Endocrine system t2 Flashcards
Leukocytes help defend the body against ___.
pathogens
do leukocytes contain hemoglobin? &why
no bc it’s not their job to carry respiratory gases
Do leuckocyts contain organelles and a nucleus?
yes
WBC are mostly found where
in the bodies tissues
Pathogen def
anything that cuases sickness and disease
how do wbc enter tissues
from blood vessels
Diapedesis:
squeezing through endothelial cells of blood vessels
Chemotaxis:
- attraction of wbc to infections sight
- molecules released from damaged cells or pathogens
Chemo:
chemicals being released
Taxis: (+/-)
positive = toward negative = away
WBC can be classified as ___ or ___. (look wise)
granulocytes or agranulocytes
Granulocyte :
with visible granules seen with light microscope
Agranulocytes:
with smaller granules not visible with light microscope
WBC granulocytes include
- neutrophils, eosinophils, basophils
WBC agranulocyes include
lymphocytes monocytes
What are neutrophils in terms of numbers?
most numerous in blood
WBC are also called?
polymorphonuclear leukocytes
What do neutrophils do?
enter tissue spaces and phagocytize infectious pathogens
What happens with neutrophils when an infection occurs?
numbers rise dramatically in chronic bacterial infections
Eosinophils stain what color
reddish granules
What do eosinophils do?
phagocytize antigen-antiboy complexes or allerengs, active in cases of parasitic worms
Basophils stain what color
blue-violet granules
Basophils contain what two things that help when it comes to inflammation?
histamine and heparin
Basophils are ____. (number wise)
rare
Histamine release causes what three things?
- causes increase in blood vessels diameter
- increased capillary permeability
- causes allergic symptoms
Allergic symptoms include (3). these symptoms help with what?
- swollen nasal membranes, runny nose, watery eyes
- flushing the upper respiratory system to get rid of pathogens
Heparin release causes what and why?
inhibits blood clotting because heparin is a blood thinner
Lymphocytes reside where
in the lymphatic organs and structures (spleen and lymph nodes)
In terms of number how common are lymphocytes?
2nd most common WBC
What are the three categories of lymphocytes?
- t-lymphocytes
- b lymphocytes
- NK cells
T-lymphocytes do what?
managing immune response in cell-mediated immunity (inside cells antigen)
B-lymphocytes do what?
becoming plasma cells and producing antibodies, roaming (outside antigen)
NK cells stands for what
(natural killer) Attacking abnormal and infected tissue cells
HIV destroys which type of lymphocyte?
t-lymphocytes
T-lymphocytes turn into an ____ making machine?
antibody
In terms of numbers how common are monocytes IN BLOOD?
not very common
Monocytes take up residence where?
in tissues
Monocytes fxn
phagocytize bacteria, viruses and debries
Monocytes exit cells and become what
macrophages
Leukopenia is what? What does it increase the risk of?
reduced number of WBC
- increases risk of developing infection
Leukopenia is a bi-product of what?
chemotherapy
Leukocytosis is what? what can cause it?
slightly elevenated leukocyte count
- may be caused by recent infection or stress
What is the order of WBC from most common to least common?
NEVER LET MONKEYS EAT BANANAS
Neutrophilia is what and associated with what
increase in neutrophils associated with bacterial infections, stress and tissue necrosis
Neutropenia is __? it may occur with what?
decreased neutrophil count
- may occur iwth anemia, drug or radiation therapy
Lymphocytosis is and increased number of what in response to what?
increased number o lymphocytes in response to viral infections, chronic bacterial infection, some leukemias, cancer of plasma cells
Lymphocytopenia? caused by what
decreased lymphocyte
- caused by HIV, other leukemias and pathogenic organism in the blood (sepsis)
Eosinophils increase in response to what
allergic reactions, parasites, some autoimmune diseases
Monocytes increase in response to
chronic inflammatory disorders or tuberculose, stress
Monocytes decrease in response to what
prolonged prednisone therapy
Acute leukemia:
short-term rapid progression
- death typically withing months in children and yound adults
Chronic leukemia
- slower progression, longer termed
- in middle-aged and older individuals
Platelets are cellular what
fragments
Platelets play an important role in blood __
clotting
Platelets circulate how long
8-10 days
A little under half of the platelets are stored where
in the spleen
Thrombocytopenia:
abnormally small number of platelets in blood
Hemostasis is
the process of blood clotting
Blood clotting stops what during injury
stops blood flowing through injured blood vessel wall
What are the three OVERLAPPPING phases of hemostasis
- vascular spasm
- platelet plug formation
- coagulation phase
Vascular spasm is:
a sudden constriction of blood vessels
Vascular spasm limits what
blood to be able to leak from vesses
How long does vasuclar spasm last for ?
few to many minutes
With vascular spasm, greater vessel damage =
greater vascoconstriciton
A platelet plus froms from
platelets arriving at injury site
The platelet plug under normal conditions
endothelial wall smooth
• coated with prostacyclin
• activates pathway inhibiting platelet activation
Platelet plug when blood vessel damaged =
collagen fibers in vessel wall exposed
• platelets sticking here
• assisted by von Willebrand factor, plasma protein
• platelets developing long processes allowing for better adhesion
• closing off of injury due to platelet plug
The circulatory system circulates blood continulously to maintain ___?
homeostasis
____ disease is the leading cause of death
cardiovascular
Transportation of the blood through the body allows exchange of substances between
capillaries and cells
Perfusion:
delivery of blood per time per gram of tissue
Adequate perfusion is …
sufficient blood delivered to maintain health of body cells
Arteries carry blood in which direction? do they contain oxygen rich or poor blood?
- carry blood away from the heart
* most (but not all) with oxygenated blood
Veins carry blood in which direction? do they contain oxygen rich or poor blood?
- carry blood back to the heart
* most (but not all) with deoxygenated blood
Capillaries are the site for what? give two examples.
- sites of exchange
- between blood and air in lungs
- between blood and body cells
The heart is composed of how many pumps?
two pumps, one left side one right side
The right side of the heart recieves which type of blood? where does it pump the blood to?
- receives deoxygenated blood from body
* pumps it to the lungs
The left side of the heart recieves which type of blood? where does it pump the blood to?
- receives oxygenated blood from lungs
* pumps it to the body
What is the main purpose for the atriums (blood wise)?
- superior chambers
for receiving blood
What is the main purpose for the ventricles (blood wise)?
- inferior chambers for pumping blood away • receive blood from respective atria
The great vessels of the heart transport blood where?
• transport blood directly to and from chambers
What are the 4 great vessels of the heart?
• pulmonary trunk, aorta, superior and inferior vena cava
The pulmonary trunk splits into which arteries and what is the purpose of those two arteries?
- splits into pulmonary arteries
* receives deoxygenated blood from right ventricle
The aorta recieves blood from where?
• receives oxygenated blood from left ventricle
The superior and inferior vena cava drain which type of blood into where?
drain deoxygenated blood into right atrium
The pulmonary veins drain which type of blood into where?
drain oxygenated blood into left atrium
The Atrioventricular valves seperate what?
• between atrium and ventricle of each side
Right AV valve, tricuspid is located where
– located between right atrium and right ventricle
Left AV valve, bicuspid, or mitral is located where
located between left atrium and left ventricle
The Semilunar valves boundary between what?
ventricle and arterial trunk
The Semilunar valves open to allow what
open to allow blood to flow through heart
The Semilunar valves close to what?
• close to prevent backflow
pulmonary semilunar valve is located where?
– located between right ventricle and pulmonary trunk
aortic semilunar valve is located where?
– located between left ventricle and the aorta
Two circuits of the heart?
pulmonary and systemic circulations
Pulmonary circulation
- carries deoxygenated blood from right side of heart
- goes through blood vessels to the lungs
- pick up of oxygen and release of carbon dioxide
- back through vessels to left side of heart
Systemic circulation
- moves oxygenated blood from left side of heart
- moves through vessels to systemic cells
- exchange of nutrients, gases, and wastes
- returns blood in vessels to right side of heart
Basic pattern of heart blood circulation
• right heart lungs left heart systemic tissues right heart
Edema:
swelling
Systemic edema may occur if which ventricle is impaired. This could mean blood is remaining where which caused fluid to enter where?
- may occur if right ventricle impaired
- more blood remaining in systemic circulation
- additional fluid entering interstitial space
Pulmonary edema may occur if which ventricle is impaired? which could cause blood to remain where? Swelling and fluid could accumulate where? this would cause what on breathing patterns?
may occur if left ventricle impaired
• more blood remaining in pulmonary circulation
• swelling and fluid accumulation in the lungs
• breathing difficulties and impaired gas exchange
Which cavity is the heart located in?
mediastinum
The right side is located more (ant/post), the left side is located more (ant/post)
anterior, posterior
The pericardium __ the heart?
encloses the heart
The pericardial sac is the ___ covering of the heart
outermost covering
The pericardial sac is how many layers and what types of tissues do the two layers consist of?
double layered
- fibrous layer, tough conn tissue
- thin serous membrane
The fibrous pericardium attaches which anatomical structures? and what does that function to do
attaches the diaphragm and base of aorta and pulmonary trunk
- restricts heart movement and prevents heart from overfiling
The thin serous membrane of the heart is called what?
parietal layer of serous pericardium
The visceral layer of serous pericardium is the second ____. it tightly adreres to what? both layers attach to what trunks?
- second serous membrane
- tightly adheres to heart
- both attaching to arterial trunks
The pericardial cavity is the space between what? what is it filled with and what does this fxn to do?
potential space between parietal and visceral layers
• serous fluid facilitating frictionless heart movement
Pericarditis is the inflammation of what? what can be the cause of this?
– Inflammation of the pericardium
– Caused by viruses, bacteria, or fungi
Pericarditis increases capillary permeability which causes what in the pericardial cavity? this may restrict what eventually resulting in the heart unable to pump called what _____?
- fluid accumulation in pericardial cavity
- becomes real space as it fills with fluid
- may restrict heart’s movement and keep chambers from filling
- results in cardiac tamponade, heart unable to pump
With pericarditis, friction rub can be heard with which device as the pericardial layers rub?
• crackling sound heard with stethoscope as pericardial layers rub
Ventricle layer walls are thicker than atrial walls why?
• because ventricles are the “pumping chambers”
The left ventricle is how many times greater than the right ventricle? why is this?
- three times thicker than right ventricle
- must generate higher pressure
- forces blood through systemic circulation
The three heart WALL layers care called what?
epicardium, myocardium and endocardium
Epicardium is made up mostly of what kind of tissue with an underlying layer of which mype of tissue
simple squamous epithelium
• underlying areolar connective tissue
The myocardium is made up of which type of tissue? it’s the thickest of the three layers bc..? What about it may change with age?
- middle heart layer
- composed of cardiac muscle tissue
- thickest of three layers
- contraction generates force to pump blood
- may change in thickness with age
– Endocardium covers what? its composed of which type of tissue with and underlying layer of what?
- covers internal surface of heart and external surface of valves
- composed of simple squamous epithelium
- underlying layer of areolar connective tissue
The fossa ovalis was once called the ___ in a fetus? what does this function to do before birth?
fetal foramen ovale
– shunted blood from right to left atrium in fetal life
The coronary sinus does what? where is the opening inside the heart?
drains blood from heart wall
• opening immediately inferior to fossa ovalis
The valves of the heart ensure what?
ensures blood flow in on direction
The heart valves consist of which type of tissue?
– Consist of endothelium-lined fibrous connective tissue flaps
Describe blood movement when the AV valves are open
– When open, cusps extend into the ventricles
• allows blood to move from atrium to ventricle
When the blood reaches the ventricle what causes the av valves to close and what prevents them from being pushed into the atrium when blood is in the ventricle?
With ventricular contraction, blood forced superiorly
-– Chordae tendinae secured by papillary muscles
The semilunar valves open ventricles contract, why?
- force of blood pushes valves open
* blood enters arterial trunks
The semilunar valves close when ventricles relax, why?
- pressure in ventricle less than pressure in arterial trunk
- backward flow of blood toward ventricle
- caught in cusps of valves, which close
- prevents blood flow back into ventricle
the cardiac muscle has a high demand for what?
nrg
The cardiac muscle metabolism requires which three things?
extensive blood supply
• numerous mitochondria
• myoglobin and creatine kinase
The cardiac muscle is able to use different types of fuel molecules like what 5 ions?
fatty acids, glucose, lactic acid, amino acids, and ketone bodies
Cardiac muscle cells mostly on which type of metabolism (oxygen wise)? and why?
• makes muscle susceptible to failure in low-oxygen
• interference with blood flow to heart muscle
– can cause damage or death
How does the ventricle contract?
- action similar to wringing of mop
* begins at apex and compresses superiorly
Right and left coronary arteries are the only branches of which major blood vessel?
• first and only branches of ascending aorta
Which surface vessel is called the widow maker and why?
• anterior interventricular artery
– supplies anterior surface of both ventricles
– supplies most of interventricular septum
– “widowmaker”, high risk of fatality if occluded
MAKE SURE TO LOOK AT SURFACE VESSEL SLIDES!
*
Teenage Athletes and Sudden
Cardiac Death.
– Sudden death caused by undetected cardiovascular disease
– Most due to congenital heart defects and coronary artery anomalies
– Result of cardiomegaly, increased thickness of heart
– Symptoms of swelling, dizziness, arrhythmia, and shortness of breath
– Revealed by standard x-ray
– Confirmed with echocardiogram
– Atherosclerosis
• coronary arteries narrowed and occluded
Coronary spasm
- sudden narrowing of vessels
* both can lead to angina or myocardial infarction
Angina pectoris
pain sensation on left side of chest, left arm, or jaw
• generally results from strenuous activity
• referred pain
• medications inducing temporary vascular dilation
– Myocardial infarction
heart attack
• sudden and complete occlusion of coronary artery
• region of myocardium deprived of oxygen
• possible tissue death
• sudden excruciating substernal chest pain radiating down left arm
• weakness, shortness of breath, nausea, anxiety, and sweating
• if large amount of tissue lost, person may die
The hearts rhythm is dependent on what?
on rhythmic stiulation of cardiac muscle cells
The automaticity of the heart begins with a stimulation by what?
by the pacemacker
The sinoatrial node initiates what? bc of this initiation what is the SA node commonly called?
initates heartbeat, referred to as the pacemacker
the AV bundle divides into left and right __?
bundles
The purkinje fibers extend from what and go where ?
extend fro left and right bundles from apex of heart through walls of ventricles
Does the parasympathetic system slow things down or make them go faster?
slows things down
The Parasympathetic innervation come from where?
comes from cardioinhibitory center
The right vagus in the parasympathetic innervation innervates which node?
SA node
The left vagus in the parasympathetic innervation innervates which node?
AV node
The parasympathetic innervation does what to the heart rate?
decreases the heart rate
The innervation pathways include which to inervations?
the parasympathetic and sympathetic innervations
The sympathetic innervation comes from where?
the cardioacceleratory center
The sympathetic innervation does what to HR and force of contration
increases
The sympathetic innervation does what to the dilation of vessels?
increases which supports increased blood flow to myocardium
Heart rate = (___/___)
beats/minute
Ectopic Pacemaker
– Pacemaker other than SA node
– Conduction system cells other than SA node
• also have ability to spontaneously depolarize
• depolarize at slower rates than SA node
– AV node the default pacemaker if SA node impaired
• AV node with inherent rhythm of 40 to 50 beats/min
• fast enough to sustain life
– Cardiac muscle with rate of 20 to 40 beats/min
• usually too slow to sustain life
Cardiac Arrhythmia is:
Abnormality in the rate, regularity, or sequence of cardiac cycle
– Atrial flutter
atria attempting to contract at 200-400 times per minute
• may persist for many years
• may degenerate into atrial fibrillation
Atrial fibrillation
- action potential more chaotic
- irregular heart rate
- may lead to serious disturbance in rhythm
– Premature ventricular contractions
result from stress, stimulants, or sleep deprivation
• abnormal action potential within AV node or ventricles
• not detrimental unless they occur in large numbers
– Ventricular fibrillation
life-threatening arrhythmia
• rapid, repetitious movement of ventricular muscle
• contractions not coordinated; heart unable to pump
• cardiac arrest
• shock applied to synchronize heart’s electrical activity
What does ECG or EKG stand for?
electrocardiogram
The EKG is what?
monitoring electrodes attached to skin at wrist, ankles and chest location
– Electrical signals collected and charted
– Provides assessment of electrical changes of heart
– Provides composite tracing of all cardiac action potentials
– Utilized during routine physical exam
P wave
reflects electrical changes of atrial depolarization
• originates in SA node
QRS complex
electrical changes associated with ventricular depolarization
• atria simultaneously repolarizing but masked by above
T wave
electrical change associated with ventricular repolarization
P-Q segment
- associated with atrial plateau at sarcolemma
* cardiac muscle cells within atria contracting
S-T segment
- ventricular plateau
* cardiac muscle cells in ventricle contracting
Waves associated with?
depolarization and repolarization
Flat lines corresponds to what?
no electrical change
Flat line between cycles? =
heart resting between beats
P-R interval
period from beginning of P wave to beginning of QRS deflection
• atrial depolarization to beginning of ventricular depolarization
• time to transmit action potential through entire conduction system
Q-T interval
time from beginning of QRS and end of T wave
• from ventricular depolarization to repolarization
Heart Blocks =
– Involve impairment within heart’s conducting system
– May result in syncope (fainting), irregular heartbeats, and palpitations
First-degree AV block
- lengthened PR interval
- action potential slowed between atria and ventricles
- asymptomatic
Second-degree block
exists along path between atria and ventricles
• failure of some action potentials to be conducted to ventricles
Third-degree block
- complete heart block
- no action potentials from SA node received by ventricles
- life-threatening
After a third degree heart block what will take over to cause heartbeat?
AV Node
Systole is what of heart chamber?
contraction
Diastole is what of heart chamber
relaxation
What happens with ventricular contraction? (4)
causes ventricular pressure to rise
• AV valves pushed and kept closed (preventing backflow)
• semilunar valves pushed open
• force blood from ventricle into arterial trunk
What happens with ventricular relaxation? (3)
• causes ventricular pressure to decrease • closure of semilunar valves – pressure no longer pushing them open • AV valves open – pressure no longer pushing them closed
End diastolic volume (EDV) is what & when does this happen?
maximum blood volume in ventricle happens during atrial systole
Isometric contration happens when?
early ventricular systole
Four normal heart sounds:
two familiar sounds, “lubb-dupp”, S1 and S2
– S1, closing of AV valves
– S2, closing of semilunar valves
• two minor sounds, S3 and S4
• provide clinically important information about heart and valves
Heart murmur
• abnormal heart sound
• result of turbulence of blood passing through heart
• some medically important, some not
• two types:
– valvular insufficiency and valvular stenosis
Valvular insufficiency
cardiac valves leaking because cusps not closing tightly
• blood regurgitating back through valve
• may get heart enlargement
Valvular stenosis
- valve cusps scarred and cannot open completely
- presents resistance to blood flow
- reduces chamber output
- chamber may enlarge and dilate
Heart rate (HR) =
number of beats per minute
Stroke volume (SV) =
volume of blood ejected during one beat
Formula for cardiac output?
HR x SV = CO
Total blood volume =
total blood volume pumped through circulation every minute
Smaller heart =
Smaller stroke volume
The resting heart rate is higher to maintain normal resting cardiac output which is why women’s heart rate is ___ compared to men’s? and infants have which type of heart rate?
women’s HR is typically faster than emn’s, infants have higher heart rate
Larger heart larger =
learger stroke volume
Athletes hearts are ___ and ____?
larger and stronger
Athletes cardiac muscle cells are ___?
hypertrophied
Larger stroke volume =
lower heart rate to maintain Cardiac output
Athletes with bradycardia is called?
excersise induces bradycadia
Cardiac reserve is an ____ in cardiac output above rest level?
increase
Formula for cardiac reserve
difference C.O. at rest and max C.O body is capable f
Cardiac reserve measure of level of exercise an individual can pursue. How is it with healthy, non-athlete, in an athlete and with a weakened heart?
increased four-fold in healthy, nonathlete
• increased up to seven-fold in athlete
• with weakened heart, may have little reserve and exercise limitation
Positive chronotropic agents do what? list 4 examples
increase HR – Thyroid hormone – Caffeine – Nicotine – Cocaine • can lead to fast and erratic heart beat, possibly fatal
Negative chronotropic agents do what?
Parasympathetic innervation
– Beta-blocker drugs
• interfere norepinephrine and epinephrine binding to beta receptors
• used to treat high blood pressure
What are the major variable incluencing storke volume?
venous return and afterload
Afterload is ? ex?
resistance in arteries to ejection of blood by ventricles
- pressure that may be exceeded before blood ejected
- ex: atherosclerosis
Chronotropic agents do what to heart rate?
– Increases or decreases, dependent on chronotropic agents
• stimulate SA node to change its firing rate
• stimulate AV node to alter amount of delay
Variables That Influence Cardiac Output, Stroke volume ?
– Venous return altering stretch of heart
– Afterload decreasing stroke volume
Variables That Influence Cardiac Output Cardiac output
Increases when both stroke volume and heart rate increase
– Decreases when both stroke volume and heart rate decrease
Bradycardia:
persistently low resting heart rate in adults
• below 60 beats/minute
• normal change in athletes
• abnormally due to:
– hypothyroidism, electrolyte imbalance, and congestive heart failure
Tachycardia
- persistently high resting heart rate
- over 100 beats/minute
- caused by heart disease, fever, and anxiety
Hypertension (blood pressure too high) can do what ot blood vessels?
can damage blood vessels and lead to cardivascular disease
Hypotension (blood pressure too low) causes hat two things
body deprived of nutrients
• may cause death if severe
Three tunics of vessels? these do what?
- tunica intima, tunica media, tunica externa
* exchange substances between blood and tissues
Tunic intima is what type of tissue? (2)
simple squamous epithelium , subendothelial layer of areolar connective tissue
Tunic media is circularly arranged layers of what type of tissue?what does this help with?
circularly arranged layers of smooth muscle cells with elastic fibers • contraction causing vasoconstriction – narrowing of vessel lumen • relaxation causing vasodilation – widening of vessel lumen
Are vessels considered organs?
yes, 2 or more vessels working together to provide common fxn
Tunica externa is mae up of which 2 types of tissues?
areolar conn tissue iwth elastic and collagen fibers
Elastic fibers in externa help with what? what abou the collagen fibers?
elastic fibers help with resilance and collagen fibers help with strength
Tunica externa contains a ___ for it’s own circulation of blood?
vasa vasorum
Veins differ in vessels in which ways?
- have thicker tunica externa and larger lumen
- less elastic and collagen fibers
- wall collapsed if no blood in it
Capillaries differ in which ways?
- contain only tunica intima
- composed of endothelium and basement membrane
- lack subendothelial layer
- allow for rapid gas and nutrient exchange
Ficks law of diffusion direct correlaiton (top)
strength of concentration gradient, temp time
Ficks law of diffusion indirect correlation (bottom)
molecular weight and distance
Three types of arteries include?
elastic arteries, muscular arteries, arterioles
elastic arteries
– Largest arteries with diameters from 2.5 to 1 cm
– Conduct blood from heart to smaller muscular arteries
– Have large proportion of elastic fibers
– Allow artery to stretch and recoil
• helps propel blood through arteries during diastole
muscular arteries
– Medium arteries with diameters from 1 cm to 3 mm
– Distribute blood to specific body regions
– Have greater amounts of muscle, less elastic tissue
• better able to vasoconstrict and vasodilate
• less able to stretch
arterioles
• Smooth muscle usually somewhat constricted
• called vasomotor tone
• regulated by vasomotor center in brainstem
– Regulate systemic blood pressure and blood flow
Atherosclerosis
– Progressive disease of elastic and muscular arteries
– Presence of atheroma (atheromatous plaque)
• thickening of tunica intima
• narrowing of arterial lumen
– May be due to response to injury to endothelium
• by infection, trauma, hypertension
• results in inflammation reaction, atheroma formation
• with atheroma enlargement lumen narrower
• unaware of plaques until restrict blood flow to region
Increased cholesterol in the blood, hypercholesterolemia
• makes prone to disease
– Males more affected than females
– Smoking and hypertension
• increase vascular injury and overall risk
– Treatment
• angioplasty to expand narrowed region of artery
• coronary bypass surgery
Aneurysm
– Part of arterial wall thins and balloons out
– Wall more prone to rupture
• can cause massive bleeding and death
– Elastic and muscular arteries
• with age less able to withstand forces from pulsating blood
– Risk increasing with age
– Most common in aorta or arteries at the base of the brain
3 types of capilaries
Continuous, fenestrated, and sinusoid type capillaries
Continuous
- most common type
- endothelial cells forming continuous lining around lumen
- rests on complete basement membrane
- cells secured by tight junctions but don’t form complete seal
- found in muscle, skin, lungs, central nervous system
fenestrated
• endothelial cells forming continuous lining
• rests on complete basement membrane
• small regions of endothelial cells extremely thin
– fenestrations
– allow movement of smaller plasma proteins
– too small for formed elements
sinusoid
• endothelial cells forming incomplete lining with gaps
• basement membrane incomplete or absent
• openings allowing for transport of large substances
– e.g., formed elements, large plasma proteins,
• found in
– bone marrow for entrance of formed elements
– liver and spleen removing aged erythrocytes
– some endocrine gland
