UNIT 3 - Cardiovascular Flashcards
What is the function of the cardiovasular system?
Transport system
for O2, nutrients, hormones, regulatory chems to all cells
trans CO2 and other products of metabolism from cells to lungs, liver and kidney,
distributes heat from inside body to extremities
What does the circulatory consist of?
Which way is blood carried in veins, arteries and lymphatic vessels?
Consists of
- heart (pump)
- vessels (distribution system)
- Blood (transport fluid)
Arteries carry blood AWAY
Veins carry bloog TOWARDS
Lymphatic carry tissue fluid to lger veins
Where are the location of the heart in dogs,
K9 - 3rd-6th intercostal space
Forms 45 degree angle w/ sternum but varies in breeds
Deep chested breeds have LGer angle, Barrel chested breeds have lower angle
Where is the heart loc in cats?
Fel - up to 1+ IC space
Extends from 3/4 to 6/7 IC space
Forms an acute angle so has increased sternal contact compared to dogs
Where is the heart loc in equine/bovine?
- -1 iC space
heart is asym -mostly on L side of thorax
loc from 2-5th IC space
apex is level of point of elbow
bovine os cordis within the heart to support valves
What are the three heart layers?
Pericardium
myocardium
endocardium
Explain what the pericardium layer is
The thin fibro-serous covering of the heart
outermost layer, extends to diaphragm and covers major blood vessels at heart base
serous pericardium lines fibrous pericardum to make the parietal layer, the visceral layer cont. over the vessels and the heart
fluid filled space between these layers is pericardial space/cavity
Explain the myocardium heart layer
The muscle layer
lies between visceral pericardium and endocardium
Explain the endocardium heart layer
The thin membrane covering the Internal surface of the heart
What is the alt names for tricuspid and mitral valve?
R AV valve
L Av valve
What does the use of chordae tendinae prevent in the hear?
Prevents valves from flipping into atria when the vents contract
The AV valves closes and blood in vent pushes the valve leaflets together so blood must leave by aortic or pulom trunk
What do the two semi lunar valves do?
Prevents blood from returning into vents when vents relax
What makes veins and arteries different from each others?
Arteries send blood away, thicker and muscular, does not have valves
Veins carry blood towards, thinner, more superficial, contain valves where 2+ veins unite to make a bigger one
Explain fluid balance in the cardiovascular system
Drives a constant circulation of the ECF
Blood pumped into caps, fluid forced out of arterial end by hydrostatic pressure generated by heart = filtration, only water + sml molecules get through these gaps in cells
Fluid reabsorbed into caps at venule end - hydrostatic pressure low, plasma proteins more conc. their osmotis pressure draws water back in, oncotic pressure generated by molecules too lg to escape cap pores
Explain blood flow, how it starts and ends
Unox blood from tissues -> veins -> cranial/caudal vena cava -> R atrium -> R AV valve -> R vent -> Pulmon semilunar valve -> Pulmon trunk -> R + L pulmon arteries
OX blood to body - > L + R pulmon veins -> L Atrium -> L AV valve -> Left vent -> Aortic semilunar valve -> Aorta -> arteries -> body tissues
What are the colors of unox blood and ox bloo?
Dark red = Un ox
Bright red = Ox
What are the two branches from th aortic arch?
Brachiocephalic trunk to supply head + R thoracic limb.
- branches off for common corotid artery to supply head and R subclavian artery to supply R thoracic limb
L Subclavian artery to supply L thoracic limb which will continue to axillary arteries to brachial arteries to median arteries
What are the rest of the body supplied by the descending aorta? list the arteries and what they supply
Celiac artery - unpaired, starts caudal to diaphram and splits to
- Hepatic - liver
- L gastric artery - stomach
- Splenic artery - spleen
Cranial mesenteric artery- unpaired, caudal to celiac artery supply most of intestines
Renal - paired, kidneys
Gonad arteries - paired, testes/ovaries, caudal to renal
Caudal mesenteric artery - unpaired, descending colon
Iliac art - pelvis and pelvic limg
INT iliac - paired, branch caudal to ext iliac and supply gluteals
Medial sacral art - unpaired, supply tail
Explain the k9 hindlimb arteries
Ext iliac arteries - paired, continue down pelvic limb as femoral art, popliteal art, and cranial tibial art
Explain what the cranial and caudal vena cava veins drain from the body
Cranial - returns blood from head + thoracic limbs, formed by convergence of L + R brachiocephalic veins
formed by ext and Int jug veings from head + subclavian veings from thoracic limbs
Caudal - returns blood from pelvis, pelvic limbs, abdomen, thoracic cavity
Common iliac veins - pelvic limbs
Gonad vein - R side caudal to renal veins, L side joins renal vein prior to draining into caudal vena, drain testes/ovaries
Renal - kidneys
Portal vein - trans blood from spleen + digestive tract to liver
hepatic - liver
Azygous - thoracic and abdominal cavities
Explain the hepatic portal circulation
Portal circulation carries blood from caps of one organ to caps of another
Blood from caps of stomach, spleen, intestines, and pancreas enter mesenteric, gastroduodenal and splenic veins and are collected in hepatic portal vein which are then trans to liver where blood enters sinusoids(lg caps)
Once in liver, can be modified or stored for future use, also for detoxification from digestive tract
Passed from sinusoids into central veins of each liver lobule and from hepatic veins and empty to caudal vena
Explain fetal circulation
Circulates thru placenta. CO and waste in fetal blood exchanged for O2 and nutrients from blood of mother
Lungs are collapses and resistant to blood blood
blood diverted through hole btw atrea called foramen ovale
artery directly connects pulmon trunk to aorta thru ductus arteriosus
Blood returns from placenta to fetuc thru umbilical vein that passes abdomen, thru ductus venosus to bypass liver and drains thru caudal vena
Describe at birth fetal circulation
Air expands in lungs to make blood flower easier
Foramen ovale + ductus arteriosus close by muscle contraction and later fibrosis.
Attachment to placenta is lost, umbilical arteries and veins atrophy and ductus venosus closes
Which circulation is highpressure, lowpressure and why?
Systemic is high bc it requires hydrostatic pressure to force blood thru caps in tissues and to pump against gravity
pulmon is low bc little resistance in vessels of lungs and can easily get fluid leaks in caps if pressure too high
What is the total blood volume distribution out of 100%?
lungs 15
body has 80
heart 5
What is systole and diastole defs
Systole - contract of vent and ejection of blood
diastole - relax of vent and heart fills
what is the definitions of systolic and diastolic blood pressure, pule pressure and peripheral/systemic resistance
Systolic BP - max pressure in arts during vent CONTraction
Diastolic BP - MIN pressure in art during vent RELAXation
Pulse pressure - diff btw systolic and diastolic pressure
Peripheral or systemic resistance - friction in arts that limit flow of blood
What are the defs of contractility, aferload, preload and stroke volume
Contractility - hearts ability to contract
Afterload - Force the vents need to overcome to push blood forward
preload (aka end diastolic volume) - amount of blood in heart b4 contractionWh
stroke volume (systolic discharge) - amount of blood ejected out of heart with vent contract.
What are the definitions of cardiac output and starlings principle? What is the formula for CO?
CO - volume of blood heart is able to pump forward in 1 minute
CO = SV x HR
Starlings principle - increased contractility of cardian muscle if fibers are stretched - more blood in vents = stronger contract
(if preload increased, then contractility increased)
What is cardiac output affected by?
Preload - determined by ven filling (end diastolic volume) affected b leaking semilunar valves or incomplete emptying due to poor contractility
contractility, afterload, hR
What determines contractility?
Preload
sympathetic stimu - inc contract
Blood + tissue Ca conc
Drugs - digoxin improves contractility
Afterload + peripheral resistance - resistance against vent pump, the tone in art system, is BP, affected by sympathetic NS (vasoconstriction in Gi, skin, renal) parasympathetic NS (vasodilation), by local mediators, reducing after load with vasodilations beneficial to heart failure
What is HR controled by?
Body temp - decreased temp = decreased Hr
Autonomic NS - cardio-regulatory center in medulla oblongata in brainstem that recieves input from baroreceptions in vessels and hart chambers
What is the cardiovascular center in medula? How does It work? What does it do?
If pressure drops, feedback inc sympathetic stim with release of norepinephrine to inc HR and contractility
- norepinephrine + epinephrine also released as hormones by adrenal medulla w/ similar affects
sympathetic stim also inc BP thru vasocontrict
If pressure rises, feedback inc parasympathetic tone thru vagus nerve to reverse the above
Vagus nerves innervate Sa and AV nodes to stim release of Acetylcholine to slow rate of depolarization to decrease Hr
Atropine blocks ACh to correct low HR
What are some other factors that can affect HR
Hormones - sympath stim to adrenal gland causes release of epineprhine to inc SV by inc contractility
increased thyroid will inc HR
- decreased T4 will decreased HR - low Hr are signs of hypothyroidism
Ion lvls - hyperkalemia (excess K) decreased hR
How does shock affect the cardiovascular system?
Defined as failure of tissue perfusion
Some types of shock, vessels dilate to volume that exceeds that of blood
= fall in BP
Systolid BP < 40 is incompatable with life
body tries to maintain flow thru vital organs like brain/heart and may shut down peripheral circulation, treatment with high IV fluid rates
What is isovulumetric contraction, ventricular ejection definitions?
Iso - just br actual pumping forward of blood, vents contract but all valves are closed and pressure in vents increases
Vent eject - semilunar valves open and vents empty
What are the 4 heart sounds of the heart?
s1 - closing of AV valves during vent cont. (lub)
s2 - closing of semilunar valves end of vent cont (dub)
s3 - Passive filling of vent
s4 - atrial contraction
Describe the cardiac cycle and what happens, what heart sounds are heart
- Atrial contraction (S4)
- Ventricular contraction
- AV valves close (S1)
- Pressure develops, opens the semilunar valves
- Blood ejected into major arteries which distend
- Ventricles relax
- Semilunar valves close (S2)
- Ventricles passively fill with blood as AV valves open
(S3)
S4S1 S2S3 S4S1 S2S3
Describe the conduction system of the heart
netowrk of specialized cardiac muscle cells that generate action potentials to initiate contraction
propagate the action pots in a coordinated spread of cardiac muscle cell excitation
Action pots are depolarized of the resting membrane pot due to influx or efflux of ions - Na, K, Ca (minor change in serum K or CA had effects on contraction)
Repolar req. pumping ions back to original conc to re-establish resting membrane pot
Describe the SA node and what it does
Small mass of cells in R atrial wall near cranial vena cava
Depolarize spontaneously at rate of 100bpm in humans
modified by input from autonomic NS (decrease resting HR to 70 bpm in humans)
pacemaker bc depolarizes faster than any other part of heart
What is the sequence of activation in the heart?
Sa node spontaneously depolarizes, signals both atria -. contract upper atriad down to squeeze blood into vent -. impulse hits band of nonconducting fibrous tissue only passed thru AV node
AV node slow conduction for atria to finish filling vent before contract, -> signal along L + R bundle of his quickly to apex -> purkinje fibre radiate upward to spread thru vent muscle -. contract wave thru vent at septum to pap muscles to base, squeezing blood upward out of pulmon + aortic valvesW
What is the refractory period
After cont, cell must relax
during relax, cell cannot contract and cannot respond to another stimuli
important for reffling of heart chambers and prevents tetanic contract and arrhythmia
What is an electrocardiogram
electrical impulse is predicatable in both magnitude and direction in a healthy heart
Can measure relative magnitude + direction of the depolarization of heart muscle
What are the waves of an ECG? What do they signal?
P-wave: Depolarization (contraction) of atria
QRS complex: Vent depolar (contract) - Atrial repolar (relax) is hidden by QRS complex
T-wave: Vent repolar (relax)
What is sinus arrhythmia
A consistently (predicatbly) irregular rhythm that changes w increased rate of inspire and decreases with expire
Normal, in dogs
What is tachycardia and bradycardia?
Rat is father than normal
Rate is slower than normal
What can bradyarrhythmia be?
Sinus bradycardia
Sinus arrect
AV block
What can tachyarrhythmia be?
Supraventriular - signal for depolar originates above AV junction
Ventricular - Signal for depolar originates below AV junction, in vents
What is atrial fibrillation?
- Rapid cont of atria in uncoordinated maner
Very rapid ineffecive atrial rate
vent conts are irregular, slower bc av node only stimmed sporadically and refractory to impulse that arrive close together
What is ventricular fibrillation?
Rapid contract of vent in smll portions of vent wall at any time
Very rapid ineffective vent rate that produce NO PULSE
will die quickly without CPR or electrical defibrillation immediately
What is a heart murmur
An abnormal sound by turbulent blood flow
Can be during systole caused by a leak in AV valve (closed), narrowing (stenosis) of semilunar vale (open) or turbulence as normal feature of blood flow in lg animals (flow murmur) or during diastole of insufficient of semilunar valves or stenosis of av valves
What does the pulse rate and pulse pressure equal?
Pule R = # of vent contracts /min
Pulse pressure is diff btw systolic + diastolic pressure
What is patent foramen ovale?
When foramen ovale fails to close so blood still passes thru atriums, unless its lg opening, no clinical signsW
What is Ventricular septal defects?
rang from sm to complete absence of septum where blood Is transmitted btw vents with considerable force, usually left to right
What is persisten ductus arteriosus?
When the ductus arteriosus fails to close at birth
Can cause a continuous murmur
What is persistent R aortic arch?
Embryonic vascular arch persists and dis places esophagus and sometimes trachea to the left, traps them in a ring formed by arch of aorta on right, pulmon art below and base of heart ventrally and ductus arteriosus dorsally and to the left.
Ring compresses trachea and esophagus = dyspnea and regurgitation
What is pulmonic stenosis?
narrowing at or below pulmon semilunar vvalve
produces systole murmur
What is aortic stenosis?
narrowing of region of outflow of left vent, difficulty emptying
What is tetralogy of fallot?
Complex malformation consisting of pulmon stenosis, intervent septal defect, malpositioning of aorta + R vent hypertrophy
What is Lsided heart failure?
congestive heart failure
back pressure inc pressure at venous ends of pulmon caps that forces fluid out in lungs and causes edema.
Exercise tolerance decr, dyspnea w/ exercise + excitement, lung congestion + coughing
What is R-sided heart failure
Fluid unable to get out of organs so organs swell and decr function
jug veins engorge and superficial veins distended
liver + spleen enlarged
fluids build up as ascites, hydrothorax and sQ edema
What is generalized heart failure?
When both L + R heart failure occur and most/all symptoms seen
Failur of 1 will = generalized failure eventually
What are some aquired cardiovascular diseases?
Dilated cardiomyopathy
Mitral insufficiency
parasites (strongylus vulgaris in horses, dirofilaria immitus (heartworms) in dogs
What is dilated cardiomyopath?
Coughing, weakness, collapse, weightloss, murmur, arrhythmias
