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Microcirculation & Physiology - Coggle Diagram
Microcirculation & Physiology
DIFFUSION
Definintion
Migration of particles from a
HIGHER
to a
LOWER
concentration
Movements
Equilibrating
Random
Happens more rapidly if:
Temperaturs increases
Larger difference in concentration (from HIGH to LOW)
There are smaller molecules
The rate of diffusion depends on
Surface area
Temperature
heat causes particles to move faster
Concentration gradient
Size of molecules
Diffusion distance
Definition
The distance between
blood capillaries
and
tissue cells
Under normal conditions each tissue cell is within
2-3 cell diameters from its supplying blood capillary
Normal diffusion distance is approximately 1/10 mm
What increases diffusion distance?
SWELLING
CAUSES
A compromised local immune response to the increased distance that defense cells have to travel
Reduced nutritional supply to cells
Frequent infections
Movement
Illustration
There is more O2 in the blood than in the tissues (except in the lungs)
O2 leaves the blood capillaries via diffusion and supplies the tissue cells
CO2 enters the blood capillaries via diffusion
Diffusion is exclusively responsible for this exchange
BLOOD CAPILLARY PRESSURE
Definition
The pressure inside blood capillaries if blood is present
Is BCP different from BP?
Blood pressure is the force of blood pushing against the walls of blood vessels. It's highest at the aorta during systole of the heart
BCP is considerably lower than BP
Is BCP Higher or lower than BP?
Blood pressure inside blood vessels decreases as the distance from the heart increases
and is lower at the blood capillary
Under normal physiological conditions there is a gradual decrease in blood pressure between the arterial and venous system.
In the veins near the heart, the pressure amounts to only 1.5 to 4mmHg
Due to low pressure in the veins, a sufficient return of venous blood to the heart depends on:
Muscle pump
Valves
Diaphramatic Breathing
Suction effect of the heart
Pulsation of adjacent arteries
PRE-CAPILLARY SPHINCTER
Capillaries
The transitionary area between arteries and veins
Actions
IMP **
Sphincter contracts**
Less blood travels into capillaries
Equaling Less volume
And
decreased BCP
BCP may decrease to allow only reabsorption along the entire length of the BCs
Less filtration occurs
IMP **
Sphincter dilates
More blood
travels into the capillaries
Equaling more volume
And increased BCP
BCP may increase to a value that allows only filtration along the length of the BCs
Controls the flow of
blood
to the
capillaries
If there are muschles demanding more blood
Because BCs do not have a muscle wall they can break easily
FILTRATION AND REABSORPTION
Filtration Definition
The
transport
of a
substance
through a
filter
, IF that filter is
permeable to water
Filtration happens in the
blood capillaries
Blood capillaries are covered with a semi-permeable membrane
The
Hydrostatic force of BCP at the arterial end tears water away from protein molecules
Hydrostatic is the pressure that water is putting on capillary wall
Pressure in the BCs
Colloid Ostmotic Pressure = 25 mmHg
(pressure in the capillaries when protein holds on to water)
IMP
Protein in the blood holds on to water. Its ability to do so is called
Colloid Osmotic Pressure
BCP in blood capillaries = 29 mmHg
Higher -> pushes fluid into the interstitial space
Reabsorption Definition: the process by which water is reabsorbed from the tissues back into the venous end of the Blood Capillaries
Pressure in the Venous End of VC
BCP in venous end = 14 mmHg
COP (Colloid Osmotic Pressure) in venous end = 25 mmHg
Reabsorption = BCP in venous end < COP of proteins
Water picks up waste products from the tissues and returns them to the venous system
This occurs due to a pressure gradient
STARLING'S LAW
States that:
the average blood capillary pressure equals the average colloidal osmotic pressure of plasma proteins
This is the body's attempt to maintain homeostasis
Henry Starling
Discovered that, under normal conditions, the average BCP is almost identical to the CP (Colloidial Osmotic Pressure) of plasma proteins
This became known as
Starling's equilibrium
Definition
Starling's Equilibrium is the balance between
hydrostatic pressure, causing fluids to flow out of the capillary membrane, and osmotic pressure, causing fluids to be absorbed from the tissues into the capillaries
The slight disequilibrium that does occur accounts for the fluid eventually returned by the lymphatics
demonstrated
Starling's equilibrium
in
1896
Recap
Filtration occurs because the BCP in the arterial end of the capillary is higher than the colloid osmotic pressure of proteins in the plasma
Water is filtered through the capillary membrane into the Interstitium
At the venous end of the capillary, BCP is lower than the colloid osmotic pressure of the plasma proteins
Water is reabsorbed back into the blood capillaries
Tissue Pressure
(Compression)
The pressure located inside the interstitial space
Hinders Filtration
WHY?
Not working on BCP OR COP - interstitial space?
Supports reabsorption
Geography
The body tends to expand at higher elevations (lower atmospheric pressure)
Lower elevation has a higher atmospheric pressure
ACTIVE HYPEREMIA
Disturbs the equilibrium of Starling's law
Definition
Anything that causes vasodilation
The sphincter in capillaries dilate to increase blood flow
This increases blood volume
Which increases BCP
Which increases the rate of filtration
more water leaves blood capillaries
Which increases the Lymphatic Load of Water
1 more item...
Causes
Massage
Inflammation/Infection
Temperatur/thermal modality
Sunbathing
Vigorous exercise
PASSIVE HYPEREMIA
Also disturbs the equilibrium of
Starling's Law
May be caused by
Increase in BCP caused by an obstruction of venous return or deficiency of venous outflow
Cardiac Insufficiency (Congestive Heart Failure)
Pregnancy
Obesity
Chronic Venous Insufficiency
DVT
Sedentary Lifestyle
Immobility
What is passive hyperemia
Where
blood pools back into capillaries
Equaling
more blood in the capillaries
This increases
BCP net-filtrate
Which increases the
lymphatic load of water
Causing the lymphatic system to
compensate
By activating the
Lymphatic Safety Factor
Which results in increased
Lymphangiomotoricity
HYPOPROTENEMIA
Disturbs the equilibrium of Sterling's law
Definition
A condition where there is an abnormally low level of protein in the blood
One common cuase is due to excess protein in the urine
If there is less protein in the blood the COP of proteins will decrease
This will increase filtration and hinder reabsorption
INSUFFICIENCIES OF THE LYMPHATIC SYSTEM
Transport capacity
The max amount of lymph transported a healthy lymph system working as hard as it can
Normally
10X higher
than normal lymphatic load
The normal amount of Lymphatic Load returned to the venous angle via the thoracic duct during a 24 hour period
2-4L
FUNCTIONAL RESERVE OF THE LYMPHATIC SYSTEM
In healthy individuals the lymphatic system is capable of carrying
10X its normal lymphatic load
The lymphatic system reacts to an increase in lymphatic load by
increasing the contraction frequency of the lymph collectors
This is known as
Functional Reserve (FR)
of the lymphatic system
Space between the LTV and the TC
LYMPH TIME VOLUME
Definition
The
amount of lymph
that the
lymphatic system is able to transport in a given time
In healthy individuals with increase lymphatic load, the lymphatic system increases its
lymph time volume
LTV is ALWAYS going to equal the LL
DYNAMIC INSUFFICIENCIES OF THE LYMPHATIC SYSTEM
LTV (Lymph Time Volume) is maxed out
Because a healthy LS (Lymphatic System) is overwhelmed
MLD increases the LTV of collectors
Should the LL (lymphatic load) exceed the transport capacity of a healthy LS
Lymphatic fluid will accumulate in the interstitial tissue
causing
edema
Edema
is caused by the accumulation of abnormally large amounts of fluid in the intercellular tissue spaces of the body
which is visible or palpable (pitting)
Edema is a
symptom not a disorder
MLD is not contraindicated but ambulation is more effective
The protein concentration in the tissues in relation to water is not higher than normal
Treatment options
Treat swelling ASAP
Ambulation, elevation, and compression
3. MLD will NOT increase TC
Our job is to use the lymphatic plexus to open up other lymphatic areas in the area that the lymph can travel to
If dynamic insufficiency is present over a long period secondary damage to the LS may occur
Dynamic insufficiency is EDEMA
MECHANICAL INSUFFICIENCIES OF THE LS
Definition
TC drops below the normal amt of LL
AKA
Low-volume insufficiency
Causes
Surgery
Radiation
Infection
Trauma
Chronic venous insufficiency
Congenital malformation
In the case of Mechanical Insufficiency.
The LS is diseases or damaged
The TC is reduced and cannot cope with a normal LL
The LS cannot activate is FR (Functional Reserve)
Mechanical Insufficiency Is Lymphedema
Combined Insufficiency
Mechanical Insufficiency is already present
something happens to increase the LL
LS is unable to compensate because lymph vessels are diseased
Swelling occurs quickly - in about a day