chap 17 Flashcards
heart disease
40% of all postnatal deaths nearly twice the number of deaths caused by all forms of cancer combined
heart pumps
over 6000 liters
of blood daily
Cardiac myocytes
comprise ~ 25% of the total number of cells in the heart, but >90% of the myocardial volume The rest population: -endothelial cells -fibroblast -inflammatory cells rare collagen is sparse
Major Disorders of CVS
Congenital heart disease
Ischemic heart disease (responsible for 80% to 90% of cardiovascular deaths)
Hypertensive heart disease (systemic and pulmonary)
Valvular heart disease
Nonischemic (primary) myocardial disease
pulmonary circulation
- moves blood though lungs
- consists of the right side of the heart, pul arts, pul caps, pul veins
- functions with a lower pressure (12 mmhg) and moves slowly which is good for gas exchange
- BLOOD VOLUME CAN BE 450 ML
systematic circulation
moves blood to tissues
- against gravity so pressure has to up to (90-100 mmhg_
hemodynamics
principals that govern blood flow in the circulatory system
shit that governs flow of blood in the circ system
- pressure
- resistance
- flow
CARDIAC OUTPUT
blood flow
laminar blood low
layers, platelets being in the middle
reduces friction and slides easily
anemics ans low blood viscosity
low blood viscosity allows the blood to move faster and accounts for the transient occurence of heart murmurs in some ppl who are anemic
heart murmur results from
turbulent flow through a diseased heart valve
distensibility
blood vessel streching and accommodating incread blood volume
most distensable vessles
veins
compliance
total quantity of blood that can be stored
vein is 24 times more compliant
heart beats
about 70 times/min
point of maximal impluse
on thorax
fifth and 6th ribs
below nipple
apox 3 inches lft of midline
conduction happens in what heart layer
myocardium
SA NODE
where the rhythmic impluse is generated
- fastest intrinsic rate of firing
- normally the pacemaker of the heart
internodal pathways
conduct the impluse from the SA node to the AV node
when the SA node dicharges
the impluses are conducted into the AV junctional and Purkinje fibers, causing them to fire
action potentials (three parts)
- resting phase
- depolarization
- repolarization
major charge carriers in cardiac muscle cells
- NA
- K
- Ca
two mains types of action potentials int he heart
- the slow response
2. fast response
acetylcholine
is released during vagal stim of the heart
-slows the heart rate by decreasing the slope of phasee 4
phase 0-4 (phases in action potential)
0-Phase 0 is the rapid depolarization phase
1-nactivation of the fast Na+ channels
2-This “plateau” phase of the cardiac action potential inward movement of Ca2), and outward movement of K
3-the “rapid repolarization” phase
4-resting membrane potential, and describes the membrane potential when the cell is not being stimulated.
absolute refactory phase
period during which no stimuli can generate another action potenial
- during theis pahse cells CANNOT deplarize
arrhythimas
rep disorders of the cardiac rhythm
- supraventricular( SA node, AV node, and junctional tissue)
- ventricular arrhythmias (ventricles)
ventricular arrhythmias
are the most serious
heart block
- occurs when the conduction of impluses in blocked
- often in the AV junction
ECG
electrical actyivity of the heart recording
SA node doesnt have a sufficent current
so it aint on the ECG
p wave
reps the atrial deplorization
QRS COMPLEX
decipts ventricular depol
T WAVE
vent repol
zero line between p wave and q wave
depol of AV node, bundle brnaches and Purkinje system
cardiac cycle
rhythmic pumping action of the heart
systole
the period during which the ventricles are contracting
diastole
the period during which the ventricles are relaxed and filling with blood.
ventricular systole into two parts
- isovolumetric contraction period- closure of AV valves FIRST HEART SOUND
- ejection period- LAST HEART SOUND
60% of stroke volume is ejected during the first quarter of systole
the remaining 40% is ejected during the next two quarters of systole.
aortic pressure reflects
changes in the ejection if blood to the left ventricle
atrial filling occurs
during both systole and diastole
three main atrial pressure waves
- vents contract av vales buldge into atria
- slow buildup of blood in atria
- atrial contraction
when the heart pumps strongly
right atrial pressure is decreased and atrial filling is enhanced
CO=
SVx HR
the av. cardiac output in normal adults
ranges from 3.5-8.0 l/ min
normal resp reserve
300%-400%
the hearts ability to increase its output (four things)
- preload
- afterload
- cardiac contractablility
- heart rate
three layers of vessles
tunica adventitia (collagen fibers tunica media tunica intima- endothelial cells
diff between systolic and dia
IS PULSE PRESSURE
PULASTIONS IN THE LARGE ARTERIES ARE EVEN GREATER THAN IN THE
AORTA
VENOUS system is a
low pressure system that returns blood to heart
hyperemia
an increase in local blood flow
nitric oxide
vessel dialation
and inhibits platelet aggregation and sec of plateletts contants
humoral control of blood flow involves
the effect of vasodilolator and consrtictor subs in the blood
norepineph
powerful vasoconstrictor
epineph
may may cause vaso dilation
angio tensiin 2
powerful vasoconstrictor
histamine
vasodil
allows leakage into tissues
serotonin
controls bleeding
VASOCON
bradykinin
intense dilaton of arts
increased caps permability
constricting venules
prostaglandins
vasocon and dil
tissue injury?
clooateral circulation is a mechanism for the
long term regulation of blood flow
medulla oblongata
where cardiac shit happens
vasomotor center
heart rate and blood vessel tone
cardioinhibitory center
parasymp-mediated SLOWING OF THE HEART RATE
cushing reflex
special type of CNS reflex resulting from an increase in intrecranial pressure
