Circulatory System• Every single living cell in the body needs a supply

of oxygen and nutrients for energy, growth, repair, and heat production.

• Each organ has it’s own separate circuit of an artery and vein which branch into smaller vessels and are linked by capillaries.

• This individual circuit ensures that every part of the body receives a rich supply of nutrients.

• In this way not all of the blood goes to each organ in turn. If this were the case then the furthest organ from the heart would receive no fresh blood.

• The only organ to receive all of the blood is the lungs so that all the blood is oxygenated.

Circulatory System• The Heart: A muscular pump that pumps blood around the body

through a system of vessels

• Blood Vessels: These transport blood around the body that is

Arteries, veins & capillaries

• Blood: Carries important substances to and from the cells in the

body through the blood vessels. That is plasma, white blood cells,

red blood cells & platelets

• Lymphatic system: this is the body’s secondary line of

defense, stops the build up of toxins and excess fluid in the body

COMPOSITION OF BLOOD

RED BLOOD CELLS• Transport of gases – mainly oxygenWHITE BLOOD CELLS• Fight infectionPLATELETS• ClottingPLASMA• Transport – mainly carbon dioxide, hormones, nutrients and waste products

Circulatory System• The circulatory system is the body’s

transport system• The system is made up of the heart, blood,

blood vessels and lymphatic system • Blood carries important substances to

the cells in the body• Blood carries waste products away from

the cells to the excretory organs• Blood is transported in blood vessels

called arteries, veins and capillaries• The heart is a muscular pump, which

forces the blood around the body, through the blood vessels, in a constant circuit

FUNCTIONS OF BLOODTRANSPORT

• Red blood cells contain haemoglobin which carries oxygen from the lungs to cells of the body

• Carbon dioxide is carried from cells to the lungs• Plasma – liquid consisting mainly of water – carries nutrients (glucose,

amino acids, vitamins, minerals), gases, waste products and hormones

DEFENCE

• White blood cells digest micro-organisms (which invade the body) and help fight infection

CLOTTING

• Platelets form a clot over damaged skin, which prevents further blood loss

REGULATION

• Blood absorbs heat, which is produced by the muscles and liver and transports it around the body to maintain a constant internal temperature

• Blood helps regulate the body’s pH balance

Blood Clotting

The process that prevents blood from clotting in an undamaged

vessel is a complex one.

Once a vessel has been damaged, platelets adhere to the damaged

area forming a plug the plasma protein fibrinogen is converted into

fibrin that creates fibres to radiate from the platelets forming a

network which traps red blood cells.

This blood clot stops further blood loss and prevents entry of bacteria.

Once the clot has dried it shrinks to form a scab, which protects the

tissues underneath while healing takes place.

Heparin is a protein normally present in the blood, which is formed in

the liver and it’s function is to prevent blood clotting in the vessels – it

is called an anti – coagulant.

BLOOD VESSELS

ARTERIES VEINS CAPILLARIES

Direction Carry blood away from the heart

Carry blood towards the heart

Link arteries and veins

Blood Type

Carry oxygenated blood Carry deoxygenated blood

Responsible for tissue fluid exchange in cells

Structure Thick, muscular elastic walls

Less thick walls, contain valves which prevent back flow of blood

Walls are very thin - only one cell thick to allow the process of diffusion

Pressure Blood is carried under high pressure

Blood is carried under low pressure

Blood pressure is higher at arterial side

Location Generally deep seated – except pulse areas

Generally superficial Form networks in tissues

Divisions Divide into smaller vessels called arterioles which deliver blood to capillaries

Divide into smaller vessels called venules which continue from capillaries

Smallest blood vessels

Tissue fluid Exchange

Blood rich in oxygen and nutrients is transported

around the body at high pressure via the arteries.

The arteries divide into smaller and smaller

vessels until they become capillary networks in

the tissues.

Fluid escapes thorough the thin walls of the

capillaries, bathing the cells delivering nutrients

and oxygen in exchange for waste products.

Tissue fluid Exchange

The tissue fluid passes back through the capillary

walls into the venous side of the capillary network,

where the pressure is lower.

Any left over fluid and molecules too large to go

Through the blood capillary, pass into the

lymphatic capillary and now becomes lymph fluid.

TISSUE FLUID EXCHANGE

Capillary

LYMPHATIC SYSTEM• The lymphatic system is the body’s

secondary line of defence (immunity)• Prevents the build up of toxins and excess

fluid in the body• Consists of lymph fluid, lymph nodes,

lymph ducts and lymph vessels• The lymphatic system is part of the

circulatory system• The lymph fluid contains waste products –

this fluid is transported by lymph vessels (which also have valves)

• The fluid is then filtered by the lymph nodes and then returned back to the venous system by the lymph ducts

THE LYMPHATIC SYSTEM

The lymphatic system is really part of the vascularsystem – the blood is contained in a closed systemof vessels which is kept circulating by the heart,from the capillaries some fluid escapes calledplasma, this is by diffusion and filtration.

This fluid then bathes the tissues directly, when thisfluid is collected into the lymph vessels it becomeslymph, which is later returned to the blood stream.

Lymph vessels start as fine, blind ended lymphcapillaries which then join to form lymphatics whichare similar in general course and structure to that ofveins.

THE LYMPHATIC SYSTEM

They are semilunar and numerous through andhave many more finer (pocket) valves, this isbecause the lymph is not pumped by the heart.

The composition of lymph is similar to bloodplasma but has less protein, less food materials andmore waste material – it has no erythrocytes but hasMore leukocytes.

THE LYMPHATIC SYSTEM

Lymph drainage is through lymph nodes

– before the lymph can be returned to the

blood stream it is filtered through one or

more of the lymph nodes, which are bean

shaped structures, situated at strategic

points in the course of the lymph vessels.

THE LYMPHATIC SYSTEM

After passing through the nodes the lymph

is then collected into the main lymph

vessels – vessels – lymph from the

right side of the head and thorax and right

arm, drain into the right lymphatic duct,

while lymph from the rest of the body drains

into the thoracic duct.

THE LYMPHATIC SYSTEM

The lymphatic system acts as the

body’s secondary line of defence

against bacterial invasion, this is

through the presence of

leukocytes at the site of infection.

BODY LYMPHATIC SYSTEM

PAROTID

SUBMANDIBULAR

SUBMENTAL

CERVICAL UPPER & LOWER

Abdominal Lymph Nodes

Thoracic Lymph Nodes

Iliac Lymph Nodes

Inguinal Lymph Nodes

Axillary Lymph Nodes

Papliteal Lymph Nodes

Buccal Lymph Nodes

THE HEART RATE – PULSEThe left ventricle contracts so strongly that it canbe felt as a pressure wave or ‘pulse’ at certainplaces along an artery where the artery is nearerthe surface of the skin.

Measuring your pulse:

• The pulse can be felt strongly in two main places – the neck and the wrist.

• To feel for your pulse you must use two fingers not your thumb as this has a pulse of it’s own.

EXPERIMENT1. Take a measurement of your resting heart rate timed over 30

seconds and then double to find your resting heart rate per minute.

2. To increase you heart rate do some vigorous exercise for 3 minutes or until you are out of breath.

3. After the exercise take you pulse again.

4. How long does it take to go back to your resting heart rate?

A healthy adult has a resting pulse rate of 60–80 beats a minute.

Someone who is unfit or who has a sedentary lifestyle may have a

pulse of 120 beats a minute.

A trained athlete or a very fit person may have a pulse of 35-40beats a minute.

THE HEART• Is a hollow muscular organ ‘pump’• Pumps blood around the body• Comprises of 4 chambers• Upper chambers = Atria• Lower chambers = Ventricles• Divided into 2 halves by the septum• Left side deals with oxygenated blood• Right side deals with de-oxygenated blood• Situated in the thoracic cavity• Between the lungs – slightly to the left• Protected by the rib cage

Aorta (Arch)

Pulmonary Artery

Pulmonary Vein

Left Atrium

Mitral Valve

Septum

Left ventricle

Superior Vena cava

Right Atrium

Tricuspid Valve

Inferior Vena cava

Right Ventricle

Deoxy, bld(from body) VC RA RV PA

Lungs(oxy) PV LA LV Aorta body

CIRCULATION OF BLOOD THROUGH THE HEART

Humans and other mammals have a double circulatory system; the blood circulates around 2 separate pathways joined at the heart.

The systemic Circulation

Or the general circulation, carries oxygenated blood from the heart to parts of the body and back again- (not including the lungs)

In both circuits, gases exchange places in the capillary vessels.

The pulmonary Circulation

Carries blood from the heart to the lungs be oxygenated and back to the heart.

The pulmonary CirculationDeoxygented blood comes from the body andtravels into the heart’s upper chamber, theright atrium, via the vena cava. The atrium contracts and blood is forced intothe right ventricle. The right ventriclecontracts and blood passes out of the heartinto the Pulmonary artery.

The pulmonary artery goes to the lungs where theblood picks up oxygen – this is now oxygenatedblood.

CIRCULATION OF BLOOD THROUGH THE HEART

The systemic Circulation

The oxygenated blood travels from the lungs viathe pulmonary vein to the left atrium of theheart.

The left atrium contracts and blood is forcedinto the left ventricle. The left ventriclecontracts and blood passes out of the heart viathe Aorta.

The oxygenated blood is transported aroundthe body through arteries that branch fromthe main artery - aorta.

CIRCULATION OF BLOOD THROUGH THE HEART

BLOOD CIRCULATIONLabel the following on diagram (use the letters as key)

A – a blood vessel rich in oxygen

B- a blood vessel low in oxygen

C- a blood vessel rich in carbon dioxide

D- a blood vessel low in carbon dioxide

E- a blood vessel under high pressure

F- a blood vessel under low pressure

G- a blood vessel that has valves

AB

CD

E

F

G

Subclavian

Jugular

Axillary

Basilic

Median

Great Saphenous

Short Saphenouse Anterior Tibial Vein

Posterior Tibial Vein

Popliteal

Femoral

Radial

Brachial

Cephalic

Vena Cava

Subclavian

Axillary

Brachial

Radial

ulnar

Deep Palmer Arch

Superficial Palmer Arch

Digital Arch

Anterior TibialPosterior Tibial

Carotid

Aorta

Iliac

Femoral

Popliteal

Blood Groups

There are four different blood groups, A, B, AB & O.

Blood from one individual cannot always be safely mixed with that of another,this is due to the two types of protein that may be present on the red blood cells– A and B. These proteins are Antigens to individuals who lack them.

Antigen – any substance that the body regards as foreign or potentiallydangerous and against which it will produce an antibody.

Antibodies - are found in the plasma and can cause the red cells of othergroups to clump together and can be fatal as the clumps of red cells block theblood vessels and obstruct the circulation – this is called Agglutination – (canalso cause kidney damage).

The antibodies are called Agglutinins.

*Agglutinated cells block the flow of blood disrupting circulation and the distribution of O2, gases and nutrients

Blood Groups

Blood group

Agglutinogen

(Antigen on RBC)

Agglutinin

(antibody in plasma)

A A Anti - BB B Anti - A

AB A + B NoneO None Anti A + Anti

B

Blood Groups Transfusion Considerations

Doner /

RecipientA B AB O

A

B

AB

O

XX

XXX

X X

Universal Recipient

Universal

Donor

The Rhesus Factor

In addition to ABO grouping there is another antigen present in the blood of about 85% of the population-it is known as the Rhesus Factor, (named after the group of monkeys it was discovered in).

Those who have this factor are known as Rhesus + positive) – 85%

Mother-fetus incompatibility

Normally, anti-Rh+ antibodies do not exist in the first-time mother unless she has previously come in contact with Rh+ blood.  Therefore, her antibodies are not likely to agglutinate the red blood cells of her Rh+ fetus. 

Rh (Rhesus) Factor

• Up to 8 genes determine if a person is Rh positive.

• The most common of these are the C, D & E genes which determine if a person has C, D and/or E antigens on the walls of the cells.

• People who do not have Rh antigens on their cell membranes are Rh negative.

BLOOD SUPPLY TO THE HEAD AND NECK

VESSEL AREA SUPPLIED/DRAINED

Internal carotid artery Supplies blood to brain and eyes

External carotid artery

Main vessel supplying book to upper part of neck/face – subdivides into branches supplying other areas: facial, occipital, temporal

Facial artery Supplies upper/lower and facial muscles

Superficial temporal arterySupplies the face by its transverse

(across) facial branch

Occipital arterySupplies upper part of the neck and back

of scalp

Internal jugular vein Brains blood from brain

External jugular veinMain vessel draining blood from face/neck

– blood is supplied to it by smaller veins which drain different area

Facial veinDrains front of scalp and superficial

structures of the face

Retromandibular vein Drains face below jaw and back of scalp

Blood PressureThe blood pressure is the amount of pressure exerted on an arterial

wall due to the contraction of the left ventricle.

The pressure in the arteries varies during each heartbeat. The

maximum pressure of the heartbeat is known as the systolic

Pressure and represents the pressure exerted on the arterial wall

during active ventricular contraction. Systolic pressure can therefore

be measured when the heart muscle contracts and pushes blood out

into the body through the arteries.

The minimum pressure, or diastolic pressure, represents the static

pressure against the arterial wall during rest or pause between

contractions. Therefore the minimum pressure is when the heart

muscle relaxes and blood flows into the heart from the veins.

Superficial Temporal Artery

Occipital Artery & Vein

Retromandibular vein Facial Artery

Facial Vein

Jugular VeinCarotid Artery

PAROTID

SUBMANDIBULAR

SUBMENTAL

CERVICAL UPPER & LOWER

LYMPH SUPPLY TO THE HEAD AND NECK – ANSWER GUIDE

NODES/DUCT/VESSEL

AREA DRAINED

Submental Nodes Drain lymph from chin

Submandibular Nodes Drain lymph from middle of cheeks

Parotid Nodes Drain lymph from sides of cheeks and forehead

Thoracic Duct Main collecting duct – collects lymph from left side of head and neck, left arm, lower limbs and abdomen.

Left Subclavian Vein Lymph from thoracic duct drains into this vein

Right Lymphatic Duct Very short in length – collects lymph from right side of head and neck and right arm

Right Subclavian Vein Lymph from right lymphatic duct drains into this vein