First line of defence

skin,mucous membrane

skin

epidermis (keratin inhibits growth of microorganisms)

dermis

sebaceous gland, sebum (inhibits growth of certain type of bacteria)

saliva and tears contains antibacterial enzymes

Second line of defence

phagocytic white blood cells

leucocytes collected in lymph nodes, thus the lymph nodes block and destroy pathogens

leucocytes such as neutrophils and monocytes act as phagocytes

Third line of defence

lymphocytes, the immune system

immune response - the produced antibodies attach themselves to pathogens and inactivate

them

T-Cells - responsible for cellular immunity

B-Cells - produce antibodies

NK-Cells - detect antigens

Immunity

Innate Acquired

Active

produce antibodies

Artificial

vaccine

to prevent diseases

BCG, polio, chicken pox

Natural

long term

chicken pox, smallpox

Passive

Given antibodies

Short term

Artificial

injection of serum

anti-tetanus

against rabies, snake venom

Natural

through mother's milk or placenta

HIV (human immunodeficiency virus)

• virus that attacks and destroy immune system

• victims may be symptom-free for many years

• victims become vulnerable to infections

• transmission

• body fluids (blood, semen, placenta)

• breastfeeding

• unprotected sex

• contaminated needles

AIDS (acquired immunodeficiency syndrome)

• end stage of infection caused by HIV

• no vaccine yet

• certain drugs can slower the progress of the disease

Clumped platelets (platelet plug is formed)

Release of thrombokinase (a.k.a. thromboplastin)

Prothrombin >thrombokinase > Thrombin

Fibrinogen > thrombin> Fibrin

•causes blood plasma to form the clot

Clot

Haemophilia

•Hereditary

•Deficiency of coagulating factors in the blood

Thrombosis

•Blood clots(thrombus) within blood vessels

•Obstructs flow of arteries

•Embolus (moving blood clot in bloodstream)

•Can cause stroke or heart attacks

interstitial fluid that has not been absorbed into bloodstream goes to the lymph capillaries

Carries leucocytes

Lymph Receives unabsorbed interstitial fluid from the spaces between the cells and returns it to the circulatory system

Lymphatic system

Blind ended tubes

Blind ended tubes

Lymphatic capillaries

One way valves to prevent backflow of the lymph

resemble veins but have thinner walls and larger lumen and more valves

Lymphatic vessels

produce and store lymphocyte

protect body from infections

Lymph nodes

Connected to lymphatic vessels from the areas below the diaphragm and from the left half of the body

Empties into the subclavian vein

Thoracic duct

Connected to lymphatic vessel from right half of the body above the diaphragm

Empties into the right subclavian vein

Right lymphatic

duct

Fluid Blood Interstitial fluid Lymph

Red blood cells ✓ ✗ ✗

Platelets ✓ ✗ ✗

White blood cells ✓ ✓ ✓

Proteins (albumin, globulins, etc.)

✓ ✓ ✓

Other solutes ✓ ✓ ✓

Importance of blood clotting

Prevent serious blood loss

Prevent the entry of microorganisms and foreign

particles

Maintain blood pressure

Maintain circulation of blood in a closed circulatory

system

Related diseases

The Lymphatic System

The importance of the lymphatic system

Maintain the fluid balance in the body

Excessive accumulation of interstitial fluid – Oedema

(probably caused by blocked lymphatic vessels)

Lacteal – lymph capillaries which transport droplets of

lipids and fat-soluble vitamins the bloodstream

The SA node generates impulses in both atria

Contraction of atria Blood pressure in atria

increase

Blood is pumped into the ventricles (deoxygenated blood to right ventricle, oxygenated blood to left

ventricle)

AV node is stimulated The Purkinje fibres

conduct electrical impulses to the heart

The ventricles contract Blood pressure in both

ventricles increase

Blood is pumped out of the heart (deoxygenated

blood to lungs via pulmonary artery,

oxygenated blood to whole body via aorta)

Increase in blood pressure

More impulses are sent to cardiovascular control centre in the

medulla oblongata

Impulses sent to heart via parasympathetic nerves

Result in weaker cardiac muscle contractions and vasodilation

(widening of blood vessels)

Heartbeat slows down

Blood pressure decreases to normal level

Decrease in blood pressure

Less impulses are sent to cardiovascular control centre in the

medulla oblongata

Sympathetic nerve increases stimulation of the SA node

Result in stronger cardiac muscles contractions and vasoconstriction

(narrowing of blood vessels)

Increase the heartbeat rate

Blood pressure increases to normal level

Blood pressure Decreases Increases

Baroreceptors Less stimulated More stimulated

Nerve impulses sent to the cardiovascular centre

Decreased rate Increased rate

Nerve impulses sent to the effectors

Via sympathetic nerves Via parasympathetic nerves

Cardiac muscle contractions and heartbeat rate

Stronger, increase Weaker, decrease

Blood vessels Narrows (vasoconstriction) Widen (vasodilation)

Blood pressure Increases to normal level Decreases to normal level

The heart generates rhythmic impulses - heart muscles relax and contract

Cardiac muscle is myogenic – it is self-excitable

Two nodes that create electrical impulses in the heart:

Sino-atrial (SA) node - cardiac pacemaker

Atrioventricular (AV) node

Impulses of AV node are conducted by specialized muscle fibres (bundle of His and Purkinje fibres) to the

ventricular walls

Thick muscular wall of left ventricle is strong enough to create a pumping force throughout the body

Average heart rate – 72 heartbeats/min

The negative feedback regulation of blood pressure

Cardiac Cycle

a series of events that occur during one complete heartbeat which includes the contraction(systole) and relaxation(diastole) of both atria and ventricles

Diastole (contraction) of heart

Lowest arterial blood pressure

Systole (relaxation) of heart

Highest arterial blood pressure

Organisms Insects Fish Amphibians Humans

Type of circulatory system

Open Closed Single

Closed Double

Closed Double

Heart Contraction Haemolymph flows from heart to haemocoel Heart Relaxation Haemolymph is draw back to heart through ostia(pore)

Gill capillaries to systemic capillaries

Pulmocutaneous circulation and systemic circulation

Pulmonary circulation Deoxygenated blood -> Oxygenated blood Systemic circulation Oxygenated blood -> Deoxygenated blood

Separation of oxygenated blood and deoxygenated blood

Incomplete Complete

Number of chambers in heart

A single blood vessel forms the heart Two Three Four

Structure • Made of myocardium (cardiac muscle fibers)

• Consists of four chambers

• Consists of tricuspid valve and bicuspid valve (prevent back flow of blood from ventricles to atria)

• Consists of semilunar valves (aortic valve and pulmonary valve) to prevent back flow of blood from arteries (aorta and pulmonary artery) to ventricles

• the wall of left ventricle is thicker than the wall of right ventricle

Functions • The heart functions as a muscular pump. Its rhythmic contractions pump

oxygenated blood into various tissues of the body.

● Water 90% ● Ions (minerals) ● Plasma proteins (albumin, globulin, fibrinogen, antibodies) ● Hormones ● Dissolved substances (nutrients, waste product, respiratory gases)

Function Blood vessels

Blood Heart

Transport System of Human

Circulatory System

● Delivers nutrients and oxygen to cells

● Carries waste products away from cells

● Protects body from infection

• Have nucleus

• Do not have haemoglobin

• Types: granulocytes and agranulocytes

• Granulocytes (granular cytoplasm, lobed nuclei): nuetrophils, basophils, eosinophils

• Agranulocytes (relatively clear cytoplasm, nuclei not lobed): lymphocytes, monocytes)

• Produced in bone marrow

Leukocytes

• No nucleus

• Have haemoglobin (red colour)

• Biconcave disc shaped (increases cell's surface)

• Facilitates diffusion of O2 and CO2

• Produced in bone marrow

• Destroyed by phagocytes in liver and spleen

Erythrocytes

• Small, irregular fragments of large cells in bone marrow

• Responsible for blood clotting Platelets

● Carries oxygenated blood (except pulmonary artery)

● Carries blood away from heart to various body parts

● Carries deoxygenated blood (except pulmonary vein)

● Carries blood back to heart from various body parts

Connects arterioles and veins

Transport medium in animals. Its flow is

regulated by the rhythmic contractions

and relaxations of the heart.