The circulatory system transports nutrients, gases, hormones, cell wastes and more throughout the body. It consists of the heart, blood vessels and blood. The heart pumps blood in a closed system of arteries, capillaries and veins. Arteries carry oxygenated blood away from the heart while veins return deoxygenated blood back to the heart. The evolution of circulatory systems progressed from simple diffusion in single-celled organisms to closed circulatory systems with multiple heart chambers in vertebrates like humans.

1. CIRCULATORY SYSTEM

2. FUNCTIONS OF
CIRCULATORY SYSTEM
1. Transport of Nutrients to all body parts
* Glucose, amino acids, lipids, inorganic salts and water
2. Transport of Oxygen & Carbon Dioxide
* Carried as free dissolve in Plasma
* Hemoglobin (RBC)
3. Transport of Hormones
4. Transport of Excretory Products
*Urea, uric acid, creatines , and wastes from Liver

3. 5. Fight against Infections and Toxins
* WBC’s of Blood
* Monocytes – Phagocytosis
* Lymphocytes – cooperate in Phagocytosis
a. T-Lymphocytes – heart of cell-mediated immune response
b. B- Lymphocytes – heart of antibody immune response
6. Maintains acid-base balance through the buffer system
w/c neutralizes acids and bases.
*Buffer – a chemical substance that resist changes in the pH of a
solution when an acid or base is added on it.

4. COMPONENTS OF
CIRCULATORY SYSTEM
1. Blood Vascular System
a. Heart
b. Blood vessels
c. Blood
2. Lymphatic System – a cooperating system, the function of
which is to turn lymph to the blood.
a. Lymph – form from blood plasma that filtered
from the blood vessels.
b. Body fluids – related to fluid balance in the body.
c. Intracellular – within the cell (40%)
d. Extracellular – outside the cell (20%)
e. Plasma – found in blood vessels (5%)
f. Intercellular – tissue fluid in interstitial
compartment.

5. Unicellular
• Single-celled organisms obtain oxygen and nutrients
directly across the surface of the cell.
• Exchanges occur directly with environment.
Ex. Amoeba, Euglena
Multi-cellular
• Multi-cellular organisms require methods for transporting
materials to and from cells which are far removed from the
external environment.
CIRCULATORY SYSTEMS
Unicellular and Multi-cellular

6. TYPES OF
CIRCULATORY SYSTEMS
1. OPEN CIRCULATORY SYSTEM
A system made up of well-developed blood vessels which pass
from the heart to body tissues.
A tubular muscle, or heart, pumps hemolymph through a
network of channels and body cavities, before draining back to
the central cavity
Ex. Mollusk and Arthropods

7. 2. Closed Circulatory System
The blood is confined in tubes throughout its course from the
heart to the tissues and back to the heart.
Ex. All vertebrates (Human)
Annelids and Cephalopods

8. INVERTEBRATE CIRCULATORY SYSTEM
Sponges and most Cnidarians
- use water from the environment as a circulatory fluid.
Pseudocoelomate Invertebrates
- use the fluids of the body cavity for circulation = Gastrovascular
cavity

9. VERTEBRATE CIRCULATORY SYSTEM
I. HEART
The main propulsive organ of the circulatory system/ pumping
organ.
Layers of the Heart
1. Endocardium (inner)
2. Myocardium (middle)
3. Epicardium (outer)
TYPES OF HEART:
a.TWO-CHAMBERED HEART
Ex. Fishes
a.THREE-CHAMBERED HEART
Ex. Amphibians and Reptiles
a.FOUR-CHAMBERED HEART
Ex. Aves and Mammals

10. TWO-CHAMBERED HEART
Ex. Fishes
The development of gills required a more efficient pump.
The first chamber – sinus venosus and atrium; second chamber –
conus arteriosus and ventricle.

11. The evolution of lungs in amphibians involved a major change in the
pattern of circulation – a second pumping circuit.
After blood is pumped from the heart through pulmonary arteries to
the lungs, it is returned to the heart via pulmonary veins.
Double circulation – gives boost to speed or pressure at which blood
is transported to the rest of the body.
Pulmonary circulation moves blood between the heart and lungs.
Systemic circulation moves blood between the heart and the rest of
the body.

13. THREE-CHAMBERED HEART
Ex. Amphibians and Reptiles
Amphibians and most reptiles have a 3-chambered heart.

14. • Amphibians obtain additional oxygen via diffusion through their
(moist) skin.
• Reptiles have a septum that partially subdivides the ventricle.
• CAVUM VENOSUM
• CAVUM ARTERIOSUM
• Separation is complete in Crocodilians (septum divides ventricle
into 2 separate ventricles; a 4-chambered heart)
• Further reduces mixing of blood in the heart.
• Atria receive blood returning to the heart
• Ventricles pump blood out of the heart
AMPHIBIAN AND REPTILIAN CIRCULATION

15. FOUR-CHAMBERED HEART

17. The heart functions as a two-cycle pump.
Both atria fill with blood and simultaneously contract, emptying the
blood into the ventricles
(atrial contraction)
Both ventricles also contract at the same time, pushing blood into
the pulmonary and systemic circulations
(ventral contraction)
The cardiac cycle includes the atrial and ventricular contraction, and
the resting period between these two
Atrioventricular (AV) valves maintain unidirectional flow between
the atria and the ventricles: tricuspid (right) and bicuspid (left)

18. Semilunar valves maintain unidirectional flow out of the ventricles
to the arterial systems
Pulmonary valve located at exit of the right ventricle
Aortic valve located at the exit of the left ventricle
Valves open and close as the heart goes through its cycle.
The closing of the valves produce the “lub-dub” sounds heard
with a stethoscope.

19. Diastole (Resting) Phase
Blood returns to the resting heart through veins that empty into the
right and left atria
As blood fills the atria and pressure rises, the AV valves open and
blood flows into the ventricles
The ventricles become ~80% full from this process; contraction of
the atria fills the remaining 20%
Ventricles are relaxed = diastole phase

20. Systole (Ventricle Contraction) Phase
Following a slight delay from the diastole phase, the ventricles
contract = systole phase
Contraction of the ventricles increases the pressure within each
chamber, causing the AV valves to forcefully close; this forces the
semilunar valves open and blood flows into the arterial systems
As the ventricles relax, closing of the semilunar valves prevents
backflow

21. Four-Chambered Heart and
its Blood Vessels
Arteries – carry blood away from the heart; branch into
arterioles.
“Elastin” – a protein in connective
tissue.
Capillaries – where materials (O2, CO2, nutrients,
metabolic wastes) are exchanged.
Veins – carry deoxygenated blood back towards
the heart.
Coronary arteries are the first branches off the
aorta and supply the heart muscle with
oxygenated blood.
Blood from the body’s organs (now low in O2) returns to the heart
via systemic veins, which empty into 2 major veins:
Superior vena cava
Inferior vena cava

22. MEASURING BLOOD PRESSURE
• As the ventricles contract, they generate tremendous pressure, which is
transferred through the arteries once the AV valve opens
• Arteries contain large amounts of elastin, an elastic protein which allows
for dilation/stretching and rebound.
• A pulse results from changes in pressure as arteries expand and contract
with blood flow.
Blood Pressure
Is a general indicator of cardiovascular health.
Arterial blood pressure can be measured with a sphygmomanometer at the
brachial artery on the inside part of the arm
A tightened cuff stops the flow of blood to the lower part of the arm; As the
cuff is loosened, blood begins pulsating through the artery = systolic
pressure; ventricles are contracting
As the cuff is loosened further, the vessel is no longer distorted and the
pulsing stops = diastolic pressure; ventricles are relaxed

23. MEASURING BLOOD PRESSURE

25. • Systolic pressure is the peak pressure at which ventricles
are contracting
• Diastolic pressure is the minimum pressure between
heartbeats at which the ventricles are relaxed
• Written as a ratio of systolic over diastolic
• Typical blood pressure is 120/75; >150 systolic or >90
diastolic = hypertension
MEASURING BLOOD PRESSURE

26. CONTRACTION OF CARDIAC MUSCLE
• Each cell in heart produces an action potential (electrical signal
that is stimulus for cell to contract); fairly long in duration; 250
milliseconds from start to finish
• Can’t start another action potential until the other is completely
finished
• The sinoatrial (SA) node located in the wall of the right atrium acts
as a pacemaker by producing spontaneous action potentials
• Action potentials are generated by a constant leakage of Na+
ions
into the cell that depolarize the membrane
• When the threshold is reached, the action potential occurs
• Allows heart muscle to carry signal over distance; conducted
rapidly over both ventricles by a network of fibers, including
Purkinje fibers, which spread electrical activity to rest of heart

27. • An electrocardiogram (ECG or EKG) records the electrical activity
of the heart.
• Illustrates via electrodes how the cells of the heart depolarize and
repolarize during the cardiac cycle (action potentials)
– Depolarization causes contraction of the heart
– Repolarization causes relaxation
– Depolarization of the atria produces first peak; depolarization of
ventricles produce second, larger peak
– Repolarization produces third peak
CONTRACTION OF CARDIAC MUSCLE

28. BLOOD VESSELS: ARTERIES
• Arteries have thicker walls than veins; arterioles have less elastin
than arteries; Arteries deeply set, no valves.

29. BLOOD VESSELS: VEINS

30. • Less muscle is needed in veins because the pressure in
veins is only ~1/10th
of that in the arteries
• Venous pressure alone is not sufficient to return blood to
the heart
• Thus, skeletal muscles surrounding the veins contract to
move blood by squeezing the veins; the venous pump
• Internal valves in veins (venous valves) ensure that blood
continues to heart; operate as one-way swinging doors
• Skeletal muscles on outside of vein contracts, pushes
against vein, causing blood to flow towards heart; this
opens one-way valves up, pressure is released and cannot
return through valves (one-way transport to heart)

31. BLOOD VESSELS: VEINS

32. • Capillaries bridges the gap between the arteries and veins; only
have the inner epithelium layer (site of gas/nutrient/waste
exchange)
• Blood flows slower through capillaries because of larger total
cross-section
– Enables materials to be exchanged
– By the time blood reaches the end of the capillary, it
releases some of its oxygen and nutrients and picks up CO2
and waste products
BLOOD VESSELS: CAPILLARIES

33. TYPES OF CAPILLARIES
1. CONTINUOUS CAPILLARIES
2. FENESTRATED CAPILLARIES
3. SINUSOIDS/DISCONTINOUS CAPILLARIES

36. Blood serves to transport, regulate, and protects.
Blood is composed of a fluid-matrix known as plasma,
within which reside different cells and other ‘elements’.
•Plasma - 55%of the blood
- consisting 90%
- water 8-10%solid elements
Normally, the following are present in the plasma of the blood:
a.Calcium
b.Prothrombin
c.Heparin (anti-prothrombin)
d.fibrinogen
COMPONENTS OF BLOOD

37. • Blood corpuscle cells – 45% of the blood
- RBC, WBC and platelets
–Ions, proteins
–Nutrients, wastes and hormones
• Red Blood Cells (Erythrocytes)
Most numerous: 5 million/mL
–Transport O2 and CO2
(hemoglobin in vertebrates)
–Mammalian erythrocytes lack nuclei
COMPONENTS OF BLOOD

38. • White Blood Cells (Leukocytes)
– Fewer in number; 1-2 for every 1000 erythrocytes
– Larger in size, and have nuclei
– Not confined to blood as erythrocytes are; can migrate out of
blood into surrounding interstitial fluid or into the lymphatic
system – where your body fights infection
– Function in body’s defense
Lymphocytes – produced in lymphoid
tissue; 20-25% of WBC.
- forms the basis of immunity by
producing antibodies.
COMPONENTS OF BLOOD

39. • Platelets (Thrombocytes)
– Cell fragments that pinch off from larger cells in the bone
marrow
– Following injury to a blood vessel, platelets release clotting
factors (proteins) into the blood
– When platelets contact collagen, they stick to it ; results in
release of several factors which activate other platelets.
Conversion of fibrogen (soluable) to fibrin (insoluable); fibrin
threads cross-link, connecting platelets and trapping other cells
in network = blood clot
Blood Clotting – primary intended to prevent excessive loss of
blood from the body.
COMPONENTS OF BLOOD

40. FORMATION OF BLOOD CLOT

41. BLOOD TYPES
• Type A, B, O (and AB)
– Each contains antibodies of other types
• Agglutinogens or antigen A or B
- CHON present normaly in cells of erythrocytes
• Agglutinis (antibodies) or anti-serum A or B – CHON present in
serum or plasma in blood.
• Rh factor – presence or absence of Rh protein
– Positive (have) or negative (do not have)
– Negatives will form antibodies against Rh blood upon exposure