Chapter 6 Flashcards
Layers of the heart
- Epicardium - outside layer of connective tissue
- Myocardium - middle layer of muscle
- Endocardium - inner layer of smooth endothelium that lines the heart
Heart chambers
2 atria (atrium) - receiving superior chambers of the heart, veins enter 2 ventricles- the inferior, discharging chambers of the heart, arteries leave
Sinoatrial node (SA)
Small mass of tissue in the right atrium, functions as a pacemaker ie sets the pace of the action potentials (electrical signals) that initiate heart contractions
Gap junctions
Allow action potentials to pass from one heart cell to another adjacent cell and allow the heart to contact in unison. A specialized intercellular connection which allow various molecules, ions and electrical impulses to directly pass between cells.
Ectopic pacemaker
Any pacemaker in the heart other than the SA node
Systole
Contraction of the ventricles
Diastole
Relaxation of the ventricles
Systematic circulation
Left side of the heart receives freshly oxygenated blood from the lungs via the pulmonary vein and pumps it to all the body cells via the aorta and systemic arteries
The aorta
The main artery of the systemic circulation. It carries blood to all the other arteries except the pulmonary artery
Systemic capillaries
Provide oxygen to all body’s cells
Venae cavae
Largest veins in the body. They receive all the unoxygenated blood coming into the right heart
Pulmonary circulation
The right heart pumps unoxygenated blood via the pulmonary arteries to the lungs, where oxygen is picked up and brought to the left heart via the pulmonary veins
Coronary arteries
Encircle the heart. They flow through and feed the myocardium during diastole
Shock
Critical condition caused by a sudden drop in blood flow through the body sharply curtailing the delivery of oxygen and nutrients to vital organs. Can be due to not enough volume or output by the heart. Hypotension, hyperventilation, weak rapid pulse, cold, clammy, grayish-blue skin, decreased urine flow and a sense of great anxiety and foreboding, confusion and sometime combativeness. Keep patient warm, give fluids by mouth or intravenously and drugs to improve cardiac and circulatory function.
Hypotension
Low blood pressure