Cardiovascular - General Flashcards
1
Q
Cardiovascular system
A
- heart and blood vessels
- jobs: hormone transported
- gas exchange
- met. waste removal
- thermoregulation - push blood flow to skin or away to control heat loss
- nutrient distribution
- move O2 and Co2
- closed system in vertebrates
- very precise distribution of blood flow
- match blood flow to metabolic rate but cost: make many blood vessels, need high bp
- need heart to generate pressure and push blood through vessels w/cardiac energy
2
Q
Circulatory Path
A
- R side of heart goes to lungs to get O2 and then back form lungs and to L side of heart - pulmonary circulation
- L side of heart w/O2 pumps blood out aorta and from there distribute to rest of body and then R side heart - systemic/general circulation
- cardiac output of blood pumped by heart
- vasculature partitions cardiac output and get it where needs to go
- artery - away from heart
- veins toward heart
3
Q
Cardiac Output vs. O2 uptake (pulmonary system) which is MR
A
- cardiac output is about 5 L/min in humans
- cardiac output = HR (bpm) x stroke vol (# of mLs pumped per beat); how much heart pumps/min
- stroke vol = EDV - residual vol = 140-70 = 70 mLs (reserve)
- 6 L/min at rest in graph; as > MR, > CO
- as exercise blood flow to skeletal muscle and skin > and < to viscera
- heart has variable cardiac output - when exercise MR goes up and use more O2 and in exercise it can get up to 18L/min
- area under each curve indicates where blood is going - can partition cardiac output
- skeletal muscle under curve at rest vs. at exercise, see large increase of blood flow to muscle - large portion
- as exercise you generate heat and have to put more blood flow to skin for thermoregulation
- viscera is GI tract, at rest have reasonable flow, as exercise blood flow goes down since don’t need it
- blood flow to heart or brain due to > in heart but about same in exercise
- heart has variable output and can partition approp
4
Q
venous vs. arterial system
A
- 1/2 blood vol is in venous system - veins are volume reservoir
- pulmonary circulation is 12% of blood volume and 16-18% in arteries
- arterial system = pressure reservoir; need high pressure to push out form heart into arterial tree
- bp on arterial side greater than venous side where low bp
- arterial is stressed side and venous unstressed
- portal system - connects 2 capillary beds
- main one = hepatic portal vesel
- GI tract to liver
- lymphatic parallels venous and drains excess fluid and drains into venous system at base of neck
5
Q
What makes blood move?
A
- high pressure system (potential energy)
- L and R side of heart pump same amount of blood so lungs can handle quite a bit; increase vascularized
- circulatory system - we convert pressure gradient into flow (KE)
- take bp to get KE
- go from high pressure to low pressure
- pressure in circ system = PE
- mvmt of blood = KE
- circ system converts PE to KE as we move thru system E falls
- Fish heart: heart pumps blood to gills and oxygenate and move to rest of body; heart must generate pressure to go through respiratory system and lot of resistance in capillary bed so to get blood through gills use some PE to help w/flow so pressure drops and lose PE
- blood out of gills at low pressure and then distribute to body while pressure falls
- then into venous sytem at low pressure we bring blood back to heart - all the time dropping pressure
6
Q
Human Heart and Pressure
A
- blood leaving R side of heart goes to lungs which is close - blood exists heart and generates enough pressure to go through lungs and pressure (PE) converted to flow (KE) so pressure drops when leaving lungs back to heart
- go to L side of heart and has to give blood to entire body so L side heart substantially more pressure as go through partitioning system, smaller and smaller vessels
- pressure drops as convert pressure to flow and then venous side at low pressure since vol storage and return to other side of heart
- capillary beds have more resistance so pressure drops
- nature of blood vessels help maintain pressure (arteries away) or volume (veins so low pressure)
7
Q
Arteries
A
- elastic endothelium inside (springs)
- pushing blood into arterial vessel, artery pushes out and elasin pushes back to create pressure - maintain pressure wave via elastic push back
- circular smooth muscle layer help partition cardiac output and can dialate to > flow or constrict <
- connective tissue on outside and endothelium on very inside
8
Q
Veins
A
- vol storage, so endothelial layer and then thin elastin so when push blood into vein it can hold and store easily/no lot of spring but stretch
- smooth muscle used to generate more pressure when needed
- one way valves in veins help move blood back to heart; flaps help prevent back flow
9
Q
Capillaries
A
- where action is, small vesels where do EXCHANGE O2 and nutrients
- 1 layer endothelial cells, no smooth muscle, no connective tissue, no elastin so makes exchange easier
- small diameter
side note: on venous side - low pressure and possible back flow so one way valves w/flaps; pressure so high on arterial side don’t need
cardiac output > in exercise so more blood flow to tissue and > blood flow you need in and out so veins pop up since> flow and more filtration so muscles look bigger
10
Q
The Heart
A
- in chest cavity - between lungs
- base at top and apex at bottom
- aorta to general circulation and pulmonary vessel to lungs
- 4 chambers and 4 one way valves
- L and R atria which sit on ventricles and don’t pump blood very far
- R and L ventricles - much more muscular
- R side is pulmonary and L side general
11
Q
General Heart Pathway
A
- venous system to superior and inferior vena cava –> rt atrium –> R ventricle –> lung –> pulm vein to L atrium –> L ventricle –> aorta
- when R atrium fills from venous system, its pressure > which > R ventricle, then antrioventricular (tricuspid) opens
- R ventricle fills passively 90%
- then atrium contracts to empty
- R ventricle contracts - back pressure closes AV valve, pressure opens pulmonary semi-lunar valve - blood to lungs/pulmonary artery
- as the R atrium collects, so does L atrium w/oxygenated blood
- bicuspid or mitral valve btwn L atrium and L ventricle
- blood leaves L vent via aortic semilunar valve to systemic circulation, so generates lot more pressure so L ventricle is much more muscular than R ventricle-going not as far to lungs
- most of filling of ventricles is passive, contraction tops off filling ventricles
- R and L sides contract together to move blood out so regulated and coordinated by electrical system
12
Q
Systole and Diastole
A
- systole - contraction; AV valves closed and semilunars are open
- diastole - relaxation, AV valves open and semilunars clsoed
- each chamber has own period of these referred to as ventricular action
- blood pressure is systolic/diastolic
- for heart circulation - most blood in vessels during ventricular diastole, not during ventricular contraction/stole is when move blood to gen circ
- “collateral” circuation in heart w/age, develop more connections between coronary blood vessels so if one compromised it can be served through another path so blockages not fatal often
13
Q
Close look at blood flow throughout heart
A
- R atrium has venous system blood that collects in thin walls
- when pressure from vol of blood is greather than pressure of ventricle, blood moves into ventricle and antrioventricular tricuspid valve opens
- most filling is passive, R atrium contracts to top off ventricle
- ventricular contraction/systole generated via pressure in ventricle chamber and push back on one way valve to close it and enough pressure to open pulmonary valve and push blood to lung
- out pulmonary valve into pulmonary arteries - deoxygenated blood taken to lung to oxygenate
- oxygenated blood returns to L atrium where collects and enough blood passive pressure opens AV bicuspid valve and L ventricle fills - atrial contraction adds last 10%
- L ventricle contracts the mitral valve/bicuspid closes and push blood up through chamber to aorta
- ventricles contract and generate lot of pressure and need to stay stable and closed so use chordae tendinase which small muscles that stabilize valves when pressure against them so no back flow into atria
14
Q
L vs. R ventricular wall
A
- L side of heart has to generate more pressure so structure looks like L ventricle and R ventricle looks like addition since don’t need as much pressure just go to lung and back
- L ventricular walls are very thick
- electrical axis to L, electrical beat of heart - need stronger signal in L side since need more pressure and muscle
15
Q
A
16
Q
Mechanics of heart via Pressure/Volume Curve
A
- EDV is end diastolic vol where AV closes and pressure builds
- see residual vol in ventricle from last contraction which didn’t push all blood out of ventricle and EDV
- can calculate an ejection fraction
- EF = stroke volume of heart /end diastolic vol = 50%
- EDV - residual volume = EF how much blood you pushed out
- see same one for right ventricle - not as much pressure required
- R ventricle the volume has no change but pressure is low lower - parallel lines
17
Q
Pressure-Volume Curve revisited
A
- when we increase force of contraction like w/exercise, we increase cardiac output (HR x SV)
- create more pressure and eject more blood (use residual vol and decrease residual vol
18
Q
Exercise and high blood pressure and pre-loaded w/pressure-volume curves
A
- exercise - through nervous system, > cardiac output, > HR, > stroke vol and more contractile strength and more pressure so > ejection vol
- high bp - higher pressure in arterial tree, heart generates more force to generate that pressure so see pressure after has to contract, after load
- more pressure to push out of aorta - closes sooner since more pressure on it to bring it closed
- preloaded - increases venous return
- heart sees load before contraction, more blood in ventricle than anticipated so increase pressure pushes out extra flow
19
Q
Cardiac Work
A
- external work = mass x distance moved
- heart: work = pressure g/cm2 x flow ml/cm3
- pressure (g) x flow (cm) = work
- for ventricular contraction on L: work = entire area
- for vent on right its its area under curve
