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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
Q

Pressor sensor

A
  • sympathetic pathway
  • increased heart rate, contractility and vasoconstriction
  • net increase in cardiac output
26
Q

depressor sensor

A

parasympatheditc, net decrease in cardiac output

-decrease in heart rate and vasodilation

27
Q

Arterial Baroreceptors

A
  • baroreceptor reflex
  • respond to pressure as the blood vessel walls stretch
  • increased baroreceptor firing in response to increased BP of increased pressure pulsatiility
28
Q

How does the arterial baroreceptor affect peripheral resistance

A
  • increase BP= decrease Q = decrease in R

- decrease BP= increase in Q = increase in R

29
Q

Arterial chemoreceptors

A
  • primarily regulate breathing
  • change according to CO2, O2 and pH
  • cause decreased heart rate and vasoconstriction if the animal is not breathing
30
Q

Cardiac receptors 2 types

A

atrial receptors and ventrical receptors

31
Q

atrial cardiac receptor

A
  • 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
Q

ventricle receptors

A

mechanoreceptors and chemoreceptors

- responsible for pain during heart attacks

33
Q

What is capillary flow in the body porportional to?

A

-metabolic activity

34
Q

what is the sequence of priority for blood flow

A

brain- heart/lungs- gut, liver muscles

35
Q

ischemia vs. hyperemia

A 
ischemia= inadequate blood supply 
hyperemia= too much blood
36
Q

what are the three neruonal and harmonal mechanisms for control

A
  • sympathetic nerves
  • ciculating catecholamines
  • parasympathetic nerves
37
Q

Sympathetic nerves and control

A

releases norepinepherine

  • binds alpha adregenic receptos
  • increases vasoconstriciton, increases areterial BP
  • brains and lungs lack alpha adrenoreceptors
38
Q

Circulating catecholamines and control

A

adrenal medulla releases epinepherine

  • primarily binds beta adrenoreceptors
  • produces vasodilation
  • increases venous return to stimulate heart to increase cardiac output
39
Q

parasympathetic nerves and control

A
  • innervation of arterioles of brain and lungs

- release of acetocholine causing vasodilation

40
Q

what physiological changes occur in active tissues

A
  • decreased oxygen, increased co2, decrease in pH, increased adenosine, increased heat, increased potassium
  • results in vasodilation
  • ischemia and reactive hyperemia
41
Q

what can cause vasodilation near active cells

A
  • heat
  • compounds produced by the endothelial cells
  • inflammatory mediators (histamine, plama kinins)
42
Q

Vasoconstriction influences near active cells

A

-compounds produced by endothelial cells (endothelin)
-inflamattory mediators (antihistidines)
-clotting factors (thromboxane A2)
agiotensin ii

43
Q

what state are fetal lungs like

A

they are collapsed- they have a high resistance to blood flow

44
Q

unique features of the fetus circulat

-ory system (4)

A

ductus arteriosis, forman ovulae, umbilical veins and arteries, ductous venosus

45
Q

ductus arteriosis

A

-joins pulmonary artery and aortic arch

46
Q

Formen ovulae

A

joins left and right atria

47
Q

Ductous venosus

A

joins umbilical vein and inferior vena cava

48
Q

what changes in the fetal circulation at birth

A

-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
Q

what occurs in cells when you excercise

A
  • decrease in o2 and pH,
  • increase in heat, CO2
  • increase in blood flow and redistribution of blood flow
50
Q

what is the nervous system’s response to increased excercise

A
  • increased sympathetic, decreased parasympathetic stimulation
  • isomeric contractions- increase BP
  • isotonic contractions- increase cardiac output (Q)
51
Q

how does Q change during excercise

A
  • increased heart rate (chronotropic) and contractility (inotropic) effect
  • increased venous returen due to skeletal muscle pumping
  • active hyperemia
52
Q

what parts of your body experience vasodilation or vasoconstriction during excercise

A

active tissue- vasodilation

gut and kidney- vasodilation

53
Q

how does the systemic blood pressure remain constant during excercise

A
  • decrease in peripheral resistance, but increased cardiac output
54
Q

How to mammals get oxygen while submersed/ nonmammmals

A

mammals- lungs, blood(hemoglobin), muscle (myoglobin), body water

non-mammals - cutaneous respiration and rectal respriation

55
Q

bradychardia

A

-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
Q

other circulatory changes during diving

A
  • 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
Q

Diving in other vertebrates (birds, amphibians and reptiles, fish)

A
  • 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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