Cardiovascular Physiology Lecture 2

Question 1

What are the four valves in the heart?

Answer 1

1. Atrioventricular (AV) valves - between atria and ventricles
   
   1. Bicuspid (mitral): between L Atrium and L ventricle
   2. tricuspid: between R Atrium and R ventricle
2. Semilunar (arterial) valves - between the ventricles and there arteries into which the ventricles pump
   
   1. aortic valve
   2. pulmonary valve

Question 2

What are valves made of?

What are the flaps called?

Answer 2

Made of fibrous tissue (collagen) covered by endothelium

The valve flaps are also called leaflets or cusps

Question 3

What are valve rings?

Answer 3

What the valves attach to

Made of cartilage

Question 4

How do the valves open and close?

Answer 4

Passively: due to differences in pressure or pressure gradients (do not require muscle)

Question 5

What happens to the atrioventricular valves when the pressure in the atria exceeds the pressure in the ventricle?

Answer 5

AV valves open

Question 6

What is the funciton of the AV valves?

Answer 6

Prevent backflow of blood into the atria as the ventricles contract

Question 7

What are the chordae tendineae?

Answer 7

Tendinous-type tissue that extend from edges of each leaflet to papillary muscle.

Question 8

What are papillary muscles?

Do they contract?

Answer 8

Cone-shaped muscles

• contraction of papillary muscles causes the chordae tendineae to become taut
  
  • holds valve in closed postion

Question 9

What is the Cardiac skeleton?

Answer 9

Fibrous skeleton of the heart

Question 10

What is the cardiac skeleton made of?

Answer 10

Dense connective tissue

Question 11

What is included in the cardiac skeleton?

Answer 11

• Heart valve rings
• dense connective tissue between the heart valves

Question 12

What are three functions of the cardiac skeleton?

Answer 12

1. physically separates the atria from the ventricles
2. electrically inactive and blocks the direct spread of electrical impulses from the atria to the ventricles
3. Provides support for the heart, providing a point of attachment for the valves leaflets and cardiac muscle

Question 13

What is coronary circulation?

Answer 13

Part of the systemic circulatory system that supplies blood to and provides drainage from the tissues of the heart

Question 14

Where do the coronary arteries originate?

Answer 14

Coronary arteries originate at aortic sinuses at base of ascending aorta

Supply blood to the heart

Question 15

What is the aortic sinus?

Answer 15

Dilation or “out-pocketing” of the ascending aorta; site where the left and right coronary arteries originate

Question 16

Where do the cardiac veins empty?

Answer 16

Coronary sinus

• collection of veins joined together to form a large vessel that collects blood from the myocardium of the heart

Question 17

What is systole?

Answer 17

Ventricular contraction

Question 18

What is diastole?

Answer 18

Ventricular relaxation

Question 19

Blood flow almost ceases when the heart is ______ and peaks while the heart is ______

Answer 19

Blood flow almost ceases when the heart is contracted (systole) and peaks while the heart is relaxed (diastole)

Question 20

What causes coronary artery disease?

Answer 20

Atherosclerosis of the coronary arteries.

atherosclerosis = condition where arteries become hardened and narrow due to plaque in the walls

Question 21

What is atherosclerotic plaque made of?

Answer 21

fat, cholesterol, calcium and other substances in the blood

Question 22

What is angina?

Answer 22

Chest pain or discomfort when blood flow to heart muscle is reduced

Question 23

What is myocardial infarction?

Answer 23

Heart attack

• atherosclerotic plaques can grow so large that they completely block arterial blood flow causing a heart attack
• heart muscle dies due to loss of blood supply

Question 24

Cardiac muscle cells _______ are joined by ________ which contain ______

Answer 24

Cardiac muscle cells myocytes are joined by intercalated discs which contain gap junctions and desmosomes

Question 25

What is a syncytium? Why is cardiac muscle called a syncytium?

Answer 25

Set of cells that act together. The cardiac muscle is called a syncytium as the myocytes are mechanically, chemically, and electrically connected and act as a single enormous muscle cell

Question 26

\_\_\_\_\_\_\_ allow excitation (AP's) to spread quickly from one myocyte to another by cell-to-cell contact

Answer 26

_Gap junctions_ allow excitation (AP's) to spread quickly from one myocyte to another by cell-to-cell contact

Question 27

What are the 2 functional syncytia of the cardiac muscle?

Answer 27

1. the left and right atria 2. Left and right ventricles

Question 28

What is autorhythmicity (automaticity)?

Answer 28

The heart contracts or beats rhythmically as a result of action potentials *that it generates itself*

Question 29

How are action potentials in the heart generated?

Answer 29

Without nervous or hormonal stimulation: Rhythmicity of the heart is **myogenic** in origin - it is muscular in origin

Question 30

What are the 2 types of specialized cardiac muscle cells (myocytes)?

Answer 30

Contractile cells Conducting cells

Question 31

do mechanical work of pumping, propel blood; do not initiate action potentials

Answer 31

Contractile cells

Question 32

Initiate and conduct AP's which are responsible for contraction of the contractile cells -myocytes which initiate and conduct AP's w/o Nervous or hormonal stimuli

Answer 32

Conducting cells (autorhythmic cells)

Question 33

The conducting cells have very few _______ and do not contribute to the heart's contraction and movement of blood

Answer 33

The conducting cells have very few _myofibrils (protein filaments needed for contraction)_ and do not contribute to the heart's contraction and movement of blood

Question 34

Most myocytes are: Conducting or Contractile?

Answer 34

Contractile (~99%)

Question 35

Conducting cells are in ______ contact with each other and the cardiac contractile cells through the \_\_\_\_\_

Answer 35

Conducting cells are in _electrical_ contact with each other and the cardiac contractile cells through the _gap junctions_

Question 36

The spread of action potentials through the ___ leads to contraction of the heart muscle

Answer 36

The spread of action potentials through the _myocardium_ leads to contraction of the heart muscle

Question 37

Where are conducting myocytes found? (6)

Answer 37

1. Sinoatrial node (SAN) 2. Internodal pathways 3. Atrioventricular node (AVN) 4. bundle of His (AV bundle) 5. left and right bundle branches 6. Purkinje fibres

Question 38

Where is the sinoatrial node located?

Answer 38

Wall of the right atrium

Question 39

Where is the Atrioventricular node (AVN) located?

Answer 39

Base of the right atrium

Question 40

The internodal pathways extend from the _____ to the _____ and also cross the ______ to the left atrium

Answer 40

The internodal pathways extend from the _sinoatrial node_ to the _atrioventricular node_ and also cross the _interatrial septum_ to the left atrium

Question 41

The Bundle of His passes through the \_\_\_\_\_

Answer 41

The Bundle of His passes through the _cardiac skeleton_

Question 42

Left and right bundle branches travel along the _______ septum

Answer 42

Left and right bundle branches travel along the _interventricular_ septum

Question 43

Left and right bundle branches make contact with **Purkinje fibres** which extend into the ______ of the \_\_\_\_\_

Answer 43

Left and right bundle branches make contact with **Purkinje fibres** which extend into the _myocardium_ of the _ventricles_

Question 44

The only electrical connection between the atria and the ventricles in a normal heart is the ______ and the \_\_\_\_\_. The _______ is non-conducting

Answer 44

The only electrical connection between the atria and the ventricles in a normal heart is the _Atrioventricular Node_ and the _Bundle of His_. The _Cardiac skeleton_ is non-conducting

Question 45

Conducting myocytes in the _______ generate AP's at the fastest rate (60-100 AP/min)

Answer 45

Conducting myocytes in the _Sinoatrial Node_ generate AP's at the fastest rate (60-100 AP/min)

Question 46

Which component of the conducting system is considered the "cardiac pacemaker"?

Answer 46

SA node - initiates AP that set the heart rate

Question 47

SA node generates AP \> ________ \> _______ of both the Left and right atria \> _____ and ______ \_\_\_\_\_ contract at the same time \> stimulus also passed by the _____ to the _____ \> wave of depolarization must pass through the ______ and the ____ to excite the ______ due to presence of the cardiac skeleton

Answer 47

SA node generates AP \> _internodal pathways_ \> _contractile cells_ of both the Left and right atria \> _left_ and _right_ _atria_ contract at the same time \> stimulus also passed by the _internodal pathways_ to the _AV node_ \> wave of depolarization must pass through the _AV node_ and the _bundle of his_ to excite the _ventricles_ due to presence of the cardiac skeleton

Question 48

Stimulus passes to the AV node through the _______ from the \_\_\_\_\_

Answer 48

Stimulus passes to the AV node through the _internodal pathways_ from the _SA node_

Question 49

What is AV nodal delay?

Answer 49

the propagation of AP's through the AVN is relatively slow: take ~100 milliseconds for the stimulus to pass through the AV Node to the Bundle of His * delay ensures that the atria depolarize and contract before the ventricles depolarize and contract

Question 50

What is wolff-parkinson-white syndrome?

Answer 50

In wolff-parkinson-white syndrome there is an extra connection in the heart called an *accessory* pathway

Question 51

What is an accessory pathway?

Answer 51

Abnormal piece of muscle that connects directly between the atria and ventricles * electrical signals bypass the AVN and move to ventricles faster than usual * Elect. impulses may also be transmitted from he ventricles back to the atria * disrupts the coordinated mvmt of electrical signals through the heart leading to abnormally face heartbeat called **tachycardia** and other **arrythmias**