2. CARDIO VASCULAR SYSTEM
CV physiology is study of the functions of the heart, the blood vessels and the
blood
3 main divisions of CVS
THE DISTRIBUTION SYSTEM - Heart, arteries, arterioles.
THE PERFUSION SYSTEM – arteries, arterioles, capillaries.
THE COLLECTING SYSTEM – venules, veins, heart.
3. MAJOR COMPONENTS OF THE
CVS
• RESISTANCE COMPONENT – the arterial system
• CAPACITANCE COMPONENT – the venous system
• CARDIAC OUTPUT
• PRE LOAD
• AFTER LOAD
• HYDROSTATIC PRESSURE
• CHRONOTROPIC EFFECT ( heart rate )
• IONOTROPIC EFFECT ( contractility )
4. IMPORTANCE OF CVS
1. The primary function of CVS is TRANSPORT ( metabolic substrates)
2. CONDUCTS chemical messengers ( harmones )
3. ELECTROLYTE BALANCE & tissue homogeneity
4. Maintains HEMOSTASIS
5. Helps to maintain COLLOIDAL OSMOTIC PRESSURE
5. WILLIAM HARVEY ( 1628 )
• Father of cardiovascular physiology
• Set forth the first proof that HEART PROPELS THE BLOOD THROUGH BLOOD
VESSELS IN A CIRCULATORY PATTERNS
• Before HARVEY’S proposal it was believed that blood flows in TIDAL FASHION
similar to respiratory system
• However the circularity of the cardiovascular system makes it difficult
• No clear ideas about tissue supply demand & supply of blood to pheriphery
6. PHYSICAL CHARACTERISTIC OF
CIRCULATION
• SYSTEMIC CIRCULATION
• Blood supplied to all parts of the body
• Also called GREATER / PERIPHERAL CIRCULATION
• PULMONARY CIRCULATION
• Blood transported to LUNGS only
7. PERFUSION PRESSURE >< TRANSMURAL PRESSURE
• PERFUSION PRESSURE
• Difference in the pressure between the two points in a blood vessel
• Causes the blood to flow through blood vessel
• TRANSMURAL PRESSURE
• Difference between the blood pressure inside a blood vessel & the fluid
pressure outside the vessel
• Causes blood to flow out of a vessel if you poked a hole in the vessel wall
8. MODE OF TRANSPORT OF BLOOD
FLOW
• BULK FLOW
• Rapid over long distances
• Transport requires ENERGY which is the HYDRO STATIC PRESSURE DIFFERENCE
• DIFFUSION
• Primary mechanism by which dissolved substances move across the wall of
blood vessels from the blood stream into the interstitial fluids or vice versa
• ENERGY source is CONCENTRATION GRADIENT
18. TYPES OF WHITE BLOOD CELLS
18
• White blood cells:
• Are leukocytes
• Protect against disease
• WBC hormones are interleukins and colony-stimulating
factors which stimulate development
• There are five types of WBCs in two categories:
• Granulocytes
• Neutrophils
• Eosinophils
• Basophils
• Agranulocytes
• Lymphocytes
• Monocytes
28. 14.3: BLOOD PLASMA
28
• Blood plasma is:
• Straw colored
• The liquid portion of blood
• 55% of blood volume
• 92% water
• Function includes transporting nutrients, gases, and
vitamins
• Helps regulate fluid and electrolyte balance and
maintain pH
30. GASES AND NUTRIENTS
30
• The most important blood gases:
• Oxygen
• Carbon dioxide
• Plasma nutrients include:
• Amino acids
• Simple sugars
• Nucleotides
• Lipids
• Fats (triglycerides)
• Phospholipids
• Cholesterol
31. NONPROTEIN NITROGENOUS
SUBSTANCES
31
• These are molecules containing nitrogen but are not
proteins
• In plasma they include:
• Urea – product of protein catabolism; about 50% of
nonprotein nitrogenous substances
• Uric acid – product of nucleic acid catabolism
• Amino acids – product of protein catabolism
• Creatine – stores phosphates
•Creatinine – product of creatine metabolism
• BUN – blood urea nitrogen; indicates health of kidney
32. PLASMA ELECTROLYTES
32
• Plasma contains a variety of these ions called electrolytes
• They are absorbed from the intestine or released as by-
products of cellular metabolism
They include:
• Sodium (most abundant with chloride)
• Potassium
• Calcium
• Magnesium
• Chloride (most abundant with sodium)
• Bicarbonate
• Phosphate
• Sulfate
33. 14.4: HEMOSTASIS
33
• Hemostasis refers to the stoppage of bleeding
• Actions that limit or prevent blood loss include:
• Blood vessel spasm
• Platelet plug formation
• Blood coagulation
36. PLATELETS
• Platelets are cell fragments produced from megakaryocytes.
• Blood normally contains 150,000 to 400,000 per microliter (µl). If this value
should drop much below 20,000/µl, there is a danger of uncontrolled
bleeding. This is because of the essential role of platelets
• in maintaining the integrity of the adherens junctions that provide a tight seal
between the endothelial cells that line the blood vessels;
• in forming a clot where blood vessels have been broken
41. EXTRINSIC CLOTTING
MECHANISM
41
• Extrinsic clotting mechanism
• Chemical outside of blood vessel triggers blood
coagulation
• Triggered by tissue thromboplastin (factor III) (not
found in blood)
• A number of events occur that includes factor VII,
factor X, factor V, factor IV, and factor II (prothrombin)
• Triggered when blood contacts damaged blood vessel
walls or tissues
• This is an example of a positive feedback mechanism
42. INTRINSIC CLOTTING
MECHANISM
42
• Intrinsic clotting mechanism
• Chemical inside blood triggers blood coagulation
• Triggered by Hageman factor XII (found inside blood)
• Factor XII activates factor XI which activates IX which
joins with factor VIII to activate factor X
• Triggered when blood contacts a foreign surface
44. FATE OF BLOOD CLOTS
44
• After a blood clot forms it retracts and pulls the edges of a
broken blood vessel together while squeezing the fluid serum
from the clot
• Platelet-derived growth factor stimulates smooth muscle cells
and fibroblasts to repair damaged blood vessel walls
• Plasmin digests the blood clots
• A thrombus is an abnormal blood clot
• An embolus is a blood clot moving through the blood vessels
45. Antithrombin III
As its name suggests, this plasma protein (a serpin) inhibits the formation of
thrombin.
It does so by binding to and thus inactivating:
prothrombin
factor 9
factor 10
Heparin is a mixture of polysaccharides that bind to antithrombin III, inducing
an allosteric change that greatly enhances its inhibition of thrombin synthesis.
Some surgical patients, especially those receiving hip or heart valve
replacements, and people at risk of ischemic stroke (clots in the brain), are
given heparin.
46. Protein C
With its many clot-promoting activities, it is probably no accident that thrombin sits
at the center of the control mechanism.
Excess thrombin binds to cell-surface receptors called thrombomodulin.
The resulting complex activates a plasma protein called Protein C and its
cofactor Protein S.
Together these inhibit further thrombin formation
o directly — by inactivating Factor 5 and
o indirectly — by inactivating Factor 8.
Vitamin K
Vitamin K is a cofactor needed for the synthesis (in the liver) of
factors 2 (prothrombin), 7, 9, and 10
proteins C and S
So a deficiency of Vitamin K predisposes to bleeding.
Conversely, blocking the action of vitamin K helps to prevent inappropriate
clotting.
48. BLEEDING DISORDERS
• A deficiency of a clotting factor can lead to uncontrolled bleeding.
• The deficiency may arise because
• not enough of the factor is produced or
• a mvon Willebrand disease (the most common)
• hemophilia A for factor 8 deficiency
• hemophilia B for factor 9 deficiencyutant version of the factor fails to perform
properly.
• hemophilia C for factor 11 deficiency
49. SCREENING TEST
• OSPT/PT-One Stage Prothrombin Time
• Detects abnormality in plasma level of F5, F7, F10
• Also the abnormality in prothrombin activity or fibrinogen concentration
• Detects LIVER DYSFUNCTION
• APTT/PTT-Activated Partial Thromboplastin Time
• Detects the abnormality in plasma levels of F12, F10, F9, F8,PROTHROMBIN,
FIBRINOGEN
• Detects the PLATELET COUNTS
50. THANK YOU
• Physiology of cardiovascular system
• Origin of blood cells and circulation mechanisms
• Hemostasis
• Coagulation cascade
• Screening tests
