The Cardiovascular System Flashcards
features of intercalated discs
interdigitating folds, mechanical junctions, electrical junctions. Because of these features the entire collection of cardiac myocytes act simultaneously. This way the heart contracts as a unit.
hypertension
high blood pressure. Normal newborn 90/55 and adults 120/80. Adults- hypertension starts at 130/80 and higher. Can lead to myocardial hypertrophy, coronary artery disease, and damage to endothelium
pericarditis
inflammation of the pericardium, due to a decrease or absence of serous fluid. This condition can be caused following bacterial pneumonia
Cardiac tamponade
increased pressure in the pericardial sac due to these fluids, which impedes or stops a beating heart
angina
chest pain due to ischemia (deficient blood delivery to the heart muscle caused by transient spasm of coronary arteries)
commotio cordis
sudden cardiac death secondary to low impact blunt trauma to the anterior chest wall. Rare, but is the second most common cause of sudden cardiac death in athletes
Systemic circuit of the heart
left heart pumps blood to circulate throughout body, this side works harder (walls of ventricle are 2-3 times thicker)
pulmonary circuit of the heart
right heart pumps blood to lungs (loads 02 and unloads CO2
AV valves
atrioventricular valves, dense CT covered by endocardium. Regulates the openings between the atria and ventricles. Right- tricuspid, Left- bicuspid
semilunar valves
regulate flow of blood from the ventricles into the great arteries. Pulmonary- controls the opening from the rt ventricle into the pulmonary trunk, aortic- controls the opening from the left ventricle into the aorta
SA node
sinoatrial node (pacemaker). increases the contraction rate of the individual cardiac cells (100 beats/min)
Sinus rhythm
normal heart rate
AV node
atrioventricular node, depolarizes at about 50 beats/min. Picks up the signal from the SA node and sends the signal to the bundle of His/AV bundle with depolarizes at about 30 beats/min
systole
contraction of the heart (the top number in BP)
diastole
relaxation of the heart (the bottom number in BP)
ectopic focus
and region of spontaneous firing other than the SA node
nodal rhythm
this is the most common ectopic focus, this is where the AV node produces a slower heart rate (about 40-50 bpm)- Bradycardia
pacemaker potential
at -40mV, fast Ca2+ channels open and Ca2+ flows in from the ECF. This produces the rising or depolarization of the action potential to about +10mV
ECG
p wave- atrial depolarization, QRS complex- on set of ventricular depolarization, t wave- ventricular repolarization
The cardiac cycle- Atrial systole/Ventricular diastole
SA node depolarizes causing atrial depolarization (P wave), atrial systole- atrial contraction forces blood into ventricles, atrial systole- continues forcing more blood into the ventricles, QRS complex marks onset of ventricular depolarization
Ventricular systole/Atrial Diastole
isovolumetric contraction- ventricles start contracting, increasing ventricular pressure, AV valves are forced close. Pressure continues to increase while volume remains unchanged; Ventricular ejection- ventricular pressure surpasses aortic/pulmonary trunk pressure. Semilunar valves open and blood is ejected from ventricles. As blood volume drops in the ventricles, interventricular pressure drops. Blood remanding gin the ventricles is called end-systolic volume (ESV). T-wave marks ventricular repolarization
Relaxation period
ventricular diastole- the aortic/pulmonary trunk pressure surpasses ventricular pressure surpasses ventricular pressure causing the semilunar valves to close. The dicrotic wave/notch is created by the rebound of blood filling the semilunar valves cusps. At this time all four valves are closed, this is know as isovolumetric relaxation. As the ventricles continue to relax, pressure rapidly falls below the atrial pressure. AV valves open and ventricular filling begins again.
EDV (End Diastolic Volume)
amount of blood in ventricle at end of diastole (rest) , ventricles are full
ESV (End Systolic Volume)
amount of blood in ventricles at end of systole (contraction), Ventricles are almost empty
SV (stroke volume)
amount of blood from one ventricle in one heartbeat (typically 70ml/beat)
Cardiac reserve
the difference between the rate at which the heart pumps blood and its maximum capacity to pump blood. Can be a health indicator. Declines with age, however, it can be improved with exercise.
Pulse pressure
systolic pressure minus diastolic pressure
ejection fraction
the % of EDV ejected from ventricle
overview of volume changes
right ventricular output greater than left ventricle= fluid in lungs, left ventricular output greater than right ventricle= fluid in body (extremity edema)
tunica interna
the endothelium that lines the lumen of vessels. Consists of simple squamous epithelium
tunica media
the middle layer of the vessel, consisting of elastic fibers and smooth muscle
tunica externa
the outer most layer, consisting of elastic fibers and collagen fibers
elastic arteries
conducting arteries, the largest diameter arteries (aorta, brachiocephalic, common carotid arteries). The tunica media consists of a large proportion of elastic fibers, which propels blood onward during diastole
muscular arteries
distributing arteries, the medium sized arteries (brachial and radial) with a much higher percentage of smooth muscle in the tunica media. The smooth muscle allows for great vasoconstriction and vasodilation
arterioles
resistance vessels, very small arteries that deliver blood to capillaries. Regulate resistance to blood flow
capillaries
exchange vessels, microscopic vessels found between arterioles and venules, consisting of a single layer of endothelial cells and a basement membrane.
metarterioles
connect arterioles to capillary beds. Contain smooth muscle to contract or relax to regulate blood flow through the capillary beds
precapillary sphincter
connect metarterioles to true capillaries and can also contract or relax to regulate blood flow
continuous capillaries
the endothelial cells form a continuous tube with the exception of intercellular clefts for gas and nutrient exchange. Found in skin, skeletal/smooth muscle, CT, and lungs
fenestrated capillaries
the endothelial cells from many fenestrations (holes) which are larger than intercellular clefts. Found where active capillary absorption of filtrate occurs and in organs such as the kidneys, SI, and endocrine glands
sinusoids
capillaries; the endothelial cells are very loosely attached forming very large openings to allow large substances like proteins or RBCs to pas through. Found in red bone marrow, liver, spleen, pituitary, and parathyroid gland
venules
small veins that accept blood from several capillaries. Consist of a tunica interna and a thin tunica media.
veins
consist of the same layers found in arteries, however the layers are much thinner. Veins of the limbs have one-way valves (folds of tunica interna)
blood distribution
40% of our total blood supply is located in the arteries, arterioles, pulmonary vessels, heart, and capillaries. 60% of the total blood volume is located in the veins and venules (blood reservoir)
BPH
blood hydrostatic pressure, pressure placed on blood from ventricular systole
Capillary exchange
diffusion, transcytosis, bulk flow (filtration and reabsorption)
IFOP
interstitial fluid osmotic pressure, osmotic pressure placed on blood from interstitial solutes
BCOP
blood colloid osmotic pressure, osmotic pressure placed on blood from solutes in the blood plasma (albumin)
main factors influencing BP
blood volume, cardiac output, peripheral resistance
what influences blood resistance
blood viscosity, vessel length, vessel radius
SNS NTs acting on the heart and blood vessels
Epinephrine/norepinephrine, ADH, Aldosterone
PNS NTs acting on the heart and blood vessels
acetylcholine
cerebral circulation
feeds the brain blood
coronary circulation
feeds the myocardium blood
anastomoses
an alternate pathway for blood flow, are often found for important organs, such as the brain and heart
hepatic portal circulation
runs from the digestive tract to the liver via the hepatic portal vein
pulmonary circulation
moves blood between the heart and lungs
