Lecture 5 - Cardiovascular system - anatomy of the heart part II Flashcards
Semilunar valve
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.)
Examples of semilunar valves
Aortic valve = three cusps
Pulmonary valve = three cusps
Atrioventricular valves
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)
Right and left atrioventricular valves
Right = tricuspid valve Left = bicuspid valve
Purpose of valves
Want unidirectional flow therefore valves prevent back flow.
Diastole in terms of atrioventricular valves
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)
Which valves are bicuspid?
Left AV valve
Which valves are tricuspid?
Right AV valve
Aortic valve
Pulmonary valve
Chordae tendineae and papillary muscles in systole
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.
Heart valves in diastole
- fluid is moving from the atria to the ventricles
- AV valves are open, SL valves are closed
Heart valves in systole
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
Chordae tendineae
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
Papillary muscles
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).
How you doin’?
yeah nah good
The cardiac circulation by DR AMY
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
Right coronary artery
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
Left coronary artery
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
Circumflex artery
Branch of the left coronary artery
Runs around to the left lateral margin of the heart
Supplies most of the left atrium
Anterior inter ventricular artery
Branch of the left coronary artery
On the anterior surface of the heart and it is running over the inter ventricular surface
Coronary sinus
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
Great cardiac vein
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
Small cardiac vein
On the right side and it is draining most of the territories that are spelled by the right coronary artery
Cardiac muscle
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
Cardiac muscle cell structure
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
Intercalated discs
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.
Skeletal muscle fibres vs cardiac muscle fibres
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
Cardiomyocytes
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.
What 3 intercellular junctions make up intercalated disks?
Desmosomes, gap junctions and adhesion belts
Adhesion belts in ICDs
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
Desmosomes in ICDs
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
Gap junctions in ICDs
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.
Conduction system of the heart
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
Purkinje cells
central nucleus
- mitochondrial, glycogen
- Lots of gap junctions
- some intercalated disks, demosomes & adhesion belts
‘bloated’ non-contractile cardiac muscle involved with electrical conduction
Vessels of the cardiac circulation
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
Thorax
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
Thoracic cavity
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.
Coronary sinus and where is it located?
Another opening that brings deoxygenated blood to the right atrium
Trabeculae carnae
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.
Which structure delineates the change between the thoracic and abdominal aorta?
Descending thoracic aorta
Which artery branches to become the right subclavian artery and the right common carotid artery?
Brachiocephalic trunk
Celiac trunk
Supplies the spleen, stomach and liver
Left and right subclavian arteries
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.
Carotid arteries
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.
Why does blood exiting the gastrointestinal tract travel through the hepatic portal vein to the liver before entering the inferior vena cava?
For detoxification to avoid the blood carrying any outside material from the GI tract into the heart where it can circulate the whole body
Are superficial veins precisely the same in different people?
Significant variation in distribution but same journey
Which blood vessel has the thickest tunica media?
Muscular artery
Which blood vessel has the thickest tunica adventitia?
Large vein
Why is it important for veins to have a much higher compliance than arteries?
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
Coronary arteries opening
The openings to the coronary arteries sit next to the aortic semilunar valve and these arteries carry oxygenated blood to the heart muscle
