CARDIOVASCULAR SYSTEM
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Transcript of CARDIOVASCULAR SYSTEM
CARDIOVASULAR SYSTEM
Presented by
Dr. SINDHU. K,
MVSc SCHOLAR,
Dept of VPT,
COVAS, POOKODE
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.
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 )
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
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
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
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
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
ORIGIN OF BLOOD CELLS
10
Blood
(4.8%) (95.1%) (0.1%)
Plasma
Hormones
MonocytesBasophilsEosinophilsNeutrophils
(54–62%) (1–3%) (<1%) (3–9%) (25–33%)
GlobulinsAlbumins
(92%) (7%)
N2 O2 CO2
Platelets Red blood cells Proteins Nutrients Gases
45% 55%
WastesWaterWhite blood cells Electrolytes
Vitamins
Lymphocytes Fibrinogen
Formed elements
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
THE ORIGIN OF BLOOD CELLS
11
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
(b)
Megakaryoblast
Myeloid stem cell
Megakaryocyte
Monocyte
Macrophage
T lymphocyte B lymphocyte
Plasma cell
Hematopoietic stem cell
Myeloblast
Progranulocyte
Erythroblast
Normoblast
Reticulocyte
Erythrocyte
In c
ircu
lati
ng
blo
od
Neutrophil Basophil
Granulocytes
Eosinophil
ProerythroblastMonoblast
Promonocyte Prolymphocyte Prolymphocyte
In r
ed b
on
e m
arro
w
Agranulocytes
(a)
Lymphoid stem cell
LymphoblastB cell
precursor
LymphoblastT cell
precursor
Neutrophilicmyelocyte
Basophilicmyelocyte
Eosinophilicmyelocyte
Eosinophilicband cell
Basophilicband cell
Neutrophilicband cell
Thrombocytes(platelets)
Act
ivat
ed i
n t
issu
es(s
om
e ce
lls)
RED BLOOD CELL PRODUCTION AND ITS CONTROL
12
• Low blood oxygen causes the kidneys and the liver to release erythropoietin (EPO) which stimulates RBC production• This is a negative feedback mechanism Within a few days many new blood cells appear in the circulating blood
Low blood oxygen
Liver Kidney
Erythropoietin
Red bone marrow
+
–
Bloodstream
Stimulation
Inhibition
Release intobloodstream
Increasedoxygen-carryingcapacity
Increasednumber ofred blood cells
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
13
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Centrifuged Blood Sample
Peripheral Blood Smear
Liquid (plasma)
“Buffy coat” white blood cells and platelets)
Red blood cells
Red blood cellsPlatelets
White bloodcells
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(b)
(a)
a: © The McGraw-Hill Companies, Inc./Al Telser, photographer :b © Ed Reschke
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
DESTRUCTION OF RED BLOOD CELLS
15
16
Bilirubin
Bone
Blood
Liver
Globin + Heme
3
2
1 Absorption
4
5
Macrophage
Hemoglobin
Iron + Biliverdin
8
6
7Bile
Red bonemarrow
Red bloodcells produced
Red blood cellscirculate inbloodstream forabout 120 days
Old redblood cells
Blood transportsabsorbed nutrients
Nutrientsfrom food
Vitamin B12
Folic acidIron
Smallintestine
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
ERYTHROPOIESIS
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
NEUTROPHILS19
• Light purple granules in acid-base (neutral) stain• Lobed nucleus• Other names
• Segs• Polymorphonuclear leukocyte• Bands (young neutrophils)
• First to arrive at infections• Phagocytic (What is this?)• 54% - 62% of leukocytes• Elevated in bacterial infections (Why?)
© Ed Reschke
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
EOSINOPHILS 20
• Deep red granules in acid stain• Bi-lobed nucleus• Moderate allergic reactions• Defend against parasitic worm infestations• 1% - 3% of leukocytes• Elevated in parasitic worm infections and allergic reactions
© Ed Reschke
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
BASOPHILS 21
• Deep blue granules in basic stain• Release histamine •Release heparin Less than 1% of leukocytes• Similar to Eosinophils in size and shape of nuclei
© Ed Reschke
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
MONOCYTES22
• Largest of all blood cells• Spherical, kidney-shaped, oval or lobed nuclei• May leave bloodstream to become macrophages• 3% - 9% of leukocytes• Phagocytize bacteria, dead cells, and other debris
© R. Kessel/Visuals Unlimited
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
LYMPHOCYTES23
• Slightly larger than RBC• Large spherical nucleus surrounded by thin rim of cytoplasm• T cells and B cells •Both important in immunity• B cells produce antibodies• 25% - 33% of leukocytes
© Ed Reschke
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
FUNCTIONS OF WHITE BLOOD CELLS
24
• WBCs protect against infection• These leukocytes can squeeze between the cells of a capillary wall and enter the tissue space outside the blood vessel (called diapedesis)
Blood capillary
Leukocyte
Connectivetissue
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
25
Epidermis
Dermis Blood vessels
1 Splinterpuncturesepidermis
5 6
2 3 4 Injured cellsrelease histamine,causing bloodvessels to dilate
Bacteriamultiply
Bacteria are introduced into the dermis
Neutrophils destroybacteria by phagocytosis
Neutrophils move throughblood vessel walls andmigrate toward bacteria
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
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14.3: BLOOD PLASMA28
• 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
PLASMA PROTEINS29
• These are the most abundant dissolved substances (solutes) in plasma
GASES AND NUTRIENTS30
• The most important blood gases:• Oxygen• Carbon dioxide
• Plasma nutrients include:• Amino acids• Simple sugars• Nucleotides• Lipids
• Fats (triglycerides)• Phospholipids• Cholesterol
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
PLASMA ELECTROLYTES32
• 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
14.4: HEMOSTASIS33
• Hemostasis refers to the stoppage of bleeding• Actions that limit or prevent blood loss include:
• Blood vessel spasm• Platelet plug formation• Blood coagulation
34
35
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
PLATELETS
PLATELET ADHESION
PLATELET PLUG FORMATION
39
• Platelet plug formation• Triggered by exposure of platelets to collagen• Platelets adhere to rough surface to form a plug
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Endothelial lining Collagen fiber
Platelet Red blood cell
1
2
3
4
Break invessel wall
Blood escapingthrough break
Platelet plughelps controlblood loss
Platelets adhereto each othe ,to end of brokenvessel, and toexposed collagen
40
© SPL/Photo Researchers, Inc.
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
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
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
INTRINSIC & EXTRINSIC PATH WAYS
FATE OF BLOOD CLOTS44
• 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
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 10Heparin 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.
Protein CWith 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 KVitamin K is a cofactor needed for the synthesis (in the liver) of factors 2 (prothrombin), 7, 9, and 10 proteins C and SSo a deficiency of Vitamin K predisposes to bleeding. Conversely, blocking the action of vitamin K helps to prevent inappropriate clotting.
FIBRINOLYSIS
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
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
THANK YOU
• Physiology of cardiovascular system
• Origin of blood cells and circulation mechanisms
• Hemostasis
• Coagulation cascade
• Screening tests