Circulation & Perfusion Flashcards
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Is how the blood flows to a capillary membrane to provide nutrients and oxygen that the tissues and organs need
Perfusion
?
Is the flow of blood throughout the heart and vessels
Circulation
Anatomy of the Heart
* Heart
- Muscle encased by ___
- 4 chambers
- 2 atria
- 2 ventricles
pericardium
The Heart
Is a muscle encased by the pericardium which is a sack of connective tissue and it’s located inside the chest cavity
Made up of 4 chambers
2 atria : ___ -walled that receive blood into the heart
2 ventricles : ___-walled that pump blood out of the heart
thin-
thick-
Valves are located between the heart chambers, and they open to allow blood to flow easily and without turbulence from one chamber to another AND they close tightly to prevent backflow of the blood or regurgitation
Base of the heart houses the atria and faces upward whereas the apex of the heart or the tip of the heart houses the ventricles and faces downward
Deoxygenated blood from organs and tissues flows through the venous system (superior and inferior vena cava) into the __ side of the heart and then into the pulmonary arteries and lungs
External gas exchange occurs at the ___-___ membrane
Oxygenated blood then flows from the lungs through the pulmonary veins into the ___ side of the heart and out into the arterial circulation through the ___
right
alveolar-capillary
left / AORTA
The Cardiac Cycle
Cardiac Cycle
* Contraction of atria
* Followed by contraction of ventricles
The Cardiac Cycle
Electrical Conduction
* Sinoatrial node (SA node)
> Pacemaker
> 60-100 beats/min
* Atrioventricular node (AV node)
* Bundle of HIS
* Right and left bundle branches
* Up the Purkinje fibers
Cardiac cycle
Includes the contraction of the 2 atria followed by contraction of the ventricles
The electrical activity of the ___ regulates the cardiac cycle
myocardium
Electrical conduction
The heart has areas of specialized nerve tissues that initiate electrical impulses without external nervous system stimulation
? - is the pacemaker of the heart and it is located in the right atrium; is going to initiate an impulse that triggers each heartbeat
Impulse travels rapidly down atrial conduction system and both atria contract as a unit
The ___ node receives that impulse - delays it for a second - and then sends that impulse into the right and left bundle of HIS and into the Purkinje fibers to the ventricles and lead to the contraction of the ventricles
sinoatrial node
atrioventricular
Electrical conduction cont’d
If there are any defects in this electrical system - impulses are going to travel more slowly or in some areas may even be blocked and this will lead to ineffective heart pumping and a decrease in cardiac output
The ___ node is in charge and initiates a rate of 60-100 bpm
If this node fails, then the atrioventricular node takes over the impulse but at a slower rate
If both of these nodes fail, the conduction fibers in the myocardium can initiate impulses - ___ conduction is at a very slow rate, usually less than 40 bpm
SA
ventricular
Systemic & Pulmonary Blood Vessels
All vessels - lined smooth endothelial layer
* Promotes nonturbulent blood flow
* Prevents platelets from sticking to walls & clotting
Arteries
* Thick elastic - allow for stretch & recoil
Arterioles
* Thinner walls
Systemic & Pulmonary Blood Vessels
Capillaries
* Connect arterioles with venules
* One cell thick allowing for gas exchange
Venules
* Thinner walls
Veins
* Thinner muscular walls, inelastic & collapse easily
Vascular system is composed of 3 types of vessels: ___, ___, and ___
All vessels are lined with smooth endothelial layer that promotes nonturbulent blood flow and prevents platelets from sticking to the sides of the walls and clotting
arteries, veins, capillaries
?
Have thick, elastic walls that allow them to stretch during muscle contraction = systole and to recoil when the heart relaxes = diastole
Arteries
?
Are smaller branches of the arteries made up of smooth muscle and thinner walls - they are controlled by the sympathetic nervous system (SNS)
Arterioles
?
Are microscopic vessels - connect the arterial and venous systems and carry blood from arterioles to venules - they are only one cell thick and this is why gas exchange is facilitated along with nutrients and waste between tissue cells and the blood
The venous system returns ___ blood to the heart
Capillaries
deoxygenated
___ and ___ have thinner muscular, inelastic walls that collapse easily - the walls contract or relax in response to feedback from the SNS
So when the blood volume is low, ___ contract to provide a smaller space for smaller volume of blood - when the blood volume is high, ___ are going to relax and enlarge to accomodate the increased volume of blood
veins; venules
veins x2
Coronary Arteries
* Supply blood to heart muscle
* Right coronary artery
* Left coronary artery
- Left circumflex artery
- Left anterior descending artery
Transport of O2 & CO2
* Adequate circulation & effective cardiovascular function regulation
- Circulate oxygenated blood to tissues and deoxygenated blood to lungs
- Hemoglobin reservoir for O2
- CO2 as product of aerobic tissue metabolism
In order to maintain or circulate oxygenated blood to organs and tissues and return deoxygenated blood to the lungs – blood flow – requires adequate circulation and effective regulation of the cardiovascular function
Hemoglobin is a reservoir for oxygen
97% of blood oxygen is bound to hemoglobin at the tissue level
Oxygen leaves hemoglobin and becomes dissolved in the blood and passes through the capillary membrane into the tissues
CO2 is a waste product of normal aerobic tissue metabolism
CO2 defuses through cellular & alveolar capillary membranes only in its dissolved state
CO2 can be carried in the blood; dissolved in the plasma (7%), attached to hemoglobin (23%), or converted into bicarbonate ions (70%)
Cardiovascular Function Regulation
* Autonomic Nervous Center (ANS)
Regulates cardiac function by:
- Cardiac rate
- Cardiac muscle contractility
- Vascular tone
* Heart
___ fibers - heart beats faster and contracts stronger
___ fibers - slow heart rate (no effect on contractility)
* Vascular system
- Sympathetic control
> Maintains partial state of contraction
> Constrict or dilate vessels in response to body needs
Sympathetic
Parasympathetic
Brainstem Centers
___
> Sense low pressure - brainstem centers stimulate sympathetic nervous system to increase heart rate & induce vasoconstriction
> Located in walls of heart and blood vessels; sensitive to pressure changes
___
> Main function to regulate ventilation
> Located in aortic arch and are sensitive to changes in blood, pH, O2 & CO2 levels
Baroreceptors
Chemoreceptors
Vascular System
- Sympathetic control maintains the blood vessels in a constant baseline state of partial contraction tone which allows a stable blood pressure and blood flow at rest or when a patient is sleeping
- Sympathetic stimulation above and beyond baseline tone varies in response to body needs
- So when there’s increased sympathetic stimulation it leads to constriction of vessels
e.g.
The skin, GI tract, and kidneys and dilation of other vessels like skeletal muscle - shunts blood flow to the skeletal muscle for a fight-or-flight response
Brainstem centers
The ___ center controls sympathetic stimulation of heart and vascular system
The ___ center controls parasympathetic slowing of the heart rate
vasomotor
cardioinhibitory
Factors That Influence Cardiovascular Function
Developmental Stage
* Young & middle adults
- Poor nutrition (too busy to prepare or eat high fat, high sugar foods)
- Lack of exercise
- Substance abuse (especially tobacco)
- Family history (of CVD)
* Older adults
- Efficiency gradually declines
> Loss of contractile strength
> Valves become thicker & rigid
> Peripheral vessels become less elastic - creates more resistance
- More prone to orthostatic hypotension
Heart becomes less able to respond to increased oxygen demands
Factors That Influence Cardiovascular Function
Stress
* Release of catecholamines (from SNS) = increased HR, contractility, vasocontriction, ↑ blood clots
Allergic reactions & air quality
* Allergic reactions include release of HISTAMINE & PROTEASE
> Vasodilation - ↑ blood flow, ↑ capillary permeability, more fluid leakage
Altitude
* Increase altitude - drop in O2 pressure - affects alveoli and tissue
Heat & cold
* Heat
> Vasodilation - ↑ cardiac output and oxygenation
> Increases metabolism (people sedentary in hot weather)
* Cold
> Vasocontriction and slow HR, metabolism
> Prolonged exposure leads to frostbite, loss of hypothalamic temperature regulation, and eventually death
Factors That Influence Cardiovascular Function
Lifestyle
Pregnancy
* ↑ demands (on O2, maternal metabolism, volume, iron requirements)
Nutrition
* Balance of proteins, carbs, fats, & nutrients
* Low-fat, low cholesterol, low sodium diet = heart healthy diet
* DASH diet - dietary approaches to stop HTN
* Especially iron and protein are important to prevent anemia which reduces blood O2 carrying capacity
* Green tea consumption has been associated with reduced mortality d/t CVD
Obesity
* Atherosclerosis & HTN = increase workload of heart
Exercise
* Improves circulation & oxygenation
* Regular aerobic exercise strengthens heart muscles - as heart becomes stronger, it becomes more efficient pump
Tobacco use
* Risk of coronary artery disease is 4x higher in cigarette smokers than non-smokers cigarette smoking
Substance abuse
* Depression of respiratory, cardiac, vasomotor centers in brain
?
Is a fatty buildup in the arteries that leads to HTN and decreased HDL (the good cholesterol)
Atherosclerosis
Factors That Influence Cardiovascular Function - Lifestyle
- DASH diet - Dietary approaches to stop HTN
- Based on a 2000-kilocalorie diet
* Grains 6-8 daily servings (whole wheat bread, cereal, oatmeal)
* Vegetables 4-5 daily servings (tomatoes, broccoli, carrots, peas, kale, spinach, beans)
* Fruits 4-5 daily servings (bananas, strawberries, oranges, prunes, raisins)
* Low-fat or nonfat dairy foods 2-3 daily servings (skim or 1% milk, low-fat cheese, low-fat yogurt)
* Meats, poultry, & fish 6 or fewer servings (lean meat, broil/roast, remove skin)
* Nuts, seeds, & legumes 4-5 servings per week
* Fats & oils 2-3 servings per day
Factors That Influence Cardiovascular Function - Medications
* Improve cardiac output and tissue oxygenation
* Slow HR or reduce the force of myocardial contraction
* Ease the workload of the heart
* Dilate blood vessels & reduce blood pressure in pulmonary & systemic circulation
* Remove excess fluid accumulation
* Block abnormal heart rhythms
___ regimen helps prevent cardiovascular disease (CVD)
> Blocks prostaglandins (substances that activate the formation of blood clots, signal injuries, & trigger pain)
- Reduction of risk of heart attack or stroke
> Recommended dose
- Adults over 50 who have a risk of CVD - 1 baby ASA 81 mg per day
Aspirin
Medications that PROMOTE Circulation
* Vasodilators (angiotensin-converting enzyme (ACE) inhibitors, angiotension II receptor blockers (ARBs), nitrates)
* Beta-adrenergic blockers
* Calcium-channel blockers
* Positive inotropic agents (cardiac glycosides [Digoxin])
* Diuretics (thiazide diuretics (HCTZ), loop-diuretics (furosemide), potassium-sparing diuretics (spironolactone)
Factors That Influence Cardiovascular Function - Pathophysiological Conditions
Cardiovascular Abnormalities
* Structure, function, & regulation
* Heart failure
* Cardiomyopathies
* Cardiac ischemia
* Coronary artery disease
* Dysrhythmias
* Valve abnormalities
* Peripheral vascular abnormalities
* Oxygen transport abnormalities
Cardiovascular abnormalities results from problems that occur with structure, function, and regulation of the cardiovascular system & they’re going to interfere with the flow of oxygenated blood to organs & tissues
Major abnormalities include heart failure (HF) which leads to an ineffective pump; includes right-sided HF, left-sided HF, or both right and left-sided HF
?
Has to do with the heart muscle; a disorder that leads to an enlargement of the heart & impaired cardiac contractility
___ if it results from a genetic disorder
___ if it results from another cardiovascular disease
Cardiomyopathy
Primary
Secondary
___ occurs when oxygen requirements of the heart are not met so prolonged ___ can lead to myocardial infarction where parts of the heart muscle start to die from lack of O2
Cardiac ischemia; ischemia
?
Is the transient chest pain (CP) d/t MI wherein tissue becomes injured but doesn’t necrose
Angina pectoris
___ is ischemic CP that has worsened in frequency, severity, or duration & if it is not relieved by usual measures & left untreated, can lead to MI
Unstable angina