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


(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


13


Centrifuged Blood Sample

Peripheral Blood Smear

Liquid (plasma)

“Buffy coat” white blood cells and platelets)

Red blood cells

Red blood cellsPlatelets

White bloodcells

14

(b)

(a)

a: © The McGraw-Hill Companies, Inc./Al Telser, photographer :b © Ed Reschke


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


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


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


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


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


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


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


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


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

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

http://users.rcn.com/jkimball.ma.ultranet/BiologyPages/B/Blood.html#platelets

http://users.rcn.com/jkimball.ma.ultranet/BiologyPages/J/Junctions.html#adherens

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


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

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.

http://users.rcn.com/jkimball.ma.ultranet/BiologyPages/S/Serine_Proteases.html#Serpins

http://users.rcn.com/jkimball.ma.ultranet/BiologyPages/A/A.html#allosteric

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

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blood flows

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origin of blood cells

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