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Cardiovascular System
Overview
Delivers oxygen and nutrients
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Cardiovascular System
Overview
- Delivers oxygen and nutrients
- Equalises body temperature
- Pulmonary circulation: heart to lungs
- Systemic circulation: heart to all body tissue
- Collateral circulation: blood vessels that take over when another artery or vein is blocked. Privileged organs include stomach and intestines
- End arteries: only artery that supplies oxygenated blood to a portion of tissue/organ.
- Noteworthy: hepatic portal vein from stomach and intestines go to the capillaries in the liver. Portal systems - One of many in the body.
Location, Orientation and Coverings
Located in central part of the thoracic cavity (mediastinum)
- Central space of the thoracic cavity located behind the sternum and between the two lungs and their respective pleura.
- Sits on top of diaphragm
- Superior part, beyond the atria is the superior mediastinum, where the sternum angle is.
- Heart is in the middle mediastinum, which is within the inferior mediastinum
- Front of heart is the anterior mediastinum
Orientation
- Atria lie to the right of their respective ventricles
- Atria lie posterior to their respective ventricles
- Right heart chambers lie to anterior to respective Left heart chambers
- Apex points to the left obliquely laterally; Base faces posteriorly
Heart is behind the precordium
- 2/3 of heart is on the left of sternum
- Superior part, on 2nd intercostal space (space between the ribs) on the left.
- Right border, from 3rd to 6th costal cartilage (cartilages that connect ribs to sternum)
- Apex is in the 5th intercostal space on the left.
- Midclavicular line touches the apex
Supports of the heart
- Fibrous pericardium (white cover), attaches to the central tendon of the diaphragm
- Superior sternopericardial ligaments and sternopericardial ligaments, secure back of sternum (sterno) to heart
- Vertebro pericardial ligament, secures vertebrae to heart
Cover and its layers
- Outside layer: fibrous pericardium, shell of the heart
- Next layer: serous pericardium, with a pericardial cavity (15-50ml of fluid) in between the parietal layer and the visceral layer (epicardium). Both layers are continuous. Important shock and friction absorber.
- Above 2 layers are pain sensitive (innervated by Phrenic nerve)
- Followed by myocardium (middle muscle of heart) and endocardium (smooth tissue that makes up lining of chambers and valves)
Pericardial sinuses
- Transverse and oblique
- Come about from embryonic stage
- Think "hot dog", with the primordial venous and arterial ends. As they come together, the part between them forms the transverse pericardial sinus
- The back part of the venous end forms the oblique pericardial sinus
- During cardiac surgery, the transverse pericardial sinus allows a surgeon to isolate the pulmonary trunk and ascending aorta and apply a temporary ligature or clamp.
- If the pericardial cavity accumulates too much fluid, the heart is compressed (cardiac tamponade)
- Life can be saved via a needle and syringe (pericardiocentesis)
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Cardiac Skeleton
The fibrous skeleton anchors the valves of the heart, and gives attachment to the cardiac musculature above and below.
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- Pulmonary artery to lungs.
- From lungs, pulmonary veins to left atrium
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