Flashcards in Cardiovascular System (Textbook) Deck (104):
What does the heart rest on?
What is the pointed apex formed by?
The left ventricle
In what directions is the heart directed?
Anteriorly, inferiorly and to the left
What is the base of the heart opposite to?
What is the base of the heart formed by?
The atria of the heart (mostly the left atrium)
What are the two parts of the pericardium?
1) Fibrous pericardium
2) Serous pericardium
What is the superficial fibrous pericardium composed of?
Tough, inelastic, dense irregular connective tissue.
What are the functions of the fibrous pericardium?
Prevents over-stretching of the heart, provides protection, and anchors the heart in the mediastinum.
What is the serous pericardium?
A thinner, more delicate membrane that forms a double layer around the heart
Which layer of the serous pericardium is fused to the fibrous pericardium?
What are the three layers of the heart wall?
What are the two tissue layers of the epicardium?
The outermost is the visceral layer of pericardium and is a thin, transparent, outer layer of the heart wall composed of mesothelium. Beneath this is a variable layer of delicate firboelastic tissue and adipose tissue.
Where does the adipose tissue of the epicardium become thickest?
Over the ventricular surfaces, where it houses major coronary and cardiac vessels of the heart.
What does the epicardium contain to supply the myocardium?
Blood vessels, lymphatics and vessels.
What is the myocardium responsible for?
The pumping action of the heart.
What is the myocardium composed of?
Cardiac muscle tissue
How much of the heart wall does the myocardium make up?
What is the endocardium?
A thin layer of endothelium overlying a thin layer of connective tissue.
What are the functions of the endocardium?
Provides a smooth lining for the chambers of the heart and covers the valves of the heart.
What is the function of the auricle?
Slightly increases the capacity of an atrium so that it can hold a greater volume of blood.
What are the sulci of the heart?
A series of grooves on the surface of the heart that contain coronary blood vessels and a variable amount of fat.
What does each sulcus mark?
The external boundary between two chambers of the heart.
Where is the deep coronary sulcus situated?
Encircles most of the heart and marks the external boundary between the superior atria and inferior ventricles.
What is the anterior interventricular sulcus?
What does it continue on around to the posterior surface of the heart to become?
A shallow groove on the anterior surface that marks the external boundary between the right and left ventricles on the anterior aspect of the heart.
Posterior interventricular sulcus, which marks the external boundary between the ventricles on the posterior aspect of the heart.
What forms the right surface of the heart?
What are the three veins from which it receives blood from?
The right atrium
Superior vena cava, inferior vena cava, and coronary sinus
What is average thickness of the right atrium?
What is the difference between the anterior and posterior walls of the right atrium?
The inside of the posterior wall is smooth and the inside of the anterior wall is rough due tot he presence of muscular ridges called pectinate muscles, which also extend into the auricle.
What is found between the right and left atrium?
A thin partition called the interatrial septum.
Describe the prominent feature of the interatrial septum.
An oval depression called the fossa ovalis, the remnant of the foramen ovale, an opening in the interatrial septum of the fetal heart that normally closes soon after birth.
What is another name for the tricuspid valve?
Right atrioventricular valve.
What are the valves of the heart composed of?
Dense connective tissue covered by endocardium
What is the average thickness of the right ventricle?
What forms most of the anterior surface of the heart?
Describe the inside of the ventricles
Contains a series of ridges formed by raised bundles of cardiac muscle fibers called trabeculae carneae.
What is the function of trabeculae carneae?
Convey part of the conduction system of the heart.
How are the cusps of the tricuspid/bicuspid valve attached to the wall of the heart?
The cusps of the valve are connected to tendonlike cords, the chordae tendineae, which in turn are connected to cone-shaped trabeculae carneae called papillary muscles.
How is the LV and RV separated internally?
What is the wall thickness of the left atrium the same as?
The wall thickness of the right atrium
What forms most of the base of the heart?
What does the left atrium receive blood from?
The lungs through four pulmonary veins.
What is different about the internal wall of the left atrium? Why is this?
It has smooth posterior and anterior walls. Pectinate muscles are confined to the auricle of the left auricle.
What is another name for the biscupid (mitral) valve?
Left atrioventricular valve
Which is the thickest chamber of the heart? What is its average wall thickness?
What are the two components of the aorta?
Arch of the aorta and descending aorta
What is the ductus arteriosus?
A temporary blood vessel present during fetal life, which shunts blood from the pulmonary trunk into the aorta. Hence only a small amount of blood enters the nonfunctioning fetal lungs.
What does a closed ductus arteriosus form?
Shortly after birth, it leaves a remnant known as the ligamentum arteriosum, which connects the arch of the aorta and pulmonary trunk.
Why are ventricles walls thicker?
They pump blood at higher pressure for greater distances.
Why are the is the workload of the right ventricle smaller than the left ventricle?
Although the LV and RV eject equal volumes of blood, the right side has smaller workload because it pumps blood a short distance to the lungs at lower pressure and the resistance to blood flow is small. Thus it works less hard than the LV to maintain the same rate of blood flow.
What is the difference between the lumen shape of the LV and RV?
LV: roughly circular
Apart from the cardiac muscle tissue, what does the heart wall also contain? What does this form?
Dense connective tissue that forms the fibrous skeleton of the heart.
What does the fibrous skeleton consist of?
Four dense connective tissue rings that surround the valves of the heart, fuse with one another and merge with the interventricular septum.
What are the functions of the fibrous skeleton?
Forms a structural foundation for the heart valves, the fibrous skeleton prevents overstretching of the valves as blood passes through them.
Also serves as a point of insertion for bundles of cardiac muscle fibers and act as an electrical insulator between the atria and ventricles.
When an AV valve is open, what does it look like?
The rounded ends of the cusps project into the ventricle.
What might happen if the AV valves or chordae tendineae are damaged?
Blood may regurgitate into the atria when the ventricles contract.
How are the semilunar valves attached to the arterial wall?
By its convex outer margin.
What is a consequence of the lack of valves between the right atrium and vena cava and the left atrium and pulmonary veins?
As the atria contract, a small amount of blood flows backward from the atria into these vessels.
What is backflow in the veins of the heart minimised?
As the atrial muscle contracts, it compresses and nearly collapses the weak walls of the venous entry points.
How are the pulmonary and systemic circuit arranged?
In series: the output of one is the input of the other.
What are the two coronary arteries?
The left and right coronary arteries branching from the ascending aorta.
Where is the left coronary artery situated ?
Passes inferior to the left auricle and divides into the anterior interventricular and circumflex branches.
What is another name for the anterior interventricular branch of the coronary arteries?
Left anterior descending artery
What does the anterior interventricular branch of the coronary arteries supply blood to? Where is it situated?
Supplies oxygenated blood to the walls of both ventricles. In the anterior interventricular sulcus.
Where does the circumflex branch of the coronary arteries lie?
In the coronary sulcus.
Distributes oxygenated blood to the walls of the left ventricle and left atrium.
What is the purpose of the right coronary artery?
Supplies small branches to the right atrium.
Where is the right coronary artery situated?
Continues inferior to the right auricle.
What does the right coronary artery divide into?
Posterior interventricular and marginal branches.
What does the posterior interventricular branch supply? What does it follow?
Supplies the walls of the two ventricles.
It follows the posterior interventricular sulcus.
Where is the marginal branch situated?
It runs along the right margin of the heart and transports oxygenated blood to the wall of the right ventricle.
What are anastomoses? Where are they found? What do they provide?
Connections between arteries. Where two or more arteries supply, the same region, they are usually connected. Provide alternate routes, called collateral circulation.
What do anastomoses provide?
Detours for arterial blood if a main route becomes obstructed. Thus the heart can receive sufficient oxygen even it one of its coronary arteries is partially blocked.
How does the blood return from the coronary arteries back to the heart?
Via coronary veins
What does most of the deoxygenated blood from the myocardium drain into?
A large vascular sinus in the coronary sulcus on the posterior surface of the heart called the coronary sinus.
What is a vascular sinus?
A thin-walled vein that has no smooth muscle to alter its diameter.
What does the deoxygenated blood in the coronary sinus empty into?
What are the principal tributaries carrying blood into the coronary sinus?
Great cardiac vein
Middle cardiac vein
Small cardiac vein
Anterior cardiac veins
Describe the how cardiac muscle is different from skeletal muscle.
Cardiac muscle fibers are shorter in length and less circular in transverse section. They also exhibit branching.
How are the ends of cardiac muscle fibers connected?
By irregular transverse thickenings of the sarcolemma called intercalated discs. These contain desmosomes, which hold the fibers together and gap junctions, which allow muscle action potentials to conduct from one fiber to its neighbour.
What does one cardiac cycle consist of?
All of the events associated with one heartbeat. Consists of systole and diastole of the atria plus systole and diastole of the ventricles.
How long does atrial systole last?
About 0.1 seconds
What causes the P wave in an electrocardiogram?
Depolarisation of the SA node, which causes atrial depolarisation.
What does the end of atrial systole coincide with?
End of ventricular diastole.
What is meant by end diastolic volume?
The volume that ventricles have at the end of its relaxation period.
What does the QRS complex in the ECG mark?
The onset of ventricular depolarisation.
How long does ventricular systole last?
About 0.3 seconds
How long does isovolumetric contraction last?
What is happening to the cardiac muscle fibres during isovolumetric contraction?
They are contracting and exerting force but not yet shortening.
What is the end-systolic volume?
The volume of blood remaining in each ventricle at the end of systole.
What is the same about the blood ejected from the left and right ventricle?
Both expel the same volume of blood per beat.
What is an equation relating SV, EDV and ESV?
SV = EDV - ESV
What does the T wave mark?
The onset of ventricular repolarisation
As the heart beats faster, what period is affected most?
Relaxation period becomes shorter and shorter, whereas the durations of atrial and ventricular systole shorten only slightly.
What causes the dicrotic wave on the aortic pressure curve?
Rebound of blood off the closed cusps of the aortic valve
List the five main types of blood vessels.
How many layers are blood vessels made up of? What differentiates these?
3 tunics of different tissues
Describe the three tunics of blood vessels.
An epithelial inner lining
A middle layer consisting of smooth muscle and elastic connective tissue
A connective tissue outer covering
What are the names of the three structural layers of a generalised blood vessel from innermost to outermost?
Tunica interna (intima), tunica media, tunica externa (adventitia)
What is the innermost layer of the tunica intima called? What is the second component of the tunica intima?
What is the endothelium continuous with?
The endocardial lining of the heart
What are the 5 functions of the basement membrane?
- A physical support base for the epithelial layer.
- Its framework of collagen fibres give it significant tensile strength, yet its properties also provide resilience for stretching and recoiling.
- It anchors the endothelium to the underlying connective tissue
- Regulates molecular movement
- Guides cell movements during tissue repair of blood vessel walls.
What is the outermost part of the tunica interna? Describe this layer.
Internal elastic lamina: a thin sheet of elastic fibers with a variable number of window-like openings that facilitate diffusion of materials through the tunica interna to the tunica media.
Describe the tunica media layer. What is the primary role of smooth muscle cells?
A muscular and connective tissue layer that displays the greatest variation. Relatively thick layer in most muscles, comprising of mainly smooth muscle cells and substantial amount of elastic fibers.
Primary role of the smooth muscle cells, which extend circularly around the lumen, is to regulate the diameter of the lumen.
How does an increase in sympathetic stimulation effect the smooth muscle of blood vessels? What causes smooth muscle fibers to relax?
I: Causes contraction, squeezing the vessel wall, and narrowing the lumen. Vasoconstriction
They relax when sympathetic stimulation decreases, or in the presence of certain chemicals such as nitric oxide, H+ and lactic acid), or in response to blood pressure.
When a small artery or arteriole is damaged, what is this called? What happens to the smooth muscle? What is another function?
Smooth muscle contracts to help limit loss of blood through the injured vessel.
Smooth muscle cells also help produce the elastic fibers within the tunica media that allow the vessels to stretch and recoil under the applied pressure of the blood.