CV system Flashcards
What is the anatomical position of the mediastinum?
Extends from the superior thoracic aperture to the diaphragm and from the sternum and costal cartilages to the bodies of the thoracic vertebrae
What does the mediastinum consist of?
Hollow visceral structures joined by loose connective tissue
What does the superior mediastinum contain?
The roots of the great vessels and the trachea
What is the anatomical position of the superior mediastinum
Extends inferiorly from the superior thoracic aperture to the horizontal plane which includes the sternal angle and passes approximately through the junction of T4 and 5
Which section of the mediastinum contains the heart?
The middle mediastinum
What is the pericardium?
A fibrous sac that encloses the heart and pericardial cavity
What does the outer fibrous pericardium do?
Protects the heart from damage caused by overfilling
What are the two deep layers of the serous pericardium?
The parietal and visceral layer
What are the parietal and visceral layers also known as?
Epicardium
What do the parietal and visceral layers do?
Enclose the fluid filled pericardial cavity which allows the heart to beat in an almost frictionless environment
Where does blood leave the heart from when travelling to the lungs?
The right ventricle
What vessels does the heart travel to the lungs by?
Right and left pulmonary arteries via pulmonary trunk
What vessels takes blood from the lungs to the left atrium of the heart?
Pulmonary veins
Where does oxygen rich blood leave the heart from?
The left ventricle
Where does de-oxygenated blood return to the heart to and via which vessel?
Right atrium - inferior/superior vena cava
What is contraction of the ventricles known as?
Systole
What is relocation of the ventricles known as?
Diastole
What is the heart formed from?
Specialised cardiac muscle known as myocardium
What are the layers of the heart (from superficial to deep)?
Epicardium, myocardium, endocardium
What is epicardium?
Connective tissue
What is myocardium?
Cardiac muscle
What is endocardium?
epithelium and connective tissue.
Lines heart and its valves
Continuous with endothelial lining of blood vessels
How do the walls of the ventricles compare to the atria?
They are thicker and muscular
Which ventricle is particularly muscular and why?
The left as it is required to pump blood around the systemic circulation
Describe ventricular contraction
Progresses in an upward spiral from the apex towards the vessels leading out of the heart
What is the atria separated by?
Interatrial septum
What are the ventricles separated by?
Interventrical septum
What are the four valves of the heart?
Tricuspid valve, mitral valve, pulmonary valve, aortic valve
How many cusps does the tricuspid valve have and where is it found?
3, between the right atria and right ventricle
How many cusps does the mitral valve have and where is it found?
2, between the left atria and left ventricle
How many cusps does the pulmonary valve have and where is it found?
3, between the right ventricle and the pulmonary trunk
How many cusps does the aortic valve have and where is it found?
3, between the left ventricle and aorta
Which valves make up the atriventricular valves?
Tricuspid and Mitral
What are the shape of the atrioventricular cusps?
Leaf shaped
Which valves make up the semilunar valves?
Pulmonary and Aortic
What are the spaces behind the aortic valves known as?
Aortic Sinuses
What structures ensure proper closure of the atrioventricular valves and prevent inversion.
Papillary muscles and chordae tendons
What are the three structures leaving the top of the aorta from left to right?
Brachiocephalic Trunk, Left common carotid artery, Left subclavian artery
Which valves are open /closed during systole?
AV closed, SL open
Which valves are open/closed during diastole?
AV open, SL closed
What are SL valves shaped like?
Pockets
What does the first heart sound (lub) correspond to?
Closing of AV valves
What does the second heart sound (dub) correspond to?
Closing of SL valves
What is listening to the sounds of the heart with a stethoscope called?
Auscultation
What is the right border formed from?
Right atrium and extends from superior to inferior vena cava
What is the inferior border formed by?
Mostly by right ventricle with small contribution from left ventricle
What is the superior border formed by?
Both atria. The aorta and pulmonary trunk arise from this border and the superior vena cava enters the heart at the right side of this border
What is the left border formed by?
Mostly formed from the left ventricle and a small portion from the left atrium.
What is the anterior (sternocostal) border related to?
Formed mostly from right ventricle and related anteriorly to the sternum and ribs
Describe the inferior (diaphragmatic) surface
Formed mostly by the left and partly the right ventricle. Related inferiorly to the centre of the diaphram
Where is the base of the heart?
On the posterior aspect, facing towards T6-9
Where is the apex of the heart?
Posterior to the 5th intercostal space in the midclavicular line and is directed antero-inferiorly and to the left
What are the three branches of the aorta?
Brachiocephalic trunk, Left common carotid artery, left subclavian artery
What are the two branches of the brachiocephalic trunk?
Right subclavian artery, right common carotid artery
What does the right subclavian artery supply?
right arm plus shoulder and thoracic wall
What does the right common carotid artery supply?
The head and neck
Where do the common carotid arteries arise from and where do the divide?
From the arch of the aorta and divide at C3
What does the internal carotid artery supply?
The brain
What does the external carotid artery supply?
Neck face and scalp
Where do the coronary arteries that supply the heart rise?
Immediately superior to the cusps of the aortic valve, from the aortic sinuses
What are the three aortic sinuses?
there are left and right sinuses from which corresponding arteries arise and a posterior sinus (no coronary arteries arise from here)
Where does the coronary circulation drain?
In to the right atrium via a series of cardiac veins and the coronary sinus
What supports the cardiac muscle?
The fibrous skeleton
What is the fibrous skeleton made from?
Dense collagen
What does the skeleton prevent?
Valves from collapsing or distending. Provides a base of attachments for leaflets and cusps of the valves
What is the skeletons most important function?
Forms an electrical barrier between the atria and ventricles
What does this barrier do?
Prevents the atria and ventricles contracting together
What does the collagen in the skeleton form?
Four fibrous rings that surround the valves openings and two fibrous trigones which lie between the rings
What type of muscle is cardiac muscle?
Striated
What does contraction of cardiac muscle rely on?
The sliding filament mechanism between thick and thin filaments of sarcomeres
What holds the cardiac muscle cells firmly together?
Intercalated discs by the action of desmosomes
What do intercalated discs also allow?
An electrical connection allowing the electrical impulse to pass through gap junctions
What are cardiac cells physically divided by?
The sarcolemma
What are desmosomes?
Tight junctions between adjacent disks.
What is the dominant pace maker in the hear?
The sinoatrial node
Where is the SA node located?
In the posterior wall of the right atrium
How is the rythym of the heart modified?
Autonomic input (symp increases para decreases)
What does the AV node act as?
A gateway to the ventricles from the atria for the electrical impulse
What is the delay that the AV node induces?
0.1 seconds
Why is this delay from the AV node important?
makes sure the atria contract before the ventricles
Where does the electrical impulse continue to after the AV node?
The AV bundle through the insulating ring of the fibrous skeleton down the ventricular septum where it bifurcates in to left and right bundle branches
What do the bundles comprise of?
Narrow, slow conducting fibres
Where do the bundles terminate?
At an extensive network of fibres called the pujinke fibres
Where are purjinke fibres found?
In the subendocardium
What are the three layers of blood vessels?
Tunica intima, tunica media, tunica adventitia
Describe the tunica intima
Inner most layer, a single sheet of endothelial cells resting on a thin layer of connective tissue which is mechanically weak. It is a barrier to plasma proteins and secreted vasoactive products
Describe the tunica media
(middle layer) consists of a layer of smooth muscle in a matrix of elastin and collagen.
Descrive the tunica adventitia
(outer most layer) A connective tissue sheath with no distinctive outer border that tethers loosely in place and in larger vessels contains a network of smaller blood vessels called the vasa vasorum which are responsible for nourishing the media.
What do some large vessels also contain?
nociceptive sensory fibres or sympathetic nerve plexi
