Heart Lecture Exam
Describe the general location and size of the heart
Weighs about 350g; beats >10,00 times a day.
Middle of chest; mediastinum, middle of thoracic cavity, apex is tilted inferiorly. Rests on diaphragm near midline of thoracic cavity.
2. Describe the pericardial sac that encloses the heart; What is its function, what is it filled with?
The pericardial sac is a membrane that surrounds and protects the heart. It anchors the heart in its place in the mediastinum and allows it freedom for rapid contraction. It contains two main parts. Fibrous pericardium (tough dense irregular tissue, anchors the heart, nonflexible) and the serous pericardium (inner) which is divided into parietal and viscera layer (the outer surface of the heart wall. Thin pericardial fluid lubricates space between visceral and parietal layers.
3. Describe the three layers of the heart wall
The outermost layer of the heart wall is the epicardium, a thin transparent outer layer (aka visceral layer). It is composed of mesothelium, and underneath that is a layer of delicate fibroelastic and adipose tissue.
The middle layer is called myocardium. Thick muscly layer which is composed of cardiac muscle and is responsible for the pumping action of the heart. Makes up approximately 95% of the heart wall.
The innermost layer is called the endocardium. Simple squamous epithelium, very thin, (known throughout the circulatory system as endothelium). It provides smooth lining for the chambers of the heart and covers valves of the heart. Minimizes surface friction as blood passes through the heart.
4. Be able to identify and distinguish between the four chambers of the heart and the four valves of the heart
Chambers
The right heart-right atrium (pumps deoxygenated blood to the right ventricle through the tricuspid valve and receives deoxygenated blood from the body through the superior and inferior vena cava)
right ventricle: right lower chamber of heart, receives deoxygenated blood from the right atrium and pumps deoxygenated blood through the pulmonary trunk by the pulmonary valve.
taking venous blood from body and pump to lungs for oxidation
The left heart consists of
left atrium (pumps oxygenated blood to the left ventricle through mitral (bicuspid valve) and receives oxygenated blood through the pulmonary veins by a process called pulmonary circulation)
left ventricle: left lower chamber of heart, receives oxygenated blood from the left atrium, delivers oxygenated blood to the aorta
takes fresh, oxygenated blood and pumps systemically (to body)
Valves
to get from the atria to ventricle to out of the body, there needs to be passing of valves.
Atrioventricular valves (AV)- open to allow blood flow from atria to ventricles, Tricuspid (R) and Bicuspid (L), open into the ventricles.
Semilunar valves- open to allow blood flow from ventricles to outflow vessels (pulmonary and aortic). Heart relaxes, blood pumps through calve, heart contracts, papillary muscles contract to protect valve and control flow of blood so it doesn’t go back up atria.
5. Be able to describe and recognize the structural and functional differences between veins and arteries.
Arteries- vessels that always conduct blood away from the heart (red, oxygenated blood)- thick, walled, and exposed to high pressures because blood is coming from strong side (left) of heart.
Veins- vessels that always bring blood back to the heart- contain deoxygenated blood. Most veins are thin, smooth muscle, walled and exposed to low pressure and minimal friction forces. Bring back deoxygenated blood back to the heart.
7. Define and distinguish between the pulmonary and systemic circuits;
Pulmonary circuit- deoxygenated blood is ejected into the pulmonary trunk and is powered by right side. Deoxygenated blood is rained into right atrium and ventricles, flows into right side from three sources: two vena cavae & coronary sinus. Deoxygenated flows from heart to lungs through pulmonary arteries to absorb oxygen and release carbon dioxide, oxygenated blood travels back through pulmonary veins.
Systemic circuit- oxygenated blood that is ejected into the aorta, systemic arteries, and arterioles, it is powered by left side of the heart, pumps blood to all body systems. Flow of blood from left ventricles of the heart (through the aorta) to the rest of the body, carries oxygenated blood and nutrients to cells, and picks up carbon dioxide and waste to return to right atrium.
8. Describe the arteries that nourish the myocardium and the veins that drain it.
The coronary arteries provide the main blood supply to the heart. The coronary arteries also supply the myocardium with oxygen to allow for the contraction of the heart and thus causing circulation of the blood throughout the body. The coronary veins all drain to coronary sinus into the right atrium.