Blood consists of plasma and formed elements including red blood cells, white blood cells, and platelets. It circulates through the body in arteries, arterioles, capillaries, venules and veins. Blood performs critical functions like transporting oxygen, nutrients, hormones, and removing waste products. Precise regulation of blood pressure, volume, pH, and temperature is vital for homeostasis.

1. Blood : Components
& Circulation
BIO 306: ANIMAL PHYSIOLOGY PRESENTATION
Students:
1) Ashwathi P. (14034)
2) Gayatri Limaye
(14086)
3) Satyam D Pawar
(14149)

2. • Blood - A connective tissue that consists of blood plasma
(liquid) plus formed elements (red blood cells, white blood
cells, and platelets).
• Pathologically important
• Temp.- 38°C, pH-7.35-45, 8% of total body weight
Volume - Adult male – 5-6 ltrs, Female – 4-5 ltrs
Color-Red(Oxygenated),Dark Red(Deoxygenated)
• Composition -
1. Blood plasma - 55%, straw coloured liquid contains
dissolved substances & blood cells
Enzymes, hormones, gases, & waste products urea, uric
acid, creatinine are part of it.
2. Blood cells - 45%, RBCs, platelets & multiple types of
WBCs comprising granulocytes & agranulocytes are part of
it.
• Functions -
1. Transports oxygen, carbon dioxide, nutrients, hormones,
heat, and wastes.
2. Regulates pH, body temperature, and water content of
cells.
3. Protects against blood loss through clotting, and against
disease through phagocytic white blood cells and
proteins such as antibodies, interferons, and
complement.
Blood – Introduction & Composition
*Fig 19.1: Tortora,
Principles of Anatomy
& Physiology, 13E

3. White Blood Cells/ Leukocytes
• Nucleated unlike RBCs & platelets
•Found throughout the body in blood & lymphatic system
•Structurally divided into granulocytes(lobed nucleus)&
agranulocytes(round nucleus) & based on cell lineage into
myloid lineage(all others except lymphocytes) & lymphoid
lineage
• Increse or decreases in particular cell type signify diff.
diseases
• Normal WBC count – 4000-11,000/μL of blood
•Have major histocompatibilty complex(MHC) on its surface,
involved in identification of pathogen & presentation to
phagocytic cells

4. Hematopoiesis
• The formation of formed elements in
blood is called
hematopoiesis/hemopoiesis.
• Occurs in yolk sac in embryo & in red
bone marrow in adults & newborn.
• Mesenchyme derived pluripotent stem
cells/hemocytoblasts are capable of
producing any type of blood cell.
• PSC give rise to Progenitor cells which
then sequentially divide & differentiate
into different cell types.
• Several hormones called hemopoietic
growth factors regulate the
differentiation and proliferation of
particular progenitor cells.
• Erythropoietin(EPO) produced by kidney
cells that lie between the tubules
increases the no. of RBC precursors.
• Thrombopoietin(TPO) produced by liver
cells increases the production of
platelets from megakaryocytes.
A class of glycoproteins called cytokines have been shown to regulate progenitor cell proliferation by acting as local
hormones.
Progenitor cells called colony forming units(CFUs) signi
the last differentiated form
Myeloid stem cells begin developing in bone
marrow give rise to RBCs, platelets &
others.
Start developing in bone marrow but
complete in lymphatic tissues

5. Red Blood Cells / Erythrocytes
• contain oxygen carrying protein
hemoglobin, giving it the red colour
• Anatomy –
- circular biconcave, diameter 7-8 μm
- plasma membrane antigens determine
blood groups
- lack nucleus & other organelles
• Physiology –
- respire anaerobically allowing maximum O2 bound
Hb to reach other cells
- biconcavity gives maximum surface area for
transport
• Hb – Globin (α2β2), each globin has an Fe heme
core which can bind to one O2 molecule, hence each
heme binds to 4 O2 molecule
- also transports 23% CO2(rest dissolved in plasma
or as bicarbonate ions)
- can bind to NO released by endothelial cells of
blood vessels causing vasodilation & regulation blood
flow.
- Also contain carbonic anhydrase enzyme which is
important for transport of CO2 as HCO3 & act as
buffer in extracellular fluid
• About 2mn RBCs produced per second & 2mn
destroyed by macrophages.
Erythropoiesis: starts in red bone marrow, proerythroblast divide several
times & then form cells which eject their nucleus to become reticulocyte.
Reticulocytes pass from bone marrow to blood vessels & mature into
RBCs in 1-2 days.
Negative feedback mechanism through erythropoietin in kidney regulates
RBC blood count.

6. BLOOD VESSELS :
Arteries--->Arterioles--->Capillaries--->Venules--->Veins
• Capillaries allow the exchange of substances between blood & body
tissues.
• Vessel structure –
- 3 layers(tunics)
• Interna –
- in direct contact with the blood in lumen, multiple parts
•Endothelium- layer of flattened cells, continuous with endocardium, lines
entire cardiovascular system,
minimizes friction, produces local chemical signals to stimulate smooth
muscles above it
• Basement membrane – made up of collagen fibers,
helps cellular movement in lumen, provides tensile
strength as well as resilience to recoil.
• Lamina – thin sheet of elastic fibers with perforations to allow transport
between interna & media
• Media :
•Connective tissue layer, comprises of smooth muscle cells & elastic fibers
•Smooth muscle cells circularly surround the lumen & change the diameter
in response to local chemical signals
•Vascular spasm to stop blood flow in case of a rupture
•Help produce elastic fibers in media
•External elastic lamina – separates media from externa
• Externa –
-consist of elastic & collagen fibres, nerves attach here
-vas vasorum-tiny vessels supplying to bigger vessels
-helps anchor the vessels to neighboring tissue

7. Platelets/Thrombocytes
• Also develop from myeloid stem cells, under the influence of thrombopoietin,
megakaryocyte colony forming cells develop into megakaryoblasts(CFU-Meg)
• CFU-Meg develop into megakaryocyte which each splinter into 2000-3000 cell
fragments, covered by cell membrane, each called thrombocyte.
• Platelets defuse from megakaryocyte & enter blood circulation
• Enucleated, biconvex discoid, 2-4μm in diameter
•Normal blood count – 150,000-400,000/ μL of blood
• has granule like vesicles that contain blood clotting factors & factors to repair
ruptured vessels.
Treatment of blood related disorders
• Many diseases including multiple types of cancer related to defective blood cells
• Based on replacement of diseased blood cells by division of healthy bone marrow
•Treatments include –
1. Bone marrow transplant - healthy bone marrow transplanted to the patient, defective bone
marrow & lymphocytes destroyed before transplant
- immunosuppressant drugs taken to stop graft-host disease( rejection by patient’s body)
- weakened immune system
2. Cord Transplant - Stem cells taken from umbilical cord of a compatible baby & injected into
the patient
- less chances of host rejection, more no. of stem cells available & can be stored indefinitely
in cold storage

8. Hemostasis
• Hemostasis is a sequence of responses
that stops bleeding.
• Quick, localized to the site of damage &
carefully regulated
• Three mechanisms reduce blood loss:
(1)vascular spasm, (2) platelet plug
formation and (3) blood clotting
(coagulation).
- Effective against damage of small vessels
but damage to larger vessels requires
medical intervention.
Platelet adhesion : platelets sense
the collagen fibers
• Platelet release reaction :
- projections indicate activated
platelets
- Serotonin & thromboxane A2 are
vasoconstrictors & reduce blood flow
Platelet Aggregation
•ADP release makes other platelets
sticky & they stick to aciivated platelts
eventually forming a platelet plug.
Blood Clotting
• extrinsic – activated by factors
external to blood (TF) released
from damaged cells.
• faster than intrinsic
• intrinsic- activated by components
of damaged cells
• slower, takes few minutes
• Factor XIII – fibrin stabilizing
enzyme
• Vitamin K – required for synthesis
of 4 clotting factors
• Deficiency leads to uncontrolled
bleeding when injured.
• Different clotting factors are
synthesized in different parts of the
body & activated when injured.
• Thrombin – 2 positive feedback
effects, on production of
prothrombinase through factor V, &
stimulates platelet aggregation
increasing intrinsic pathway.

9. Shock & Homeostasis :
• Shock is a failure of the cardiovascular system to
deliver enough O2 nutrients to meet cellular metabolic
needs.
• If shock persists, cells and organs become
damaged, and cells may die unless proper
treatment begins quickly.
• Symptoms of shock:
Measures taken up by the action of local &
general responses include:

10. Capillary Exchange
Capillary exchange occurs in systemic
capillaries.
3 mechanisms :
• Diffusion: conc. dependent movement through
fenestrations in capillary & through endothelial cells
- fenestrations of diff. size in capillaries of diff.
organs
• Transcytosis :
- mainly for large, lipid-insoluble molecules that
cannot cross capillary walls in any other way.e.g. insulin
- endocytosed material exit on the other side of the
cell by exocytosis
• Bulk Flow: Filtration and Reabsorption
• Regulated by Sterling’s law
• Pressure-driven movement of fluid
and solutes from blood capillaries into interstitial
fluid is called filtration.Pressure-driven
movement from interstitial fluid into blood
capillaries is called reabsorption

11. Factors affecting Blood Pressure :
Increase : Control by external factors
Autoregulation :
• Physical changes : Smooth muscles show myogenic response to control BP via lumen diameter
• Vasodilating & vasoconstricting chemicals : released by many blood cells & endothelial vessel cells in
response to changes in BP

12. Systemic circulation
The systemic circulation includes the arteries and arterioles that carry
oxygenated blood from the left ventricle to systemic capillaries, and the veins
and venules that return deoxygenated blood to the right atrium.
Left atrium
(Oxygenated
blood)
Left ventricle Aorta Systemic
arteries
Systemic
capillaries
(Exchange of
gases and
nutrients with
tissues)
Systemic
veins
Superior vena cava,
Inferior vena cava,
Coronary sinus
Right atrium
(Deoxygenated
blood)

13. *Tortora,Principles of Anatomy & Physiology,13E

14. Veins of the systemic circulation
Three systemic veins, the coronary sinus, superior vena cava, and inferior vena
cava, return the deoxygenated blood to the right atrium of the heart.
The coronary sinus receives blood from the cardiac veins;
the superior vena cava receives blood from other veins superior to the
diaphragm, except the air sacs of the lungs;
the inferior vena cava receives blood from veins inferior to the diaphragm.

15. The aorta
The aorta is the largest artery of the body, with a diameter of 2-3 cm. Its four
principal divisions are the ascending aorta, arch of the aorta, thoracic aorta,
and abdominal aorta.
Each division of the aorta gives off arteries that branch into distributing arteries
that lead to various organs.
Within the organs, the arteries divide into arterioles and then into capillaries that
exchange gases and nutrients with the systemic tissues (except alveoli of
lungs).

18. PULMONARY CIRCULATION

19. CO2
Heart Lungs
O2
How does blood get oxygen????
❑ The deoxygenated blood is transported from the right atrium to right
ventricle through the tricuspid valve. It then moves through the SYSTAMIC
circulation getting oxygenated blood.
❑ The lung rich in oxygenated blood take up the CO2 from blood through
diffusion and give O2 to the blood. This is mediated by simple diffusion
guided by the partial pressure of O2 and CO2.
❑ The lungs and heart are connected together by PULMONARY circulation.

20. Oxygenated blood
Left atrium
Right atrium
Aota pulmonary capillaries
Systemic arteries Pulmonary arteries
Systemic arterioles Pulmonary trunk
Systemic capillaries Right ventricle
Systemic veins Right atrium
Systemic venules Superior inferior venacava
SCHEMATIC REPRESENTATION OF THE
BLOOD FLOW
IN PULMONARY CIRCULATION

22. Coronary
circulation

23. Myocardium is having its own circulatory system so as to serve the oxygen
requirement of the heart tissues. And this circulation is termed coronary
circulation.

24. Circulation of blood between two different organ without the involvement of heart. It
mainly exist for the transport of nutrients and desired components between different
cell types. Eg: portal system of the liver called hepatic portal system.
Portal circulation

25. The circulatory system of a fetus, called the fetal circulation, exists only in the fetus and
contains special structures that allow the developing fetus to exchange materials with its
mother. The exchange of materials between fetal and maternal circulations occurs through the
placenta, which forms inside the mother’s uterus and attaches to the umbilicus (navel) of the
fetus by the umbilical cord.
Fetal circulation

26. CONCLUSIONS
❖ RBCs – enucleated, most numerous, carry O2 to all parts of the body
❖ WBCs – nucleated, defence mechanism of the body, inhabit blood & lymph, diff. types perform diff. function
❖ Platelets-Cell fragments, aggregate at the damaged site in response t chemical stimuli
❖ Clotting & Homeostasis: Extrinsic & intrinsic pathway responsible for insoluble fibrin threads, clotting at
undesired locations(thrombosis) corrected by fibrinolysis, mediated by plasminogen.

27. REFERENCES
❑ Blood components & Clotting – All text from Chapter 19 & 21,Tortora, Principles of Anatomy & Physiology,13E
- All figures from Chapter 19 & 21,Tortora, Principles of Anatomy & Physiology,13E except for
Shock & Hemostasis – Google Images search