Cardiovascular System I Flashcards
What is the pericardium?
The pericardium is a fibroserous fluid filled sack that the heart and roots of the great vessels (aorta, pulmonary artery and vein, sup./inf. vena cava) sit in
- Outer layer of dense connective tissue called pericardium
- Inner layer that includes the parietal and visceral layers, in between those layers is the pericardial cavity which contains a film of fluid that helps the heart to beat frictionless
Explain the pericardial layers
Fibrous pericardium -> inelastic, keeps heart in position and prevents overfilling
Parietal layer -> adherent to fibrous pericardium
Visceral layer -> loosely bound to heart, also called the epicardium
What are the main functions of the pericardium? (4)
- Fixes the heart in mediastinum and limits motion because of attachment to diaphragm, sternum, and tunica adventita (outer layer) of great vessels
- Prevents overfilling of heart because of inextensible fibrous layer that prevents heart from increasing in size too rapidly
- Lubrication from the thin film in the pericardial space that reduces friction as it moves within the thoracic cavity
- Protection from infection because the pericardium is a physical barrier between the muscular part of the heart and adjacent organs that are more prone to infection, like lungs
What is the blood supply and innervation of the pericardium?
Blood supply
Arterial supply = pericardiacophrenic, musculophrenic arteries, branches of the thoracic aorta (bronchial, esophageal, superior phrenic), and coronary arteries (visceral layer only)
Venous drainage = pericardiacophrenic, internal thoracic, and azygous system
Innervation
Fibrous and parietal sensory = somatic sensory innervation to fibrous/parietal layers via phrenic nerves (C3-5)
_Visceral sensor_y = cardiac plexuses (epicardium is insensitive to pain)
What is pericarditis, and possible causes?
-Inflammation of the pericardium associated with chest pain
Possible causes:
- viral, bacterial, fungal infections
- trauma
- heart attack and heart surgery
- kidney failure, HIV/AIDS, cancer, tuberculosis
- autoimmune disease (lupus, scleroderma, rheumatoid arthritis)
What is pericardial effusion, and possible causes?
-Presence of abnormal amount of fluid, leading to intrapericardial pressure that could lead to cardiac tamponade
Possible causes:
- local and systemic disorders
- idiopathic
How would you alleviate cardiac tamponade?
Pericardiocentesis -> aspiration of fluid from pericardial space
Describe normal blood flow through the heart
Blood from the upper and lower body travel through the sup. and inf. vena cava as well as blood from the coronary sinuses drain into the right atrium through the tricuspid valve into the right ventricle (this is deoxygenated blood)
Blood is then pumped through the pulmonary valve through the pulmonary arteries to the lungs where oxygen exchange occurs in alveoli
Blood then exits the lungs through the pulmonary veins into the left atrium where it is then pumped through the mitral valve to the left ventricle which pumps out the aortic valve to the four branches of the aorta that feed the body, as well as pulmonary arteries that feed the heart itself
Looking at the heart anteriorly, what are the main structures you would see?
Mostly aorta, sup./inf. vena cava, right atrium and right ventricle, part of the left ventricle and the apex of the heart
Also would see a large atrioventricular groove (coronary grove) and anterior interventricular groove
Looking at the heart posteriorly, what are the main structures that you would see?
Still would see the aorta and inf./sup. vena cava, left atrium and left ventricle, pulmonary veins, left auricle, right atrium
Also would see the coronary sinus (atrioventricular groove) and posterior interventricular groove
What are the main parts of the right atrium?
First of all, it can be divided into two parts:
Sinus venarum -> smooth thin-walled posterior part that receives the venae cavae and coronary sinus, derived from the “embryonic sinus venosus”
The pectinate muscles (including the auricle), is divided from the sinus venarum by the “crista terminalis”
Interatrial septum divides the right atrium from the left atrium
What divides the right atrium from the left atrium?
Interatrial septum
What is the remnant of the fetal foramen ovale and it’s valve?
fossa ovalis
Explain the steps in the formation of the interartial septum
- 1st septum is formed (septum primum)
- An opening forms (foramen or ostium primum) before fusing of the septum primum
- The septum secundum and foramen/ostium secondum (foramen ovale) forms
- A “flap valve” is created that allows blood to bypass the lungs and travel directly from mothers blood into the right atrium to the left atrium of the fetus
T or F. At 7 weeks, a fetus’ ventricles are not seperated yet, and blood is shunted from the right atrium to the left atrium.
True, at 7 weeks, blood flow is shunted directly from the right atrium to the left atrium via a flap created by the primary (septum primum) and septum secundum because this oxygenated blood from the mother does not need to travel to the fetus lungs. After all the fetus lungs are still collapsed and would not participate in gas exchange at all, so it is closed off.
The foramen ovale is the opening in which blood can shunt from the right atrium to the left atrium in the fetus. After birth, the foramen ovale becomes the _______________, and pressure in the right atrium _____________ and the pressure in the left atrium ______________.
The foramen ovale is the opening in which blood can shunt from the right atrium to the left atrium in the fetus. After birth, the foramen ovale becomes the fossa ovalis**, and pressure in the right atrium **decreases/**l**owers** and the pressure in the left atrium **increases/higher.
___% of individuals have an atrial septal defect. What clinical effects would this have?
25%
This would allow oxygenated blood to leak from the left atrium to the right (patent foramen ovale) increasing demand in the pulmonary system. This increased work load would lead to hypertrophy in the right atrium, right ventricle, and pulmonary trunk
The right ventricle receives blood through the ____________________, which is guarded by the _____________. The muscular elevations on the internal surface of the R. ventricle are the _________________.
The right ventricle receives blood through the right atrioventricular orifice, which is guarded by the tricuspid valve. The muscular elevations on the internal surface of the R. ventricle are the trabeculae carneae.
What are trabeculae carneae?
They are rounded or irregular muscular columns which project from the whole of the inner surface of the right ventricle.
The interventricular septum has two parts, what are they?
Muscular part and a membraneous part (sup. and post.) that helps to open and close the tricuspid and pulmonary valve, blood travels in a U-shaped flow from the right atrium to the right ventricle
During systole, the septum stiffens. The pulmonary valve is a semilunar valve that guards the pulmonary trunk.
What are the three cusps of the tricuspid valve, and their function? What muscles help to open and close this valve? What connects the muscle to the AV cusps?
Anterior, posterior and septal -> function to prevent backflow into the atria during ventricular contraction
Mostly the anterior papillary muscle, projecting from the septomarginal trabecula, contract when the valve is closed and relax when the valve is open. The papillary muscle is connected to the AV cusps by the chordae tendineae
Ventricular diastole, AV valves are _____.
Open
Ventricular systole, AV valves are ______.
Closed
What are the main differences between atria and auricles?
The left ventricle receives blood from the left atrium through the _______________, guarded by the _________. Describe the anatomy of the left ventricle and how blood flows out the aorta.
The left ventricle receives blood from the left atrium through the left atrioventricular orifice**, guarded by the **mitral valve.
Internally, the L. ventricle has trabeculae carneae, but finer and more numerous thant the R. ventricle. Also, the walls are two times thicker. The walls that lead to the aorta are smoother, called the aortic vestibule in which blood travels 180 degrees through the aortic valve -> a semilunar valve that guards the acsending aorta
The membranous part of the intraventricular septum is ________ to the muscular part of the interventricular septum.
The membranous part of the intraventricular septum is superior to the muscular part of the interventricular septum.
Ventricular septal defects are __% of all congenital heart defects. Most occur in the ________ portion and _________ close, the defects that occur in the _________ portion have to be corrected sugically.
Ventricular septal defects are 25% of all congenital heart defects. Most occur in the muscular** portion and **spontaneously** close, the defects that occur in the **membranous portion have to be corrected sugically.
Mitral valve = _________, and contains _________ muscles as well as ____________.
Mitral valve = Bicuspid valve**, and contains **papillary** muscles as well as **chordae tendineae.
This is the most commonly diseased vavles in the heart, and prolapse can occur in as many as 7% of females that can potentially lead to endothelium damage and increased risk of infection.
Mitral valve prolapse can result in englargement of the ___________.
Mitral valve prolapse can result in englargement of the left atrium.
Which valves are semilunar valves, also called _________ valves?
Which valves are semilunar valves, also called tricuspid valves?
The pulmonary and aortic valves are three cusp shaped valves, and are NOT associated with chordae tendinae and papillary muscles
Describe the structure and function of semilunar valves. How and why are they morphologically different from AV valves?
Early in development they start as one 4 cusp valve, and eventually the L and R cusp split to form two three-cusp vessels. The aortic valve has the posterior cusp and the pulmonary valve has the anterior cusp that split during development.
Compare and contrast AV valves and semilunar valves
Explain diastole versus systole in terms of what chambers are relaxed and contracted
Cardiac diastole = all chambers relaxed, blood flows into heart
Atrial systole, ventricular diasole = atria contract, pushing blood into ventricles
Atrial diastole, ventricular systole = ventricles contract, pushing blood out of heart
Where is the SA node, and it’s function?
Where is the AV node, and it’s function?
SA Node -> Located in wall of right atrium near opening of sup. vena cava and sup. end of crista terminalis
“Initiates muscle contraction and heart rate”
AV Node -> Located in interatrial septum superior to opening of coronary sinus
“Slows down conduction, beats slower and it’s bundle passes to membranous part of interventricular septum dividing into L. and R. branches”
Conducting system of heart on an EKG trace
How does the presence of an internal conducting system facilitate heart transplants?
Since the heart is made up of modified cardiac myocytes that can beat without innervation because of a specialized tissue that stimulates contraction (SA node, AV node). In a transplant all you will lose is parasympathetic and sympathetic innervation.
Sympathetic cardiac innervation is responsible for what?
Increasing heart rate
Impulse conduction
Force of heart beat
Blood flow in coronary arteries
Preganglionic cell bodies (lateral horns of T1-T5 of spinal cord)
Postganglionic cells (cervical and superior thoracic paravertebral ganglia) carried by splanchnic nerves to the SA and AV nodes
Parasympathetic cardiac innervation is responsible for what?
Decreasing heart rate
Decreasing force of contraction
Constricting coronary arteries
Preganglionic is from the vagus nerve
Postganglionic cells are located in cardiac tissue (atrial wall and interatrial septum near SA/AV nodes and along coronary arteries)
