Circulatory system Flashcards
What are the 5 types of vessels (in order from heart)
- Arteries
- Arterioles
- Capillaries
- Venules
- Veins
what is an artery
a vessel that takes blood from the heart
what is a vein
a vessel that takes blood to the heart
what is the function of arteries
they are designed for rapid transport, they are large in diameter with low resistance. They are elastic and designed to withstand pressure
What is the function of arterioles
They are the primary control of resistance in the circulatory system. They are muscley and able to dialate and constrict
What is the function of capillaries
location of nutrient exchange
What is the function of venules
they collect blood from capillaries
what is the function of veins
serve as a blood resevoir because they can dialate and constrict
how do arteries act as pressure resevoirs
they are elastic and can expand when pressure is high, then an inflow decreases they shrink back down to size and push the blood to the rest of the body
how does pressure and resistance affect blood flow through a vessel
Flow = pressure gradient/ resistance
what is the pressure gradient
the difference in pressure between the aorta and the vena cava (85mmhg)
pressure in aorta
85 mmhg
pressure in vena cava
0 mmhg
pressure gradient in systemic circut
85 mmhg
pressure in respiratory circut
15 mmhg
is flow equal in systemic circut and respiratory circut
yes
is resistance in pulmonary circut high or low
low
what are the factors that affect resistance to flow
- viscosity of fluid
- length of vessel
- radius of vessel
which factor affecting resistance is most important
radius of vessel
why does radius of vessel matter so much
the smaller the vessel the more surface area contact that occurs with the blood and the more resistance that occurs
how much does vessel diameter affect resistance
R = 1/r^4
doubling the vessel size gives 1/16 the resistance cutting in in half gives 16 times the resistance
What is normal systolic BP
120 mmhg
what is normal diastolic BP
80 mmhg
how do you find pulse pressure
systolic - diastolic
how do you find MAP with systolic and diastolic BP
systolic + 2 diastolic / 3
why does diastolic get twice the credit in MAP equation
it lasts about twice the time as systolic
What is TPR
total peripheral resistance (combined resistance of all the vessels in the circuit)
How can you measure BP
- inserting a cannula directly and measuring it
2. auscultatory method
how do you do the auscultatory method
- you put a cuff on their arm and pump it up
- you listen to the vessel
- when you first hear some noise you check your pressure gage and that is systolic
- when the noise goes away you check your pressure gage and that is the diastolic BP
what is pulse pressure
is the pressure that is caused by the contraction of the heart
what is mean arterial pressure
it’s the average pressure in the artery
What two factors affect MAP
- Cardiac output
- Total peripheral resistance
MAP = CO x TPR
what are the factors that affect CO
- heart rate
2. stroke volume
how do we change TPR
Arteriole diameter
what part of the brain controls sympathetic controle of vasoconstrictor muscles
vasomoter center in medulla of brain
what are baroreceptors
pressure receptors
how often are baroreceptors firing
always
when high pressure, baroreceptors …
fire more
when low pressure, baroreceptors …
fire less
practice drawing what happens when BP is high and low
ok i will
how does general vasoconstriction protect the brain?
if blood volume is low, most vessels constrict, but not the brain, this ensures that the brain gets what it needs.
how does general vasoconstriction help muscles during exercise
- vessels to intestines constrict
- arterioles in muscle dialate,
- precapilary sphincters relax
what are the factors that affect venous return
- Low pressure gradient (pushes blood to heart)
- Low resistance in veins (doesn’t slow it down)
- one way valves in veins (prevent backflow)
- Muscle pump (squeezes blood only up because of valves)
- Respiratory movements (Pressure in thorax decreases with respiration and pulls blood into thorax)
- sympathetic constriction of veins (squeezes vessels and pushed blood to the heart
What are the major components of blood
- erythrocytes
- leukocytes
- platelets
- plasma
What are erythrocytes and what do they do
biconcave cells (surface area), have lots of hemoglobin and no organelles. they transport O and Co2.
What are leukocytes and what do they do
fight off infection
what are platelets and what do they do
(thrombocytes) they are fragments of megakaryocytes that are important in hemostasis. they plug up holes in vessels
what is plasma and what does it do
water portion of blood (91-92% water), it carries proteins, hormones, urea, and dissolved gasses
what are the important plasma proteins
albumin (most abundant)
Globulins
fibrinogen
what is the function of albumin
- helps maintain oncotic pressure (prevent adema)
2. serves as a carrier for fatty acids and hydrophobic substances (hormones)
What is the function of globulin
- helps in blood clotting
2. helps in immunodefense
what is the function of fibrinogen
helps in blood clotting
what is oncotic pressure
its the osmotic pressure developed across the capillary membranes due to the proteins in plasma
how do the proteins in plasma affect oncotic pressure
they can’t diffuse so they are stuck inside and water wants to come in to balance out osmoles
what is the direction of osmotic movement
from low concentration of solutes to high
how does albumin prevent adema
it’s the most abundant plasma protein so it’s presence keeps osmotic pressure pushing water into the capillaries
How does oncotic pressure work
25 mmhg of oncotic pressure tries to push water into veins, when blood first enters capillaries the pressure is greater than that so water flow out, but as is leaves capillaries it is less than 25 mmhg so the oncotic pressure pushes water into the capillaries
How and where are RBC (erythrocytes) produced
- Kidneys detect low O2 levels (due to lower capacity of RBC’s to carry O2)
- Kidneys release erythoropoetin (EPO)
- EPO stimulates erythropoesis in bone marrow
- these new RBC’s are detected by kidneys and EPO secretion is lessened.
What is a hematocrit
its a measurement of what percent of blood is made up by RBC’s
is hematocrit usually higher in men or in women
men (42- 54) …..45……
women (38 - 46)
how is a hematocrit measured
they centrifuge the blood and see what percent of blood (by volume) is made up of RBC’s
how does blood doping affect hematocrit
blood doping is when you put more RBC’s in your blood, or EPO
how does dehydration affect hematocrit
it raises the hematocrit, but not because it increases RBC’s but because it decreases plasma
what is anemia
a deficiency of RBC’s, which leads to a decrease of oxygen transportation
what are the symptoms of anemia
dyspnea
tachicardia
fatigue
at what point do we diagnose anemia
<37 hematocrit in women
what are the types of anemia
- hemorrhagic (loss of blood)
- Pernicious (nutritional deficiency (B12))
- Sickle-cell (abnormal hemoglobin)
- Renal (kidney disease = decrease erythropoesis)
- aplastic (bone marrow cells destroyed) (radiation and drugs)
What is polycythemia
too many RBC’s
what are the types of polycythemia
- Primary (bone marrow tumor)
- secondary (chronic hypoxia - high altitude)
- Blood doping (inject RBC’s or EPO)
what is hemostasis
cessation of bleeding
what are the three major steps of hemostasis
- vasoconstriction
- formation of platelet plug
- formation of fibrin mesh
What is fibrinogen
a plasma protein
how is fibrogen different than fibrin
fibrinogen is kind of the inactive version, when fibrinogen comes in contact with collagen it turns into fibrin and forms the fibrin mesh (clot)
what activates platelets
the Von willebrand factor (vwf)
what do platelets do
aggregate in the hole
they secrete hormones to cause vasoconstriction
they also secrete ADP which encourages platelet aggregation
what role does collagen play in hemostatis
- it binds to vwf, which causes platelets to aggregate
2. they also cause fibrinogen to turn to fibrin and create the fibrin mesh or fibrin clot
what does thrombin do
it stimulates the creation of fibrin and does positive feedback to create more of itself
what is the difference between intrinsic and extrinsic pathway to formation of fibrin cloth
the intrinsic pathway has 7 steps and all of it’s chemicals are found in the blood
the extrinsic pathway only has 4 steps and it’s chemicals are released by the damaged tissue
do both intrinsic and extrinsic work together, how
yes, intrinsic works inside the vessel and extrinsic works in the surrounding tissues
what does it mean to have A blood
your red blood cells have A antigens
What are AB bloodies called
universal acceptor
What are O bloodies called
universal donor
O has no antigens
yep
What is the Rh-factor
rh + has antigen d
rh- doesn’t have antigen d
what about rh is bad
if mother is rh negative and baby is rh positive it’s bad
