By:M. Thiru murugan Unit – II: The cell: Structure, reproduction and function Tissues including membranes and glands : types, structure and functions Body cavities and their contents Cell Cell is the basic Structural and functional unit Unicellular Organisms - made up of only one cell Multicellular Organisms - made up of more than one cell. Cells vary in shape & size Types of Cells: Based on cellular structure, there are two types of cells: Prokaryotes - Prokaryotic cells have no nucleus. Eukaryotes - characterized by a true nucleus. Structures of cell: It consist of 3 parts: Cell membrane outer boundary of cell Nucleus - control center Cytoplasm material between cell membrane & nucleus Cell (plasma) membrane: Cell structure that regulates passage of materials between cell & its environment; aid in protection & support of cell Cell wall – cell structure that surrounds cell membrane 2. Nucleus Nucleus - organelle that controls the cell’s activities & contains DNA Parts of nucleus: Nuclear envelope - 2 membranes that surround nucleus of a cell Nucleolus - cell structure that contains RNA & proteins; where ribosomes are made Chromosomes - threadlike structure in a cell that contains genetic information that is passed on from one generation of cells to the next Chromatin – long, tangled strands of DNA 3. Cytoplasm Cytoplasm – (jelly-like) area between nucleus & cell membrane of a cell Surrounds organelles Organelle – tiny cell structure that performs a specialized function within the cell Cell Organelle and its Functions: Nucleolus: The nucleolus is the site of ribosome synthesis. Also, it is involved in controlling cellular activities and cellular reproduction Nuclear membrane: The nuclear membrane protects the nucleus by forming a boundary between the nucleus and other cell organelles. Endoplasmic reticulum: The endoplasmic reticulum is involved in the transportation of substances throughout the cell. It plays a primary role in the metabolism of carbohydrates, synthesis of lipids, steroids and proteins. Golgi Bodies: Golgi bodies are called the cell’s post office as it is involved in the transportation of materials within the cell Ribosome: Ribosomes are the protein synthesizers of the cell Mitochondria: The mitochondrion is called “the powerhouse of the cell.” It is called so because it produces ATP – the cell’s energy Lysosomes: Lysosomes protect the cell by engulfing the foreign bodies entering the cell and helps in cell renewal. Therefore, it is known as the cell’s suicide bags Chloroplast: Chloroplasts are the primary organelles for photosynthesis. It contains the pigment chlorophyll Vacuoles: Vacuoles stores food, water, and other waste materials in the cell Reproduction Cell division: Cells need to divide for a number of reasons, including the growth of an organism and to fill gaps left by dead and destroyed cells after an injury, for instance. There are two types of cell division: Mitosis Meiosis Mitosis: Mitosis

1. By:
M. Thiru murugan
Introduction to the detailed
structure of the body

2. Unit – II:
a)The cell: Structure, reproduction and function
b)Tissues including membranes and glands : types,
structure and functions
c)Body cavities and their contents

3. Cell
• Cell is the basic Structural and functional unit
• Unicellular Organisms - made up of only one cell
• Multicellular Organisms - made up of more than one cell.
• Cells vary in shape & size
Types of Cells:
• Based on cellular structure, there are two types
of cells:
• Prokaryotes - Prokaryotic cells have no nucleus.
• Eukaryotes - characterized by a true nucleus.

4. Structures of cell:
• It consist of 3 parts:
1. Cell membrane outer boundary of cell
2. Nucleus - control center
3. Cytoplasm material between cell membrane & nucleus
1) Cell (plasma) membrane:
• Cell structure that regulates passage of materials between cell
& its environment; aid in protection & support of cell
• Cell wall – cell structure that surrounds cell membrane

5. Cell Diagram

6. 2. Nucleus
• Nucleus - organelle that controls the cell’s activities &
contains DNA
• Parts of nucleus:
• Nuclear envelope - 2 membranes that surround nucleus
of a cell
• Nucleolus - cell structure that contains RNA & proteins;
where ribosomes are made
• Chromosomes - threadlike structure in a cell that contains
genetic information that is passed on from one generation of
cells to the next
• Chromatin – long, tangled strands of DNA

7. 3. Cytoplasm
• Cytoplasm – (jelly-like) area between nucleus & cell membrane of a
cell
• Surrounds organelles
• Organelle – tiny cell structure that performs a specialized function
within the cell
Cell Organelle and its Functions:
• Nucleolus: The nucleolus is the site of ribosome synthesis. Also, it
is involved in controlling cellular activities and cellular reproduction
• Nuclear membrane: The nuclear membrane protects the nucleus
by forming a boundary between the nucleus and other cell organelles.

8. • Endoplasmic reticulum: The endoplasmic reticulum is
involved in the transportation of substances throughout
the cell. It plays a primary role in the metabolism of
carbohydrates, synthesis of lipids, steroids and proteins.
• Golgi Bodies: Golgi bodies are called the cell’s post office
as it is involved in the transportation of materials
within the cell
• Ribosome: Ribosomes are the protein synthesizers of the
cell
• Mitochondria: The mitochondrion is called “the
powerhouse of the cell.” It is called so because it
produces ATP – the cell’s energy

9. •Lysosomes: Lysosomes protect the cell by
engulfing the foreign bodies entering the cell
and helps in cell renewal. Therefore, it is known as
the cell’s suicide bags
•Chloroplast: Chloroplasts are the primary
organelles for photosynthesis. It contains the
pigment chlorophyll
•Vacuoles: Vacuoles stores food, water, and
other waste materials in the cell

10. Reproduction
•Cell division: Cells need to divide for a number of
reasons, including the growth of an organism and to fill
gaps left by dead and destroyed cells after an injury, for
instance.
•There are two types of cell division:
1. Mitosis
2. Meiosis

11. Mitosis:
• Mitosis is how most of the cells in the body divide. The “parent” cell
splits into two “daughter” cells.
• Both daughter cells have the same chromosomes as each other and the
parent.
• They are referred to as diploid because they have two complete copies of
the chromosomes.
Meiosis:
• Meiosis creates sex cells, such as the male sperm and female egg cells.
• In meiosis, a small portion of each chromosome breaks off and sticks to
another chromosome; this is called genetic recombination.
• This means that each of the new cells has a unique set of genetic
information.

12. Functions of Cell
1. Provides Support and Structure
2. Facilitate reproduction
3. Allows Transport of Substances
4. Energy Production
5. Engulf foreign bodies
6. Store water & waste
7. Controlling cellular activities
8. Synthesize protein

13. Tissues
Tissues: Group of cells
Types or classification: 4
basic tissues:
1. Epithelial tissue
2. Connective tissue
3. Muscular tissue
4. Nervous tissue

14. Classification of tissues
Epithelial tissue Connective tissue Muscular tissue Nervous tissue
A.Simple epithelium
i. Squamous
ii. Cuboidal
iii. Columnar
iv. Pseudo
stratified
B. Stratified
epithelium
1. Transitional
2. non-keratinized
3. keratinized
Cells.
1. Fibroblast/
Fibrocyte
1. Adipose
/fat cells
2. Plasma cells
3. Mast cells
4. Macrophag
es
5. Leucocyte
6. Pigment
cells
7. Mesenchy
mal cells
Fibres
i. Collagen fibres
ii. Elastic fibres
iii. Reticular fibres
i. Skeletal
muscle
ii. Smooth
muscle
iii. Cardiac
muscles
i. CNS
ii. PNS
iii. ANS

15. I. EPITHELIAL TISSUE:
•Epithelial tissue lines the external & internal
surfaces of our body.
•Function: i. Protection ii. Secretion
iii. Absorption iv. Forms glands & ducts
•Types:
1. Simple epithelium
2.Stratified epithelium

16. • Simple epithelium: A simple epithelium is an epithelial
tissue made up of only one layer of epithelial cells
• Stratified epithelium: Multilayered epithelium is known as
stratified epithelium
II. CONNECTIVE TISSUE:
• it connects different components of our body. It is made up of
cells, fibres and matrix.
• Functions:
i. Providing support to different parts of our body.
ii. Connects different components of our body.
iii. It is a medium for exchange of nutrients, metabolites and
oxygen between blood and cells.

17. III. Muscle tissue:
• There are three types of muscles namely-
a. Skeletal muscle- they help in locomotion e.g. biceps
femoris.
b. Smooth muscles- they are present in the viscera of
our body e.g. muscle in the wall of stomach.
c. Cardiac muscle- it is seen only in the heart.
Contraction of this muscle helps in pumping of blood
throughout our body.

18. IV. NERVOUS TISSUE:
•It consists of central nervous system, peripheral
nervous system and autonomic nervous system.
•It helps in sending different kinds of
information to brain and bringing its responses
back from brain to the organ.

19. Membranes
• Membranes cover surfaces, line body cavities,
and form protective sheets around organs
Types:
1. Epithelial membranes
2. Connective tissue membranes

20. 1. Epithelial membranes:
i. Cutaneous: skin – epidermis, dermis
ii. Mucous: mucous membrane or mucosa is a
membrane that lines various cavities in the
body and covers the surface of internal organs.
iii. Serous membranes: membranes lining closed
internal body cavities. The pleura, pericardium
and peritoneum are serous membranes that line
respectively the pleural, pericardial and peritoneal
cavities.

21. 2. Connective tissue membranes:
•The connective tissue membrane is formed solely
from connective tissue.
•These membranes encapsulate organs, such as
the kidneys, and line our movable joints.
•A synovial membrane is a type of connective
tissue membrane that lines the cavity of a freely
movable joint

22. Functions of body membranes
1. Line or cover body surfaces
2.Protect body surfaces
3.Lubricate body surfaces

23. Glands
Definition: A gland is an organ which produces and releases
substances that perform a specific function in the body.
Classification of glands: 2 types
• Exocrine glands produce enzymes and release through a
duct e.g. the salivary glands.
• Endocrine glands (ductless glands) produce hormones
release directly into the blood stream, e.g. thyroid gland.
• Mixed variety: some glands possess both exocrine and
endocrine function e.g. Pancreas.

24. Exocrine glands
These can be classified according to the no. of
cells:
1. Unicellular glands: example goblet cell (in GIT &
certain passages of respiratory tract).
2. Multicellular glands: are composed of many cells,
which line an epithelial invagination from free
surface.

25. Endocrine glands
Major endocrine glands are:
 Pituitary gland
 Thyroid gland
 Parathyroid glands
 Pancreas
 Adrenal glands
 Ovaries
 testes

26. Body cavities and their contents
• Body cavities A body cavity is a fluid-
filled space inside the body that
holds and protects internal organs.
Human body cavities are separated by
membranes and other structures.
• Two types of body cavities:
1. Ventral Cavity: Thoracic Cavity,
Abdominal cavity and pelvic cavity.
2. Dorsal Cavity: Cranial Cavity &
Spinal cavity.

27. Ventral Cavity:
Thoracic cavity is subdivided into pleural cavities, the mediastinum, and the
pericardial cavity
• Pleural cavities: each houses a lung
• Mediastinum: contains the pericardial cavity, and surrounds the remaining
thoracic organs
• Pericardial cavity: encloses the heart
Abdominopelvic cavity separated from the superior thoracic cavity by diaphragm
• Abdominal cavity: contains the stomach, intestines, spleen, liver, and other
organs
• Pelvic cavity: lies within the pelvis and contains the bladder, reproductive organs,
and rectum

28. Dorsal cavity
• Dorsal cavity protects the nervous system, and is
divided into two subdivisions
• Cranial cavity is within the skull and encases the
brain
• Vertebral cavity runs within the vertebral column
and encases the spinal cord

29. Other Body Cavities
•Oral and digestive – mouth and cavities of the
digestive organs
• Nasal – located within and posterior to the nose
• Orbital – house the eyes
•Middle ear – contain bones (ossicles) that transmit
sound vibrations
•Synovial – joint cavity