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Physiology > Unit 4b -Circulation Basics Continued > Flashcards

Unit 4b -Circulation Basics Continued Flashcards

1
Q

what is the relationship between heart size and body size and o2 consumption

A

heart rate - 0.6% of body mass in vertebrates

smaller body- smaller heart- higher 02 consumption

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2
Q

Blood volume characteristics

A
  • humans have 5L
  • vertebrates 5-15% of weight
  • left/right heart have equivalent volume, not pressure
  • entire ejected volume is accomodated in vascular stretching
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3
Q

Stroke volume

A

SV= end diastole volume (just before contraction) - end systole volume (volume of ventricle after contraction)
-blood ejected by the heart

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4
Q

what factors incfluence stroke volume through end diastole volume and end-systolic volume (4 and 2)

A

end-diastole

  • venous filling pressure
  • pressure generated during atrial contraction
  • distensibility of the ventricular wall
  • the time available for filling the ventricle

end systole

  • pressure generated during venricular contraction
  • the pressure in the outflow channels from the heart
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5
Q

Heart beat sequence

A

filling (ventricle filling by the atrial contraction is only 30% of the blood pumped into the aorta- most comes from venous filling pressure- blood directly through the atria into the ventricles- atrial contraction tops it off)

contractions
emptying and relaxing

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6
Q

Isomeric vs. Isotonic contraction

A
  • isomeric= constant colume, increase muscle tension, ventricular presure
  • isotonic = constant pressure, large change in volume
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7
Q

Q=

A

SV x Heart rate (f) (L/min)

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8
Q

two methods of increasing cardiac output

A
  • increase frequency of beating- pigeon

- increase stroke volume- trout

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9
Q

Positive inotropic effect vs. negative inotropic effect

A

positive inotropic- increases muscle contraction

negative inotropic- slows contractions/ weakens their force

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10
Q

Positive inotropic effect on heart contractions

A
  • decrease end-systolic volume or increase end-diastolic volume
  • controls the duration of the action potential and intercellular ca2+ mechanisms
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11
Q

Frank-starling mechanism

A
  • stretch produces more forecul contractions

- stroke volume is proportional to diastolic filling

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12
Q

Sympathetic innervation of catecholamines (beta receptors)

A
  • increases the rate of ventricular emptying
  • increases ventricular contractility though increasing intracellular ca2+
  • stimulates pacemaker to go off more
  • same stroke volume, shorter time
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13
Q

Laminar flow

A
  • smooth flow, streamlined
  • force (pressure) required to slide adjacent layers past each other
  • viscosity - internal friction, resistance to sliding
  • plasma skimming
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14
Q

plasma skimming

A

separation of blood and plasma in a vessel

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15
Q

turbulent flow

A

irregular, noisy,

  • used for blood pressure measurments
  • velocity is seldom high enough to cause turbulence
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16
Q

Change in pressure =

A

Q x R (cardiac output x resistance)
pressure is related to velocity - decreases from atrial to venous sides
-R compares resistance to flow

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17
Q

R is porportional to….

A

Ln/r^4

length x viscosity/ radius ^ 4

r is the main determinant of R

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18
Q

Q is porportional to….

A

r^4 and R

= pi/8 x change in pressure r^4/ Ln

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19
Q

Fahraeus- LIndquist Effect

A

flow is inversely porportional to viscosity

  • plasma skimming, tendency for RBCs to accumulate in the center of bloodstream
  • reduces resistance
  • apparent increase in viscostily for small vessels bc Redblood cells fills the lumen of the blood vessel
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20
Q

Poiseulle’s equation

A

applies to steady flow in straight, rigid tubes

  • blood vessels are not rigid tubes
  • -elastic fibres in wall allow distension
  • -increase in presure = increase in radius
  • -flow rates higher at absolute pressure
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21
Q

Compliance

A
  • change in volume/ change in presuure
  • high distendibility = high compliance (think of a baloon that can expand more when you put in less or the same pressure
  • venous system has high compliance - volume reservoir
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22
Q

Why do we need to control arterial blood pressure

A
  • keep an adequate supply of blood to the heart
  • supplying blood to other organs
  • mainanance of tissue volume and composition fo interstitial fluid
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23
Q

mechanisms for controling circulation - time and location

A

timing - acute vs. chronic

locaiton - affect the central cardiovascular system or the peripheral (capillary system)

24
Q

What controls blood pressure

A

p= QR Q=SV*f

heart rate and vasoconstriction/ vasodilation

25
Pressor sensor
- sympathetic pathway - increased heart rate, contractility and vasoconstriction - net increase in cardiac output
26
depressor sensor
parasympatheditc, net decrease in cardiac output | -decrease in heart rate and vasodilation
27
Arterial Baroreceptors
- baroreceptor reflex - respond to pressure as the blood vessel walls stretch - increased baroreceptor firing in response to increased BP of increased pressure pulsatiility
28
How does the arterial baroreceptor affect peripheral resistance
- increase BP= decrease Q = decrease in R | - decrease BP= increase in Q = increase in R
29
Arterial chemoreceptors
- primarily regulate breathing - change according to CO2, O2 and pH - cause decreased heart rate and vasoconstriction if the animal is not breathing
30
Cardiac receptors 2 types
atrial receptors and ventrical receptors
31
atrial cardiac receptor
- afferent fibers embeded in the atrial wall - stretch sensitive secratory cells - ---secreate ANP- (antrial natriuretic peptide) - ---decrease BP and blood volume by increasing uring production and sodium excretion
32
ventricle receptors
mechanoreceptors and chemoreceptors | - responsible for pain during heart attacks
33
What is capillary flow in the body porportional to?
-metabolic activity
34
what is the sequence of priority for blood flow
brain- heart/lungs- gut, liver muscles
35
ischemia vs. hyperemia
``` ischemia= inadequate blood supply hyperemia= too much blood ```
36
what are the three neruonal and harmonal mechanisms for control
- sympathetic nerves - ciculating catecholamines - parasympathetic nerves
37
Sympathetic nerves and control
releases norepinepherine - binds alpha adregenic receptos - increases vasoconstriciton, increases areterial BP - brains and lungs lack alpha adrenoreceptors
38
Circulating catecholamines and control
adrenal medulla releases epinepherine - primarily binds beta adrenoreceptors - produces vasodilation - increases venous return to stimulate heart to increase cardiac output
39
parasympathetic nerves and control
- innervation of arterioles of brain and lungs | - release of acetocholine causing vasodilation
40
what physiological changes occur in active tissues
- decreased oxygen, increased co2, decrease in pH, increased adenosine, increased heat, increased potassium - results in vasodilation - ischemia and reactive hyperemia
41
what can cause vasodilation near active cells
- heat - compounds produced by the endothelial cells - inflammatory mediators (histamine, plama kinins)
42
Vasoconstriction influences near active cells
-compounds produced by endothelial cells (endothelin) -inflamattory mediators (antihistidines) -clotting factors (thromboxane A2) agiotensin ii
43
what state are fetal lungs like
they are collapsed- they have a high resistance to blood flow
44
unique features of the fetus circulat | -ory system (4)
ductus arteriosis, forman ovulae, umbilical veins and arteries, ductous venosus
45
ductus arteriosis
-joins pulmonary artery and aortic arch
46
Formen ovulae
joins left and right atria
47
Ductous venosus
joins umbilical vein and inferior vena cava
48
what changes in the fetal circulation at birth
-lungs inflate, reducing resistance to flow -placental circulation ceases, increasing systemic resistance to flow pressure in left atrium exceeds right- closes the formen ovulae -ductus arteriousis becomes occluded
49
what occurs in cells when you excercise
- decrease in o2 and pH, - increase in heat, CO2 - increase in blood flow and redistribution of blood flow
50
what is the nervous system's response to increased excercise
- increased sympathetic, decreased parasympathetic stimulation - isomeric contractions- increase BP - isotonic contractions- increase cardiac output (Q)
51
how does Q change during excercise
- increased heart rate (chronotropic) and contractility (inotropic) effect - increased venous returen due to skeletal muscle pumping - active hyperemia
52
what parts of your body experience vasodilation or vasoconstriction during excercise
active tissue- vasodilation | gut and kidney- vasodilation
53
how does the systemic blood pressure remain constant during excercise
- decrease in peripheral resistance, but increased cardiac output
54
How to mammals get oxygen while submersed/ nonmammmals
mammals- lungs, blood(hemoglobin), muscle (myoglobin), body water non-mammals - cutaneous respiration and rectal respriation
55
bradychardia
-the diving reflex in mammals ==sitmulation of facial water receptros stimulation of arterial chemoreceptos (o2, cos2, pH) lack of stimulation of lug stretch receptors parasympathetic activity
56
other circulatory changes during diving
- vasoconstricion and redistribution of blllod flow to brain and heart (muscles us anaerobic respiration - mainenance of arterial BP: lower heart rate + fewer capillary beds open - recovery- seals hyperventilate after they dive
57
Diving in other vertebrates (birds, amphibians and reptiles, fish)
- birds- bradychardia triggered by chemoreceptors not submerssion - reptile and amphibians- cutanious and rectal respiration are importnat - fish- "reverse" diving reflex when removed from water

Physiology (9 decks)

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