Exam 2 Flashcards
what are the three layers of the heart what are they made of
Epicardium- visceral layer of the pericardium (outer)
Myocardium- thicker layer, cardiac muscle tissue
Endocardium- lining of the heart- inner – made up of endothelial cells (simple squamous epithelial cells)
what are the 4 chambers of the heart and what do they do with blood
2 atria- receive blood from the body
2 ventricles- pumps blood out of the heart
—– are blood vessels that carry blood towards the heart
veins
—– are blood vessels that carry blood away from the heart
arteries
What are the 3 veins that the right atrium receives blood from
Superior vena cava- blood from upper body
Inferior Vena Cava- blood from lower body
Coronary Sinus – drains blood from the myocardium
The Left Atrium (LA) receives blood from
pulmonary veins. - blood from lungs
The Right Ventricle (RV) pumps blood into the
pulmonary arteries -> lungs
The Left Ventricle (LV) pumps blood into the
aorta-> all body tissues (except lungs)
Name the pathway and its pump- blood vessels that carry blood to and from all body tissues and back to the heart (longest circuit)
Systemic circuit- left ventricle is pump
Name the pathway and its pump- blood vessels toward the lungs and returns blood to the heart
Pulmonary circuit and the right ventricle is the pump
Name the pathway and its pump- blood vessels that carry blood to and from the myocardium (shortest pump)
Coronary circuit and the left ventricle is the pump
what is the longest circuit
systemic circuit
what is the shortest pathway
coronary circuit
Allow for one-way flow of blood through the heart (prevent backflow)
heart valves
heart valves open and close due to
pressure differences
what are the 4 heart valves and where are they located
2 Atrioventricular valves (AV valves)- Between the atria and ventricles
2 semilunar valves (SL valves)- Between the ventricles and the arteries carrying blood out of the heart
what are the 2 AV valves and their location
Tricuspid valve – between RA and RV
Bicuspid valve (or mitral valve)- Between LA and LV
what are the 2 SL valves and their location
Aortic SL valve – between LV and Aorta
Pulmonary SL valve- Between RV and pulmonary artery
heard when both AV valves close
1st heart sound
heard when both SL valves close
2nd heart sound
—-are not heard when heart valves open
heart sounds
—-cause valves to open and close
pressure differences
when atrial pressure is higher than ventricular pressure is
lower due to venous return the AV valves open
when ventricular pressure is higher (ventricles contract) than atrial pressure is
lower- the AV valves close and it is the 1st heart sound
what is the function of the papillary muscle and chordae tendineae
holds the AV valves in their closed position
when ventricular pressure is high (when ventricles are contracting) the pressure in aorta or pulmonary arteries is low
both SL valves open (no sound)
When pressure (high) in aorta or pulmonary arteries > ventricular pressure (low)
both SL valves close= 2nd heart sound
when both ventricles are relaxed the pressure
drops
blood flows —- into the 2 atria
continuously due to no valves
Cardiac muscle cells / fibers are
Striated
Involuntary – cannot consciously control
Branched
Interconnected by intercalated discs
intercalated disc contains 2 kinds of cell junctions:
Desmosomes- anchoring junction
Gap junctions- communicating junctions
the heart acts as a function
syncytium (coordinated unit)
Can shorten
Have a stable membrane potential
Do not self-depolarize- cannot start action potentials
contractile fibers (99% of all cardiac muscle tissue)
Cannot shorten
Have an unstable membrane potential
Self-depolarizes- can start own action potentials
Autorhythmic fibers (1% of all cardiac muscle tissue)
cannot start action potentials (A.P.) because they have a stable membrane potential
contractile fibers
can initiate A.P because of their unstable membrane potential
Autorhythmic fibers
Made of autorhythmic fibers
That initiates and transmits electrical impulses (A.Ps) through the heart
That results in rhythmic contractions
The Cardiac Conduction System
order of cardiac conduction system
- sinoatrial node (the pacemaker of the heart)
- atrioventricular node
- atrioventricular ventricle (the only electrical connection between atrium and ventricles )
- left and right bundle branches
- purkinje fibers (release AP)
the normal rhythm of heartbeat set by the SA node
sinus rhythm
start and conduct the A.Ps through the heart
autorhymic fibers
respond to the A.Ps of the autorhythmic fibers
contractile fibers
will then reach threshold and generate A.Ps
contractile fibers
phases of sinus rhythm and they ions they move
Depolarization- due to sodium ions (na+) entering the cell
Plateau- calcium (Ca2)ions enter the cell
Repolarization- Action potential ends due to K+ ions leaving the cell
A recording of the flow of electrical impulses (A.P.s) produced by the heart
electrocardiogram
three waves of EKG in one heart beat
P wave- atrial depolarization
QRS complex- ventricular depolarization
T wave- ventricle repolarization
time span between beginning of P wave and beginning of the QRS complex
P-Q interval
time span between the beginning of the QRS and the end of the T wave
Q-T
time span between the end of the QRS and the beginning of the T wave
Steady ventricular depolarization
S-T
all events associated with one heartbeat
cardiac cycle
systole is
contraction
diastole is
relaxation
depolarization causes
systole
repolarization causes
diastole
length of the cardiac cycle
.8 secons
length= .1 sec
atria= systole
ventricles= diastole
atrial systole
length= .3 sec
atria= diastole
ventricles= systole
ventricular systole
length= .4 sec
atria= diastole
ventricles= systole
relaxation period
Both atria contract shortly after P wave
AV valves remain open
SL valves remain closed
Ventricles fill with blood
atrial systole
Both ventricles contract shortly after QRS
AV valves close (1st heart sound)
Isovolumetric contraction period occurs in beginning- constant volume of blood in ventricles - all 4 chambers close
SL valves open
Blood pumped out of ventricles and into aorta and pulmonary arteries
ventricular systole
Ventricles relax shortly after T wave
SL vales close (2nd heart sound)
Isovolumetric relaxation period occurs in beginning
AV valves open in middle of period
Blood fills ventricles
relaxation period
constant volume of blood in ventricles; all 4 valves closed
isovolumetric
(brief period at beginning of Ventricular Systole) ventricles contract while valves closed
isovolumetric contraction
(brief period at beginning of Relaxation Period) – ventricles relax while valves closed
isovolumetric relaxation
amount of blood pumped out of each ventricle per minute
cardiac output
how is cardiac output measured
CO = HR (heart rate) x SV (stroke volume)
decreases HR to resting conditions
Decreases HR= decrease cardiac output
parasympathetic divison
increases HR and stimulates adrenal medulla to release epinephrine & norepinephrine
Increase HR= increase CO
sympathetic divison
amount of blood pumped out of each ventricle per heartbeat
stroke volume
factors affecting SV
preload, contractility, and afterload
The degree of stretch of heart wall
preload- Increase preload= increase SV= increase CO
increase in contractile force independent on stretch/ preload
contractility- Increase contractility= increase SV= increase CO
back pressure exerted on the SL valves due to arteriole pressure
afterload- Increase in afterload= decrease SV= decrease CO
Can lead to hypertension
the cardiovascular centers located in the
medulla oblongata
there are about —- miles of blood vessels in the body
60000
blood vessels are made of
living cells
3 kind of blood vessels
Arteries- blood vessels that carry blood away from the heart
Veins- blood vessels that return blood to the heart
Capillaries- exchange vessels
walls of arteries and veins have 3 layers
tunica interna-
tunica media
tunica externa
innermost layer of blood vessel wall
Endothelial cells (simple squamous epithelial)
tunica interna
middle layer of blood vessel wall
Smooth muscle tissue
Causes vasoconstriction and vasodilation
tunica media
outermost layer of blood vessel wall
Mainly collagen fibers
tunica externa
capillaries walls have 1 layer
tunica interna
thin capillary walls allow for
rapid exchanges
high pressure system, thickest layer is tunica media, all layers have more elastic fibers
the arterial system
(largest diameter)- conducting arteries
Examples: aorta, pulmonary arteries
elastic arteries
distributing arteries
Examples: radial artery, brachial artery
muscular arteries
(smallest diameter)- resistance vessels (affect BP)
arterioles
The tunica media allows muscular arteries and arterioles to
constrict and dilate
—-therefore can regulate blood flow into arterioles in specific organs
muscular arteries
—therefore can regulate blood flow into capillaries
arterioles
characteristics of capillaries
5-0 micrometers in diameter
Tunica interna only- thin walls
Tight junctions join cells together
Clefts- gaps between neighboring cells
continuous capillaries-
least permeable- most common- muscle tissue ad skin
fenestrated capillaries
has pores, very permeable- small intestine, filtration membrane of kidneys
sinusoids
large pores and clefts, extremely permeable- red bone marrow, spleen, liver
Movement of substances between plasma and interstitial fluid
capillary exchange
capillary exchange is aided by
diffusion, transcytosis, and bulk flow
passive process that moves particles from high to low concentrations
diffusion
using vesicles to shuttle substances across the cell
transcytosis
solutes and particles in a fluid move together due to pressure differences across the capillary wall
bulk flow
bulk flow outside of plasma and into interstitial fluid (positive NFP numbers cause)
filtration
bulk flow of interstitial fluid into the plasma (negative NFP numbers cause)
reabsorption
determine the direction of bulk flow
pressure differences
force exerted by a fluid against a wall
Acting at the capillary
hydrostatic pressure
force opposing hydrostatic pressure due to nondiffusing molecules
Nondiffusing molecules- proteins
acting at capillary
osmotic pressure
total pressure that promotes filtration
Net filtration pressure (NFP)
filtration occurs at the
beginning of capillary with NFP at +10 mm Hg
reabsorption occurs at the
end of capillary with NFP of - 9 mm Hg
Low pressure system
Has thinner walls and wider lumens than arteries (tunica externa is thickest layer)
Blood reservoirs of the vascular system
venous system
venous system consists of
Venules (smallest diameter)
Veins (large diameter) =Superior and inferior vena cava
- Valves present in veins to prevent backflow
Venous sinuses- specialized, broad veins supported by surrounding tissue; only has the tunica interna
Ex. Coronary sinus and dural sinus
branches of blood vessels providing alternate routes for blood to reach a particular region
anastomoses
—- drop along the vascular system
blood pressures
highest pressure (120-> 35 mm Hg)
arterial system
(35-> 16 mm Hg)
capillaries
lowest pressure (16 -> 0 mm Hg)
venous system
venous return of blood is aided by
Muscular pump-
Respiratory pump
Valves
amount of blood flowing through an organ in a given period of time (ml/min)
blood flow (F)
hydrostatic pressure of the blood
blood pressure (P)
opposition to blood flow
Resistance (R)
equation of blood flow
F= change in pressure/ R
increase in pressure = increase in flow
decrease in pressure, decrease in flow
resistance increases= decrease in flow
Constriction of the ventricles
increases blood pressure-> increases blood flow
what increases and decreases resistance
Greater blood viscosity increase resistance - polycythemia
Greater total blood vessel length increases resistance- obesity
Vasoconstriction increases resistance
Vasodilation decreases resistance
hydrostatic pressure exerted by blood- measures across the systemic circuit
blood pressure
maximum pressure in artery when ventricles contract (120)
systolic pressure
minimum pressure in artery during ventricular diastole (~80mm Hg)
diastolic pressure
systolic pressure minus diastolic pressure
pulse pressure
average pressure in artery
Mean Arterial Pressure (MAP)
neutral regulation of blood pressure is
short term
increase in BP:
Sympathetic increases HR and contractility
Sympathetic causes vasoconstriction
Decrease BP:
Parasympathetic decreases HR
Sympathetic causes vasodilation
Only the ——- of the Autonomic Nervous System can change the diameter of blood vessels Only the sympathetic division of the Autonomic Nervous System can change the diameter of blood vessels
sympathetic divison
hormonal regulation of BP is
short term
short-term regulation by:
Nervous system (parasympathetic and sympathetic)
hormones
long-term regulation by:
kidneys adjusting blood volume
normal BP is
about 120/80
high blood pressure (>140/90)
hypertension
low blood pressure (systolic pressure <100mm Hg)
hypotension
due to sudden change in position
orthostatic hypertension
long-term low blood pressure due to poor nutrition
chronic hypotension
sudden low blood pressure caused by circulatory shock
acute hypotension
condition when there is not enough blood in the blood vessels and blood cannot circulate normally
circulatory shock
shock due to loss of a large amount of blood
hypovolemic shock
shock due to extreme vasodilation- due to severe allergic reaction
vascular shock
shock when heart cannot pump adequately to circulate blood
cardiogenic shock
internal resistance of fluid to flow
blood viscosity
pathway through the pulmonary
Oxygen rich= Capitals
Oxygen poor= lower case
ra-> rv-> pulmonary arteries-> luNGS-> PULMONARY VEINS-> LA->LV->AORTA-> BODY tissues-> vena cava-> ra
pathway of systemic circuit
Oxygen rich= Capitals
Oxygen poor= lower case
la-> lv-> pulmonary arteries-> luNGS-> PULMONARY VEINS-> RA->RV->AORTA-> BODY tissues-> vena cava-> va
pathway of the coronary circuit
Oxygen rich= Capitals
Oxygen poor= lower case
AORTA-> CORONARY ARTERIES->MYOCArdium-> coronary veins-> coronary sinus-> ra
Angiotensin II- vasoconstriction
Epinephrine and norepinephrine- vasoconstriction- high HR
Antidiuretic hormone-vasoconstriction
hormones that raise BP
Atrial natriuretic peptide (ANP)-vasodilation
hormone that lowers the BP
renal regulation of BP is
long-term
Kidneys increase and decrease BP by
increasing and decreasing blood volume
