circulation the presence of a circulatory system: reduces the distance a substance must travel to...
TRANSCRIPT
CirculationCirculation
The Presence of a Circulatory System:The Presence of a Circulatory System:
Reduces the distance a substance must Reduces the distance a substance must travel to enter or leave a cell.travel to enter or leave a cell.
Uses “Blood” to carry these molecules to the cells.Uses “Blood” to carry these molecules to the cells.
O2 diffuses from the air in the lungs (or similar structures) across epithelium to the “blood” which carries it to all parts of the body.
Once in the capillaries, O2 diffuses across epithelium again to the tissues.
CO2, of course, moves in the opposite direction.
Circulatory systemsCirculatory systems All animals have:All animals have:
circulatory fluid = circulatory fluid = ““bloodblood”” tubes = tubes = blood vesselsblood vessels muscular pump = muscular pump = heartheart
open closed
hemolymph blood
Open circulatory systemOpen circulatory system
InvertebratesInvertebrates• insects, insects,
arthropods, arthropods, mollusksmollusks
No separation No separation between blood & between blood & interstitialinterstitial fluid fluid ((HemolymphHemolymph))
Closed circulatory systemClosed circulatory system InvertebratesInvertebrates
• earthworms, squid, earthworms, squid, octopusesoctopuses
VertebratesVertebrates Blood confined to Blood confined to vesselsvessels
& separate from & separate from interstitial fluidinterstitial fluid• 1 or more hearts1 or more hearts• large vessels to smaller large vessels to smaller
vesselsvessels• material diffuses material diffuses
between blood vessels between blood vessels & interstitial fluid& interstitial fluid
closed system = higher pressures
Vertebrate circulatory systemVertebrate circulatory system Adaptations in closed systemAdaptations in closed system
number of heart chambers differsnumber of heart chambers differs
4 chamber heart is double pump = separates oxygen-rich & oxygen-poor blood; maintains high pressure
What’s the adaptive value of a 4 chamber heart?
2 3 4
low pressureto body
low O2
to body
high pressure & high O2
to body
Evolution of vertebrate circulatory Evolution of vertebrate circulatory systemsystem
fish amphibian reptiles birds & mammals
A A
VV V VV
A AAAA
V
2 chamber 3 chamber 3 chamber 4 chamber
Evolution of 4-chambered heartEvolution of 4-chambered heart
convergentevolution
Selective forcesSelective forces increase body sizeincrease body size
• protection from predationprotection from predation• bigger body = bigger stomach for bigger body = bigger stomach for
herbivoresherbivores endothermyendothermy
• can colonize more habitats can colonize more habitats flightflight
• decrease predation & increase prey decrease predation & increase prey capturecapture
Effect of higher metabolic rateEffect of higher metabolic rate greater need for energy, fuels, Ogreater need for energy, fuels, O22, waste , waste
removalremoval• endothermic animals need 10x energyendothermic animals need 10x energy• need to deliver 10x fuel & Oneed to deliver 10x fuel & O2 2 to cellsto cells
Vertebrate cardiovascular systemVertebrate cardiovascular system Chambered heartChambered heart
atriumatrium = receive blood = receive blood ventricleventricle = pump blood out = pump blood out
Blood vesselsBlood vessels arteriesarteries = carry blood = carry blood awayaway from heart from heart
• arteriolesarterioles veinsveins = return blood = return blood toto heart heart
• venulesvenules capillariescapillaries = thin wall, exchange / diffusion = thin wall, exchange / diffusion
• capillary beds = networks of capillariescapillary beds = networks of capillaries
Exchange across capillary wallsExchange across capillary walls
Arteriole
Bloodflow
Venule
Lymphaticcapillary
Interstitialfluid
Fluid & solutes flows Fluid & solutes flows out of capillaries to out of capillaries to tissues due to tissues due to blood blood pressurepressure “ “bulk flow”bulk flow”
Interstitial fluid flows Interstitial fluid flows back into capillaries back into capillaries due to due to osmosisosmosis plasma proteins plasma proteins osmotic osmotic pressure in capillary pressure in capillary
BP > OP BP < OP
15% fluid returns via lymph
85% fluid returns to capillaries
Capillary
Pressure is greatest in the arteries, lowest in veins
MammalianMammaliancirculationcirculation
What do blue vs. red areas represent?What do blue vs. red areas represent?
pulmonary
systemic
systemic
Mammalian heartMammalian heartto neck & head
& arms
AV
SL
AV
Heart valvesHeart valves 4 valves in the heart4 valves in the heart
flaps of connective tissueflaps of connective tissue prevent backflowprevent backflow
Atrioventricular (AV) valvesAtrioventricular (AV) valves between atrium & ventriclebetween atrium & ventricle keeps blood from flowing back keeps blood from flowing back
into atria when ventricles contractinto atria when ventricles contract• ““lub”lub”
Semilunar valvesSemilunar valves between ventricle & arteriesbetween ventricle & arteries prevent backflow from arteries into prevent backflow from arteries into
ventricles while they are relaxingventricles while they are relaxing• ““dub”dub”
AV
SL
AV
Lub-dub, lub-dubLub-dub, lub-dub Tempo is controlled by Tempo is controlled by Sinoatrial Sinoatrial
nodenode (SA node) (SA node) located at right atrium by superior located at right atrium by superior
vena cavavena cava Contraction at SA node causes both Contraction at SA node causes both
atria to contract (lub)atria to contract (lub) Wave contraction passes down to Wave contraction passes down to
Atrioventricular nodeAtrioventricular node (AV node) (AV node) Impulse is delayed by 0.1 sec (atria Impulse is delayed by 0.1 sec (atria
need to empty)need to empty) Causes ventricle to contract (dub)Causes ventricle to contract (dub)
Heart murmurHeart murmur defect in valves causes hissing sound when defect in valves causes hissing sound when
stream of blood squirts backward through stream of blood squirts backward through valvevalve
Cardiac cycleCardiac cycle
systolic________diastolic
pump (peak pressure)_________________fill (minimum pressure)
1 complete sequence of pumping1 complete sequence of pumping heart contracts & pumpsheart contracts & pumps heart relaxes & chambers fill heart relaxes & chambers fill contraction phasecontraction phase
• systolesystole• ventricles pumps blood outventricles pumps blood out
relaxation phaserelaxation phase• diastolediastole• atria refill with bloodatria refill with blood
110
____
70
Measurement of blood pressureMeasurement of blood pressure
High Blood Pressure (hypertension)High Blood Pressure (hypertension) if top number (if top number (systolicsystolic pumping) > 150 pumping) > 150 if bottom number (if bottom number (diastolicdiastolic filling) > 90filling) > 90
Blood:Blood: It’s more than just red stuff.It’s more than just red stuff.
Plasma:
55%The fluid portion of blood.Water accounts for over 90%
Contains:Electrolytes- to maintain osmotic balance, buffer
•Nutrients•Respiratory gases
•Hormones
So, if blood is 55% plasma, the rest must be ….._________CELLS!
Blood: Blood: Erythrocytes-Erythrocytes- also called Red Blood Cells (RBCs)also called Red Blood Cells (RBCs)
So, what about those cells?
Leukocytes-Leukocytes-
•Transport oxygen (which binds to Hemoglobin)
• Lack nuclei or mitochondria
also called white blood cells (WBCs)
• Function in defense and immunity• DO have nuclei & mitochondria
Basophils
Lymphocytes
EosinophilsNeutrophils
Include:
Actually spend most of theirtime in interstitial fluid andthe lymphatic system.
Clotting: Clotting: a real fixer-upper…a real fixer-upper…
Platelets:Platelets:1. Clump & stick to the jagged edges of the cut.
Provides immediate but temporary “plug”
2. Release clotting factors which catalyze the reaction:Fibrinogen Fibrin
Fibrin aggregates to form the clot