Lecture exam 2 Flashcards
What type of circulatory pathway would drain blood from an organ using four different blood vessels
Venous anastomosis.
What is the major difference between the tunica media of an artery and the tunica media of a vein
The tunica media of an artery has much more smooth muscle, along with collagen fibers and elastic fibers, than the tunica media in a vein.
Why are fenestrated capillaries prevalent in the kidneys?
Fenestrated capillaries contain many small holes for rapid filtration of wastes and small solutes.
Determine the pulse pressure for an individual with a blood pressure of 122/67.
55 (systolic pressure - diastolic pressure).
What might happen to the blood pressure of an individual with aplastic anemia? EXPLAIN.
Blood pressure will probably decrease. Aplastic anemia causes a reduction in the production of formed elements. Fewer formed elements in the blood means the blood is less viscous, which reduces resistance. Thus, blood pressure will eventually decrease.
What happens to blood pressure if chemoreceptors in the carotid arteries detect a decline in oxygen levels? EXPLAIN.
Blood pressure will rise. A reduction in oxygen levels stimulates the chemoreceptors to signal the vasomotor center in the medulla oblongata to trigger systemic vasoconstriction to increase blood pressure.
Why are aldosterone and ANP antagonists
Aldosterone promotes the retention of sodium ions, which increases water retention leading to an increase in blood pressure. ANP promotes the excretion of sodium ions, which reduces water retention leading to a decrease in blood pressure.
Which pressure exerts the greatest influence on capillary filtration during bulk flow?
Blood hydrostatic pressure.
What does an antidiuretic do to blood pressure? EXPLAIN.
Blood pressure will increase. An antidiuretic promotes conservation of water by the kidneys. This increases blood volume causing blood pressure to rise.
What type of circulatory shock might occur if you fell out of bed and landed on your head?
Neurogenic shock.
Average mL of blood flow per minute
5250
What is blood flow?
pumping action of the heart, measured as the amount of blood traveling through any organ, tissue, or blood vessel in a given period of time.
What does velocity of blood flow depend on
cross-sectional area through which it flows.
Blood perfusion
flow of blood through a given volume or mass of tissues per unit of time. mL/min/g
what is the total blood flow in a resting individual
it is constant with their cardiac output but flow through a particular organ varies
larger gradient =
better flow
hemodynamics are based on
blood pressure and resistance
blood flow is directionally proportional to
the difference in pressure between two points
blood flow is inversely proportional to
the resistance it encounters
What is blood pressure
the force exerted by blood against the walls of a blood vessel when it encounters resistance as it flows
What is BP determined by
cardiac output, blood volume, and resistance
what is cardiac output the product of
stroke volume and heart rate
Occurs during ventricular contraction
systolic BP. average 120 mm/Hg
occurs during ventricular relaxation
diastolic BP. average 75 mm/Hg
the difference between systolic BP and diastolic BP
Pulse Pressure
mean arterial BP (MAP)
propels blood to the tissues and measures the stress on blood vessels based upon diastolic and pulse pressure
normal MAP
90 mm/Hg
Peripheral resistance
opposition to blood flow because of friction between blood and the walls of the blood vessels
Resistance relationship with viscosity
direct relationship
Blood viscosity depends on
ratio of erythrocytes to plasma volume and concentration of proteins in blood plasma
Reducing # of RBC’s
reduces viscosity and decreases resistance
Reduction in concentration of plasma proteins
reduces viscosity and decreases resistance
Increase in # of RBC’s
increases viscosity and resistance
Dehydration
increases blood viscosity and resistance
Resistance and vessel length relationship
direct. longer blood vessels provide more friction and greater peripheral resistance
Each added pound of adipose tissue adds how many km of vessel length
300 km
what has the greatest short term influence on blood flow
blood vessel radius
vasoconstriction
reduces radius of blood vessel. cooling promotes this. decrease in BP
vasodilation
increases radius of a blood vessel. warming promotes this. lactic acid, histamines, and nitric oxide are vasodilators
Resistance and vessel radius relationship
inverse
laminar flow
blood exhibits this by moving faster near center of blood vessel due to less friction and slower near walls of blood vessel due to more friction
what does decreasing radius of a blood vessel by half due to resistance
it increases resistance by 16 times
differences in cross sectional area
makes blood flow decline from arteries to capillaries and increase from capillaries to veins
autoregulation
ability of an organ to regulate its own blood supply by varying the resistance of the arterioles in order to meet the metabolic demands for oxygen, nutrients, and waste removal
what vasoactive chemicals alter blood vessel radius
ones released by platelets,leukocytes, or endothelial cells.
the cardiovascular center in the medulla oblongata contains
contains a cardiac center and a vasomotor center, which exerts neural control over blood vessels by transmitting impulses that maintain vasomotor tone
vasomotor tone
describes a state of moderate constriction that varies from organ to organ
baroreflexes
negative feedback responses to change in blood pressure that gets detected by receptors in aorta and carotid arteries. correct momentary drops in BP within 3-5 seconds
increase in BP stimulates receptors to
send signals to vasomotor center to reduce vasomotor tone and vasodilation
chemoreflexes
autonomic responses to changes in pH, oxygen concentration, or carbon dioxide concentration detected by aortic bodies and/or carotid bodies
stimulate chemoreceptors to cause widespread vasoconstriction to increase BP
acidosis, hypoxia, or hypercapnia.
angiotensin II
vasoconstrictor that raises BP when kidney perfusion is inadequate.
angiotensin converting enzyme (ACE)
can be blocked by drugs to reduce angiotensin II levels which reduces BP
aldosterone
promotes the retention of sodium ions which promotes water retention and raises BP
atrial natriuretic peptide
increases the excretion of sodium ions which will reduce blood volume and lower BP
antidiuretic hormone (vasopressin)
vasoconstrictor released from posterior lobe of pituitary gland which causes kidneys to conserve water and raise BP
epinephrine and norepinephrine
vasoconstrictors that raise BP and bind to adrenergic receptors on smooth muscle to stimulate contractions.
capillary exchange
the movement of substances into and out of the capillaries
diffusion
important exchange mechanism used to move glucose and oxygen between the blood and tissues and to move wastes and CO2 between tissues and blood
transcytosis
occurs when endothelial cells transport fluid-filled vesicles that contain albumin, fatty acids, or insulin across capillaries
bulk flow
passive process by which dissolved substances move from the blood into the interstitial fluid by filtration and from the interstitial fluid into the blood by re-absorption
Filtration results from
blood hydrostatic pressure and interstitial fluid osmotic pressure
blood hydrostatic pressure (BHP)
is generated by the heart’s pumping action and is higher at arterial end of capillary bed than at venous ends
interstitial fluid osmotic pressure (IFOP)
draws water out of the capillaries because of solutes present in interstitial fluid
reabsorption results from
colloid osmotic pressure and interstitial fluid hydrostatic pressure
blood colloid osmotic pressure (BCOP)
draws water into capillaries cause of proteins present in plasma
interstitial fluid hydrostatic pressure (IFHP)
is negligible
net filtration pressure equation
(NFP)=(BHP + IFOP) - (BCOP + IFHP)
BHP is higher at what end of a capillary bed and why
arterial end/ there is no outward pressure and fluid moves out of capillary and into interstitial space
BCOP is higher at what end of a capillary bed and why
venous end/ there is net inward pressure and fluid moves into capillary from interstitial space
what percent of the 20 liters of fluid filtered out of the capillaries each day will get absorbed into blood
85%/ remaining fluid gets absorbed by lymphatic system to prevent fluid from accumulating in tissues which is returned to the blood
Pressure gradient from venules to vena cavae
favors blood flow back to right atrium even though BP remains steady at 15 mm Hg. Gradient will increase when blood volume increases or when veins dilate. It will decrease when veins constrict or if pressure increases in right atrium due to leaky tricuspid valve
skeletal muscle pumps in the limbs
they squeeze blood out of veins towards the heart
At rest both valves in venous segment are
open and blood flows toward the heart
muscle contraction compresses the vein
which forces blood through proximal valve and closes distal valve
muscle relaxation cause the proximal valve to close
and blood enters venous segment through open distal valve
thoracic (respiratory) pump
aids in blood flow toward the heart because differences in pressure during inhalation and exhalation squeeze the inferior vena cavae
physical activity increases venous return because
heart beats faster and harder, blood vessels dilate, muscle contractions increase and respiratory rate and depth increases.
hypertension
persistent high blood pressure that is defined as systolic BP above 140 mm Hg and diastolic BP above 90 mm Hg. myocardium stretches excessively and loses efficiency
hypertension increases
afterload/ which makes ventricles work harder to expel blood
hypertension is a major cause of
stroke- arteries in brain become more prone to rupture/ kidney failure- arterioles thicken and renal blood flow decreases. positive feedback releases angiotensin II and aldosterone which raise BP to improve blood flow through kidneys
What percent does primary hypertension count for
90% and results from a collection of factors that cant be attributed to a single cause
obesity increases
the overall length of blood vessels which increases peripheral resistance and raises BP
What contributes to primary hypertension
sedentary lifestyle, diets high in saturated fat and cholesterol, diets low in potassium magnesium and calcium.
what role does nicotine play in primary hypertension
it contributes to it by stimulating vasoconstriction and increasing afterload which makes myocardium work harder
treatments for hypertension
weight loss, aerobic exercise, dietary changes, and drugs.
diuretics decrease BP by
reducing blood volume
ACE inhibitors block the formation of
angiotensin II which decreases sodium and water retention so BP decreases and cardiac output improves.
beta-blockers decrease heart rate and contractility by
preventing response to norepinephrine when it binds to adrenergic receptors
calcium channel blockers inhibit the flow of calcium ions into
cardiac muscle which reduces cardiac workload
what causes secondary hypertension
kidney disease, atherosclerosis, hypersecretion of aldosterone, cushing disease and polycythemia
coronary atherosclerosis can be triggered by
damage to endothelium of an artery causes moncytes to adhere to damaged endothelium and penetrates it
in coronary atherosclerosis monocytes become macrophages and
absorb fats and cholesterol to form fatty streaks on artery wall. platelets adhere to damaged endothelium and release chemicals that stimulate formation of atherosclerotic plaque. smooth muscle and elastic tissue get replaced by scar tissue and artery becomes rigid and more susceptible to obstruction
hypertension tends to run in
families and children whose parents have hypertension are twice as likely
hypertension is % more common among blacks than whites
30%
hypertension is more common among
men between 18-54 and women older than 65
cardiac output fails to
deliver enough oxygen and nutrients to meet our metabolic needs
cardiogenic shock
is caused by inadequate pumping of the heart usually due to MI(heart attack)
hypovelemic shock
characterized by low BP, weak pulse, and tachycardia following significant blood loss from a sudden hemorrhage or from dehydration
hypovelemic shock can lead to
trauma, internal bleeding, excessive sweating diarrhea or vomiting can eliminate much fluid that water is transferred from blood to tissues. venous return declines stroke volume decreases and cardiac output fails.
obstructive shock
occurs when blood flow is blocked (pulmonary embolism)
vascular shock
occurs when too much blood accumulates in the limbs.
anaphylactic shock
is a severe allergic response that releases huge amounts of histamines which triggers rapid vasodilation
neurogenic shock
produced by head trauma,which can lead to loss of vasomotor tone
septic shock
occurs when bacterial toxins trigger vasodilation
transient vascular shock
may occur after prolonged exposure to sun cause cutaneous blood vessels dilate and blood can accumulate in lower limbs upon standing
aneurysm
thin weakened section in a blood vessel that bulges outward and may eventually rupture leading to hemorrhage
varicose veins
weak, distended superficial veins with leaky valves in the legs which cause pooling. fluid leaks into the surrounding tissues and causes pain and inflammation
edema
accumulation of excess fluid in a tissue due to increased capillary filtration and reduced capillary reabsorption
stroke
sudden death of brain tissue due to cerebral ischemia. brief episodes of cerebral ischemia produce transient ischemic attacks characterized by dizziness, headache, loss of vision and other sensory losses
lymphatic system consists of a network
of lymphoid tissues and lymphatic vessels that drain excess fluids that seeped out of the blood into the tissue spaces
lymphatic vessels absorb
lipids and lipid-soluble vitamins from the gastrointestinal tract and transport them to the blood
lymphoid tissues protect against
foreign cells microbes toxins and cancer cells
lymph is
a relatively clear, colorless fluid that is similar to blood plasma but it contains fewer proteins and its composition varies throughout the body
intestinal lymph
is milky white following a meal because of its high fat content
lymph in a lymph node
may be filled with lymphocytes, macrophages, and debris
lymphatic capillaries
microscopic vessels which are located everywhere in the body except in avascular tissues
lymphatic capillaries compared to blood capillaries
slightly larger but have closed ends
endothelial cells in lymphatic capillaries
overlap one another and act as valve-like flaps
small intestine contains specialized
lacteals to transport dietary lipids
interstitial fluid can flow into lymphatic capillary when
fluid pressure in tissues is high but cant flow out when fluid pressure in tissues is low
lymphatic capillaries unite to form
lymphatic vessels, which pass through lymph nodes
lymphatic vessels unite to form
lymphatic trunks which different parts of the body
lymphatic trunks converge to form
lymphatic ducts which return fluid to the blood
thoracic duct drains
left side of head, neck, chest, left arm, and entire body below the ribs
right lymphatic duct drains
lymph from upper right region of body into right subclavian vein
lymph flows slowly and is controlled by
contractions of skeletal muscle and respiratory movements
lymphatic cells can be loosely scattered
in mucous membranes or tightly clustered and encapsulated in lymphatic organs
develop in the thymus gland and carry out immune responses
T lymphocytes
mature in bone marrow and produce antibodies to protect the body against disease-causing organisms
B lymphocytes
macrophages phagocytize
foreign antigens and become antigen-presenting cells
dendritic and reticular cells are
antigen-presenting cells in lymphatic organs
lymphatic cells form
dense lymphatic nodules in lymph nodes and the tonsils, and form Peyer’s patches in the small intestine.
lymph nodes
bean shaped structures located along lymphatic vessels in the mammary glands, armpit region and groin
a lymph node is covered by
a fibrous capsule that extends inward and divides the node into compartments.
interior of a lymph node consists of
a stroma(contains reticular tissue) and parenchyma which contains lymphocytes and antigen-presenting cells
outer cortex of parenchyma contains
germinal centers where B lymphocytes multiply
inner medulla of parenchyma contains
B lymphocytes, macrophages, and reticular cells
lymph flows into a lymph node through
afferent lymphatic vessels, then passes through sinuses, and finally exits the lymph node by way of an efferent lymphatic vessel
lymph nodes filter and cleanse lymph as
it flows toward the blood stream
macrophages and reticular cells remove
most impurities, and foreign substances from lymph
swollen glands
when large numbers of bacteria get trapped in a lymph node it becomes inflamed, swollen, and tender to the touch
lymph nodes alert the immune system to
pathogens that have entered the body
lymphocytes destroy
foreign substances by a variety of immune responses
viruses can infect lymph nodes and
create reservoir of viral particles that escape detection by immune system (HIV)
cancer cells in lymphatic system
may form secondary tumors when they lodge in lymph nodes. they can establish new growths in a lymph node which blocks flow of lymph and causes swelling.
cancerous lymph nodes are
swollen but seldom painful
tonsils
are concentrations of lymphoid tissue at the entrance to the pharynx and they guard against ingested or inhaled pathogens
one pharyngeal tonsil is located where
in the nasal cavity and adenoid pharynx
pair of palatine tonsils are located
in the back of the mouth. these can be removed
pair of lingual tonsils are located
in the base of the tongue
thymus gland is located
in the mediastinum posterior to the sternum and its two lobes are surrounded by a fibrous capsule that divides each lobe into several
each lobule consists of
an outer cortex and an inner medulla
cortex contains
lymphocytes, reticular epithelial cells, and macrophages
medulla contains
mostly reticular epithelial cells and thymic corpuscles
reticular epithelial cells
secrete thymic hormones that cause T-lymphocytes to mature and migrate to lymph nodes, spleen, and other lymphatic tissues
thymus gland is ___ in an infant and grows even ___ during childhood
very large, larger. after puberty the tissue gets replaced by adipose tissue and areolar tissue until thymus gland is barely distinguishable in an adult
the spleen is the
largest lymphatic organ and contains different kinds of lymphoid tissue.
white pulp contains
lymphocytes and macrophages and plays a role in immunity
red pulp consists of
venous sinuses filled with red blood cells
spleen produces RBC’s in a fetus and
monitors blood for foreign antigens and phagocytizes bacteria. macrophages remove worn out RBC’s and defective platelets and phagocytoze them to recycle hemoglobin
abdominal trauma
can rupture the spleen and cause severe internal bleeding which cant be stopped until it is removed. red bone marrow and the liver will take over some of the funtions
without a ___ an individual is more likely to get infections
spleen
edema describe the accumulation
of excess fluid in a tissue either because capillary filtration exceeds re-absorption or lymphatic vessels become obstructed
elephantiasis
is caused by a roundworm transmitted via mosquito which blocks flow of lymph and produces chronic edema
lymphadenopathy
enlarged tender lymph nodes
lymphomas
are lymphatic cancers that usually originate in isolated lymph nodes
hodgkins disease
swollen, painless lymph nodes and alternating fever and night sweats. chemo and radiation to cure
non-hodgkins lymphomas
result from uncontrolled multiplication of lymphocytes that metastasize characterized by swollen lymph nodes or swelling in the spleen and peyers patches.
nonspecific resistance
is built-in protection against invasion by a wide range of pathogens
pathogens are
disease producing agents that include infectious organisms toxic chemicals and radiation
why does the body harbor bacteria
homeostasis provides ideal temp. moisture, pH, and nutrients for microbial life
what are the first lines of defense against pathogens
skin and mucous membranes
typically to dry and nutrient-poor for microbes to survive
the skin
secrete oily sebum and a coat of antimicrobial chemicals and lactic acid from sweat covers skin
sebaceous glands
line body cavities that are open to the exterior and secrete mucous to trap microbes that try to enter
mucous membranes
contains hyaluronic acid which gives it sticky consistency that makes it difficult for microbes to penetrate
areolar connective tissue
provide mechanical barrier against microbes
keratin and epidermal cells
lacrimal apparatus
secretes tears to keep microbes from infecting the eyeballs
saliva
dilutes the number of microorganisms and washes them from the teeth and mouth
sweat glands
produce perspiration to flush microorganisms from the skin
mucous, tears, saliva, and perspiration contain
lysozyme which dissolves bacterial walls
urine
prevents microbial growth in the urinary system by constantly flushing the urethra
acidic secretions from gastric glands
in the stomach and vagina slow bacterial growth
organisms that get past the skin and mucous membranes
are attacked by phagocytes. phagocyte adheres to a pathogen by recognizing its carbohydrate signature
neutrophils
usually phagocytize bacteria but they also kill bacteria with chemicals
neutrophil release chemicals to
form a “killing zone” around itself which kills more bacteria than it could otherwise
“killing zone”
contains hydrogen peroxide and hypochlorite to kill bacteria but neutrophil also dies. may contribute to rheumatoid arthritis
natural killer cells
large lymphocytes produced in red bone marrow which kill a wide variety of bacteria and host cells that have become cancerous or gotten infected with viruses
when a natural killer cell encounters a microbe or abnormal host cell
it secretes perforins to rupture membrane and destroy target cells
natural killer cells are found in
blood, spleen, lymph nodes, and red bone marrow
macrophages develop from
monocytes and become scavenger cells
wandering macrophages leave the blood to
seek out pathogens in the tissues
fixed macrophages stand guard in
certain tissues or organs and phagocytize pathogens that come to them
antimicrobial proteins
provide a second line of defense against bacteria and viruses
interferons
are proteins that have been produced and released by cells that have become infected with viruses. They are not virus specific
interferons stimulate
uninfected neighbor cells to manufacture antiviral proteins that can interfere with viral replication
interferons enhance
phagocytosis and activate natural killer cells
complement system describes
a group of 30 or more proteins that are synthesized by the liver and circulate in the blood plasma in an inactive form
activation by a pathogen splits one of these proteins into fragments
that can destroy pathogen by inflammation or immune clearance, phagocytosis, or cytolysis
classical pathway
requires activation of antibodies which make it part of immune response
alternative pathway
non-specific active complement fragments can bind to viruses, bacteria, or yeast
lectin pathway
binds plasma proteins to particular carbohydrates to initiate a reaction cascade
inflammation
local response to tissue damage that is designed to limit the spread of a pathogen to remove debris associated with damage tissue and to initiate tissue repair
inflammation is characterized by
redness, swelling, heat, and pain
inflammation can occur anywhere in the body
most common in skin
inflammation is mediated by small cytokine proteins
that alter physiology or behavior of recipient cell
cutaneous inflammation
can result from mosquito bite, sunburn, or poison ivy
local vasodilation increases blood flow to
the damaged tissue and causes hypermia which produces redness and heat in the inflamed region
mast cells release histamines and other cells release
kinins, prostaglandins, and leukotrines. all chemicals increase permeability of blood vessels and promote filtration of fluid into interstitial spaces.
swelling presses on nerve endings this
combines with toxins, prostaglandins, kinins, to produce pain sensations
swelling is good because
fluids move foreign substances into the lymphatic system also delivers complement proteins and clotting factors to damaged tissues
after inflammation begins
the damaged tissue gets flooded with leukocytes which leads to an increase in WBC count that is characteristic of inflammation
neutrophils accumulate in capillaries (margination)
to identify inflammation site
diapedesis allows
leukocytes to change their shape and crawl through capillary walls to enter interstitial fluid
pathogens must be contained and
destroyed before they can spread throughout the body
fibrinogen filters into the fluid around a damaged tissue and
forms a clot which sequesters bacteria and other microbes
heparin prevents the blood from
clotting in the immediate vicinity of the injury so any pathogens that are present get trapped
neutrophils are attracted by chemicals that
guide them to the site of injury or infection (chemotaxis)
neutrophils recruit monocytes and more neutrophils by
secreting cytokines
monocytes arrive within 8-12 hours following
the injury and become wandering macrophages that engulf any remaining bacteria, host cells, worn-out neutrophils
dead phagocytes, debris, and dead pathogens get surrounded by
thick yellowish pus
pus is usually absorbed from
the infection site but if it cant drain from the inflamed region a blister may form
immune system consists of
cells and tissues that defend the body against specific invading agents such as bacteria, toxins, viruses, and foreign tissues
immune system is a ___ system rather than an organ system
functional
specificity enables the immune system to
identify particular pathogens and to distinguish between self and non-self molecules
immune system has a memory for encounters with
previously identified antigens allows it to aggressively respond to subsequent invasions by these pathogens
cellular immunity (cell-mediated)
uses lymphocytes to directly attack and destroy foreign cells or host cells infected with bacteria viruses or yeast. protects against parasitic worms, cancer cells, and cells from transplanted organs
humoral immunity (antibody mediated)
uses antibodies to label pathogens for destruction by other mechanisms. protects body against bacteria and bacterial toxins
naturally acquired active immunity occurs when
antibodies or T cells are produced in response to a particular pathogen (measles, chicken pox)
naturally acquired passive immunity
is temporary immunity resulting from the natural transfer of antibodies from an immunized donor to a non-immunized recipient (mother to baby via breastfeeding)
artificially acquired active immunity
results from vaccination (polio, smallpox)
artificially acquired passive immunity
is temporary immunity resulting from an injection of serum that contains antibodies that were produced outside of the body
horse serum can be used for emergency treatment of
certain snakebites
an antigen is an
antibody generating molecule that shows immunogenicity and reactivity
immunogenicity is the ability to
provoke an immune response
reactivity is the ability to
interact with specific antibodies or cells
antigen may be a
microbe, bacterial cell walls, toxins, incompatible blood cells, pollen, or egg whites can be antigenic
most antigens are
large, complex proteins that are unique to each individual
epitope or antigenic determinant is a
specific region of an antigen that can trigger an immune response. most have several epitopes that either induce production of specific antibodies or activate specific T cells.
haptens
are small molecules that attach to larger molecules and create unique complexes that the immune system can recognize as foreign (poison ivy, penicillin)
T lymphocytes are born in
red bone marrow from stem cells. they travel to the thymus gland where thymic hormones stimulate them to develop surface antigen receptors and become immunocompetent
when B or T cells becom immunocompetent they display
surface receptors to recognize and bind to a specific antigen
positive selection
produces identical T cells that are programmed to respond to a particular foreign antigen
negative selection
eliminates any T cells that bind to self-antigens
fetal stem cells that remain in bone marrow differentiate into
B lymphocytes
the presence of a foreign antigen must be detected
for an immune response to occur
exogenous antigens are found in
the extracellular fluid outside of the bodys cells. (bacterial toxins, pollen, dust)
endogenous antigens are produced
inside of the bodies cells (viral proteins, abnormal proteins associated with cancer cells)
major histocompatibility complex (MHC)
each individuals family of genes on chromosome 6 that code for MHC proteins that act as sefl-antigens
MHC-I proteins are found
on the plasma membrane of all body cells except RBC. they are continually synthesized by a cell and transported to its plasma membrane
MHC-II proteins occur only on
antigen presenting cells (human leukocyte antigen HLA). help T cells recognize foreign antigens
antigen presenting cells (APC)
can be B cells, macrophages, or dendritic cells that process and present exogenous antigens for destruction
a foreign antigen is ingested by
phagocytosis. digestive enzymes split the antigen into fragments. antigen fragments are joined with MHC protein molecules. antigen MHC protein complex is inserted into plasma membrane of the APC to be displayed. Apc migrates to lymphatic tissue to present the antigen to T cells so immune response can begin
interleukins
coordinate the activities of various leukocytes that are involved in the immune response
lymphokines
are produced by lymphocytes
monokines are produced by
monocytes
cell mediated immunity requires the activation of
a small number of T cells by a particular antigen
when an antigen presenting cell encounters and processes a foreign antigen it
present that antigen to a T cell usually in a lymph node which recognizes it and binds to the antigen fragments that are displayed on the APC.
activation also requires co-stimulation by
interleukins. prevents system from destroying healthy cells
once a T cell is activated it
proliferates and differentiate into a clone of identical cells that can recognize the particular antigen and carry out an immune attack
proliferation peaks within
one week of exposure to the antigen
helper (T)h cells recognize
and antigen-MHC-II complex and secret interleukins. they attract neutrophils and natural killer cells, attract macrophages and stimulate phagocytosis, activate T cells and B cells
Cytotoxic (T)c cells recognize
foreign antigens combined with MHC-I proteins and become killer cells that can deliver a lethal hit to a target cell.
(T)c perforin forms holes in the
target cells membrane causing cell to burst
(T)c lymphotoxin activates enzymes in the
target cell that destroy cell’s DNA
(T)c tumor necrosis factor kills
cancer cells
Regulatory (T)reg cells release
interleukins that will inhibit T and B cell activity and turn off immune response once pathogen has been destroyed. Prevents auto-immune reactions
Memory (T)m cells remain from
a proliferated clone. programmed to recognize the original antigen so immune system can destroy that pathogen before symptoms can occur
antigen challenge
first encounter between an immunocompetent and inactive lymphocyte and an invading antigen in the spleen or lymph node
if a B cell is provoked in the antigen challenge
humoral response is intiated
antibody mediated immunity is an indirect method of protection where
B lymphocytes are activated to produce antibodies that bind to antigens in order to destroy them
an antigen binds to one or more of the thousands of antigen receptors on the surface of an
immunocompetent B cell which links them together
when helper T cell recognize the antigen-MHC protein combination they produce
interleukins and other cytokines that function as co-stimulators to activate B cell
activated B cells enlarge and divide into
a clone of plasma cells
plasma cells can synthesize and release
antibodies for a specific antigen at a rate of up to 2000 molecules per second for 4-5 days
activated B cells that dont differentiate into plasma cells become
memory cells that respond rapidly if antigen reappears in the future
immunoglobin consists of
4 large complex polypeptide chains each of which contain a variable region that is specific for a particular antigen and a constant region that will determine how the antibody works
constant region determines
class to which antibody belongs
variable region forms
antigen binding site
IgG antibodies are the most
abundent and they are found in blood in the lymph, and in the intestines
IgG antibodies protect against
bacteria and viruses by enhancing phagocytosis and neutralizing toxins by triggering complement system
what are the only antibodies that can cross the placenta from mother to fetus
IgG
IgA antibodie are found in
tears, saliva, mucous, and milk.
IgA antibodies provide
localized protection against bacteria and viruses
IgM antibodies are the first to be
secreted by plasma cells after initial exposure to antigen
IgM antibodies include
anti-A and anti-B antibodies of the ABO blood group which are potent agglutinating agents
what does it mean if IgM antibodies are present in blood plasma
some kind of infection
IgE antibodies are found mainly in the
tonsils, skin, and mucous membranes. stimulate mast cells and basophils during inflammation and allergy reactions. also release histamines
IgD antibodies are located on
B cell membranes where they act as antigen receptors
antibodies neutralize an antigen by
binding to its active region and blocking its effects
IgG and IgM expose
complement binding sites on target cell/activates complement system
antibodies have multiple antigen-binding sites so they can
cause agglutination
antibodies link antigen molecules together to create
a complex that is too large to remain dissolved in the plasma
precipitation makes antigens more susceptible to
phagocytosis
antibody titer
can measure the level of a specific antibody present in the blood
primary immune response occurs following an initial exposure to an antigen and it produces
and releases antibodies over a period of time
secondary immune response occurs if the same antigen
invades the body at a later time and gets recognized by the memory cells. produces rapid response within hours of re-exposure
hypersensitivity occurs when
the immune system causes tissue damage because it reacts to an antigen that most people would tolerate
allergy is an reaction to
an environmental allergen (mold,dust,pollen,foods)
initial contact with an allergan produces
no symptoms! but sensitizes the person to that particular antigen
Type I (immediate) hypersensitivity
occurs within seconds after a person gets re-exposed to an allergen to which they are sensitive and it lasts about 30 seconds
abnormally large number of helper (T)h cells differentiate and stimulate
B cells to mature and secrete IgE antibodies
IgE antibodies bind the allergen to
the surface of mast cells and basophils and stimulate these cells to release histamines and other inflammatory chemicals/ causes vasodialtion, smooth muscle spasms, and excessive production of mucous.
localized effects of Type I sensitivity include
swelling, watery eyes, runny nose, and hives. mights be relieved with anti-histamine
food or drug allergies might cause
gastrointestinal cramping, vomiting, diarrhea
asthma is triggered by
inhaling allergens that cause contraction of smooth muscles in airways which reduces airflow
anaphylactic shock is
a severe systemic reaction. typically occurs when an allergen enters the blood of an individual who is hypersensitive. death may occurs unless epinephrine is given to dilate bronchioles increase CO and restore BP
Type II hypersensitivity (cytotoxic) occurs when
IgG or IgM antibodies attack antigens on blood cells or tissue cells which stimulates macrophages to phagocytize and destroy them (blood transfusion, hemolytic disease of newborn, insulin-resistant diabetes)
Type III hypersensitivity (immune complex) occurs when
antigen antibody complexes form beneath the endothelium of blood vessels and activate the complement system and trigger intense inflammation (rheumatoid arthritis, lupus, autoimmune disorder)
Type IV ( delayed) hypersensitivity is carried out by
macrophages and cytotoxic T cells that have been activated by helper-T cells
Type IV hypersensitivity usually appears within
12-72 hours following exposure ( poison ivy toxins, tuberculosis skin test)
autoimmune diseases occur when the
immune system fails to recognize self-antigens and produces auto-antibodies that attack its own tissues(multiple sclerosis, myasthenia gravis, graves disease, type I diabetes)
antibodies for streptococcus bacteria can react with
antigens on heart valves which damages them during rheumatic fever
if sperm cells enter the blood
auto-antibodies can be produced and cause sterility
viruses and other drugs can change the structure of a
self-antigen which causes the immune system to view it as a foreign antigen and produce auto-antibodies against it
virus may infect pancreatic islets and trigger
an autoimmune attack against the beta cells that produce insulin
severe combined immunodeficiency disease (SCID) is a collection of
genetic disorders that interfere with the production or maturation of T cells and B cells
in SCID victims become vulnerable to
various infections
how is SCID treated
with a bone marrow transplant or with stem cells form the umbilical cord
acquired immunodeficiency syndrome (AIDS) describes a
severely depressed immune system because of an infection by the human immunodeficiency virus (HIV)
HIV invades
helper T cells and tricks them into producing new viruses. Helper T cells are destroyed which compromises non-specific defense mechanism, cellular immunity, and humoral immunity
victims of AIDS becom =e more vulnerable to
opportunistic infections and may die from pneumonia or kaposi sarcoma
