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
Where does the left atrium receive oxygenated blood from? Describe the anatomy of the left atrium
Four pulmonary veins feed oxygenated blood into the left atrium
The left atrium has a mostly smooth interior (posterior wall), except for the pectinate muscles in the left auricle (anterior) which are more rough. Also, the left atrium is thicker than the right atrium.
