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
Hyperventilation
Over breathing
Cyanosis
Greyish-blueish skin
Oliguria
Decreased urine flow
Hypertension
Normally defined as a systolic pressure of 140 mm Hg or higher and/or diastolic pressure of 95 mm Hg or higher on tow are more measurements on two or more occasions
Essential hypertension
Aka primary hypertension or idiopathic hypertension is hypertension that has no identifiable cause. The silent killer.
baroreceptor
A sensory nerve ending in some large blood vessels. Eg, the common carotid artery of the neck that is sensitive to stretching of the arterial wall. The stretching results from changes in blood pressure.
common carotid artery
Neck. Sensitive to stretching of the arterial wall
Cardiac arrest
Indicates a sudden stop in effective and normal blood circulation due to failure of the heart to pump blood. Brain is the first organ effected. Loss of consciousness and breathing is shallow and minimized. Over 5 mins = permanent brain damage
cardiac arrest causes
- Myocardial infarction (heart attack)
- Cardiac rhythm disturbance ( arrhythmia -most common fatal is ventricular fibrillation)
- Extremely high or low body tempurature
heart murmur
An abnormal continuous or periodic sound originating in the heart valves
Atherosclerosis
Means clogging of the arteries. Fatty substances form a deposit of plaque on the inner lining of the arterial walls
Ichemia
Loss of local blood flow due to mechanical obstruction
Angina pectoris
Severe constricting pain (angina) in the chest (pectoris)due to ichemia of the heart muscle; usually caused by coronary disease
Cell Necrosis
Cell death
Ichemic necrosis
A death of an area of the heart muscle, usually results of occlusion (blocked) of a coronary artery
Infarction
Cell death (necrosis) caused by a local lack of oxygen, due to an obstruction of tissue’s blood supply (ichemia). the resulting lesion is referred to as an infarct
Lesion
A region in an organ or tissue that has suffered damage through injury or disease, such as a wound, ulcer, abscess or tumor
Myocardial infarction
Death of some heart tissue and is commonly know as heart attack
A-FIB
Atrial fibrillation - an abnormal heart rhythm characterized by rapid and irregular beating. Starts as brief periods of abnormal beating which become longer and possibly constant over time. Most episodes have no symptoms. Increases risk of heart failure, dementia and stroke. Hypertension is the most common alterable risk factor. Diagnosis by feeling pulse - confirmed my electrocardiogram ECG. AF often treaded with medications to slow HR to a normal range.
Position for CPR
Supine - on the back
Sternum
Breast bone
AED
Automated external defibrillator - portable electronic devise that automatically diagnosis the life threatening cardiac arrhythmias of ventricular fibrillation and ventricular tachycardia
fibrillation
Vermicular twitching of individual muscle fibres (vermicular = wormlike)
Defibrillation
More successful if performed within 5 minutes of cardiac arrest and changes of survival decreases up to 10% for every minute that passes after the arrest
