Exam 2 Flashcards
The heart has _ Chambers
4
The heart pumps blood through what circuts?
pulmonary and systemic circuits
where does the right side of the heart receive blood from? where does it pump it to?
Receives oxygen poor blood from body tissues. Pumps it to the lungs
Does the R side of the heart receive O2 poor or rich blood?
oxygen poor blood
Does the L side of the heart receive O2 poor or rich blood?
oxygen rich blood
where does the left side of the heart receive oxygen from? where does it pump it to?
receives oxygen rich blood from the lungs and pumps it out to body tissues
the heart is the size of the
FIST
the heart is found in the
mediastinum of the thoracic cavity
the base of the heart is directed to
the right shoulder
the apex of the heart is directed to
the left hip
the heart is enclosed in a double-walled sac called the
pericardium
fibrous pericardium is
tough, superficial protection
serous pericardium produces
serous fluid
serous paricardium layers
1) parietal layer- outer
2) visceral layer (epicardium) - inner
Layers of heart wall
epicardium- outer
myocardium- middle
endocardium- inner
Epicardium
the visceral serous pericardium
the thick myocardium consists of mainly
cardiac muscle- the thickest layer of the heart wall
endocardium
+what is it made up of
-thin lining of the chambers
-simple squamous
partitions seperate the heart….
longitudinally (L from R)
the interartial septum seperates
the top chambers
the interaventricular septum seperates
the large inferior chambers
the right and left atria are
recieving chambers; holds blood and then pushes it to ventricles
three large veins (name them) enters the…
enters the R atrium
1) superior vena cava
2) inferior vena cava
3) coronary sinus- returns blood from the heart wall
four pulmonary veins enter the… from where??
Left atrium from the lungs (w o2 rich blood)
the ventricles are the __ chambers
discharging
the right ventricle pumps blood
into the pulmonary trunks->to lungs
the left ventricle pumps blood
(to where and then to where)
into aorta–> body tissues
heart valves make blood flow in….
one direction
there are two atrioventricular (AV) valves one at each..
atrial-ventricular junction
L A-V Valve=
Bicuspid valve= Mitral
R A-V Valve=
Tricuspid Valve
AV valves prevent
backflow of blood to the atria
When the ventricles are relaxed, the AV valves…
hang open
when the ventricles contract…
blood is pushed up against the (AV) valves and shut them (“Lub” sound S1) SYSTOLE
Each flap of the AV valves are anchored to
chordae tendinea (strings) teathered to papillary muscle
Aortic and semilunar (SL) valve are located at the
base of the arteries
Aortic and semilunar (SL) valve are located at the base of the arteries exciting the heart and prevent
backflow to ventricles when ventricles relax (diastole)
when ventricular pressure rises above pulmonary and aortic pressure…
the semilunar valves open and blood flows to artery
When the ventricles relax, blood briefly flows back to the heart….
slight start of back flow shuts semilunar valves (S2 sound “dup”)
There are no valves at the entrances of the
vena cava or pulmonary veins
blood flows into the atrium then to
the right side of the heart pumps blood into the
pulmonary circuit
blood flows into the atrium then….
the left side of the heart pumps blood into the
systemic circuit
Equal volumes of blood are pumped to the pulmonary and systemic circiuts at the same time but…(wall thickness)
The R ventricular wall is thinner than the L ventricular wall because the L ventricular wall has to pump against more resistance
The R ventricular wall is thinner than the L ventricular wall because
the L ventricular wall has to pump against more resistance
(Coronary Circulation)
The heart receives little or no nourishment from the blood
passing through the chamber
(Coronary Circulation)
The heart receives little or no nourishment from the blood passing through the chamber SO
a series of vessels, the coronary circulation, exists to supply blood to the heart itself
(Coronary Circulation) The heart receives little or no nourishment from the blood passing through the chamber SO a series of vessels, the coronary circulation, exists to supply blood to the heart itself
What supplies the blood?
The Left and Right coronary arteries
Intercalated discs connect
cardiac muscle fibers into a functional unit
Microscopic Anatomy:
Cardiac muscle is
striated, contract with sliding filament
Microscopic Anatomy:
Cardiac cells are
short, fat, branched, 1 or 2 nucleus per cell
Intercellular space is filled with
a matrix of loose connective tissue
Intercellular space is filled with a matrix of loose connective tissue that connects
the muscle to the cardiac skeleton
cardiac cells are connected to eachother at
intercalated discs
intercalated discs contain
-desmosomes for mechanical coupling
-gap junctions for electrical coupling
Cardiac muscle cells have
-Large mitochondria: occupies 25-35% of cells total volume
-Have myofribrils arranged in sarcomeres
Some cardiac cells are self excitable and….
start their own depolarization. these (through gap junctions) excite the rest of the heart
all fibers of the heart contract….
as a unit or not at all because unlike skeletal muscles motor units, gap junctions electrically tie all cardiac muscle cells together
the hearts cell action potentials and absolute refractory period is longer than…
preventing…
a skeletals muscles, preventing tetanic contractions
caridac muscle has more mitocondria than…
indicating…
skeletal muscles
indicates reliance on aerobic respiration
pacemaker cells trigger action potentials throughout…
the heart
Setting the basic rhythm: the intrinsic conduction system
The heart does not rely on the
nervous system to provide stimulation
Setting the basic rhythm:
the intrinsic conduction system consists of cardiac pacemaker cells that instead of having a stable resting potential have a
pacemaker potential
Setting the basic rhythm: the intrinsic conduction system
What is a pacemaker potential?
a gradual depolarization ( caused by special ion channels) that reaches threshold for action potentials- depolarizing phase Ca++ entry and polarizing K+ exit
impulses pass through the cardiac pacemaker cells in the following order: sinoatrial node
a) SA node in R atrium- quick pacemaker starts the beat
b) AV node at bottom of interatrial steptum near top of interventricular septum
c) AV bundles splits to bundle branches in interventricular septum
d) bundle branches divide to give subendocardial conducting network (purkinje fibers)
Modifying basic rhythm: Extrinsic innervation of the heart
The ANS modifies the heartbeat through
cardiac centers in the medulla
cardiac centers in the medulla
a) the cardioacceleratory center
projects to the sympathetic neurons that increase heart rate and contractile force
cardiac centers in the medulla
b) the cardio inhibitory center
projects to parasympathetic neurons that decrease HR through the vagus nerve
Action potentials in the contractile cardiac muscle cells are generated by the following mechanisms
- When cardiac muscle cells are stimulated through their gap junctions
through their gap junctions their volt gated Na+ channels open and Na+ enters so the cell depolarizes
Action potentials in the contractile cardiac muscle cells are generated by the following mechanisms
- Depolarization then opens slow
Ca++ channels and so Ca++ enters produces plateau phase of the AP
Action potentials in the contractile cardiac muscle cells are generated by the following mechanisms
- after roughly 200msec
Ca++ channels close, K+ channels open. K+ leaves cell and so cell depolarizes
An electrocardiogram..
monitors and amplifies the electrical signal of the heart
A typical EKG has 3 deflections
1) P-wave: atrial depolarization
2) QRS wave: ventricrular depolarization
3) T-wave: ventricular repolarization
the cardiac cycle describes the
mechanical event associated with blow flow through the heart
systole is the
contractile phase
a cardiac cycle consists of a series of
pressure and volume changes in the heart during one heartbeat
during mid and late diastole , ventricular filling occurs
as blood flows passively into the ventricles
What branches from the L coronary artery?
-Anterior interventricular artery
-circumflex artery
What part of the heart does the anterior interventricular a. serve?
front of ventricles
What part of the heart does the circumflex serve?
L atrium and back of L ventricle
What branches from the R coronary a.
-R marginal a.
-posterior interventricular a.
What part of the heart does the right marginal a. serve?
R side of heart
What part of the heart does the posterior interventricular a. serve?
back of ventricles
What part of the heart does the coronary sinus serve?
posterior heart
what branches from the coronary sinus
-great cardiac vein
-middle cardiac vein
-small cardiac vein
What part of the heart does the great cardiac vein serve? 2
anterior interventricular sulcus and left coronary groove
What part of the heart does the middle cardiac vein serve?
posterior interventricular sulcus
What part of the heart does the -small cardiac vein serve
r margin of heart
what part of the heart do the anterior cardiac veins serve
front of heart
at the end of diastole, the atria
contracts pushing the last bit of blood into the ventricles
during (ventricle) systole…2 steps
A) ventricles contract causing closure of AV valves (1st heat sounf “lub”)
b) and then opening of the semilunar valves, ejecting blood into the main arteries
in early diastole there is…
isometric relaxation as semilunar valves shut (“DUB”)
the first heart sound, lub, corresponds to
closure of the AV valves in early systole
the second heart soung, dub, corresponds to
closure of the Semilunar valves in diastole
what are heart murmers?
extraneous heart sounds due to turbulent backflow through a valve that does not close tightly
stroke volume and HR are regulated to alter
cardiac output
cardiac output is defined as the
amount of blood pushed out of 1 ventricle in 1 minute
cardiac output equation
C.O= S.V.x HR
product of stroke volume and heart rate
cardiac output at rest is typically
around 5L/min (5,000 mL/min)
stroke volume is the amount
normal stroke volume at rest
of blood pushed out of a ventricle per beat
(around 70mL at rest)
cardiac output changes with
demand
cardiac reserve is the difference
between resting and maximal cardiac output
so
C.O=70mL/beat x 70beat/min=4,900mL/min
stroke volume represents the difference between
+equation
the EDV (the fill) and the ESV (the remainder)
S.V.= EDV-ESV
the frank-sterling law of the heart states the critical factor controling S.V. is
the critical factor controlling stroke volume is preload, the degree of stretch of cardiac muscle cells immediately before they contract
the most important factor determining the degree of strech of cardiac muscle is
which is influenced by
The EDV.
Venus return to the heart
Influenced by- respiuratory pump, skeletal muscle pump, fill time
contractility is
the contractile strength achieved at a given muscle length
contractility is influenced by
EPI, TH, symph NS, Ca++
ESV!
(e.g. increase norepi-> increase ca++ in heart cells= decrease ESV increase S.V. and C.O)
afterload is the ventricular pressure that must be overcome before
blood can be ejected by the heart and does not become a significant determinant of stroke volume except in hypertensive individuals
Regulation of HR:
sympathetic stimulation in pacemaker cells
increases HR by making pacemaker potential steeper
Regulation of HR:
parasympathetic inhibition of cardiac pacemaker cells
decreases HR by aCH by changing K+ and flattning pacemaker potential
Regulation of HR:
hormones such as epinephrine and Thyroxine
increase HR
Regulation of HR:
other factors influencing HR
age, gender, excersise, and body temp
Homeostatic imbalance of HR:
Congestive heart failure occurs when
pumping efficiency of the heart is so low that blood circulation cant meet tissue needs
Homeostatic imbalance of HR:
pulmonary congestion (and possibly pulm edema) occurs when
the L side of the heart is failing and blood backs up into pulmonary circut
the three major types of blood vessels are
capillaries, veins, arteries
arteries carry blood..
away from the heart
veins carry blood…
towards the heart
in systemic circulation arteries carry..
veins carry..
oxygen rich blood
oxygen poor blood
in pulmonary circut arteries carry
veins carry
oxygen poor blood
oxygen rich blood
most blood vessels have _ layers
3
tunica intima-
endothelium- lowers friction for smooth flow
tunica media-
smooth muscle+elastin
controls dilation (constriction/ relaxation)
tunica externa-
lots of collegen to reinforce + connect the vessel
vaso vassorum (tunica externa)
small vessels in outer layer of big vessels wall
Arteries are _resivoirs, _vessels, or _vessels
pressure resivoirs, distributing vessels, or resistance vessels
elastic arteries
contain lots of elastin, allows them to abosrb big pressure pulses from nearby heart
muscular arteries
distributing arteries- have lots of smooth m. in tunica media
arterioles
are small and play a big part in fine tuning blood flow into capillaries
connect artries and capillaries
cappilaries are _ vessels
exchange
cappilaries are the smallest vessels and allow for exchange between
What do they exchange?
blood+ intersitial fluid: exchange materials such as nutrients/ waste and respiratory gases
continuous capillaries
-most common type; eg. in blood brain barrier
-only allows small, nonpolar molecules to be exchanged
fenestrated cappilaries
have pores in cells allowing for more exchange; eg in small intestine
sinusoid capillaries
-slightly larger, very leaky capillaries; still fenestrated+ large intercellular clefts; eg in spleen
capillary beds are
microcirulatoy networks that consist of a vascular shunt and true capillaries
capillary beds
- when tissue is active precapillary sphincters …
relax which increases the flow into true capillaries
capillary beds
- when tissue is inactive pre capillary sphincters
contract which decreases the flow into true capillaries and send blood into vascular shunt
veins are blood _ and _ blood towards the heart
blood resivoirs
return blood
venules are often formed where
capillaries converge
venules
-are leaky/ absorbative (sometimes more absorbative than caps)
-allow WBCs in and out
venules join to form
veins
veins are
-blood resivoirs
-thin-walled vessels
-large lumens
-contain about 65% of total blood volume
compared to arteries, veins have
-more volume
-lower pressure
-more interconnected and variable
blood flows from
high to low pressure against resistance
blood flow is
the amount of blood going through an area in a certian period of time
units mL/min
blood pressure is
the force exerted by blood against the vessel walls
unit: mmHg
resistance is
what causes it?
-the friction between blood and vessels
-comes from: blood viscosity, vessel length, vessel diameter
Flow calculation
Flow=pressure gradient/ resistance
if peripheral resistance increases then
blood flow decreases
if blood pressure increases at source then
blood flow increases
the most important factor influencing local blood flow
peripheal reistance
constriction or resistence of blood vessels dramatically changes
local flow
what happens to BP when blood flows from arteries through capillaries and into veins
decreases
the pumping action of the heart generates
blood flow
list High BP to low BP in vessels
Aorta, Arteries, Arterioles, Capillaries, Venuoles, Veins, Vena Cava, R atrium
systemic BP is highest in the _ and falls thoughout the circut until it reaches 0 mmHg in the
highest in the aorta lowest in the R atrium
arterial BP reflects
how much the arteries close to the heart can be streched (compliance or distendability) and the volume forced into them at a given time
when the L ventricle contracts, blood is forced into the….
producing….
aorta, producing a peak pressure, called systolic pressure, abut 120mmHg in a healthy adult
diastolic pressure occurs when the
ventricles enter diastole, the aortic valve closes, and the walls of the aorta recoil, which maintain a pressure at 70-80mmHg, so that blood continues to flow forward into smaller vessels
pulse pressure is the difference in
systolic and diastolic pressure
the mean arterial pressure (MAP) represents…
calculation…
the pressure that propels blood into tissues
(1/3) systolic pressure + (2/3) diastolic pressure
capillary pressure is _, and ranges from
is low, ranging from 15-40mmHg, protects the capillaries from rupture but is still adequate to exchange between blood and tissues
venus blood pressure is
low, not pulsatile, and changes very little during the cardiac cycle, reflecting culmulative effects of pheripheral resistance
blood pressure is regulated by
short and long term controls
maintaining blood pressure involves
cardiac output (which party depends on blood volume and peripheral resistance)
baroreceptors are
-neurons that sense blood pressure moment to moment
they are clusters of neurons in the medulla oblongata, cardioacceleratory, cardioinhibitory, and vasomotor centers. forms the cardiovascular center that regulates BP by altering cardiac output and blood vessel diameter
short term neural controls help maintain
adequate MAP
baroreceptors located in the aortic arch and carotid sinus detect..
send impulses….
detect stretch and send impulses to vasomotor center, inhibiting its activity and promoting vasodilation of arterioles and veins
vasomotor center
part of the medulla wired to sympathetic NS
chemoreceptors detect
a rise in CO2 levels of the blood and stimulat the cardioacceleratory and vasomotor centers which increase vasoconstiction and cardiac output
the cardioaccelratory and cardioinhibitory centers are
part of the medulla wired to autonomic NS
(BP)
the hypothalamus and cortex can modify…
arterial pressure by signaling the medullary centers
Hormonal Control
epinepherine and norepinephrine
increase BP, Increase C.O. and cause vasoconstriction, increasing resistance
Hormonal Control
Angiotestin II acts as a
increases the release of what
vasoconstrictor increasing BP
also increases the release of ADH and release of aldosterone
Hormonal Control
aldosterone
increases Na+ (and H2O) retention increases BP
Hormonal Control
artrial natriuretic peptide acts as a
stimulant of Na+ excretion ( and H2O) and also dialates blood vessels
decreases BP
Hormonal Control
antidiruretic hormone
increases H2O retention to conserve blood volume, increases vessel constriction
increases BP
Long-Term Regulation: Renal Mechanisms
The direct renal mechanism
counteract changes in BP by autonomic adjustments in filtration (and thus urine production)
Long-Term Regulation: Renal Mechanisms
The indirect renal mechanism is the renin-angiotestin-aldosterone mechanism which
increases BP and adjust (as needed)
-decreased BP= increase renin release; renin helps make AT1; AT1 is convereted to AT2 by ACEs
-AT2 constricts vessels, stimulates thirst, increase ADH and aldosterone
The goal of blood pressure regulation is to
keep BP high enough to provide adequate tissue profusion, but not so high that blood vessels are damaged
alterations in blood pressure may result in
hypotention or transient or persistent high blood pressure
circulatory shock is any condition where
blood flow is inadequate and cannot meet the needs of the tissue
hypovolemic shock results from
significant loss of blood volume
cardiogenic shock results from
heart pumps inefficiently usually due to infarction
vascular shock is characterized by
lots of vasodialation- poor circulation- drop in BP
intrinsic and extrinsic controls determine how
blood flows through tissues
tissue perfusion is involved in
delivery of oxygen and nutrients to, and removal of wastes from tissue cells
autoregulation
local regulation of blood flow
how does autoregulation work
intrinsic adjustments of blood flow (constriction or dialation) based on local tissue needs
metabolic controls of autoregulation are most strongly stimulated by
O2 levels (locally)
if low, dialate
if high, constrict
myogenic control involves
local response (contraction) of smooth muscle in response to stretch
blood flow to skeletal muscles varies with
levels of activity and fiber type
muscular autoregulation occurs almost entirely in response to
O2 levels decrease locally during excerise so they dialate
cerebral blood flow is regulated
related by
CO2 increase with activity
PH decrease with activity
Causing dilation
autoregulatory controls of blood flow to the longs is opposite to
from what they are in the systemic circut because we want to load into veins only when there is O2
-low pulmonary O2 causes vasoconstriction instead of dilation seen in the systemic circut
slow blood flow through capillaries promotes
diffusion of nutrients and gases and bulk flow of fluids
velocity, or speed of blood changes as
it passes through the systemic system
velocity (blood flow) is fastest
in aorta and decreases as total vessel diameter increases, so is slowest in the capillaries
flow through capillaries reflects the action of
action of arterioles and sphincters that are the autoregulatory controls
capillary exchange of nutrients, gases, and metabolic wastes occur between __ and __ through__
between blood and interstitial space through diffusion
hydrostatic pressure (HP) Is
the force of fluid against a membrane
it is blood pressure- higher at arteriole end of capillary
collodid osmotic pressure (OP) is created by
large solutes in plasma (e,g. albumins)
Fluids will leave the capillaries if
net HP excedes OP, but fluid will enter capillaries if OP exceeds HP
-generally some fluids leave capillaries near arterioles, where some (but not all) is reabsorbed into plasma near venuoles
Just need part 3 flashcards done
where is the SA NODE
r atrium- quick pacemaker starts the beat
where is the AV node
bottom of the interatrial septum near top of interventricular septum
where does the AV split to bundle branches
interventricular septu,
bundle branches divide to give
subendocardial conducting network (purkinje fibers)
