cardiovascular system Flashcards
pericardium
thick sac that protects the heart and anchors it to the diaphragm
the inner and outer layers of the pericardium are covered by a smooth layer of endothelium
a special lubricating fluid between the layers allows the heart to slide around with very little friction
myocardium
the bulk of the heart and composed mainly of cardiac muscle and is the layer that contracts
the myocardium muscle fibers are highly branched and attached by collagen connective tissue fibers that link all parts of the heart together
endocardium
the heart is lined with a white sheet of endothelium which is continuous with the blood vessel linings
fossa ovalis
marks a place of opening between the artria in developing fetuses
it allows fetal blood to move directly from the right to left atrium bypassing the lungs which are underdeveloped
This closes during birth so the baby can begin to breath on their own and recieve oxygen
pulmonary valve
controls the flow leaving the right ventricle into the pulmonary trunk
aortic valve
controls the flow of blood out of the left ventricle into the aorta
the aortic valve is stronger than the pulmonary valve because of the increased blood pressure needed to send blood pumping to the entire body.
mitral (bicuspid) valve
controls the flow of blood from the left atrium into the left ventricle
tricuspid valve
controls the floe of blood from the right atrium to the right ventricle
three types of blood vessels used to transport blood
arteries - carry blood away from the heart -except pulmonary
veins -carry blood back to the heart
capillaries - change materials with tissues
arteries
elastic, thick-walled vessels that can expand and contract to accommodate the larger blood flowing from the heart at the end of each heart beat
large arteries expand and recoil to help the heart pump blood through the systemic circulation
have palatable pulses
arterioles
small arteries are constricted and dilated by muscles controlled by the automatic and parasympathetic systems which control blood pressure
contracting the arterioles increase blood pressure through decreasing the available volume and relaxation decreases it
peripheral resistance
arterioles are the vessels primarily responsible for providing differing levels of peripheral resistance (varying blood pressure) to blood flow depending on the internal and external affecting the body
veins
are thinner walled vessels that are under less pressure from the heart
these do not have pulses
have internal valves that open toward the heart and close at the end of a heart beat to prevent blood from flowing backward as the blood is returned to the heart
compliance
veins have compliance which means they stretch with very little recoil
because of their compliance veins have the largest amount of blood in the CVS
lumen
the opening in the center of a vessel
three layers of arteries and veins
tunica externa, turnia media and tunica intima
tunica externa
most superficial layer of the artery or vein which helps anchor the vessel to the surrounding structures
turica media
middle muscular layer of a vessel has an external elastic membrane, a layer of smooth muscle, a layer of internal elastic membrane
tunica intima
innermost layer of a vessel that contains a layer of subendothelial tissue and a layer of endothelium
capillaries
branching of arterioles causes formation of even narrower tubes called capillaries.
these are interconnected to form capillary beds which perform gas exchange of materials with cells of the body
venules
the blood is collected from capillary beds by small veins called venules - many which join to form a vein to return blood to the heart
left coronary artery
runs towards the left side of the heart and divides the interventricular branch and the circumflex branch
anterior interventricular branch
supplies blood to both ventricles
circumflex branch
supplies the left atrium and left ventricle
right coronary artery
runs towards the right side of the heart and divides into posterior interventricular artery and marginal artery which supply the right atrium and right ventricle
circle of willis
also know as the cerebral arterial circle
has a unique feature of providing alternate circulation in case one of the arteries becomes blocked
this is important because neurons can only survive minutes without oxygen before they die
basilar artery
two vertebral arteries rise superiorly along both sides of the spinal cord joining to form the basilar artery at the base of the pons
the basilar artery branches into left and right posterior cerebral arteries
blood is classified as what and contains what
connective tissue
liquid portion called plasma
cellular portion called formed elements composed of red blood cells, white blood cells, and platelets
serum
is identical to blood but the clotting proteins have been removed
this is done by letting the blood sit in a tube until it clots and centrifuging the sample to seperate the solids from liquid portions
used for many laboratory tests
osmotic pressure
is the net pressure of blood that moves fluids from the tissues into the circulatory system
driven by proteins in the plasma that remain in the capillaries
in the case of blood at the capillaries, water has an automatic tendency to slow towards the proteins pulling fluids back into the circulatory system
opposed hydrostatic pressure
Functions of plasma
helps buffer the pH of blood keeping it near 7.4
helps in transporting large organic molecules in blood
aides in clotting
maintains blood osmotic pressure because of proteins in plasma
hydrostatic pressure
hydrostatic pressure of blood which pushes fluid into the tissues by the pressure of blood pumping from the heart
**It is important for the body to maintain homeostasis between osmosis and hydrostatic pressure so that fluids flow into the tissues and then return to the circulatory system
red blood cells (erythrocytes)
most abundant cell in the body.
small bioconcave discs that carry oxygen
each red blood cell has 250 million hemoglobin molecules
live for 120 days and destroyed by the liver and spleen
Hemoglobin
contains iron that loosely combines with oxygen helping to carry oxygen in the blood
Where are red blood cells manufactured
In red bone marrow of the skull, ribs, vertebrae, and the ends of long bones
Anucleate
without a nucleus - red blood cells must lose their nucleus and synthesize hemoglobin before they are released in the blood
what happens when red blood cells are destroyed?
Hemoglobin is released so that the iron can be recycled
The iron gets recycled to the red bone marrow for reuse
the heme portion undergoes chemical degradation, and are excreted by the liver as bile products
white blood cells vs red blood cells
white blood cells aka leukocytes
White blood cells are larger than red blood cells, have a large nucleus, lack hemoglobin
inflammatory response
when microorganisms enter the body our to injury the body responds through an inflammatory response because of the swelling and redness
the swelling and redness are due to an increase of blood flow to the injured site which sends an immune defense cells (white blood cells)
How do white blood cells help in an inflammatory response
they squeeze through capillary walls and enter the tissue fluid where they destroy foreign material
pus
pus contains a large portion of dead white blood cells that have fought foreign invaders and undergo cell death
Three types of white blood cells
granulocytes- have granules in cytoplasm
aganuolecytes- do not have granules in cytoplasm
lymphocytes -include B and T cells
platelets
aka thrombocytes - involved in blood clotting or coagulation
not “true cells” but fragments of large bone marrow predecessor called megakaryocyte (cells with multi nucleus)
these stop bleeding by sticking to the edges of a wound and begin to clot the opening
much smaller than red blood cells
coagulation cascade
once platelets start sticking the edges of a wound and begin the coagulation process than this triggers a coagulation cascade -or a series of events to start blood clotting mechanism
release of prothrombin activator is released by the platelets and injured tissues which coverts it to thrombin
prothrombin –> thrombin
fibrinogen
Blood clotting needs involvement of fibrinogen - a protein manufactured by the liver that freely floats in the blood
thrombin helps convert fibrinogen to fibrin
fibrin threads wind around the platelet plug in the damaged area of the blood vessel and provide a framework for the clot
fibrin
the activated form of fibrinogen (thrombin activates it)
fibrin threads wind around the platelet plug and for a framework for the clot
Red blood cells get caught in the fibrin and make the clot look red
the network of fibrin and platelets work together to make a platelet plug to stop bleeding (only temporary before destroyed by plasmin)
plasmin
destroys the fibrin network and restores fluidity of plasma
any dysfunction in the clotting cascade can lead a variety of clotting disorders
pulmonary circuit
the heart is a double pump because it has two circuits
the right circuit is called the pulmonary circuit and the left circuit is called the systemic circuit
Valves assure the blood flow in which way?
One way direction
forward from the vessels into the atria, into the ventricles, then out the ventricles
pulmonary circuit
systemic circuit
P- sends deoxygenated blood to the lungs to be oxygenated
S- sends oxygenated blood from the heart to the cells of the body
The blood pathway (simple)
one way path from the heart, lungs, body
The blood pathway (complicated) – returning deoxygenated form cells of the body to entering the heart
Two large veins called the inferior and superior vena cavae return deoxygenated blood to the right atrium
right atrium through tricuspid valve to right ventricle.
through pulmonary valve into pulmonary arteries (only arteries that carry deoxygenated blood)
lungs
blood gets oxygenated by capillary bed in lungs (and gets rid of CO2
carried by pulmonary veins to heart entering left atrium
oxygenated blood flows through bicuspid valve (mitral valve) into left ventricle
which pumps it through the aortic valve into the aorta
Aortic arch turns posteriorly carrying oxygenated blood supply to the cells of all body tissues with oxygen and nutrients
deoxygenated blood then is returned to the right atrium through the vena cavae which completes the circuit.
aorta
largest vessel in the body
the aortic arch turns posteriorly carrying oxygenated blood supply to the cells of all body tissue with oxygen and nutrients
deoxygenated blood is then returned to the right atrium through the vena cavae which completes the circuit
how many times does the heart beat and for how long?
the heart contracts or beats about 70 times per minute and each heartbeat lasts about 0.85 seconds
systole/diastole
S- refers to contraction of heart chambers
D-refers to relaxation of chambers
for the heart to work as a pump it must contract and relax in a cyclical pattern
cardiac cycle
has three general phases
first atria contract for 0.15 seconds while the ventricles relax
second the ventricles contract for .30 seconds while the atria relax
third, all chamber relax for .40 seconds
why is the atria contraction shorter than the ventricles contraction?
the atria only have a short way to travel to the ventricles
The ventricles contraction needs to be longer to pump blood to the much larger systemic and pulmonary circularity circuits
lub dub
when the heart beats the sounds are called lub dub as the valves of the heart close
lub is heard when the atrioventricular (bicuspid and tricuspid) valves closes
dub is heard when the semilunar valves close
stethoscope is used to hear heart sounds
systolic pressure
results from blood being forced into the arteries during ventricular systole
diastolic pressure
is the pressure in the arteries during ventricular diastole
what is blood pressure?
contraction of the left ventricle forces blood into the arteries under pressure
sphygmomanometer
blood pressure is measured with sphygmomanometer
it is measures the amount of pressure required to stop the flow of blood through the artery. typically the brachial artery
bulb is squeezed to inflate the bladder with air
the bladder is held in place over an artery by the cuff
manometer -displays the pressure in millimeters of mercury
the pressure inside the bladder is slowly released by the valve
emptying the bladder of air allows blood to flow through the artery again
stethoscope
is used to listen to the first sounds of blood flow displayed on the manometer. when taking blood pressure
blood pressure reading
consist of two numbers
for example 120/80 which represents systolic and diastolic respectively
Describe how blood pressure falls as it travels from aorta through arterioles and beyond
As blood flows from the aorta, through into various arteries and artrioles -blood pressure drops from arteries to aterioles
the difference between systolic and diastolic pressure gradually diminishes as blood reaches arterioles
int he capillaries there is a slow, even flow of blood to allow for diffusion of oxygen and wastes in and out of capillary beds
blood pressure in veins is very low and can zero at times
what factors enable the veins to return blood to the heart
low resistance in venous walls, meaning veins can stretch to accommodate larger volume
presence of internal valves prevents back flow of blood
assistance of muscular contraction in the limbs and chest enables blood in the veins to maintain a flow significant enough to return blood to the heart
electrical impulses
The heart has an elaborate electrical system that is responsible for maintaining its intrinsic rhythmic abilities
contractions of cardiac muscle start with heart muscle itself, making it somewhat independent of any nerve supply from the CNS
If removed from the body the heart can continue to beat on its own with proper oxygen and nutrients
what systems regulate the heart rate
the nervous system and endocrine system through neurotransmitters acetylcholine and norepinephrine
the interaction with these systems allow the heart rate to change based on emotional and physical stressors
Sinoatriol node
the electrical impulse that controls the cardiac cycle begins at the SA node (sinoatrial node) found in the right atrium
Know as the pacemaker of the heart because it begins the electrical impulses neccesary for the cardiac cycle
SA node is a small mass of specialized cardiac muscle that contains both cardiac and nervous tissue characteristics
The electrical impulse begins at the SA node and spreads through the atria, creating left and right artiole systole
Atrioventricular node (AV node)
the SA node impulse travels through the AV node into bundle of His
The impulse then continues to travel towards the ventricular apex (downward point of the heart)
to the Purkinje fibers causing the left and right ventricles to contract
EKG or ECG
electrocardiogram - a device used to measure electrical impulses in the heart
different parts of the ECG tracing represent the rhythmical electrical impulses and corresponding mechanical events in the heart
commonly used to monitor and diagnose patient conditions
P-wave
arterial depolarization (active firing of nerve impulse) and arterial systole are denoted as P-wave
QRS
ventricular depolarization and ventricular systole and denoted as QRS complex
T-wave
ventricular repolorization (returning to rest) and ventricular diastole are denoted as T wave
Note - there is no way to note the repolarization of the atria, as its activity is lost within the QRS complex
syncope
fainting
cardiovascular issues can be experienced by a healthy person
For example is a person stands perfectly still for a long time (store clerk) blood tends to pool in the veins
once the veins are fully distended, they can not accept blood from the capillaries
large amounts of plasma are forced out of the thin capillary walls, causing a drop in arterial blood pressure
once arterial blood pressure drops blood flow to the brain is reduced and causes fainting (syncope) because of decreased oxygen to the brain
edema
heart failure causes an abnormal backup of fluids in the body (edema) and/or high blood pressure
pulmonary edema
left sided heart failure tends to cause pulmonary edema, or a backup of fluid in the lungs also know as congestive heart failure
peripheral edema
right sided heart disease tends to cause peripheral edema or back up of fluids in the body and limbs
hypertension
defined as a condition when systolic and diastolic pressures are significantly higher than 120/80 mmHg
called the silent killer because it may be undetected until of heart attack or stroke
atherosclerosis
an accumulation of soft masses or fatty acids, often cholesterol, inside the arteries
these deposits called plaque accumulate beneath the inner linings of arteries
as a plaque continues to build up it tends to protrude into the vessel, interfering with normal blood flow
can cause a blood clot to form on the irregular arterial wall
may cause clot in immediate area or can dislodge and travel clogging a smaller artery in its path
thrombus
stationary blood clot
embolus
is a clot dislodges and moves along with blood it is called an embolus
thromboembolism
is an embolus that becomes lodged in a vessel as it travels
pulmonary thromboembolism (PE)
a blockage of a major artery in the lungs, causing shortness of breath and angina (chest pain)
infraction
occurs if the vessel is totally blocked by a thrombus or embolism, causing tissue death in the area supplies by the clogged artery
can result in death if unresolved and complications that arise
myocardial infraction
medical term for heart attack
occurs when a portion of the heart muscle dies because of lack of oxygen
angina pectoris
if a coronary artery is partially blocked due to plaque the individual may suffer from angina pectoris (chest pain), characterized by radiation pain in the left arm
Often heart attack is followed by at least one or serval of these symptoms-
Head- lightheadedness
Arms, back, neck, jaw, between shoulders - pain and discomfort, numbness
chest- pressure, pain, fullness, or squeezing (lasts for more than a few minutes or comes and goes)
skin- cold sweat
Lungs- trouble breathing, shorteness of breath
Stomach- upset stomach, urge to throw up
Other symptoms- women may feel very tired -sometimes for days or weeks. Women may also have heartburn, cough, heart flutters, or loss of appetite
Medical treatment for thromboembolism
includes two drugs given intravenously to dissolve clot -
streptokinase (normally produced by bacteria)
t-PA - genetically engineered
both of these drugs convert plasminogen, a molecule found in blood to plasmin - an enzyme that dissolves blood clots
Aspirin
if a person has symptoms of angina or thromboylic stroke, and anticoagulant drug such as aspirin may be given by emergency response team
aspirin reduces the coagulation of platelets and therefore lowers the probability a clot will form
Surgical procedure to clear clogged arteries
Angioplasty is a procedure where a surgeon threads a plastic tube into the artery of an arm or leg
The tube is guided through the blood vessel towards the heart
when the tube reaches the segment clogged by plaque in the coronary artery, the balloon attached to the end of the tube is inflated, forcing the vessel to open
