1. CHAPTER 8 :
HUMAN HEALTH
AND
DISEASES

3. • Health:
• Health is defined as a state of complete
physical, mental and social well-being.
• When people are healthy, they are more efficient at
work. This increases productivity and brings
economic prosperity.
• Health also increases long life and reduces infant
and maternal mortality.
• The good health is maintained by balanced
diet, personal hygiene and regular exercise.

4. • The health is affected by –
1. Genetic disorders .
2. Infections.
3. Life style including Diet, rest and exercise. Drug
and alcohol abuse also affect our health adversely.
• Diseases are grouped into infectious and noninfectious.
• Diseases which are easily transmitted from one
person to another are called infectious diseases.
• Diseases which are not transmitted from one
person to another are called non infectious
diseases..
• Cancer is the non-infectious that cause death.

5. • COMMON DISEASES IN HUMANS:
• organisms belonging to
bacteria, viruses, fungi, protozoans, helminths, etc., cou
ld cause diseases in man. Such disease causing
organisms are called pathogens.
• TYPHOID:
• Pathogen: Salmonella typhi (bacterium)
• Organs affected: small intestine, migrate to other
organs through blood.
• Method of transmission: contamination of food and
water.

6. • Symptoms:
• High fever (390 to 400 C)
• Weakness, stomach pain, constipation, headache
and loss of appetite.
• Intestinal perforation may leads to death.
• Test: Typhoid fever could be confirmed by Widal
test.

7. • PNEUMONIA:
• Pathogen: Streptococcus pneumoniae and
Haemophilus influenzae.
• Organs affected: Alveoli of lungs, alveoli get filled
with fluid.

8. • Method of transmission: Inhaling the
droplets/aerosols released by infected person.
• Symptoms:
• Fever, chills, cough and headache.
• In severe cases the lips and finger nails turn gray to
bluish colour.

9. • COMMON COLD:
• Pathogen: Rhino viruses.
• Organs affected: nose and
respiratory passage
• Method of transmission:
• Direct inhalation of droplets from infected person.
• Through contaminated objects like
pen, books, cups, computer key board.

10. • Symptoms:
• Nasal congestion and discharge, sore
throat, hoarseness, cough. tiredness, etc.,
• It usually last for 3-7 days.

11. • MALARIA:
• Pathogen: Plasmodium. (P. vivax, P. malariae, P.
ovale, P. falciparum)
• Malignant malaria caused by P. falciparum is fatal.
• Organs affected: liver, RBC.
• Method of transmission: By biting of female
anopheles mosquito (vector)

12. • Symptoms: high fever and chill, fever occurs on
every alternate day, vomiting.

15. • life cycle of malaria parasite:
• The malarial parasite requires
two hosts – human and
Anopheles, to complete their
life cycle.
• Life cycle of plasmodium
starts with injecting
sporozoites through the bite
of infected female Anopheles
mosquitoes.
• The parasite initially
multiplied within the liver
cells and then attack the red
blood cells (RBCs) resulting in
their rupture.

16. • There is release of a toxic
substance called hemozoin
from the ruptured RBCs. It
is responsible for the chill
and high fever.
• From the infected human
the parasite enters into the
body of Anopheles
mosquito during biting and
sucking blood.
• Further development takes
place in the body of
Anopheles mosquitoes.

17. • The female mosquito takes
up gametocytes with the
blood meal.
• Formation of gametes and
fertilization takes place in
the intestine of mosquito.
• The zygote develops further
and forms thousands of
sporozoites.
• These sporozoites migrated
into the salivary gland of
mosquito.
• When the mosquito bite
another human sporozoites
are injected.

18. • AMOEBIASIS (Amoebic dysentery)
• Pathogen: Entamoeba histolytica a
protozoan parasite.
• Organs affected: large intestine of
man
• Method of transmission:
• House fly acts as mechanical carrier.
• Contamination water and food with
faecal matter.
• Symptoms:
• Loose motion and abdominal pain.
• Stools with excess mucous and
blood clots.

19. • ASCARIASIS:
• Pathogen: Ascaris lumbricoids
(nematode)
• Organs affected: intestine of
man
• Method of transmission:
Contaminated
water, vegetables, fruits.
• Symptoms:
• Internal bleeding, muscular
pain, fever, anemia.
• Blockage of the intestinal
passage.

20. • FILARIASIS OR ELEPHANTIASIS:
• Pathogen: Wuchereria
(W.bancrofti and W. Malayi)
(nematode parasite)
• Organs affected: lymphatic
vessels of the lower limbs, genital
organs.
• Methods of transmission: biting
of infected female culex mosquito.
• Symptoms:
• Chronic inflammation of the
organs.
• Abnormal swelling of lower
limb, scrotum, penis.
• Hence the disease named as
elephantiasis or Filariasis.

21. • RING WORMS:
• Pathogen:
Microsporum, Trichophyton and
Epidermophyton (fungi)
• Organs affected: Skin, nails, folds
of skin, groin.
• Method of transmission:
• Acquired from the soil.
• Using towel, clothes or even
comb of infected individuals.
• Symptoms:
• Appearance of dry, scaly lesions in
skin nails and scalp.
• Lesion accompanied with intense
itching.

22. • PREVENTION AND CONTROL OF INFECTIOUS DISEASES:
• Maintenance of personal and public hygiene.
• Personal hygiene includes Consumption of clean drinking
water, food vegetable fruits. Keeping the body clean.
• Public hygiene includes Proper disposal of waste and excreta
• Periodic cleaning water reservoirs, pools.
• Avoiding close contact with the infected persons.
• For vector borne diseases controlling vectors and the
breeding places.
• Avoiding stagnation of water in and around residential areas.
• Use of mosquito nets.
• Window and doors must be fitted with wire mesh.
• All these precautions are use full for vector borne disease like
dengue and Chickungunya, malaria and filarial etc.

23. Immunity:
Immunity is the ability of an organism to resist infection or to
overcome infection.
• There are two types of immunity:
1. Innate (non-specific) Immunity.
2. Acquired (specific) Immunity.
• Innate or Non-specific Immunity: It is the inborn or natural
immunity.
It is of two types,
1. Surface barrier.
2. Cellular and Biochemical barrier.
• Surface barrier: It is the first line body defense. It includes the
external barriers that checks the entry of pathogens into
body.
• It is identified as physical barrier and Physiological (chemical)
barrier.

24. Physical barrier:
The important physical barrier are skin, hair and cilia of
nasal cavity, mucous lining and muscular action.
Skin:
• The skin prevents entry
of pathogens.
• The sweat produced by
sweat gland and oil
produced by sebaceous
gland are bactericidal
and fungicidal properties.

25. • Mucus lining: The mucus lining found in respiratory
tract, digestive tract, urinary tract and reproductive
tract secretes mucus. The mucus traps the microbes
and makes them immobilize.
Physiological barriers:
Chemical secretion like lysozymes, skin secretion, saliva
and ear wax forms physiological barriers.
Lysozyme:
• It is an antibacterial enzyme present in tears, nasal
secretion, saliva, and most of the body fluids. It lyses
the bacterial cell.
Skin secretion :
• The sweat and sebum has antibacterial and antifungal
properties. It avoids the growth of bacteria and fungus
on skin.

26. Saliva:
• The saliva contains lysozyme that lyses the
bacteria.
• Gut secretion:
• The gastric juice contains dil HCl. It kills the
microbes enters through food.
• Ear wax :
• The ear wax secreted in external auditory canal is
bactericidal in nature. It repels the insects. It
traps the dust.

27. Cellular and biochemical barrier:
It is the second line body defense. It includes
1. Phagocytes
2. Natural killer cells (NK cells)
3. Interferons.
4. Inflammatory response.
• Phagocytes: The process of engulfing and destroying
the microbe by some cells is called phagocytosis.
• The cells that involves in phagocytosis are called
phagocytes.
• The neutrophils and monocytes (macrophages)
types of WBC are the important phagocytic cells.

28. Process of phagocytosis

29. • Natural killer cells (NK
Cells):
• Natural killer cells are
non-phagocytic large
lymphocytes.
• It mainly recognizes
the viral infected cells
and tumor cells.
• It destroys them by
secreting cytolysin.
Hence these are called
killer cells.

30. • Interferon:
• Interferon are the antiviral glycoprotein
produced by viral infected animal cell. It
protects the neighboring cells from viral
infection.
• It mainly stimulates neighboring cells to
synthesis a protein that interfere with viral
replication. It also activates macrophages and
NK cells to recognize infected cells.

31. Interferon:

32. • Inflammatory response: It is the localized response
to injury, infection or irritation. The symptoms are
getting redness, swelling, pain, increasing body
temp etc.
• Acquired (specific) immunity:
• It is the defense mechanism acquired by healthy
person against specific pathogens and infection. It
forms the third line body defense.
• Lymphocytes are the important components
activating specific body defense.
• The two types of lymphocytes are T- lymphocyte
and B – lymphocyte.

33. • T – lymphocytes
• The undifferentiated
lymphocytes
originate from the
stem cells of bone
marrow,
• Some of them
migrate to thymus
gland and
differentiated into Tlymphocyte. .

34. • B– lymphocytes:
• The undifferentiated
lymphocytes originate from
the stem cells of bone
marrow.
• some migrate to Bursa
equivalent and differentiated
into B-lymphocyte.
• Bursa equivalent is a
hypothesized lymphoid
tissue in bone marrow.
• (Bursa equivalent is found in
mammals, Bursa fabricius is
found in birds.)

35. • Antigen: Any foreign substance that enters our body
and stimulates immune response is called antigen.
Antigen has two properties:
• Antigenicity: It is the ability of an antigen to
generate specific immune response to produce
antibody.
• Immunogenicity.
• It is the ability of an antigen to react with specific
antibody.
• Biochemically antigens are proteins, large
polysaccharides, lipids, fatty acids or nucleic acids.
Sometimes entire pathogen acts as antigen.

36. Antibody or immunoglobin (Ig)
• The protein molecule that produced by Blymphocytes against a specific antigen is called
antibody.
• These are mainly classified in to 5 types. They
are, IgM, IgA, IgD,IgE, IgG. ( MADE-G)
• IgM is a pentamer and is a mega globulin. It is the
first reaches the injured site.
• IgA is the secretory antibody.
• IgD it binds to B - Lymphocytes and acts as a
surface receptor.
• IgE play imp role in allergy.
• IgG crosses placenta and protects foetus.

37. Structure of Antibody.
• Antibody is mainly known
as immunoglobulin. It is a
Y shaped made up of four
polypeptide chains.
• Among four chains two
are longer chains called
heavy chains.
• Two are smaller called
light chain.
• The four polypeptide
chains are held together
by di-sulphide bond.

38. • Each chain contains
constant and variable
region.
• In constant region the
amino acid sequence are
constant and same in all
antibodies.
• In variable region the
amino acid sequence
varies with different
antibodies.
• The variable region is
present at the tip of Y
arm forms antigen
binding site.

40. Role of B – lymphocytes:
• The lymphocytes produced at bone marrow
differentiates in bursa equivalent in to B –
lymphocyte.
• When the antigen enters in to the body number of B
– lymphocytes stimulated to produce antibody.
• Once the antigen specific antibody producing B –
lymphocyte activated, it multiplies rapidly to produce
number of cloned cells.
• The cloned B – lymphocytes differentiates in to
plasma cells. These cells produces specific antibody
against antigen in large quantity.
• The cloned B – lymphocyte that undifferentiated
remains as memory B cells. When the same antigen
enters again in future, memory cells response rapidly
to destroy them.

42. Cell mediated immunity ( CMI ): It is the
immunity mediated by T – lymphocytes.
Role of T – lymphocytes:
• The lymphocytes produced at bone marrow
differentiates in thymus in to T – lymphocyte. It
does not produce any antibody. It directly acts
on antigen.
• When the antigen enters in to the body, the
antigen specific T – lymphocyte stimulated and
becomes active.
• The activated T – lymphocyte multiplies rapidly
to produce number of cloned cells.

43. According to function of T – lymphocyte, these are
identified in to ,
• Killer T-cells: These T - cells recognizes specific
pathogen and destroys by lyses.
• Helper T – cells: These T – cells helps in
stimulating antigen specific B – cells to produce
antibody.
• Suppressor T – cells: These T – cells suppress the
immune response of both B and T cells, when
infection is controlled.
• Memory T – cells: These T – cells are
programmed to recognize and response to the
specific antigen that enters in future.