ch 18 cardiovascular system- the heart 1/28 Flashcards
what is the hearts purpose
to pump and circulate blood throughout the tissues and to the lungs
pulmonary circuit of blood circulation
any of the blood vessels that carry blood to and from the lungs
pulmonary arteries
pump oxygen poor blood from the right side of the heart to the lungs to become oxygenated
pulmonary veins
pump oxygenated blood from lungs to left side of heart
which side of the heart is the pulmonary circuit on
right side. bc it pumps blood out to lungs
system circuit of blood circulation
any blood vessels that carry blood to and from the body tissues, like skeletal or skin
where does oxygenated blood leave the heart through to go to body tissues?
aorta
where does oxygen poor blood return to the heart?
superior and inferior vena cavas
what side of the heart is the systemic circuit on ?
left side, pumps blood out via aorta and oxygen gets used by tissues to then return to right side by pre/post vena cava
what is the difference between the 2 sides of the heart even tho they pump same blood volume per minute (roughly)
the pressure of the sides
right vs left side of heart and the corresponding pressure
right- low pressure, thinner walls for less contracting bc its to the lungs, so its not going very far therefore low pressure needed
left- high pressure, a lot of muscle tissue needed bc this blood goes out to entire body tissues, more pressure needed. Thick walls
gross anatomy of heart- where is it tipped
inferior tip of heart points to left hip, its tipped in the thoracic cavity- its how blood vessels attach the tip allows the flow to be more open and steady
heart is covered in
pericardium
fibrous vs serous pericardium
fibrous- outermost portion, thick and tough anchors heart in chest cavity and protects it sp bacteria can’t seep in
serous- internal portion, which is divided into visceral and parietal layers, then fluid filled sacs around heart. allows 2 layers to not rub directly agains each other
epicardium
outermost layer, visceral layer of pericardium
myocardium
middle Layer with cardiac muslce cells
MOST important and thickest heart wall, helps to generate contractions
endocardium
innermost layer, produces slick layer that covers all internal heart surfaces. allows heart to relax a bit every time it contracts and not rub against blood n heart directly
heart chambers
4 chambers, 2 atria
atrias are
superior receiving chambers, blood enters here first
right atrium
receives oxygen poor blood from systemic circuit, blood enters precava, postcava, and coronary veins
left atrium
receives oxygenated blood from lungs, so blood can enter pulmonary veins (there r two of these veins bc there’s 2 lungs)
atria features
pectinate muscle- increases contractile force of atrium without thickening atrium walls, generates the forces
auricle- two ears that sit on external surface of heart, allows atriums to receive more blood
ventricles are
inferior pumping chambers, move the pulmonary and systemic circuits and generate the most force. contractions begin at the Bottom apex, to the top of ventricle
why is it necessary for contractions to begin at bottom of heart to the top
bottom up bc blood vessels leave at the top and allows blood to move up to vessels.
right ventricle
pumps oxygen poor blood to lungs
pulmonary trunk
artery, pumps from the heart to the lungs, oxygen poor blood
left ventricle
pumps oxygenated blood to rest of body
aorta
pumps from heart to body tissues with oxygen rich blood
ventricle features
trabecular carneae- ridges of muslce that assist with proper heart valve functioning, helps control valve open and close
papillary muscle- assists in opening and closing the heart valves
what exactly is the blood cycle (very detailed)
oxygen poor blood goes to right atrium via pre and post vena cava, right atrium contracts to right ventricle, then right ventricle contracts pushing blood up to pulmonary trunk. blood then flows up and out to lung tissue where blood gets oxygenated. blood returns back to heart, return to pulmonary veins to left atrium, contracts, pushes to left ventricle. then goes up aorta, travels through aorta out to body tissue (systemic) so tissues steal oxygen and now blood is oxygen poor again to right atrium.
heart valves
prevents backward flow of blood through the heart
atrioventricular valves (AV)
prevents back flow of blood from ventricles to atria, separates the two tricuspid and mitral valves
2 valves in AV valves
tricuspid valve (right side) and bicuspid or mitral (left side)
AV valve features
chordae tendinae- anchors valve to papillary muscle in the ventricle, only important valves get closed. and papillary muscles take up slack of chordae tendinae, preventing AV valves from flipping into atria
SL valves, semilunar
prevents back flow of blood from blood vessels into ventricles, tissue flaps like half moon
what r the SL valves
aortic semilunar valve- sits at base of aorta
pulmonary semilunar valve- sits at base of pulmonary trunk
heart murmurs
condition caused by dysfunctional heart valves, regurgitation of blood, can be congenital or develop later
stenosis
valves don’t allow enough blood to get through valve. general term for abnormal narrowing, the stiff heart valves don’t open or close easily
what sound does abnormal vs normal heart sound like
lub dub is normal, lub woosh dub is abnormal bc blood flows back a bit
are murmurs always dangerous?
no but can indicate other dangerous heart conditions, children it can indicate congenital heart disease and adults it can indicate acquired heart disease
which valve is more likely to have a heart murmur
bicuspid/mitral
what happens in a heart attack
coronary arteries can be blocked which will stop blood flow to the chest
coronary circulation, systemic circuit q
blood supply that provides blood w nutrients, heart walls are so thick but oxygen has to diffuse
left n right coronary arteries supply
left and right corresponding sides of heart
coronary veins
drain oxygen poor blood into right atrium, usually in back of heart drains to coronary sinus
do the blood in the chambers actually help the heart?
nO!
cardiac muslce cells, myocytes
contract to propel blood through heart, contract at a rhythm to push blood between 2 circuits. these myocytes are connected to each other
how are plasma membranes connected
intercalated discs, have desmosomes and gas junctions. cellular velcro!
functional syncytium
muslce cells contract simultaneously, allowing heart to function as a single unit to allow flow at the right time
why is it important to have 25-30% of mitochondria in myocyutes
muslce cells always need ATP fir function, aerobic mechanisms produce so much ATP in the mitochondria, to prevent fatiguing. a heart with no fatigue means it won’t stop beating! good
2 most important cardiac muslce cells
pacemaker cells- noncontractile cells that spontaneously depolarize, they tell cardiac cells what to do, by generating AP cells which depolarize with no NS influence- brain won’t control heartbeat directly
contractile cardiac cells- depolarize in response to depolarization of pacemaker cells, rhythmic to propel the blood
pacemaker cells do what how
AP initiation is in 3 steps- pacemaker potential, depolarization, depolarization.
pacemaker potential in pacemaker cells (step 1)
slow depolarization, Na+ channels open K+ close, Na+ enters and makes membrane potential decrease, and slowly climbs until -40 (threshold potential). Ca+ opens at -40 and enters, depolarizing at AP sending message to contract. resting membrane potential is -60 but not for long bc its always beating
depolarization of pacemaker cells
Ca2+ channels open at threshold potential (-40) and Ca+ rushes in, creating AP. AP is short lived, at 0 Ca2+ closes and won’t enter. K+ opens and K+ leaves so once K and Ca are gone, membrane potential is more negativ
repolarization of pacemaker cells
Ca2+ Channels close, K+ open and K+ leaves, continues until resting membrane potential, once that is reached steps will repeat. this happens 72-75 bpm bc hear beats that many times
pacemaker cells are found in
the 5 nodes, which communicate by spreading depolarizing events
sinoatrial nodes (SA)
primary pacemaker of heart, embedded in upper right atrial wall, generates 75 impulses/min, this determines the rate of the next 4 nodes, eventually it will reach the AV node
atrioventricular (AV) node
found at bottom of right atrium in intertribal wall, generates 50 impulses/min which divides atria, delayed by 0.1 second, alliowing atria to completely contract and push blood down to ventricles!
what would happen if the SA node stopped?
AV node takes over at slower rate, so heart will beat slower which Is not good
atrioventricular (AV) bundle (bundle of his)
AV sent here from AV node, found in inter ventricular septum, divides node bc impulses from AV node travels, the ONLY place where atria and ventricles are electrically connected, the 2 branch bundles depolarize at like 50 bpm allowing APs to get to bottom of heart.
bundle branches
right and left branches in wall that divides ventricles, helps conduct impulses towards apex of heart
subenocardial conducting network (purkinje fibers)
found at heart apex, along outer ventricle walls, depolarizes contractile cells of both ventricles, more elaborate on left side than right. this is bc pumping chambers on left side move blood more than right, also difference in wall thickness. depolarizes at 30-35 per minute
autonomic NS in automatic innveration of heart
innervation slightly modifies the intrinsic built in conduction system created by pacemaker cells.
where are cardiac centers found
medulla oblongata
cardioaccelatroy center
sympathetic division, fight or flight, postgang fibers innervate SA/AV nodes, heart muscles, coronary arteries. more blood is moved, depolarize happens fast, HR increase
cardioinhibitory center
parasympathetic divison, rest n digest, via vagus nerve (only cranial nerve to go below brain into body), postgang motor neurons in heart wall innverate SA and AV nodes. more active in resting
