Anatomy Flashcards
(104 cards)
What are the two sides of the heart divided by and why is this needed?
The septum, without this there would be the mixing of blood which would reduce the efficiency of the heart.
How is heart location described?
- In the thoracic cavity.
- Deep to the sternum.
- Deep to costal cartilages.
- Protected by ribs, vertebrae and sternum.
- Between the lungs (mediastinum)
- More on the left side than the right.
Describe the three layers of the heart
1) Epicardium- this is external, visceral serous pericardium
2) Myocardium- middle, muscle layer
3) Endocardium- internal lining that is continuous with endothelium of blood vessels connecting with the heart.
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Name the 4 cardiac valves and describe location
Pulmonary valve (between right ventricle and pulmonary trunk) Tricuspid valve (between right atrium and right ventricle) Mitral/bicuspid valve (between left atrium and left ventricle) Aortic valve (between left ventricle and aorta)
What do valves prevent?
The backwards flow of blood
Describe the mediastinum and where the heart is
- The Mediastinum is the area that lies in between the lungs.
- It is divided into the inferior and superior mediastinum.
- The inferior mediastinum is further divided into anterior, middle and posterior.
- The heart is located in the middle mediastinum.
Describe the pericardium
• The Pericardium forms the boundaries of the middle mediastinum and is the tissue surrounding the heart.
• It has two layers:
1) The fibrous pericardium- a thick outer layer that prevents overfilling.
2) Serous Pericardium- an inner membranous layer that secretes serous fluid. It reflects back on itself, it stops friction. There is a visceral layer of the serous pericardium that covers the heart and a parietal layer that lines the fibrous pericardium
What functions does the fibrous skeleton of the heart provide?
- Keeps orifices of valves patent
- Forms the fibrous rings of the cardiac valves
- Forms an electrical insulator by separating conducting impulses of atria and ventricles allowing one normal route for electrical conduction in the heart
How does the heart’s conduction system work?
Electrical impulse starts spontaneously at SA node (pacemaker), travel through cardiac muscle of atria and cause them to contract. Travel down through the septum and spreads out to myocardium through conducting fibres causing the ventricles to contract
What is fibrillation?
The uncoordinated contraction of the cardiac muscle
What are external factors that can also affect heart rate and force of contraction?
Nerves that supply the heart e.g. sensory nerves and motor nerves- these include sympathetic nerves that speed the heart up and increase force of contraction. Circulating hormones such as adrenaline can also have an effect.
What does pulmonary circulation refer to?
The circulation of blood in which deoxygenated blood is pumped from the heart to the lungs and oxygenated blood is returned to back to the heart.
Describe the route blood takes through the heart
Deoxygenated blood is taken back to the heart by the vena cava and into the right atrium and the ventricle, the pulmonary artery then takes the deoxygenated blood to the lungs where it is oxygenated and returned to the heart by the pulmonary vein. It is then pumped through the left atrium and ventricle before being pumped around the body by the aorta.
What is systemic circulation?
This is what occurs between the heart and the entire body.
What are great vessels?
Vessels directly connected to a chamber of the heart.
Why are arterioles said to have sympathetic tone?
Only the sympathetic nervous system effects blood vessels, as only contraction is active, relaxation is simply the act of not contracting so does not involve the parasympathetic system.
What are the four parts of the aorta?
Arch of the aorta, ascending aorta, thoracic aorta, abdominal aorta.
What is the blood supply to the brain provided by?
The circle of Willis.
What is the blood brain barrier created by and what is the purpose?
Tight junctions between brain capillary endothelial cells and this prevents the diffusion of some substances from capillary into the brain.
What are end arteries?
The only arterial blood supply to a given area of the body. The hands have true end arteries and the heart has false end arteries.
What is infarction
irreversible cell death due to hypoxia (lack of oxygen) caused by loss of arterial blood supply.
What does the ascending aorta branch into and what does the arch of the aorta branch into?
Ascending: left and right coronary artery
Arch: the brachiocephalic trunk, left common carotid artery, and left subclavian artery.
What does the abdominal aorta bifurcate into?
Common iliac arteries.