Lecture 5 - Cardiovascular system - anatomy of the heart part II

Question 1

Semilunar valve

Answer 1

Separates ventricle from outflow artery

Function - prevents blood returning to ventricles during filling (diastole)

Right side - Pulmonary (semilunar) valve, 3 cusps
Left side - Aortic (semilunar) valve, 3 cusps

Pushed open as blood flows out of the heart. Close as blood starts to back flow. (close when pressure in the ventricles starts to fall down and the pressurised pipe we have pushed it into will tend to push the blood backwards towards the less pressured ventricle and this backflow causes the leaflets to close and seal and stop the blood from returning.)

Question 2

Examples of semilunar valves

Answer 2

Aortic valve = three cusps

Pulmonary valve = three cusps

Question 3

Atrioventricular valves

Answer 3

Separates the atrium and the ventricle

Function - prevents blood returning to atria during ventricular contraction

Right side -tricuspid valve (3 leaflets)
Left side - bicuspid (mitral) valve (2 leaflets)

Question 4

Right and left atrioventricular valves

Answer 4

Right = tricuspid valve
Left = bicuspid valve

Question 5

Purpose of valves

Answer 5

Want unidirectional flow therefore valves prevent back flow.

Question 6

Diastole in terms of atrioventricular valves

Answer 6

This is the filling phase of the heart, for the heart to push out blood to the periphery it has to fill itself first. The right and left atrioventricular valve is open and the right and left semilunar valve is closed (because you don’t want the blood just pushed through the outflow arteries to come back into the pump again)

Question 7

Which valves are bicuspid?

Answer 7

Left AV valve

Question 8

Which valves are tricuspid?

Answer 8

Right AV valve
Aortic valve
Pulmonary valve

Question 9

Chordae tendineae and papillary muscles in systole

Answer 9

Chordae tendineae holds the free edge of the leaflets to stop the free edges prolapsing up into the atrial chambers. The papillary muscles are attached to these cords. Papillary muscle contracts early in ventricular systole and pre-tenses these chord tendineae so that when the pressure starts to build ip instead of the valve leaflet slamming shut, this system prevents this.

Question 10

Heart valves in diastole

Answer 10

• fluid is moving from the atria to the ventricles

- AV valves are open, SL valves are closed

Question 11

Heart valves in systole

Answer 11

pressure in the ventricles has reached a point where blood is ejected from the ventricles through the SL valves
- SV valves are open and AV valves are closed

Question 12

Chordae tendineae

Answer 12

a group of tough, tendinous strands in the heart.

play a vital role in holding the atrioventricular valves in place while the heart is pumping blood

Question 13

Papillary muscles

Answer 13

The papillary muscles are muscles located in the ventricles of the heart. They attach to the cusps of the atrioventricular valves (also known as the mitral and tricuspid valves) via the chordae tendineae and contract to prevent inversion or prolapse of these valves on systole (or ventricular contraction).

Question 14

How you doin’?

Answer 14

yeah nah good

Question 15

The cardiac circulation by DR AMY

Answer 15

Oxygenated blood goes out right coronary artery and supplies the right ventricles myocardium and deoxygenated blood is drained by the small cardiac vein into the coronary sinus and then it goes back to the left atrium

Oxygenated blood goes out left coronary artery and into the interventricular artery which supplies the anterior of the left ventricle and also directs blood from the left coronary artery and goes into the circumflex artery which supplies the lateral and posterior of the left ventricle. And then the blood is drained by the great cardiac vein and into the coronary sinus and then into the right artrium

Question 16

Right coronary artery

Answer 16

one of two main coronary vessels that supply the myocardium (the other being the left coronary artery)

Orginate of the aorta, run in the groove in the epicardium between the right atrium and the right ventricle

Supplies the right ventricle

Question 17

Left coronary artery

Answer 17

one of two coronary vessels (heart vessels) that supply blood to the heart muscle

Runs under the little flap of left atrium but runs to a point where it branches to form the anterior inter ventricular artery

Question 18

Circumflex artery

Answer 18

Branch of the left coronary artery

Runs around to the left lateral margin of the heart

Supplies most of the left atrium

Question 19

Anterior inter ventricular artery

Answer 19

Branch of the left coronary artery

On the anterior surface of the heart and it is running over the inter ventricular surface

Question 20

Coronary sinus

Answer 20

Last part of the venous drainage, the opening will be opening into the right atrium and taking the deoxygenated blood that has been involved with supplying the heart muscle itself, straight back to the right side of the heart so that it can be reoxygenated

Posterior surface of the heart

Question 21

Great cardiac vein

Answer 21

On the left side

More blood going to the left so bigger network of veins draining back, blood runs around in the left coronary groove and to the posterior of the heart and then into a structure called the coronary sinus

Question 22

Small cardiac vein

Answer 22

On the right side and it is draining most of the territories that are spelled by the right coronary artery

Question 23

Cardiac muscle

Answer 23

Features of both smooth and skeletal muscle as well as cardiac muscle specific specialisations
Only found in the heart
Function - beating of the heart
Also called myocardium

Question 24

Cardiac muscle cell structure

Answer 24

Striated - like skeletal muscle (smooth muscle is a non-striated muscle)

Short, branched cells - stubby in shape, not like skeletal muscle cells which are very long and linear in their array

One (or occasionally 2) nuclei per cell - smooth muscle tends to be mono nucleated (cardiac in terms of nuclei looks more like smooth muscle), skeletal muscle cells are different because they are multinucleate

Central (oval shaped), nucleus - centrally located, mono nucleated (sometimes binucleated) cells

Cytoplasmic organelles packed at the poles of nucleus - so that the bulk of the cytoplasm can be filled with contractile elements

Interconnected with neighbouring cells via intercalated disks (ICDs) - specialised feature of cardiac muscle that you won’t see in smooth or skeletal muscle

Question 25

Intercalated discs

Answer 25

Cardiac muscle consists of individual heart muscle cells (cardiomyocytes) connected by intercalated discs to work as a single functional organ. They play vital roles in bonding cardiac muscle cells together and in transmitting signals between cells.

Question 26

Skeletal muscle fibres vs cardiac muscle fibres

Answer 26

Cardiac muscle fibres are usually mono nucleated whereas skeletal is usually multinucleate
Skeletal muscle fibres are long and linear in array whereas cardiac is short and branched cells
No ICDs in skeletal muscle fibres
Skeletal have nuclei in the periphery compared to cardiac which has it centrally
Mitochondria is 20% of the volume of cell for cardiac whereas in skeletal it is about 2%
Irregular branched sarcomeres in cardiac, skeletal they are lined up perfectly and are parallel to one another

Question 27

Cardiomyocytes

Answer 27

Cells that make up the heart muscle/cardiac muscle and are primarily involved in the contractile function of the heart that enables the pumping of blood around the body.

Question 28

What 3 intercellular junctions make up intercalated disks?

Answer 28

Desmosomes, gap junctions and adhesion belts

Question 29

Adhesion belts in ICDs

Answer 29

Linking actin to actin
In the vertical portion (perpendicular to the contractile apparatus)
Area where actin in one cell gets linked to the actin in another cell via some transmemiranous proteins - a ‘tug’ in one cell can be transferred to the other cell (physical propagation of contraction -from one cell to another) which can generate lots of force

Question 30

Desmosomes in ICDs

Answer 30

Linking cytokeratin with cytokeratin
Link cytoskeletons of neighbouring cells so that when the adhesion belt tension goes up the cells are all buttoned together by desmosomes (holds it all together)
Vertical portion

Question 31

Gap junctions in ICDs

Answer 31

Involved in electrochemical communication
In the horizontal portion - parallel to the contractile apparatus
Far more delicate intercellular junction hence in horizontal portion, communication junction (stimulates contraction electrochemically)

Gap junctions contain pores with low resistance to ionic current. Gap junctions help myocytes to work as a functional syncytium. Gap junctions allow current to flow between electrical cells. Gap junctions allow current to flow between contractile cells.

Question 32

Conduction system of the heart

Answer 32

Its actions greatly increase the efficiency of the heart (ICDs) - means that we pump down from the atrium to the ventricles and go up from the ventricles to the outflow arteries and we have to coordinate the contraction up and down in order to have a very efficient conduction system
This system is responsible for the coordination of heart contraction and of AV valve action - causes pretension in the chorine tendinae through papillary muscle, the papillary muscles are the first part of the ventricular wall to contract and the conduction system makes sure that this happens, ensures that the AV valves do not slam shut
Autonomic nerves alter the rate of conduction impulse generation - nervous input influences this process, if it is sympathetic then it increases the rate of firing, parasympathetic decreases the rate of firing

Question 33

Purkinje cells

Answer 33

central nucleus

• mitochondrial, glycogen
• Lots of gap junctions
• some intercalated disks, demosomes & adhesion belts

‘bloated’ non-contractile cardiac muscle involved with electrical conduction

Question 34

Vessels of the cardiac circulation

Answer 34

Aorta to coronary arteries, myocardial capillaries, cardiac veins, coronary sinus, right atrium - begins in the aorta which is the first part of the systemic circulation, carrying oxygenated blood via coronary arteries to the myocardial capillaries where exchange occurs and then we drain that via cardiac veins round to the posterior of the heart to the coronary sinus which then returns the now deoxygenated blood to the right side of the heart for deoxygenation

Question 35

Thorax

Answer 35

The thorax contains the lungs, heart and other structures, some of which pass inferiorly into the abdominal cavity. The ribs and vertebrae provide horizontal landmarks

Question 36

Thoracic cavity

Answer 36

The thoracic wall and diaphragm enclose the thoracic cavity. It includes two pleural cavities, containing the lungs and the mediastinum, which lies in between and is occupied by the heart and other structures. Layers of pleura separate the three divisions go the thoracic cavity. The pleura seperate the three divisions of the thoracic cavity. The pleura are serous membranes that surround a lung and line the thoracic cavity, just as peritoneum is a serous membrane that covers the abdominal viscera and lines the abdominal cavity. Serous membranes secrete fluid that lubricates internal structures. Parietal pleura lines the thoracic cavity whilst visceral pleura covers the lungs.

Question 37

Coronary sinus and where is it located?

Answer 37

Another opening that brings deoxygenated blood to the right atrium

Question 38

Trabeculae carnae

Answer 38

Muscular beamlike structures on the inner surface of the myocardium forming ridges or bridges

ounded or irregular muscular columns which project from the inner surface of the right and left ventricle of the heart.

Question 39

Which structure delineates the change between the thoracic and abdominal aorta?

Answer 39

Descending thoracic aorta

Question 40

Which artery branches to become the right subclavian artery and the right common carotid artery?

Answer 40

Brachiocephalic trunk

Question 41

Celiac trunk

Answer 41

Supplies the spleen, stomach and liver

Question 42

Left and right subclavian arteries

Answer 42

The left subclavian artery is the fifth branch of the aorta and the third branch from the arch of the aorta. The right subclavian artery arises from the brachiocephalic artery and its branches.

Question 43

Carotid arteries

Answer 43

The carotid arteries are major blood vessels in the neck that supply blood to the brain, neck, and face. There are two carotid arteries, one on the right and one on the left.

Question 44

Why does blood exiting the gastrointestinal tract travel through the hepatic portal vein to the liver before entering the inferior vena cava?

Answer 44

For detoxification to avoid the blood carrying any outside material from the GI tract into the heart where it can circulate the whole body

Question 45

Are superficial veins precisely the same in different people?

Answer 45

Significant variation in distribution but same journey

Question 46

Which blood vessel has the thickest tunica media?

Answer 46

Muscular artery

Question 47

Which blood vessel has the thickest tunica adventitia?

Answer 47

Large vein

Question 48

Why is it important for veins to have a much higher compliance than arteries?

Answer 48

Veins are able to adapt to larger volumes of blood by adjusting structure therefore high compliance as they bring back the blood from the body to the heart. Arteries have low compliance due to high pressure

Question 49

Coronary arteries opening

Answer 49

The openings to the coronary arteries sit next to the aortic semilunar valve and these arteries carry oxygenated blood to the heart muscle