Cardiovascular system

Question 1

What is the pericardium?

Answer 1

A membrane that surrounds and protects the blood.

Question 2

What are the two components of the pericardium?

Answer 2

1) The fibrous Pericardium

2) The serous pericardium

Question 3

What is the fibrous pericardium composed of?

Answer 3

Made out of tough, elastic dense irregular connective tissue.

Question 4

Where is the fibrous pericardium placed?

Answer 4

It’s attached to the diaphragm - open end is fused to connective tissue of the blood vessel entering and leaving the heart.

Question 5

What is the function of the fibrous pericardium?

Answer 5

1) Prevents it from over-stretching
2) Protection
3) Anchors the heart in the mediastinum

Question 6

Describe the structure of the serous pericardium.

Answer 6

• More delicate and thinner membrane that surrounds the heart.

1) The outer layer= parietal layer
2) The inner layer = visceral/epicardium layer

Question 7

Between the parietal and visceral layer of the serous pericardium, what does it secrete?

Answer 7

Pericardial fluid. This reduces friction between the two layers.

Question 8

What is the space between the parietal and visceral layer called?

Answer 8

Pericardial cavity.

Question 9

What do sulci generalyl contain?

Answer 9

Fat and coronary blood vessels

Question 10

What boundaries does the coronary sulcus mark?

Answer 10

External boundary between the superior atria and inferior ventricle.

Question 11

What boundaries does the anterior interventricular sulcus mark?

Answer 11

Boundary between the right and left ventricles on the anterior side.

Question 12

What boundaries does the posterior interventricular sulcus mark?

Answer 12

boundary between the right and left ventricles on the posterior side.

Question 13

What three veins does the atria receive blood from?

Answer 13

Superior vena cava, inferior cava, coronary sinus.

Question 14

Why is the anterior wall of the right atria rough?

Answer 14

Due to the pectinate muscles.

Question 15

What is between the left and right atrium?

Answer 15

The interatrial septum.

Question 16

What is a particular feature of the interatrial septum?

Answer 16

The FOSSA OVALIS - the remnant of the formane ovale, an opening in the interatrial septum of the fetal heart that normally closes soon after birth.

Question 17

What is the valve of the right ventricle called?

Answer 17

The triscupid valve.

Question 18

What muscles are present in the right ventricle?

Answer 18

The trabeculae carnae.

Question 19

How are the triscupid valves conencted to the heart wall?

Answer 19

Via the chordinae tendineae to the pupillary muscles.

Question 20

What are the ventricles separated by?

Answer 20

The interventricular septum.

Question 21

Describe the structure of the left atria?

Answer 21

posterior and anterior walls are smooth.

the pectinate muscles lie in the auricle.

Question 22

What valve does the blood flow from the left atria to the left ventricle?

Answer 22

The mitral/biscupid valve.

Question 23

Describe the characteristics of the left atrial muscle?

Answer 23

Has both pectinate and trabeculae carneae.

Question 24

Discuss the blood flow from the left ventricle

Answer 24

• Some blood flows through the coronary arteries

- The remaining blood through the descending aorta and the arch.

Question 25

Of the ventricle, what is a feature of the heart that is remnant of the fetal heart?

Answer 25

The ductus arteriosus shunts blood from the pulmonary trunk into the aorta. This leaves the remnant, ligementum arteriosum.

Question 26

Outline the operation of the atrioventricular valves when they are open.

Answer 26

[PARACHUTES] 1) The rounded ends of cusps project onto ventricle. 2) Ventricle and papillary muscles are relaxed and the chordae tendineae slack. 3) Blood moves from high pressure in atria to low pressure in ventricle.

Question 27

Outline the operation of the atrioventricular valves when they are closing.

Answer 27

[PARACHUTE] 1) The ventricles contract, the pressure of the blood drives the cusps upwards. Their edges meet and close the opening. 2) The papillary muscles contract which tightens the chordae tendineae.

Question 28

Outline the operation of semi-lunar valves.

Answer 28

They are made of 3 crescent moon haped cusps. Open: When the pressure in the ventricles is greater than in the arteries. Closed: Back flowing blood fills the valve cusps and they close.

Question 29

Outline the landmarks of the conduction system in "chronological" order

Answer 29

1) Sinoatrial node 2) Atrioventricular node 3) Bundle of His 4) Right and left bundle branches. 5) Purkinje fibres

Question 30

Describe the conduction system in regards to the sinoatrial node.

Answer 30

- Located in the right atrium - Spontaneously depolarises triggering action potential which are carried by GAP JUNCTIONS in the INTERCALATED DISCS of the muscle fibres. - Causes atria to contract (atrial systole)

Question 31

Describe the conduction system when the excitation reaches the atrioventricular node.

Answer 31

- Reaches it ~ 0.03 secs. - Located in the interatrial septum. - Conduction slows here as there are fewer fibres and less gap junctions. * **This gives a 0.1 sec DELAY enough time for the atria to contract to fill the ventricles before they contract.

Question 32

Why is the bundle of His important?

Answer 32

This is the only site where action potentials can conduct between ventricles and atria.

Question 33

Describe the action potentials when they reach the left/right bundle branches.

Answer 33

- They extend through the interventricular septum towards the apex of the heart. - Purkinje fibres then rapidly conduct the action potential upward causing the ventricle to contract.

Question 34

Where are elastic arteries most common?

Answer 34

As very large arteries near the heart. They have elastic walls.

Question 35

Outline the actions of the elastic artery during systole.

Answer 35

They expand to store the bolus of blood leaving the ventricle.

Question 36

Outline the actions of the elastic artery during diastole.

Answer 36

They push the blood along by elastic recoil. | i.e. they smooth the pulsatile flow of blood leaving the ventricles.

Question 37

Describe the structure of elastic arteries.

Answer 37

They have many thin sheets of elastin in the middle tunic.

Question 38

Describe the structure of the muscular artery.

Answer 38

Has many layers of smooth muscle wrapped around the vessel in the middle tunic.

Question 39

What is the function of the muscular artery?

Answer 39

1) Distributes blood around the body at high pressure. 2) Its smooth muscle adjusts the rate of blood flow which varies the diameter of the vessel e. g. the flow is proportional to the fourth power of the radius.