Blood vessels & Blood - Lectures 14-15-16 Flashcards
- walls of blood vessels contain (3)
- inner layer is ___________ –> secretes what? + regulates (3)
- smooth muscle + elastic connective tissue + fibrous connective tissue
- endothelium –> secretes paracrine factors + regulates blood pressure, blood vessel growth and absorption
what is muscle tone?
a state of partial contraction –> smooth muscles always in contraction, never totally relaxed
what are the 3 layers of blood vessel structure?
- tunica intima = most inside
- endothelium: specialized epithelial cells
- under endothelium = 1 layer of basement membrane (layer of collagen to support cells together)
- some elastic components - tunica media:
- lost of smooth muscles for contractions
- some elastic tissues (especially arteries) - tunica externa:
- connective tissues: collagen + fibroblast to hold blood tissues together
ARTERIES:
- 2 main functions
- 2 characteristics
- pressure reservoir
- distribute blood to different tissues and organs using smooth muscles (contract = less blood VS relax = more blood goes through)
- thick layers of vascular smooth muscles
- lots of elastic and fibrous connective tissue
ARTERIOLES:
- main function?
- part of the _________
- characteristic
- generate variable resistance using 80% of smooth muscle
- part of microcirculation
- less elastic + more muscular
METARTERIOLES:
- btw (2)
- branches of ________
- 2 characteristics
- between arterioles and capillaries
- branches of arterioles
- partial smooth muscle layer
- precapillary spincters open and close to direct blood flow to capillaries or venous circulation
CAPILLARIES:
- function?
- has all 3 layers of blood vessels?
- walls are (3)
- what contributes to capillary impermeability? –> characteristics
- primary site of exchange between blood and interstitial fluid! very leaky
- has tunic intima. almost no tunic media and externa
- walls lack smooth muscle + flat layer of endothelium + basal lamina = tunic intima
- pericytes! contractile cells associated with capillaries –> projection hold endothelial cells + secrete paracrine factors that promote growth and differentiation
VEINULE AND VEINS
- main function?
- 2 characteristics
VENULES:
- function?
- 3 characteristics: what type of pattern flow?
VEINS:
- function?
- 4 characteristics: more numerous than arteries? Close/far of body surface? Thin/thick walls? Elastic?
- contain what which prevent backflow?
- volume reservoir
- large lumen + not much smooth muscle and elastic
VENULES: - receive blood from capillaries
- thin exchange epithelium + little connective tissue + convergent pattern of flow
VEINS: - volume reservoir!
- thin walls of vascular smooth muscles + more numerous than arteries + lie closer to body surface + less elastic tissue
- contain one-way valves to prevent backward flow (especially for legs bc hard to push back to heart bc low BP in veins)
what do precapillary sphincters do?
- in most situations, open or closed?
- control if blood goes through capillary bed
- if contracted, blood from arterioles directly go to veinules (no exchange with interstitial fluid)
- if open, artery blood goest through capillaries
- most situations –> closed! only 7% of blood in capillaries
where is vein located in calf muscle? why?
in between muscle cells!
- so when muscle contracts, squeeze vein to help blood go back to heart
Blood pressure is highest in _______ and lowest in ________
- what is pulse pressure? how to calculate?
- decreases over what?
- how to aid venous return (3)
- highest in arteries, lowest in veins
- pulse pressure measures strength pressure wave produced by ventricular contraction
- pulse pressure = systolic pressure - diastolic pressure
- decreases over distance due to friction
1. valves
2. skeletal muscle pump
3. respiratory pump
- what is mean arterial pressure (MAP)? how to calculate?
- hypotension/hypertension compared to MAP
- MAP represents driving pressure –> arterial blood pressure reflects driving pressure for blood flow
- MAP = diastolic pressure + 1/3(systolic pressure - diastolic pressure)
*not just (systolic + diastolic)/2 bc heart spends more time in relaxation than contraction - hypotension lower than MAP, hypertension higher than MAP
blood pressure is estimated by ____________
- _________ sounds?
sphygmomanometry
- Korotkoff sounds
how do arteries act as a pressure reservoir when ventricle contracts? 3 steps ish
- ventricle contracts –> semilunar valve opens + blood ejected from ventricles flows into arteries –> aorta and arteries expand and store pressure in elastic walls!
- aorta = lots of elastic tissues –> when blood comes, expand like a balloon so pressure doesn’t increase too much
how do arteries act as pressure reservoir when ventricle relaxes? 3 steps
isovolumic ventricular relaxation –> semilunar valve shut, preventing flow back into ventricle –> elastic recoil of arteries sends blood forward into rest of circulatory system = maintains driving pressure during ventricular diastole
when person gets older, BP increases or decreases? why?
increases! because elastic tissues get lost –> heart can’t expand that much to BP increases –> heart needs to pump harder
- mean arterial pressure proportional to what (2)
- if flow in exceeds flow out, then blood volume (increase/decrease) and MAP (increase/decrease)
- if flow out exceeds flow in, then blood volume (increase/decrease) and MAP (increase/decrease)
- proportional to cardiac output (CO) and resistance in arterioles
- in > out –> BP increases, MAP increases
- out > in –> BP decreases, MAP decreases
how does blood volume affect blood pressure:
- blood volume constant during day?
- if blood volume increase, pressure (increase/decrease). explain
- if blood volume decrease, pressure (increase/decrease). explain
- relatively constant!
- if blood volume increases, pressure increases –> kidney is responsible for removing excess fluid volume
- if blood volume decreases, pressure decreases –> lost fluid volume compensated through drinking or intravenous infusion + vasoconstriction and sympathetic stimulation of heart
- increase blood volume leads to increase blood ________
- how to compensate ? 2 pathways
increase blood volume leads to increase blood pressure
1. compensation by cardiovascular system –> vasodilation + decrease cardiac output –> decrease BP to normal
2. compensation by kidneys –> excretion of fluid in urine –> decrease blood volume –> decrease blood pressure to normal
resistance in arterioles is influenced by:
1)_________ reflexes –> branches into 2 –> what receptors?
2) _________ control
- which of the 2 is more powerful?
1) systemic reflexes –> in all blood vessels
a) autonomic nervous system –> SNS induces smooth muscle contraction (exception: vasculature of erectile tissue) –> NE on alpha receptors = vasoconstriction
b) hormones: adrenal medulla secretes 80% Epinephrine vs 20% NE –> a receptors with low affinity = vasoconstriction
2) local control –> more important than systemic effects! can override them
2 ways local control can influence resistance in arterioles?
1) ________ _________ adjusts blood flow
- vascular smooth muscle vs stretched vascular smooth muscle
2) _________ signals influence vascular smooth muscle
- secreted by what?
- 3 examples
- active hyperemia vs reactive hyperemia (another flashcard)
- myogenic autoregulation: no need for systemic signal –> when blood comes, vessels expand/stretch –> induces contractions
- vascular smooth muscle regulates its own state of contraction
- stretched: mechanically gated Ca2+ channels –> contracts to resist stretching - paracrine signals influence vascular smooth muscle
- by vascular epithelium or nearby cells
- nitric oxide (induce smooth muscle relaxation through cGMP) + kinins and histamines are potent vasodilators
active vs reactive hyperemia
ACTIVE: matches blood flow to increased metabolism
- increase of tissue metabolism –> need more O2 + produces more CO2 –> release of metabolic vasodilators into ECF –> arterioles dilate –> decrease resistance = more blood flow –> O2 and nutrients supply to tissue increases as long as metabolism is increased
REACTIVE: follows a period of decreased blood blow
- blocked blood flow –> metabolic vasodilators accumulate in ECF –> arterioles dilate but occlusion prevents blood flow –> than unblock –> decrease resistance increases blood flow (increase blood flow at that area (opposite of hemorrhage)) –> as vasodilators wash away, arterioles constrict and blood flow returns to normal
blood distribution varies according to what?
- governed by 2
- possible bc arterioles are arranged in __________: flow in aorta = flow in __________
- individual arterioles regulate _____ flow –> compensated by remaining __________
- cerebral blood flow stays nearly __________
- according to metabolic need of individual tissues
- by local control mechanisms (can override systemic factors) + homeostatic reflexes
- arranged in parallel!: flow in aorta = flow in arterioles
- regulated their own flow –> compensated by remaining arterioles
- constant
distribution of blood in body at rest:
- which 2 organs are pretty stable? vs which organs are variable?
- brain (14%) and kidneys (20%) (to remove waste) are pretty stable
- heart (4%), liver and digestive tract (27%), skeletal muscle (21%), skin (5%), bone and other tissues (9) are variable
blood flow through individual blood vessels is determined by the vessel’s what?
- formula for blood flow –> what is the biggest variation/change in the formula!
- determined by vessel’s resistance to flow!
- blood flow = deltaP / Resistance
- resistance = 8Ln/pi*r^4
- radius!!!! what changes the most because of 4th power while length and viscosity remain pretty constant
what center regulated the cardiovascular function?
- the ____________ reflex controls blood pressure
- 4 steps of the reflex arch
- cardiovascular control center (CVCC)
- baroreceptor reflex
- receptor –> afferent –> CNS/medulla –> efferent –> effectors (heart and blood vessels)
- where are baroreceptors (mechanoreceptors)? (2)
- produce _________/______ action potential to _____ _______
- changes in pressure reflected by changes in ________ of _______ ________
- in carotid arteries and aorta
- produce continuous/tonic action potential in brain stem
- changes in frequency of action potential
- ALWAYS FUNCTIONING!
3 parts of the medullary cardiovascular control center
- cardioaccelerator centers:
- send signal to heart
- SNS: increase HR and increase cardiac output - cardioinhibitor centers:
- send signal to heart
- PSNS: decrease HR and CO - vasometer centers:
- send signals to smooth muscles in blood vessels
- SNS: induces contraction = increase blood pressure
- plasma and cells exchange materials across what?
- most cells are located within ____ mm of the nearest ________
- capillary density is related to what?
- across thin capillary walls
- 0.1 of nearest capillary
- related to metabolic activity of cells: increase activity = increase capillaries
2 conditions in order to have material exchange between plasma and cells
- leakiness
- have to get through capillary slowly! if too fast = no time to exchange
capillaries have the thinnest walls
- describe (2)
- single layer of flattened endothelial cells
- supported by basal lamina/basement membrane
3 types of capillaries + describe
- CONTINUOUS capillaries:
- most capillaries
- have leaky junctions/intercellular clefts (inverse of tight junctions) - FENESTRATED capillaries:
- have intercellular cleft + large pores = more leakiness
- ie kidney glomerulus - SINUSOIDAL capillary:
- modified capillary vessel
- basement membrane is separated –> lots holes (like swiss cheese)
- in bone marrow, liver, spleen
rank their leakiness from lowest to highest
- sinusoidal, continuous, blood brain barrier, fenestrated
BBB < continuous < fenestrated < sinusoidal
- blood flow rate depends on (2): formula?
- velocity of blood flow formula?
- aorta VS capillaries: cross sectional area vs velocity of blood flow
- on velocity and cross sectional area: Q = V * A
- V = Q/A
AORTA: small cross sectional area (300 ish cm^2) = high velocity (30 cm/sec)
CAPILLARIES: big cross sectional area (5000 ish cm^2) = low velocity (0.028 cm/sec)
- exchange btw plasma and interstitial fluid occurs by (2)
- 3 ways to have capillary exchange?
- by paracellular pathway (btw cells) OR endothelial transport (transcytosis)
1. diffusion
2. transcytosis
3. bulk flow
describe movement by diffusion: 3 characteristic
- high concentration to low
- small dissolved solutes and gases (O2, CO2)
- depending on lipid solubility and concentration gradient
describe vesicular transport = transcytosis
- endo vs exocytosis
- larger solutes and proteins
- in most capillaries, large molecules (included selected proteins) are transported by transcytosis
ENDOCYTOSIS: big particles get into cells –> attach to membrane –> form vesicle and move inside
EXOCYTOSIS: big particle moves from inside the membrane to interstitial fluid
capillary filtration and absorption take place by __A___ ___B___
- define __A____ ____B____
FILTRATION:
- what?
- caused by what? –> decreased/increases over length of capillary due to what?
ABSORPTION:
- what?
- caused by what? due to what?
WHAT determines final direction of bulk flow?
- BULK FLOW!
- mass movement as a result of hydrostatic or osmotic pressure gradients
FILTRATION: - fluid movement OUT of capillaries
- caused by hydrostatic pressure (PH) –> IF hydrostratic pressure (PIF) is negligible (?)
- PH decreases over length of capillary due to friction
ABSORPTION: - fluid movement INTO capillaries
- caused by colloid osmotic pressure (pi) also called oncotic pressure
- due to presence of proteins in fluid + capillaries have plasma proteins
- IF has no osmotic pressure
NET PRESSURE determines direction of bulk flow: PNet = PH - pi
PH vs pi
- net filtration at arterial end: which is bigger?
- net filtration at venous end end: which is bigger?
- arterial end: PH > pi
- venous end: PH < pi
does hydrostatic pressure or colloid osmotic pressure change/vary the most?
- hydrostatic pressure! high in arteries vs low in veins
- colloid osmotic pressure stays mostly the same (around 25 mm Hg)
7200 L of blood passes through capillaries
- 24 L filtered out
- 20.5 L absorbed back into blood vessel
- what happens to the 3.5L?
it goes through lymph tubes and gets reintegrated to cardiovascular system
LYMPHATIC SYSTEM: 3 functions
- returns _______ and ______ to ________ system
- picks up ______ absorbed and transfer it to ______ system
- serves as _____ for _________
- returns fluid and protein back to cardiovascular system
- interacts with GI tract –> picks up fat absorbed –> transfer to circulatory system
- serves as filter for pathogens = immune system
lympathic system allows for ____-way movement of ________ _____ into the circulatory system
- 4 components of lymphatic system
- one-way movement of interstitial fluid
1. lymph (liquid)
2. lymph capillaries (blind ended)
3. lymph vessels (with semilunar valves that empty into venous circulation)
4. lymph nodes
what is edema?
- how does it happen? (2)
- ex
- accumulation of fluid in interstitial space
- inadequate drainage of lymph OR filtration greater than absorption (caused by lack of protein so no osmotic pressure = more liquid goes out)
- ex: long flight: liquid stays in feet = feet swell –> accumulation of liquid in interstitial fluid
Blood composed of
1. ___________ –> into lots of categories
2. _________ _______ –> into 3 subcategories
- plasma
- cellular elements:
- RBC
- WBC
- platelets
- plasma is the _______ ________
- fluid of matrix of blood: 3 main categories
1. ________
2. _______ –> 3 types + others
3. _______ –> 5 ish
- extracellular matrix
1. water (92%)
2. proteins (7%): - albumin (54%): transport (hydrophobic molecules like FA and hormones) + contribute to osmotic pressure
- globin/globulins (38%): (a, b y) transport + osmotic pressure + antibodies + clotting factors + enzymes
- fibrinogen (7%): blood clotting
- others (ie transferrin for iron transport)
3. remaining 1%: - Ions (Na+, K+, Cl-, H+’ Ca2+, HCO3-)
- organic molecules (glucose, lipids, amino acids, nitrogenous waste)
- gases (O2, CO2)
- trace elements
- vitamins
difference btw blood plasma and interstitial fluid?
composition is identical except that plasma has plasma proteins (albumins, globulins, fibrinogen, transferrin)
3 types of cells ish in blood? + subtypes
- red blood cells/erythrocytes: transport oxygen and carbon dioxide
- platelets –> split off to make megakaryocytes –> essential to blood clotting
- white blood cells (leukocytes)
- lymphocytes/immunocytes
- monocytes –> macrophages/phagocytes
- neutrophils: phagocytes and granulocytes
- eosinophils: granulocytes
- basophils: granulocytes –> tissue basophils are called mast cells
*granulocytes = can contain different type of chemicals that can be released!
differences btw RBC and WBC
- amount
- lifespan
- location
RBC:
- 20 trillion! (37 trillion total cells in body!)
- 4 months
- always in blood vessels
WBC:
- a lot less
- short! except memory cells -> neutrophils around 6 hours
- out of blood vessels to go to different tissues for defense
what is normal pH range for blood?
- how to maintain?
7.35-7.45
- lots of buffering system + kidney makes sure to keep blood in correct pH range
- blood cells are produced where?
- what is production of blood cells called? controlled by what?
- to types of (where blood cells are produced) –> describe + active or inactive?
- bone marrow
- hematopoiesis –> controlled by cytokines (vague term… cytokines are produced by immune cells and will affect other cells)
1. RED bone marrow: - red bc contains hemoglobin from RBC
- active
- 25% RBCs and 75% WBC (bc WBC need to be regenerated much faster than RBC)
2. YELLOW bone marrow: - yellow bc contains adipose cells
- inactive
gradual process of hematopoiesis (4 steps ish)
- stem cell/pluripotent hematopoeitic stem cell –> uncommitted stem cell
- uncommitted stem cell –> committed progenitor cells
- differentiation (depends on cytokines)
- maturation and into blood circulation
*steps 1-3 are in bone marrow
maturation process of erythrocyte (2 steps)
- does it have nucleus?
- what shape? why?
- erythroblast (nucleus) –> reticulocyte (no nucleus) –> erythrocyte (fully mature without nucleus)
- no nucleus bc more space for hemoglobin –> RBC is kinda not a cell
- donut shaped –> can change shape to squeeze btw vessels + more surface area
erythropoiesis vs eryrhopoietin
- erythropoiesis = production of red blood cells
- erythopoietin: type of cytokine that regulates red blood cell production (IMPORTANT!) –> produced by kidney when not enough RBC
- what is the mean corpuscular volume (MCV)?
- what is the mean corpuscular hemoglobin (MCH)?
- what test includes MCV and MCH?
- MCV = average volume of one blood cell –> a corpuscule is a small unattached cell (diminutive of corpus, body)
- MCH = amount of hemoglobin per RBC
- complete blood count (CBC)
complete blood count:
- what percentage is plasma, packed RBC and WBC?
- plasma (around 58%)
- packed RBC (around 42%)
- WBC + platelets (<1%)
what is hematocrit?
- percentage of total blood volume that is occupied by packed/centrifuged red blood cells
- hematocrit = ratio of RBC to plasma, expressed as a percentage
- males: 40-54%
- females: 37-47%
mature RBCs lack _________
- morphology can provide clues to the presence of _________
- MCV = what?
- lack nucleus
- disease
- MCV = size of red blood cell
bone marrow: hidden where?
- highly ________ tissue filled with what? (2)
- hidden within bones of skeleton
- highly vascular tissue –> filled with blood sinuses, widened regions lined with epithelium
- hemoglobin plays a role in _______ transport
- how many globin molecules per hemoglobin? how many heme groups?
- heme is a _______ ring with an ___A___ atom at its center
- oxygen transport
- 4 globin = 4 heme groups
- porphyrin ring with iron center
IRON:
- comes from where?
- transported in blood by what?
- taken up where?
- excess stored where by what?
- diet
- transferrin
- bone marrow
- in liver by ferritin
RBCs:
- live for about ______ days
- older RBCs _______ or _______ in ________
- after RBC “dies”: aa from globin are incorporated into what?
- what is sometimes reused in new heme groups?
- remnants of heme groups are converted to what?
- what is jaundice?
- 120 days
- rupture or phagocytized in spleen
- into new proteins
- iron from heme groups sometimes reused
- bilirubin, excreted in bile! –> bilirubin metabolites excreted in urine
- jaundice results from elevated levels bilirubin
RBC disorders increase or decrease oxygen transport?
- anemia = hemoglobin content is too high/low
- types of anemia? (4)
- decrease!
- too low!
- hemolytic anemia (example hereditary spherocytosis), sicle cell disease, iron-deficiency anemia
- polycythemia vera
- each RBC has how many hemoglobin?
- what is the max O2 capacity of 1 RBC?
- 300 million hemoglobin!
- around 1 billion O2!!!
- what does hemostasis prevent?
- how? (3 steps)
- prevents blood loss from damaged vessels
1. vasoconstriction so that less blood flows to that region
2. platelet plug begins with platelet adhesion (platelet attach to damaged tissue and attract more platelets to block)
3. exposed collagen and tissue factor lead to coagulation cascade = clot/thrombus
- platelet activation begins with what?
- 3 steps ish
- with clotting process!
1. platelets stick to collagen in damaged vessels
2. released of platelet-activating factor (PAF) –> thromboxane A2
3. prostacyclin (produced by smooth muscles) –> prevent platelets from coming together (?)
- platelets will not adhere to intact ___________
- damage triggers platelet plug formation when _______ has been exposed
- describe platelet plug formation (4 steps)
- endothelium
- when collagen has been exposed
1. exposed collagen binds and activates platelets
2. release of platelet factors
3. factors attract more platelets
4. platelets aggregate into platelet plug
coagulation convers what into what?- 2 pathways (explain difference) converge into common pathway (explains 3 steps)
- platelet plug into a clog
1. intrinsic pathway –> contact activation pathway –> all clotting factors exist within blood already
VS extrinsic pathway –> cell injury pathway –> some factors from blood but need external factor
2. common pathway:
a) prothrombin converted to thrombin
b) thrombin convers fibrinogen into insoluble fibrin polymers
c) fibrin fibers become part of the clot
explain fibrinolysis
- inactive plasminogen activated to plasmin by tissue plasminogen activator
- fibrin polymer broken down to fibrin fragments by enzyme plasmin
