Download Lecture 11 th week

Department of medical physiology
11th week
Semester: winter
Study program: Dental medicine
Lecture: RNDr. Soňa Grešová, PhD.
Department of medical physiology
Faculty of Medicine PJŠU
Cardiovascular system
10th week
1. General hemodynamics
2. Local control of blood flow by the tissues and
humoral regulation
3. Blood pessure regulation
1. General hemodynamics
-
-
Venous side
Large lumen
Thin wall
Low pressure
system
Hight volume
system
Driving blood
from exchange
vessels
Deoxygenated
blood
Unstress volume
-
Copyright: Hall, J. E., & Guyton, A. C. (2006). Guyton and Hall
textbook of medical physiology. Philadelphia, PA: Saunders
Elsevier.
Arteries side
Small lumen
Thick wall
Hight pressure
system
Low volume
system
Provides blood to
exchange vessels
Oxygenated
blood
Stressed volume
1. General hemodynamics pressures
Copyright: Hall, J. E., & Guyton, A. C. (2006). Guyton and Hall textbook of medical physiology. Philadelphia, PA: Saunders Elsevier.
1. General hemodynamics –
Cross-Sectional Areas and Velocities of Blood Flow
• Velocity is rate of linear
displacement of blood per unit
time
𝑉=
𝑄
𝐴= 𝜋×𝛾2
- Because the same volume of
blood must flow through each
segment of the circulation
each minute, the velocity of
blood flow is inversely
proportional to vascular crosssectional area.
Copyright: Hall, J. E., & Guyton, A. C. (2006). Guyton and Hall textbook of
medical physiology. Philadelphia, PA: Saunders Elsevier.
1. General hemodynamicsInterrelationships Among Pressure, Flow, and Resistance
• Blood flow (Q) – blood
which passes from a part of
circulatory system per time
• Pressure gradient is
different from 1 point to
2nd point
• Resistence is obstruction of
blood flow
Copyright: Hall, J. E., & Guyton, A. C. (2006). Guyton and Hall textbook of
medical physiology. Philadelphia, PA: Saunders Elsevier.
Ohm’s law:
∆𝑃
𝑄=
𝑅
1. General hemodynamicsInterrelationships Among Pressure, Flow, and Resistance
•
•
•
Poiseuille’s Law
Resistance
- series
- paralel
Reynolds’ number
- Laminar Flow
of Blood
in Vessels
- Turbulent Flow of Blood
When Reynolds’ number rises above 200 to 400,
turbulent flow will occur at some branches of vessels but
will die out along the smooth portions of the vessels.
However, when Reynolds’ number rises above approximately
2000, turbulence will usually occur even in a
straight, smooth vessel.
Copyright: Hall, J. E., & Guyton, A. C. (2006). Guyton and Hall textbook of medical physiology.
Philadelphia, PA: Saunders Elsevier.
1. General hemodynamicsmicrocirculation
•
Fluid filtration across capillaries is determined by
hydrostatic and colloid osmotic pressures, and
capillary filtration coefficient
•
Pc – the capillary pressure, which tends to force
fluid outward through the capillary membrane
•
πp – the capillary plasma colloid osmotic pressure,
which tends to cause osmosis of fluid inward
through the capillary membrane
•
PIF – the interstitial fluid pressure, which tends to
force fluid inward through the capillary membrane
when Pif is positive but outward when Pif is
negative
•
πIF - the interstitial fluid colloid osmotic pressure,
which tends to cause osmosis of fluid outward
through the capillary membrane
Copyright: Hall, J. E., & Guyton, A. C. (2006). Guyton and Hall
textbook of medical physiology. Philadelphia, PA: Saunders Elsevier.
1. General hemodynamicsmicrocirculation
•
Analysis of the forces causing Filtration at
the arterial end of the capillary
•
Analysis of Reabsorption at the venous
end of the capillary
Copyright: Hall, J. E., & Guyton, A. C. (2006). Guyton and Hall textbook of medical physiology. Philadelphia, PA: Saunders Elsevier.
1. General hemodynamicsmicrocirculation
•
•
If the sum of these forces, the net filtration pressure, is positive, there will be a net fluid
filtration across the capillaries. If the sum of the Starling forces is negative, there will be a net
fluid absorption from the interstitial spaces into the capillaries.
The net filtration pressure (NFP) is calculated as: 𝑁𝐹𝑃 = 𝑃𝑐 − 𝑃𝑖𝑓 − Π𝑝 + Π𝑖𝑓
Copyright: Hall, J. E., & Guyton, A. C. (2006). Guyton and Hall textbook of
medical physiology. Philadelphia, PA: Saunders Elsevier.
1. General hemodynamicsmicrocirculation
•
Continuous capillaries
– Exocrine glands, Nervous tissue, Muscle, Lung
•
•
•
•
Endothelial cell body forms a continuous lining
Transport of material across the endothelium is by
diffusion and by pinocytosis
the junctions between the capillary endothelial cells are
mainly “tight” junctions that allow only extremely small
molecules such as water, oxygen, and carbon dioxide to
pass into or out
Fenestrated capillaries
– Endocrine glands, Kidney, Gut
•
•
•
Continuous basement membrane
numerous small oval windows called fenestrae
penetrate all the way through the middle of the
endothelial cells, so that tremendous amounts of very
small molecular and ionic substances
Discontinuous Capillaries
– Bone marrow, Spleen, Liver
•
•
Basement membrane is discontinuous
the clefts between the capillary endothelial cells are
wide open, so that almost all dissolved substances of
the plasma, including the plasma proteins, can pass
Copyright: Hall, J. E., & Guyton, A. C. (2006). Guyton and Hall
textbook of medical physiology. Philadelphia, PA: Saunders
Elsevier.
2. Local control of blood flow by the
tissues and humoral regulation
• Local control
• Short term regulation =
acute control (second to
minutes)
– changes in vasodilatation
(adenosine, carbon dioxide,
adenosine phosphate
compounds, histamine,
potassium ions, and hydrogen
ions) or vasoconstriction of
the arterioles, metarterioles,
and precapillary sphincters
e.g., tissue metabolism, oxygen,
Copyright: Hall, J. E., & Guyton, A. C. (2006). Guyton and Hall
textbook of medical physiology. Philadelphia, PA: Saunders Elsevier.
2. Local control of blood flow by the
tissues and humoral regulation
• Local control
• Long-term local control
– change in the physical size
or number of the blood
vessels (vascular
endothelial growth factor
(VEGF), fibroblast growth
factor, and angiogenin),
occurs over days to months
• e.g., tissue vascularity, oxygen,
2. Local control of blood flow by the
tissues and humoral regulation
• Local control
• Humoral control
- Substances secreted or
absorbed into the body fluids that cause
vasoconstriction or vasodilatation, e.g. hormones, peptides and ions
• Vasoconstrictors agents
- Norepinephrine and Epinephrine
- Angiotensin II.
- Vasopressin
- Endothelin-A
- Serotonin (from platelets)
- Tromboxane A2 (from platelets)
• Vasodilatator agents
- Bradykinin
- Histamine
- Nitric oxide (from endothelial cells)
- Prostacyclin (from endothelial cells)
Copyright: Hall, J. E., & Guyton, A. C. (2006). Guyton and Hall
textbook of medical physiology. Philadelphia, PA: Saunders Elsevier.
3. Blood pressure
• The force of blood against artery walls
• Recoreded as two numbers
1. Systolic pressure (120 mmHg)
- heart contracts
2. Diastolic pressure (80 mmHg)
- heart relaxes
3. Blood pressure regulation
BP
Systolic BP
Diastolic BP
Total peripheral resistance
CO
SV
preload
HR
contractility
afterload
Regulatory mechanisms of systemic
circulation
1.
Local
a) myogenic autoregulation (stretch gated Ca channels)
b) metabolic autoregulation (CO2, ADP, organic acids)
c) Endothelial regulation (constr.: Endothelin, TX A2), (dilatat.: NO, PGI2)
d) enzymatic regulation (constr.: Serotonin, dilatat.: Histamin, bradykinin)
2.
General
a) short-therm regulation
I. nervous regulation (SNS, dilatation =pas. mechanisms, PSNS)
II. humoral regulation (N/Epi, Endothelin, ANP, RAAS stress)
III. vascular reflexes (baroreceptors, chemoreceptors)
b) long-therm regulation
I. ADH (osmoreceptors)
II. Aldosterone (RAAS)
BP
Diastolic BP
Systolic BP
Total peripheral resistance
CO
HR
(N)-Epi
Glucagon
Thyroid H
SNS
PSNS
•
•
Circulating
factors
SV
preload
•
Atrial Ref. Volum.RBainbridge response
Bezold-Jarisch reflex
HR
•
Blood Volume
- Renal retention
Aldosterone
ADH
SNS
ANP
- Thirst
Venous tone
(N)-Epi
SNS
contractility
(N)-Epi
Glucagon
Thyroid H
SNS
PSNS
afterload
TPR
Ang II
(N)-Epi
Innervation
α1 R
β2R
Viscosity
Local
regulators
Endothelin
O2
NO
H+
Adenosine
PG
3. Blood pressure regulation
Short-term regulation (neural)
1. Baroreceptors
- carotic sinus
- aortic arch receptors
Copyright: Hall, J. E., & Guyton, A. C. (2006). Guyton and Hall
textbook of medical physiology. Philadelphia, PA: Saunders Elsevier.
3. Blood pressure regulation
Short-term regulation (neural)
2. Peripheral Chemoreceptors
3. Central chemoreceptors
- carotic body
- aortic body
Copyright: Hall, J. E., & Guyton, A. C. (2006). Guyton and Hall textbook of medical physiology. Philadelphia, PA: Saunders Elsevier.
+ Inotropic effect: LV contractility is
strong, operating with less pressure, CO
Preload
- Inotropic effect: LV contractility is less,
operating with hight pressure, CO
Cardiac Output
Afterload
Venoconstrictor:
VR, RAP, CO
Arterioloconstrictor:
TPR, afterload, CO
Venodilatator:
VR, RAP, CO
Arteriolodilatator:
TPR, afterload, CO
3. Blood pressure regulation
Short-term regulation (neural)
Medulla oblongata
1. Nucleus of tractus
solitarius
2. Cardioinhibitory center
3. Cardioacceleratory
center
4. Vasomotor center
Copyright: Hall, J. E., & Guyton, A. C. (2006). Guyton and Hall textbook
of medical physiology. Philadelphia, PA: Saunders Elsevier.
3. Blood pressure regulation
Short-term regulation (neural)
Copyright: Hall, J. E., & Guyton, A. C. (2006). Guyton and Hall textbook of medical physiology. Philadelphia, PA: Saunders Elsevier.
3. Blood pressure regulation
Short-term regulation (humoral)
• Atrial natriuretic
peptide
- natriumuresis
3. Blood pressure regulation
Long-term regulation
• Long- term regulation =
long-term control
- Regulation reninangiotensine-aldosteron
system (RAAS)
Copyright: Hall, J. E., & Guyton, A. C. (2006). Guyton and Hall textbook of
medical physiology. Philadelphia, PA: Saunders Elsevier.
3. Blood pressure regulation
Long-term regulation (humoral)
• ADH – antidiuretic
hormon
3. Blood pressure regulation
Copyright: Hall, J. E., & Guyton, A. C. (2006). Guyton and Hall textbook of medical physiology. Philadelphia, PA: Saunders Elsevier.
4. Special hemodynamics
1. Pulmonary circulation
2. The coronary circulation
3. Cerebral circulation
4. Renal blood circulation
5. Splanchnic blood circulation
6. Skeletal muscle blood circulation
7. Circulation of blood through the skin
8. Fetal circulation