The lymphatic system works with the circulatory system to transport lymph, maintain fluid balance, and help fight infection. The lymphatic system is made up of lymph vessels, lymph nodes, and lymph fluid. Lymph vessels collect excess tissue fluid called interstitial fluid from between cells and return it to the bloodstream. Lymph nodes along the vessels filter out pathogens and debris. Together, the lymphatic and circulatory systems work to maintain fluid balance and transport nutrients, waste, and immune cells throughout the body.

1. 1.4
THE LYMPHATIC SYSTEM

2. Learning outcomes..
 At the end of lesson, you should be able to:
 Describe the formation interstitial fluid
 State the composition of interstitial fluid
 State the importance of interstitial fluid
 Describe the fate of interstitial fluid
 Describe the structure of the lymphatic system
 Explain how the lymphatic system complements the
circulatory system
 Compare the content of blood, interstitial fluid and lymph
 Predict what will happen if interstitial fluid fails to return to
the circulatory system
 Conceptualize the relationship between the lymphatic
system and circulatory system

3. Lymphatic system
 The three parts of the lymphatic system are:
 The lymph vessels
 The lymph nodes
 The lymph fluid
 The functions of the system are:
 Maintains fluid balance within our tissues
 Transports fat (an important nutrient) absorbed from
the intestine to the bloodstream
 Is a vital part of the immune system as it removes
microorganisms and other disease-causing
substances from body tissues.

8.  Lymph vessels begin as small closed end tubes
found in the spaces between cells within tissue.
 After the tissue fluid enters the lymph capillaries
(the smallest vessels) it is referred to as
fluid.
 Lymph capillaries merge to form larger lymph

10. Drainage area..
Right drainage area Left drainage area

11. Drainage area..
Right drainage area Left drainage area
 Drains lymph from the right  Drains lymph from the left side
side of the head and neck of the head and neck
 The right arm  The Left arm and the left upper
 Upper right quadrant of the quadrant
body.
 The lower trunk and both legs
 Lymph from this area flows
into the right lymphatic  The cisterna chyli temporarily
duct. stores lymph as it moves
 This duct empties the upward from the lower areas of
lymph into the right the body.
subclavian vein.  The thoracic duct transports
lymph upward to the left
lymphatic duct.
 The left lymphatic duct empties

12. What is going to happen to the
lymph fluid?
 Back to the blood to become plasma again.

14. Arterial end of capillaries
• High pressure  forces water & dissolved
substances out into the interstitial
spaces
• The fluid is called interstitial fluid.
Venous end of capillary
• Blood absorbs 90% ISF
• 10% of ISF passes back into blood
circulatory system as lymph via the
lymphatic system.

15. Composition of interstitial fluid
(ISF)
 Similar in composition in blood plasma
 Do not have erythrocytes, platelet and large
protein molecules.
 Consists of a water solvent containing amino
acids, sugars, fatty
acids, coenzymes, hormones, neurotransmitter
s, salts, as well as waste products from the
cells.

16. Importance of interstitial fluid
(ISF)
 It forms the internal environment of the body.
 Bathes the cells and supplies them with
oxygen and nutrients.
 Waste products such as CO2 and urea diffuse
out from the cells into interstitial fluid.
 Keep the body within normal range range
homeostatic process.

17. How the lymphatic system
complements the circulatory
system
 Lymph travels through the lymphatic vessels
by the contraction on the surrounding skeletal
muscles.
 Lymph flow in one direction.
 One end of the vessel is closed and back flow
is prevented by valves present in the larger
vessels.
 Smaller lymphatic vessels join to form larger
vessels.
 The vessels from the left side of the body, the
alimentary canal and the right side of the lower

18. Cont.
 It carries lymph to the left subclavian vein and
back to the bloodstream.
 Right lymphatic duct transport lymphs from the
right side of the head and chest into the right
subclavian vein.

19. Role of Lymphatic System in
Transport
1. Collects the ISF and returns it back to the
circulatory system
2. Lacteals:
 lymphatic capillaries in the villi of the illeum
 Absorbs fat and fat-soluble vitamins and transport
them to the blood circulatory system
3. Lymph nodes:
 Filter out bacteria and foreign particles (by
phagocytes)
4. Lymphocytes in the lymphatic tissues:
 Produce antibodies (aid destruction of pathogens
and the neutralization of toxins)

20. Comparison of the Cardiovascular and Lymphatic Systems
Cardiovascular System Lymphatic System
(Blood) (Lymph)
Blood is responsible for collecting and Lymph is responsible for collecting and
distributing oxygen, nutrients and removing waste products left behind in
hormones to the tissues of entire body. the tissues.
Blood flows in a closed continuous loop Lymph flows in an open circuit from the
throughout the body via the arteries, tissues into lymphatic vessels. Once
capillaries, and veins. within these vessels, lymph flows in
only one direction.
Blood is pumped. The heart pumps Lymph is not pumped. It passively
blood into the arteries that carry it to all flows from the tissues into the lymph
of the body. Veins return blood from all capillaries. Flow within the lymphatic
parts of the body to the heart. vessels is aided by other body
movements such as deep breathing
and the action of nearby muscles and
blood vessels.

21. Blood consists of the liquid Lymph that has been filtered and
plasma that transports the red is ready to return to the
and white blood cells and cardiovascular system is a clear
platelets. or milky white fluid.
Blood is visible and damage to Lymph is invisible and damage
blood vessels causes obvious to the lymphatic system is
signs such as bleeding or difficult to detect until swelling
bruising. occurs.
Blood is filtered by the kidneys. Lymph is filtered by lymph nodes
All blood flows through the located throughout the body.
kidneys where waste products These nodes remove some fluid
and excess fluids are removed. and debris. They also kill
Necessary fluids are returned to pathogens and some cancer
the cardiovascular circulation. cells.
Blood vessel damage or Lymphatic vessel damage or
insufficiency produces swelling insufficiency produces swelling
that containing low-protein fluid. containing protein-rich fluid.

22. Assignment 1.6
1. Compare the contents of blood and lymph.
BLOOD SIMILARITIES LYMPH
BLOOD DIFFERENCES LYMPH
Glucose
Protein molecules
Oxygen
Waste materials
Erythrocytes
Leucocytes
Platelets

23. 1.5
Role of the circulatory system in
the body’s defence mechanisms

24. Learning outcomes..
 At the end of lesson, you should be able to..
 State another function of circulatory system besides
transport
 Identify the three lines of defence mechanism of body
 Describe the process of phagocytosis
 State the meaning of antigen and antibody
 State the meaning of immunity and immunization
 Relate antigen and antibody to immunity
 Name and give examples of various Types of immunity
 State the effects of Human Immunodeficiency virus (HIV)
on the body’s defence mechanism
 Describe the transmission of HIV
 Suggest ways to prevent the spread of Acquired Immune
Deficiency Syndrome ( AIDS)

25. H1N1 viruses

26. Leishmania donovani parasites
(photo: CDC)

27. Cholera bacteria

29. Body’s defence mechanism
 Human bodies have three lines of defence
against pathogens.
 Firstline of defence (skin, mucous membrane)
 Second line of defence (phagocytes)
 Third line of defence (lymphocytes)

31. First line of defence
 Skin
 Acts as a physical barrier
 Made up of dead keratinized
layer which is difficult to
penetrate
 Sebaceous glands secrete
sebum which contain lysozymes
to destroy bacteria

32. First line of defence
 Mucous membranes
 Mucus in the nasal cavity trap dust particles and
spores
 Cilia (respiratory tract) sweep the trapped
particles to the pharynx.
 Gastric juices (in stomach) will killed
microorganisms that enter the stomach.

34. Second line of defence
 If the pathogens are able to get past the first
line of defence, for example, through a cut in
your skin, and an infection develops, the
second line of defence becomes active.
 Some WBC such as neutrophils act as
phagocytes. They are attracted by the
chemicals produced at the sites of infection.
 The phagocytes move towards the pathogens
and engulf them by phagocytosis.

38. Third line of defence
 Lymphocytes are WBC found in the lymph
nodes and in the blood circulatory system.
 Two types of lymphocytes:
 T-lymphocytes
 Attackcells infected by pathogens or
 Produce certain chemicals to coordinate immune
response
 B-lymphocytes
 Produce antibodies

39. Cont.
 Antibody – protein produced by lymphocytes
in response to the presence of an antigen.
 Antigen – foreign substance which stimulates
the body to produce an immune response
 Antibodies are specific in action and promote
the destruction of antigens in different ways.

42.  After an infection, some lymphocytes remain in
the body as memory cells.
 Memory lymphocytes help to defend the
body against further infection by the same
antigen.

44. Types of immunity
 Immunity: the ability of an organism to defend
itself against infection by pathogens.
 Types of immunity:
 Activeimmunity (natural & artificial)
 Passive immunity (natural & artificial)
 Immunisation: the process by which an
individual's immune system becomes fortified
against an agent (known as the immunogen).

45. Types of immunity
Immunity
Active
Own
antibodies
Natural
Exposure to
Artificial
infectious Immunization
agent

46. Acquired Passive Immunity
 Inherited natural immunity: inherited by
individual through the placenta or mother’s
milk.

47. Active natural immunity
 Active natural
acquired
immunity: acquired
after a person
recovers from an
infection.
 Eg; measles or
chickenpox.

48. Natural active immunity

49. Active artificial immunity
 Active artificial
acquired immunity:
 Eg; vaccine (contains
killed or weakened
antigens).
 Active because the
a/bodies produced by
the body itself
 Artificial because it is
obtained through
vaccination.
 the process is known
as immunisation.

50. Artificial active immunity

51. Passive immunity
1. Passive natural immunity: when a/bodies
from the mother transported across the
placenta to the foetus. Lasts for a few
months.
2. Passive artificial immunity: injecting serum
containing a specific a/bodies prepared from
human/animal’s blood.

52. Passive artificial immunity
 Usually used to treat
patient with serious ill.
Eg: rabies, tetanus or
snake bites
 Give temporary
immunity.

53. Difference between passive and
active immunity

54. Assignment 1.6
1. Describe the process of phagocytosis.
Drawing will help you to get marks. (10
marks)
2. Name and give examples of various types of
immunity. (10 marks)

55. Artificial passive
immunity

56. Human Immunodeficiency Virus
(HIV)
- Effects on the body’s defence mechanism
 AIDS (acquired immune deficiency syndrome) is
caused by HIV.
 HIV infects the helper T-cells (important to activate
other lymphocytes in the body’s defence
mechanisms against disease).
 Once infected, it takes a long incubation period
before the symptoms appear.
 A person’s immune system gradually decrease in
function and tend to get infected by secondary
infection such as pneumonia, meningitis and
fungal diseases.
 He/she may develop a cancer. Eg: Kaposi’s

59. Kaposi’s sarcoma

60. Transmission of HIV
There are several possible ways in which the virus
can enter.
1. Having sex with an infected partner
2. Injection-drug users who share needles or
syringes that are contaminated with blood from
an infected person.
3. Women can transmit HIV to their babies during
pregnancy or birth, when infected maternal cells
enter the baby's circulation, or through
breastfeeding.
4. HIV can be spread in health-care settings
through accidental needle sticks or contact with
contaminated fluids.

63. Transmission of HIV
5. Transfusion of contaminated blood or blood
components.
6. The virus does not spread through casual
contact such as preparing food, sharing
towels and bedding, or via swimming
pools, telephones, or toilet seats. The virus is
also unlikely to be spread by contact with
saliva, unless it is contaminated with blood.

65. Ways to prevent the spread of
AIDS
 Abstain from sex.
 Use a condom in other situations.
 Do not share needles or inject illicit drugs.
 If you work in a health-care field, follow
recommended guidelines for protecting yourself
against needle sticks and exposure to
contaminated fluids.
 If you have engaged in risky behaviors, get tested
to see if you have HIV.
 Strict screening of blood before transfusion.
 Awareness campaign and counseling.

66. Appreciating a healthy
cardiovascular system
1.6

67. Learning outcomes..
 At the end of lesson, you should be able to:
 Selectand practice suitable ways to maintain a
healthy cardiovascular system.

68. Risk factors for cardiovascular
diseases (CVD)
Cardiovascular diseases share risk factors with
other major diseases.
 Tobacco smoking
 Poor diet and nutrition
 Physical inactivity
 Overweight and obesity
 High blood pressure
 High blood cholesterol
 Diabetes
 High alcohol consumption

69. Atherosclerosis

70. How to take care of healthy
cardiovascular system?
 Follow a well-balanced diet that is low in saturated
fats, cholesterol and salt.
 Maintain a healthy weight to reduce stress on the
heart, blood vessels, and lymph vessels.
 Participate in regular aerobic exercise for at least
30 minutes three to four times per week.
 Avoid the use of tobacco products and exposure to
secondhand tobacco smoke.
 Avoid illegal drugs including stimulants, marijuana
and ecstasy.