided by interatrial septum
• atria are receiving chambers
• all blood enters the heart through these chambers

Ventricles

• two lower chambers of the heart
• have thicker walls than atria because that have to pump blood to entire body
• divided by ‘ inter ventricular serum ‘

Question 8

Valves of heart

1. Tricuspid valve
   - controls opening between right atrium and right ventricle

Answer 8

2. Mitral valve
   - controls opening between left atrium and left ventricle
   - also known as ‘ bicuspid valve ‘
3. Pulmonary semilunar valve
   - located between right ventricle and pulmonary artery
   - pulmonary means pertaining to lungs
4. Aortic semilunar valve
   - located between left ventricle and aorta
   -

Question 9

Systemic and pulmonary circulation

-

Answer 9

Pulmonary circulation
- flow of blood ONLY between heart and lungs

Pulmonary arteries

• carry deoxygenated blood from Right ventricle into lungs .
• only place in body where deoxygenated blood is carried by arteries instead of veins
• in lungs carbon dioxide from body is exchanged for oxygen from inhaled air
• pulmonary veins carry oxygenated blood from lungs to Left atrium through 4 pulmonary veins

Question 10

Systemic circulation

• includes flow of blood to all parts of body accept lungs

Answer 10

• oxygenated blood flows from Left ventricle and into arterial circulation
• the veins carry deoxygenated blood into Right atrium
• from here the blood flows into pulmonary circulation before being pumped out of the heart into arteries again

Question 11

Heartbeat

Answer 11

• ability to pump blood effectively throughout body
• contraction and relaxation of heart must occur in exactly the correct sequence
• electrical impulses from nerves stimulate the myocardium of the chambers of the heart
• heartbeat also known as conduction system

Question 12

Conduction system

1. Sinoatrial node (SA)
2. Ateioventricular node ( AV )
3. Bundle of His

Answer 12

• an electrical impulse from the SA node travels to the AV node and causes ventricle to contract

Question 13

Sinoatrial node

Answer 13

• often referred as SA node
• located in posterior wall of
  Right atrium , near entrance of superior vena cava
• SA node establishes basic rhythm and rate of heartbeat - known as the ‘ natural pacemaker ‘ of the heart
• electrical impulse from the SA node start each wave of muscle contraction in the heart
• the impulse from right atrium spreads over both atria causing them to contract simultaneously.
• this contraction forces blood into ventricles

Question 14

The Atrioventricular node

Answer 14

• also known as ‘ AV node ‘
• impulse from SA node travels to AV node
• AV node is located in floor of Right atrium near interatrial septum
• ## transfers electrical impulse to ‘ bundle of HIS ‘

Question 15

Bundle of His ( HISS)

Answer 15

• group of fibers
• located within interventricular septum
• the fibers carry electrical impulse to ensure sequence of heart contractions
  -The electrical impulses travel to
  Right and Left ventricle and Purkinje fibers

Question 16

Purkinje fibers

Answer 16

• specialized conductive fibers
• located within wall of ventricles
• the fibers relay electrical impulses to cells of ventricles
• that causes ventricles to contract
• this contraction forces blood out of the heart and into aorta and pulmonary artery

From there blood is taken to lungs

Question 17

Electrical waves

Answer 17

• the conduction system of heart can be visualized as wave movement
• this wave is shown on a monitor or as an Electrocardiogram- EKG or ECG
• ‘sinus rhythm’ refers to normal bearing of heart

P Wave
- due to stimulation ( contraction) of atria

QRS complex

• stimulation of ventricles .
• the atria relax as ventricles contract

T Wave
- is the recovery(relaxation) of the ventricles