lecture 7 - anatomy and flow of the heart Flashcards
Describe the position of the heart in the thoracic cavity.
Located in the thoracic cavity but specifically in the mediastinum which is also known as the central compartment of the chest. It lies behind the sternum and in front of the spine. The heart is almost tilted so that it is directed towards the right shoulder with the apex (bottom) pointed down toward the left. Is positioned between the lungs and surrounded by a protective sac (pericardium).
Identify and describe the location, structure, and function of the fibrous pericardium
Fibrous pericardium – is the tough outermost layer of the pericardial sac which directly surrounds the heart. It is on the outside of the serous pericardium and anchors the heart to things like the sternum, vessels, and diaphragm. It is the connective tissue layer that helps protect the heart and maintain its position. The fibrous one functions to prevent the heart from over-expanding when blood volume increases and against infection or inflammation.
identify and describe the location, structure, and function of the parietal and visceral layers of the serous pericardium
The parietal layer of the serous pericardium – is the outer layer of the serous pericardium and lines the internal layer of the fibrous pericardium. It is a smooth serous membrane that does not directly touch the heart but is attached to the fibrous pericardium. This layer helps form the smooth lining around the heart and reduce friction between it and the surrounding structures.
The visceral layer of the pericardium (epicardium) – is the visceral layer which is the inner layer of the serous pericardium and is in direct contact with the heart muscle (myocardium). It is a thin layer that is tightly adhered to the surface of the heart often through connective tissue and different fats. It functions as the protecting layer that adheres to the heart and reduces friction to play a role in circulation, and the blood vessels run through this.
identify and describe the location, structure, and function of serous fluid
Serous fluid – the serous fluid is between the visceral and parietal layers and is a thin watery secretion which is produced by the mesothelial cells of both layers.
identify and describe the location, structure, and function of pericardial cavity
Pericardial cavity – is the potential space that exists between the parietal and visceral layers of the serous pericardium. It contains serous fluid and functions to allow the heart to move freely within the thoracic cavity while creating minimal friction.
also helps to cushion and protect the heart when it beats
describe the structure and function of the epicardium
The Epicardium (visceral layer of the serous pericardium) – is the outermost layer of the heart wall which contains blood vessels, nerves, adipose tissues, all which help to protect and nourish the heart.
- It functions to protect the outer layer of the heart, lubricate and reduce friction and contain the coronary blood vessels that help supply oxygen and nutrients to the heart muscle (myocardium).
- Protects, provides lubrication, contains coronary vessels
describe the structure and functions of the myocardium
Myocardium – the myocardium is the thick middle layer of the heart wall which is also known as the cardiac muscle (cardiac muscle fibers). This is the thickest layer and can vary in thickness based on where it is in the heart. The left ventricle for example has a thicker myocardium than the right because it needs to pump blood to the entire body with high pressure.
- Its main function is to contract and generate the forces necessary to pump blood through the heart and out into the circulatory system. The myocardium also is involved in the heart’s electrical conduction system
- Pumps blood by contracting, helps regulate heart rhythm
describe the structure and function of the endocardium
Endocardium – is the innermost layer of the heart wall which lines the chambers of the heart and covers the heart valves.
- Provides a smooth surface for blood flow helping to prevent clotting and friction. Helps the heart to regulate the direction of blood flow.
- Ensures smooth blood flow within the heart and covers the heart valves
Explain the structural and functional differences between atria and ventricles.
o The atria are thin-walled chambers which sit on top of the heart. Allows for low-pressure blood collection
o The ventricles are two thick-walled chambers that force blood out of the heart. Needs thicker walls so that there can be more forces on the walls to force the movement of blood.
On the external surface of the heart identify the 4 chambers, apex and base.
The point of the heart at the bottom is the apex and the base is the top of the heart. The atria are the top two chambers, and the right atria appears on the left while the left one appears on the right. The ventricles are the bottom two chambers. The same goes for these, the left is on the right, and the right is on the left.
- if looking at the heart from an anterior view the chambers are opposite (left on right and right on left). if looking at the heart from a posterior view the right chamber is on the right and the left chamber is on the left
Identify and describe the structure and function of the primary internal structures of the heart, including chambers, septa, valves, papillary muscles, chordae tendineae, and venous and arterial openings.
- Septa: mix of muscle and fibrous tissue
- Interatrial septum: in between the atria
- Interventricular septum: between the two ventricles, is thick and helps the ventricles contract with a lot of pressure
- Fibrous skeleton: fibrous tissue coated with endothelium, has four opening to let blood move from atria to ventricles, from ventricles to pulmonary trunk and aorta, also separates electrical signals that control contraction of atria and ventricles
- Each opening of the fibrous skeleton is guarded by a valve (ONE WAY FLOW OF BLOOD)
- Atrioventricular valves: valves between the atria and ventricles
- Semilunar valves: at the opening leading to the pulmonary trunk and aorta
- Chordae tendineae: extensions of the flaps of AV valves connecting to the papillary muscles, made of collagen
- Papillary muscle: extension of the myocardium in the ventricles to which the chordae tendineae attach
- Venous and arterial openings
Describe the blood flow to and from the heart wall, including the location of the openings for the left and right coronary arteries, left and right arteries, cardiac veins, and coronary sinus.
Superior/inferior vena cava -> right atrium -> tricuspid valve (AV) -> right ventricle -> pulmonary artery -> lungs -> left atrium -> mitral valve (AV) -> left ventricle -> aorta -> rest of body
Describe the microscopic anatomy of the myocardium, including the location and function of the intercalated discs.
o Striated, many mitochondria, usually a single central nucleus, branched, junctions between cells are intercalated discs (here sarcolemmas from the other cells are joined by desmosomes, tight junctions, and gap junctions)
o The intercalated discs allow for the cardiac muscle cells to create a contraction in a wave-like pattern that can stimulate the heart so that it works like a pump.
Trace the path of blood through the right and left sides of the heart, including its passage through the heart valves, and indicate whether the blood is oxygen-rich or oxygen-poor.
o Oxygen-poor blood enters the heart through the superior and inferior vena cava into the right atrium, then passes through the tricuspid valve into the right ventricle; from there, it is pumped through the pulmonary valve into the pulmonary artery to the lungs where it becomes oxygen-rich; the oxygenated blood returns to the heart through the pulmonary veins, entering the left atrium, then passing through the mitral valve into the left ventricle, finally exiting through the aortic valve into the aorta to be distributed throughout the body.
what is the serous membrane and what is it also known as
- it lets the heart be lubricated so that it can move around without damage or dying
- also called the pericardium
color on diagrams to indicate oxygenated versus deoxygenated
red - oxygenated
blue - deoxygenated
arteries versus veins
arteries - carries blood away
veins - carries blood towards
why is the left ventricle thicker than the right
because the left ventricle has to be able to push blood to all areas of the body so it has a lot more pressure on it. Because of the increased amount of pressure their is a thicker myocardium
what do the valves do simultaneously
the aortic and pulmonary open at the same time the tricuspid and bicuspid close
proper direction of flow of blood in the heart
enters the right atrium via the vena cava, moves to the right ventricle through the tricuspid valve, then pumped to the lungs through the pulmonary artery, returns to the heart via the pulmonary veins into the left atrium, passes through the mitral valve to the left ventricle, and finally exits the heart through the aorta to the body
simple steps of blood flow
1 - leaves the right ventricle and goes to the pulmonary (lungs)
2 - enters the heart back through the left atria
3 - then goes to the left ventricle
4 - then goes out to the body
5 - comes back through the right atrium
