Elina_Physiology_Regulation Of Blood Flow And Pressure

Front 1

Что означает The Fick principle ?

Back 1

The Fick principle can be utilized to calculate the blood flow through an organ.

Front 2

Как вычисляется поток,проходящий через орган?

Back 2

uptake
Q Flow= A-V

Required data are: oxygen consumption of the organ
A - V oxygen content (concentration) difference across the organ (not P02)

Front 3

Pulmonary venous (systemic arterial) oxygen content %vol

Back 3

Pulmonary venous (systemic arterial) oxygen content = 20 vol%
= 20 volumes 01 per 100 volumes blood
= 20 mL 02 per 100 ml. blood
= 0.2 mL 02 per mL blood

Front 4

Cardiac index =

Back 4

cardiac output
Cardiac index = body surface area

Front 5

Flow is regulated by

Back 5

Flow is regulated by constricting and dilating the smooth muscle surrounding the arterioles

Front 6

2 вида OF BLOOD FLOW REGULATION

Back 6

1- Intrinsic Regulation (Autoregulation)
2- Extrinsic Regulation

Front 7

Intrinsic Regulation (Autoregulation) two main theories

Back 7

-Metabolic hypothesis
-Myogenic hypothesis

Front 8

Metabolic hypothesis

Back 8

Metabolic hypothesis
• Tissue produces a vasodilatory metabolite that regulates flow, e.g.)adenosine in the
coronary circulation.
A dilation of the arterioles is produced when the concentration of these metabolites
increases in the tissue. The arterioles constrict if the tissue concentration decreases.

Front 9

Myogenic hypothesis

Back 9

Myogenic hypothesis
Increased perfusing pressure causes stretch of the arteriolar wall and the surrounding
smooth muscle.
Because an inherent property of the smooth muscle is to contract when stretched, the
arteriole radius decreases, and flow does not increase significantly.

Front 10

autoregulatory range.

Back 10

the autoregulatory range is the range of pressure over which flow remains nearly constant

Front 11

Major Characteristics of an Autoregulating Tissue
Blood flow in most cases is proportional

Back 11

Blood flow in most cases is proportional to tissue metabolism.

Front 12

Major Characteristics of an Autoregulating Tissue
Blood flow is independent of

Back 12

Blood flow is independent of nervous reflexes (e.g., carotid sinus).

Front 13

Major Characteristics of an Autoregulating Tissue
Autoregulating tissues include

Back 13

• Cerebral circulation
• Coronary circulation
-Skeletal muscle vasculature during exercise
Control of renal blood flow is also commonly referred to as autoregulation even though it is
partially controlled by neural and hormonal influences.

Front 14

Extrinsic Regulation
These tissues are controlled by

Back 14

These tissues are controlled by nervous and humoral factors

Front 15

Extrinsic Regulation
sympathetic adrenergic activity,i.e., norepinephrine
acting on

Back 15

sympathetic adrenergic activity,i.e., norepinephrine
acting on альфа'. receptors, causing constriction.

Front 16

Extrinsic Regulation

epinephrine acting on

Back 16

epinephrine acting on B receptors can cause dilation.

Front 17

Extrinsic Regulationat
Что будет при high levels, circulating epinephrine

Back 17

at high levels, circulating epinephrine has a vasoconstrictor
effect through a-adrenergic receptors; so the response to epinephrine is dose-dependent

Front 18

Extrinsic Regulation
Circulations with mainly extrinsic regulation (those most affected by nervous reflexes

Back 18

-Cutaneous circulation
- Resting skeletal muscle

Front 19

Control of Resting muscle

Back 19

Flow is controlled mainly by increasing or decreasing sympathetic a-adrenergic activity. But ~2
receptors can contribute to the regulation of blood flow

Front 20

Control of Exercising Muscle

Back 20

The increase in flow is mainly via vasodilatory metabolites, but this cannot occur without a
significant contribution via an increase in CO.
• В2 activation via circulating epinephrine can contribute to the increase in flow.
• Sympathetic adrenergic nerves have no effect on flow in exercising muscle. (a receptors
become less responsive to norepinephrine.)

Front 21

Coronary Circulation
Characteristics of left coronary flow (flow to the left ventricular myocardium)

Back 21

Left ventricular contraction causes severe mechanical compression of intramyocardial vessels.
Therefore:
• Verylittle if any blood flow occurs during systole.
• Most of the blood flow is during diastole.

Front 22

Coronary Circulation
Characteristics of right coronary blood flow (flow to the right ventricular myocardium):

Back 22

Right ventricular contraction causes modest mechanical compression of intramyocardial vessels.
Therefore:
• Significant flow can occur during systole.
The greatest flow under normal conditions is still during diastole.

Front 23

Coronary Circulation
Oxygenation

Back 23

In the coronary circulation, the tissues extract almost all the oxygen they can from the blood,
even under "basal" conditions. Therefore:
-The venous P02 is extremely low.
-Because the extraction of oxygen is almost maximal under resting conditions, increased
oxygen delivery to the tissue can beaccomplished only by an increased blood £low.
-In the coronary circulation, flow must match metabolism.
-Coronary blood flow is most closely related to cardiac tissue oxygen consumption

Front 24

Coronary blood flow (mLImin) is determined by

Back 24

- the pumping action, or stroke work times
- heart rate,of the heart.

Front 25

Increased pumping action means ( coronary flow)

Back 25

Increased pumping action means increased metabolism, which means increased production of
vasodilatory metabolites, which means increased coronary flow.

Front 26

Increased pump function occurs with

Back 26

-Exercise: increased volume work (more volume pumped at the same pressure)
-Increased arterial pressure (hypertension): increased pressure work (a similar volume
pumped against a greater pressure)
-increased systolic
ventricular pressure development will require a greater increase of coronary blood
flow than a similar increase in stroke volume only.

Front 27

Cerebral Circulation
от чего зависит поток в

Back 27

Flow is proportional to arterial PC02.

Front 28

Under normal conditions the main factor regulating cerebral blood flow is

Back 28

arterial PC02

Front 29

Hypoventilation increases arterial peo

Back 29

thus it increases cerebral blood flow.

Front 30

• Hyperventilation decreases arterial PCOl ,

Back 30

thus it decreases cerebral blood flow.

Front 31

Что будет с цебральным поток при снижении in arterial P02?

Back 31

a (large) decrease in arterial P02 will increase cerebral blood flow. Under
these conditions, it is the low arterial P02 that is determining flow.

Front 32

Baroreceptor влияют ли на церебральный поток?

Back 32

Baroreceptor reflexes do not affect flow.

Front 33

Сutaneous Circulation controlled via

Back 33

controlled via sympathetic adrenergic nerves

Front 34

Сutaneous Circulation
Largc venous plexus innervated by

Back 34

sympathetics

Front 35

Сutaneous Circulation
A-V shunts innervated by

Back 35

A-V shunts innervated by sympathetics

Front 36

Sympathetic stimulation to the skin will cause

Back 36

-Constriction of arterioles and a decrease in blood flow
-Constriction of the venous plexus and a decrease in blood volume in the skin
-Increase in velocity of blood (decreased cross-sectional area)

Front 37

Sympathetic activity to the skin Для чего нужна?

Back 37

Sympathetic activity to the skin varies mainly with the body's need for heat exchange
with the environment.

Increased skin temperature directly causes vasodilation, which increases heat loss.

Front 38

Temperature regulation
Sensor represents the temperature-sensitive neurons in the...

Back 38

anterior hypothalamus

Front 39

Temperature regulation
Circadian rhythm:

Back 39

low point, morning; high point, evening

Front 40

When a fever is developing, body temperature is rising.. what .mechanisms include?

Back 40

heat-conserving and heat-generating mechanisms include

Front 41

heat-conserving and heat-generating mechanisms include

Back 41

-Shivering
- Cutaneous vasoconstriction

Front 42

body ternperature is decreasing. what mechanisms include:

Back 42

Heat-dissipating

Front 43

Heat-dissipating mechanisms include:

Back 43

-Sweating (sympathetic cholinergics)
•-Cutaneous vasodilation

Front 44

Renal and Splanchnic Circulation
какая регуляция работает при normal conditions?

Back 44

autoregulation.

A small change in blood pressure will invoke an autoregulatory response to maintain
renal blood flow.

Front 45

Situations in which there is a large increase in sympathetic activity (e.g., hypotension)
usually cause

Back 45

vasoconstriction and a decrease in blood flow.

Front 46

Renal and Splanchnic Circulation
ПОчему venous P02 is high ?

Back 46

Renal circulation is greatly overperfused in terms of nutrient requirements, thus the
venous P02 is high.

Front 47

Pulmonary Circuit
Low-pressure circuit,
arterial=
venous=

Back 47

arterial =15 mm Hg,
venous =5 mm Hg

Front 48

Pulmonary Circuit
Characteristics

Back 48

-Low-resistance circuit
-Very compliant circuit; both arteries and veins are compliant vessels
-Hypoxic vasoconstriction (low alveolar P02 causes local vasoconstriction)
-Passive circuit; total flow not regulated
-Blood volume proportional to blood flow

Front 49

Pulmonary Circuit
Because of the passive nature of the pulmonary circuit, pulmonary pressures are
proportional to

Back 49

the output of the right ventricle.

Front 50

Pulmonary Circuit
Because of the very compliant nature of the pulmonary circuit, large changes in
the output of the right ventricle are associated with

Back 50

only small changes in pulmonary
pressures.

Front 51

Pulmonary response to exercise

Back 51

• A large increase in cardiac output means increased volume pumped into the circuit.
This will produce a rise in pulmonary pressures.
-Because of the passive, compliant nature of the circuit, the response to a rise in pressure
is vessel dilation.
• This response leads to apical blood vessel recruitment. The overall response is a large
decrease in resistance.
• Consequently, during exercise, there is only a slight increase in pulmonary pressures.
If the pulmonary circuit was not a passive, very compliant circuit, increasing the
output of the right ventricle would cause pulmonary hypertension.

Front 52

Pulmonary response to hemorrhage

Back 52

-A large decrease in CO means decreased volume pumped into the circuit. This will
produce a decrease in pulmonary pressures.
-Because of the passive, compliant nature of the circuit, the response to a decrease in
pressure is vessel constriction. This results in a large increase in resistance.
• Consequently, during hemorrhage, there is often only a slight decrease in pulmonary
pressures.
• Vessel constriction also means less blood is stored in this circuit.

Front 53

Fetal Circulation
какой % фетального СО goes to the placenta.

Back 53

55%

Front 54

Fetal Circulation
The umbilical vein and ductus venosus have highest O/OHb02 saturation

Back 54

80%

Front 55

Fetal Circulation
inferior vena caval blood Hb02)

Back 55

26%

Front 56

Fetal Circulation
saturation of
blood entering the right atrium is

Back 56

67%.

Front 57

Fetal Circulation
Superior vena caval blood

Back 57

(40% Hb02)

Front 58

Fetal Circulation
% of the right ventricular output flows into the ductus arteriosus and % to the lungs

Back 58

90% into the ductus arteriosus
only 10% to the lungs

Front 59

Fetal Circulation
saturation of aortic blood is

Back 59

60%.

Front 60

Fetal Circulation (описать)

Back 60

The umbilical vein and ductus venosus--mixed with inferior vena caval blood--entering the right atrium--blood is directed through the foramen ovale to the left atrium, left ventricle, and
ascending aorta to perfuse the head and the forelimbs.---Superior vena caval blood is directed through the tricuspid valve into
the right ventricle and pulmonary artery and shunted by the ductus arteriosus to the
descending aorta--

Front 61

Arterial-venous difference is positive if

Back 61

substance extracted by the organ, e.g., 02' substrates like glucose, lactate in
heart muscle

Front 62

Arterial-venous difference is negative if

Back 62

if substance produced by the organ, e.g., CO2, glucose in liver, lactate in
skeletal musele and ischemic heart muscle

Front 63

Skeletal Muscle
• Resting muscle venous P02 =

Back 63

Skeletal Muscle
• Resting muscle venous P02 - 45 mm Hg

Front 64

Skeletal Muscle
Exercising muscle venous P02 =

Back 64

Exercising muscle venous P02 - 20 mm Hg

Front 65

BASIC ALTERATIONS DURING EXERCISE
Pulmonary Circuit

Back 65

Blood flow (CO): large increase
Pulmonary arterial pressure: slight increase
• Pulmonary vascular resistance: large decrease
Pulmonary blood volume: increase
-Number of perfused capillaries: increase
• Capillary surface area: increase, which means increased rate of gas exchange

Front 66

BASIC ALTERATIONS DURING EXERCISE
Systemic Circuit
Arterial system

Back 66

P02: no significant change, hemoglobin still fully saturated
PC02: no significant change, increase in ventilation proportional to increase in
metabolism
pH: no change or a decrease due mainly to the production of lactic acid
• Mean arterial pressure: slight increase
• Body temperature: slight increase
-• Vascular resistance (TPR): large decrease, dilation of skeletal muscle beds
-Blood flow: large increase

Front 67

BASIC ALTERATIONS DURING EXERCISE
Systemic Circuit
Venous system

Back 67

Venous system
• P02: decrease
• PC02: increase

Front 68

BASIC ALTERATIONS DURING EXERCISE
Regional Circulations
Exercising skeletal muscle

Back 68

Blood flow increases.
• Vascular resistance decreases.
• Capillary pressure increases.
• Capillary filtration increases.
• Lymph flow increases.
• Venous P02 decreases and can reach extremely low levels.
• Extraction of oxygen increases.

Front 69

BASIC ALTERATIONS DURING EXERCISE
Regional Circulations
Cutaneous blood flow

Back 69

Cutaneous blood flow
Initial decrease, then an increase to dissipate heat

Front 70

BASIC ALTERATIONS DURING EXERCISE
Regional Circulations
Coronary blood flow

Back 70

Coronary blood flow
Increase due to increase in volume work of the heart

Front 71

BASIC ALTERATIONS DURING EXERCISE
Regional Circulations
Cerebral blood flow

Back 71

Cerebral blood flow
No significant change (arterial CO2 remains unchanged)

Front 72

BASIC ALTERATIONS DURING EXERCISE
Regional Circulations
Renal and GI blood flow

Back 72

Renal and GI blood flow
Any change would be a decrease. This is more likely in the splanchnic circuit

Front 73

BASIC ALTERATIONS DURING EXERCISE
Regional Circulations
Heart

Back 73

Heart
Exerciseproduces an increase in the volume work of the heart that is mainly carried out by an
increase in heart rate rather than an increase in stroke volume.
In light and moderate exercise, there may be no increase in preload. Preload does increase in
heavy exercise.

Front 74

BASIC ALTERATIONS DURING EXERCISE
Regional Circulations
Physical conditioning

Back 74

Physical conditioning
• Regular exercise will raise maximal oxygen consumption (V02max) by:
Increasing the ability to deliver oxygen to the active muscles. It does this by increasing
the CO.
The resting conditioned heart has a lower heart rate but a greater stroke volume (SV)
than does the resting unconditioned heart.
During exercise, there is an increase in stroke volume, as much as35% above resting levels.
However, the maximal heart rate remains similar to that of untrained individuals.
Regular exercise also increases the ability of muscles to utilize oxygen. There are:
An increased number of arterioles, which decrease minimal resistance during exercise.
An increased capillary density, which increases the surface area and decreases diffusion
distance.
An increased number of oxidative enzymes in the mitochondria.