Circulation and Perfusion Flashcards
What is the cardiac cycle?
-contraction of the atria followed by contraction of the ventricles
What is electrical conduction as it relates to the heart?
electrical activity that initiates contraction of the myocardium
What is the sinoatrial (SA) node? Location?
- pacemaker
- right atrium
What is the atrioventricular (AV) node?
electrical activity passes from AV node to bundles of HIS and purkinje fibers to ventricles
Difference between arteries, arterioles, and capillaries?
arteries- thick elastic walls
arterioles- smaller and thinner than arteries, made of smooth muscle, controlled by sympathetic nervous system
capillaries- one cell thick, exchange gases, nutrients, and wastes between tissue and blood
Purpose of veins and venules?
- thin, muscular, inelastic
- contract or relax in response to sympathetic nervous system (holding tank for changes in blood volume)
What does hemoglobin do?
carries oxygen
What are coronary arteries for?
- supply the heart with blood
- the coronary sinus fills with blood during diastole (only arteries in the body that fill during diastole)
What are baroreceptors? Location?
- sensitive to pressure changes
- located in walls of heart and vessels (esp aortic arch and carotid artery)
- example- if they sense a drop in pressure, they send a message to stimulate the sympathetic nervous system to increase heart rate and vasoconstriction
What are chemoreceptors? Location?
- sensitive to changes in pH, o2 levels, co2 levels
- located in aortic arch and carotid arteries
What is the vasomotor center for?
controls sympathetic stimulation of the heart and vascular system
What is the cardioinhibitory center for?
controls parasympathetic slowing of the heart rate
How does developmental stage affect cardiac function?
Adults: lifestyle (tobacco), stress, hereditary, diet, exercise, obesity
Older adults: thicker and more rigid valves, decreased heart strength, lower exercise tolerance
How does stress affect the heart?
- stimulates release of catecholamines from sympathetic nervous system
- results in increase in heart rate, vasoconstriction, blood clotting
How do allergens affect the heart?
histamine and protease cause -blood vessels to dilate
- local tissue damage from protease
- fluid leaking into tissues from increased capillary permeability
How does altitude affect the heart?
- increased RBC production
- increased vascularity of tissues
- increased ability of tissue to use oxygen
How do heat and cold affect the heart?
Heat: -vasodilation -increased metabolism Cold -vasoconstriction -decreased metabolism -less o2 demand -decreased heart rate
How does lifestyle affect the heart?
Pregnancy:
- high o2 demand
- increased blood volume
- need for additional iron to make blood
Nutrition:
- high saturated fat diets causes athersclerosis, coronary artery disease, hypertension
- low-fat, low-sodium, low-cholesterol diets are heart healthy
Obesity:
- excess fat around heart decreases the effectiveness of the heart as a pump
- workload of the heart is more, because more tissue
Exercise:
- improves perfusion
- increases metabolic demand
- increased heart rate
- heart is strengthened
Tobacco:
-risk for stroke, peripheral arterial disease, aortic aneurysm, heart disease, atherosclerosis, hypertension, decreased HDL
Substance abuse:
- depress respiratory, cardiac, and vasomotor centers
- alcohol use causes fat in heart, thrombi in arteries, heart enlargement, dysrhythmias
What are beta-adrenergic blocking agents used for?
- reduce workload of the heart
- reduce dysrhythmias
- control hypertension
What are calcium channel blocking agents?
- block flow of calcium into cells of heart and vessels
- decrease blood pressure
- decrease strength of contractions
- slow heart rate
- dilate arteries
What are signs of peripheral arterial abnormalities?
- pallor
- pain
- weak/absent pulse
- poor capillary refill
- cool skin
- tissue dysfunction
What are signs of peripheral venous abnormalities?
- edema
- brown skin discoloration
- stasis ulcers
What are oxygen transport abnormalities?
Anemia- low levels of RBCs, hemoglobin or both
Carbon monoxide- binds to hemoglobin making o2 transport impossible
What to assess for during a physical exam of the heart?
Pain: location, duration, frequency, radiation
Fatigue: pts subjective experience, level 1-10
Dyspnea: hypoxia, anxiety
Peripheral circulation: pulses, color and temp of skin, hair on extremities, edema, ulcers
How to test blood oxygenation?
- pulse oximetry
- capnography
- ABGs (arterial blood gases)
What is an ECG?
Electrocardiogram
-rendering of electrical activity of the heart, NOT mechanical (what the heart actually does)
What are some nursing diagnosis’ for the cardiovascular system?
- decreased cardia output
- risk for decreased cardiac tissue perfusion
- ineffective tissue perfusion
- risk for shock
What is a thrombus?
stationary clot adhered to the vessel
What is a embolus?
clot that travels the bloodstream
What are the signs of cardiac arrest?
- pale/grey, cool skin
- absence of carotid pulse
- apnea
- pupil dilation
