Cardiovascular system Flashcards
heart tissues
Pericardium:
-fibrous protective sac enclosing the heart
Epicardium:
-inner ayer of pericardium
Myocardium:
-heart muscle, major portion of the heart
Endocardium:
-smooth lining of the inner surface and cavities of the heart
heart chambers
RA: receives blood from vena cava
Tricuspid valve
RV: receives blood from RA and pumps blood via pulmonary artery to lungs for O2
“low pressure pulmonary pump”
LA: receives oxygenated blood from lungs and 4 pulmonary veins
Bicuspid valve
LV: receives blood from LA and pumps via aorta t/o systemic circulation
“high pressure systemic pump”
Heart valves
Atrioventricular valces: prevent back flow during ventricular systole
- R tricuspid
- L bicuspid
Semilunar valves: prevent backflow from aorta and pulmonary A into ventricle during diastole
- Pulmonary valve: prevents R backflow
- Aortic valve: prevents L backflow
systole=
ventricular contraction
end systolic ventricle volume ~50 mL
diastole=
ventricular relaxation and filling
end diastolic ventricle volume ~ 120 mL
atrial contraction
“atrial kick”
occurs during the last 1/3 of diastole and completes ventricular filling
comprising last 20-30% of end diastolic volume
coronary circulation
arteries: arise directly from aorta near aortic valve; blood circulates to myocardium during diastole
- R coronary A
- L coronary A
- —L anterior descending
- —Circumflex
Veins: parallel arterial system; coronary sinus receives venous blood from the heart and empties into the RA
Conduction:
specialized conduction tissue: allows rapid transmissionof electrical impulses throughout the myocardium (NSR)
Normal sinus rhythm:
- Origin in SA node- impulse spreads t/o both atria, which contract together
- impulse stimulates AV node, is transmitted down bundle of His Purkinje fibers
- impulse spreads t/o the ventricles which contract together (atrial kick)
SA node
- located at junction of vena cava and RA
- **main pacemaker of the heart; initiates impulse rate of 60-100 bpm
- has sympathetic and parasympathetic innervation affecting both HR and strength of contraction
AV node
- located at junction of RA and RV
- has sympathetic and parasympathetic innervation
- merges with bundle of His
- intrinsic firing rate of 40-60 bpm
Purkinje tissue
- R and L bundle braces of the AV node are located on either side of intraventricular septum
- terminate in Purkinje fibers, specialized conducting tissue spread t/o ventricles
- intrinsic firing rate of 20-40 bpm
Stroke volume=
the amount of blood ejected with each myocardial contraction
normal range= 55-100 mL/beat
Influenced by:
1- L ventricular end diastolic volume: the amount of blood left in the ventricle at the end of diastole (AKA preload). The greater the preload, the greater the quantity of blood pumped– Frank starling law
2-contractility: ability of the ventricle to contract
3- Afterload: the force the LV must generate during systole to overcome aortic pressure to open the aortic valve
Cardiac output
the amount of blood discharged from the L or R ventricle per minute
average adult at rest= 4-5 L/min
determined by HR x SV
Left ventricular end diastolic pressure
pressure in the LV during diastole
normal range 5-12mm Hg
Ejection fraction
percentage of blood emptied from the ventricle during systole
clinically useful measure of LV function
EF= SV/LVEDV
SV= blood ejected with contraction LVEDV= blood left in ventricle at end of diastole (preload)
normal EF averages >55%
-lower EF= more impaired LV
atrial filling pressure
the difference between the venous and atrial pressures
R atrial filling pressure is decreased during strong ventricular contraction and atrial filling is enhanced
R atrial filling pressure is affected by changes in intrathoracic pressure; decreases during inspiration and increases during coughing or forced expiration
venous return increases when blood volume expands and decreases during hypovolemic shock
diastolic filling time decreases with:
increased HR and with heart disease
myocardial oxygen demand (MVO2)
represents the energy cost to the myocardium
clinically measured by the product of HR and SBP
AKA Rate pressure product (RPP)
MCO2 increases with activity and with HR and/or BP
R coronary artery supplies:
RA
most of RV
and in most individuals the inferior wall of LV, AV node and bundle of His
Supplies SA node 60% of the time
L coronary artery supplies:
most of the LV
2 divisions:
1- L anterior descending: supplies LV and the inter ventricular septum
- in most individuals the inferior areas of the apex
- may also give off branches to RV
2- Circumflex: supplies blood to the lateral and inferior walls of the LV and portions of the LA
-supplies SA node 40% of the time
arteries
transport oxygenated blood from areas of high pressure to lower pressures in the body tissues
only exceptions:
- umbilican vein (in utero)
- pulmonary veins
arterial circulation is maintained by heart pump
influenced by elasticity and extensibility of vessel walls, and by peripheral resistance, amount of blood in the body
arterioles
terminal braces of arteries that attach to capillaries
primary site of vascular resistance
capillaries
include small blood vessels that connect the ends of arteries (arterioles) with the beginning of veins (venues)
form an anastomosing network
function for exchange of nutrients and fluids between blood and tissues
capillary walls are thin and permeable
veins
transport dark, unoxygenated blood from tissues back to the heart
larger capacity, thinner walls than arteries, greater number
1 way valves to prevent back flow
venous system includes both superficial and deep veins (deep veins accompany arteries while superficial ones don’t)
venous circulation is influenced by muscle contraction, gravity, respiration (increased return with inspiration), compliancy of R heart
lymphatic system
includes:
- lymphatics (superficial, intermediate, and deep)
- lymph fluid
- lymph tissues and organs (lymph nodes, tonsils, spleen, thymus, thoracic duct)
drains lymph from bodily tissues and returns it to venous circulation
major lymph nodes:
- submaxillary
- cervical
- axillary
- mesenteric
- iliac
- inguinal
- popliteal
- cubital
what order does lymph travel ?
lymph travels to lymphatic capillaries to lymphatic vessels to ducts to L subclavian vein
lymphatic contraction occurs by?
lymphatic contraction occurs by:
- parasympathetic, sympathetic and sensory nerve stimulation
- contraction of adjacent muscles
- abdominal and thoracic cavity pressure changes during normal breathing
- mechanical stimulation of dermal tissues
- volume changes within each lymphatic vessel
how does lymphatic system contribute to immune system function?
- lymph nodes collect cellular debris and bacteria
- remove excess fluid, blood waste and protein molecules
- produce antibodies
neurohumeral influences of cardiovascular system:
1- parasympathetic stimulation (cholinergic)
2- sympathetic stimulation (adrenergic)
3-additional control mechanisms
- baroreceptors (pressoreceptors) - control HR
- chemoreceptors -sensitive to changes in blood chemicals: O2, CO2, lactic acid
- body temperature
- ion concentration
4-peripheral resistance
parasympathetic stimulation
cholinergic
control located in medulla oblongata, cardioinhibitory center
via vagus nerve (CN X), cardiac plexus; innervates all myocardium; releases acetylcholine
slows rate and force of myocardial contraction; decreases myocardial metabolism
causes coronary artery vasoconstriction
sympathetic stimulation
adrenergic
control located in medulla oblongata, cardioacceleratory center
via cord segments T1-4, upper thoracic to superior cervical chain ganglia
- innervates all but ventricular myocardium
- releases epinephrine and norepinephrine
causes an increase in the rate and force of myocardial contraction and myocardial metabolism
causes coronary artery vasodilation
the skin and peripheral vasculature receive only postganglionic sympathetic innervation
-causes vasoconstriction of cutaneous arteries; -sympathetic inhibition must occur for vasodilation
drugs that increase sympathetic functioning= sympathomimetics
drugs that decrease sympathetic functioning= sympatholytics
baroreceptors
(pressoreceptors)
main mechanisms controlling HR
located in walls of aortic arch and carotid sinus; via vasomotor center
Circulatory reflex: respond to changes in BP
- increased BP results in parasympathetic stimulation, decreased rate and force of cardiac contraction; sympathetic inhibition, decreased peripheral resistance
- decreased BP results in sympathetic stimulation, increased HR and BP and vasoconstriction of peripheral blood vessels
- increased RA pressure causes reflex acceleration of HR
chemoreceptors
located in carotid body
sensitive to changes in blood chemicals: O2, CO2, lactic acid
increased CO2 or decreased O2, or decreased pH (elevated lactic acid) results in an increase in HR
increased O2 levels result in a decreased HR
neurohumoral influences: ion concentrations
hyper/hypo kalemia
hypo/hyper calcemia
hypo/hyper magnesemia
Hyperkalemia
increased concentration of potassium ions:
- decreases the rate and force of contraction
- produces ECG changes – widened PR interval and QRS, tall T wave
Hypokalemia
decreased concentration of potassium ions:
- produces ECG changes – flattened T waves, prolonged PR and QT intervals
- arrhythmias may progress to ventricular fibrillation
Hypercalcemia
increased calcium concentration
increases heart actions
Hypocalcemia
decreased calcium concentration
depresses heart actions
Hypermagnesemia
increased magnesium is a calcium blocker which can lead to arrhythmias or cardiac arrest
Hypomagnesemia
decreased magnesium causes ventricular arrhythmias, coronary artery vasospasm and sudden death
peripheral resistance
increased peripheral resistance increases arterial blood volume and pressure
decreased peripheral resistance decreases arterial blood volume and pressure
influenced by arterial blood volume: viscocity of blood and diameter or arterioles and capillaries
patient interview
Presenting symptoms:
- chest pain, palpitations, SOB
- fatigue
- dizziness, syncope
- edema
Positive risk factors
Negative risk factors
- high serum
- HDL >60 mg/dL
PMH:
- other diagnoses, surgeries
- meds
social history:
quality of life issues
- functional mobility
- ADLs, sleep
observation and inspection of skin color for possible signs of decreased CO and low O2 saturation
- cyanosis
- pallor
- diaphoresis
cyanosis
bluish color of the skin, nail beds, lips and tongue
related to decreased CO
pallor
washed out, absence of pink, rosy color
associated with decreased peripheral blood flow, PAD
diaphoresis
excess sweating and cool, clammy skin
non-modifiable risk factors for cardiovascular disease
Age:
- men >45
- women >55
Family history:
-cardiac event in 1st degree male relative pre-menopausal women
Modifiable risk factors for cardiovascular disease (goals to reduce risk)
Cholesterol:
- total: 40 mg/dL (men); >50 (women)
- Triglycerides:
physical exam for cardiovascular system
pulse
heart sounds
heart rhythm
blood pressure
respiration
oxygen saturation
pain
grading scale for peripheral pulses
0= absent pulse, not palpable
1+= pulse diminished, barely perceptible
2+= easily palpable, normal
3+= full pulse, increased strength
4+= bounding pulse